Oscillator

Abstract

To provide an oscillator that can detect a failure in a plurality of temperature sensors.SOLUTION: An oscillator comprises: a vibration element; an oscillation circuit that oscillates the vibration element; a temperature control element that controls the temperature of the vibration element; a plurality of temperature sensors; a failure detection circuit; and a container that accommodates the vibration element, the oscillation circuit, the temperature control element, the plurality of temperature sensors, and the failure detection circuit. The failure detection circuit detects a failure in the plurality of temperature sensors and the temperature control element on the basis of output values from the plurality of temperature sensors in a state where the temperature control element is in operation.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an oscillator.

Background Art

[0002] Patent Document 1 describes an oscillator that monitors whether abnormal heat generation occurs in a temperature control element by two temperature sensors, and when abnormal heat generation occurs in the temperature control element, disables the operation of the temperature control circuit to prevent abnormal heat generation in the temperature control element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the oscillator described in Patent Document 1, abnormal heat generation in the temperature control element is prevented for safety purposes. However, in a high - precision oscillator that performs temperature control and temperature compensation using multiple temperature sensors to achieve high frequency accuracy, when any one of the multiple temperature sensors fails, the frequency accuracy decreases. Therefore, it is desirable to be able to detect failures of multiple temperature sensors.

Means for Solving the Problems

[0005] One aspect of the oscillator according to the present invention is a vibration element, an oscillation circuit that oscillates the vibration element, a temperature control element that controls the temperature of the vibration element, a plurality of temperature sensors, a failure detection circuit, and a container that houses the vibration element, the oscillation circuit, the temperature control element, the plurality of temperature sensors, and the failure detection circuit. The failure detection circuit performs failure detection of the plurality of temperature sensors and the temperature control element based on output values of the plurality of temperature sensors in a state where the temperature control element is operating.

Brief Description of the Drawings

[0006]

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Embodiments for Carrying Out the Invention

[0007] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention described in the claims. Also, not all of the configurations described below are essential constituent elements of the present invention.

[0008] 1. First Embodiment 1-1. Structure of the Oscillator FIG. 1 is a cross-sectional view showing the oscillator of the present embodiment. FIG. 2 is a plan view of the oscillator as viewed from the upper surface side. FIG. 3 is a cross-sectional view showing the inner package of the oscillator and its interior. FIG. 4 is a cross-sectional view showing the vibrator of the oscillator.

[0009] The oscillator 1 shown in FIGS. 1 and 2 is a thermostatic crystal oscillator, and includes an outer package 2, an inner package 3, a control IC 4, and a vibrator 5. The inner package 3, the control IC 4, and the vibrator 5 are housed in the outer package 2.

[0010] As shown in FIG. 1, the outer package 2 has an outer base 21 and an outer lid 22. The outer base 21 has a substrate 27, a frame-shaped wall portion 28 standing upright upward from the edge of the upper surface of the substrate 27, and a frame-shaped leg portion 29 standing upright downward from the edge of the lower surface of the substrate 27. An upper recess 211 that opens to the upper surface 21a of the outer base 21 is formed by the upper surface of the substrate 27 and the wall portion 28, and a lower recess 212 that opens to the lower surface 21b of the outer base 21 is formed by the lower surface of the substrate 27 and the leg portion 29. Therefore, the outer base 21 has a substantially H shape in cross-sectional view.

[0011] The upper recess 211 has a first upper recess 211a that opens to the upper surface 21a, a second upper recess 211b that opens to the bottom surface of the first upper recess 211a and has a smaller opening than the first upper recess 211a, and a third upper recess 211c that opens to the bottom surface of the second upper recess 211b and has a smaller opening than the second upper recess 211b. The control IC 4 is disposed on the bottom surface of the first upper recess 211a, and the inner package 3 is disposed on the bottom surface of the third upper recess 211c.

[0012] The outer lid 22 closes the opening of the upper recess 211 and is joined to the upper surface 21a of the outer base 21 via a sealing member 23 such as a seal ring or a low melting point glass. Thereby, the upper recess 211 is hermetically sealed, and an outer accommodation space S2 as an accommodation space is formed inside the outer package 2. On the other hand, the opening of the lower recess 212 is not sealed and faces the outside of the outer package 2. The inner package 3 and the control IC 4 are accommodated in the outer accommodation space S2, and the vibrator 5 is disposed in the lower recess 212.

[0013] A plurality of internal terminals 241 disposed on the bottom surface of the first upper recess 211a, a plurality of internal terminals 242 disposed on the bottom surface of the second upper recess 211b, a plurality of internal terminals 243 disposed on the bottom surface of the lower recess 212, and a plurality of external terminals 244 disposed on the lower surface 21b, that is, the top surface of the leg portion 29, are disposed on the outer base 21. Each internal terminal 241 is electrically connected to the control IC 4 via a bonding wire BW1, each internal terminal 242 is electrically connected to the inner package 3 via a bonding wire BW2, and each internal terminal 243 is electrically connected to the vibrator 5 via a conductive joining member B1.

[0014] Each of these terminals 241, 242, 243, and 244 is appropriately electrically connected via internal wiring 25 formed within the outer base 21, electrically connecting the control IC 4, the inner package 3, the oscillator 5, and the external terminal 244. The internal wiring 25 is connected to the external terminal 244 through the inside of the leg portion 29. And the connection with an external device (not shown) is made at the external terminal 244. A side terminal 245 connected to the external terminal 244 is arranged on the side surface of the leg portion 29. The side terminal 245 is a castellation. Therefore, the solder H spreads over the side terminal 245 to form a fillet, making the mechanical and electrical bonding with the external device stronger. However, it is not limited to this, and for example, the side terminal 245 may be omitted.

[0015] As shown in FIG. 3, the inner package 3 has an inner base 31 and an inner lid 32. The inner base 31 has a recess 311 that opens to the lower surface 31b.

[0016] The recess 311 has a first recess 311a that opens to the lower surface 31b, a second recess 311b that opens to the bottom surface of the first recess 311a and has a smaller opening than the first recess 311a, and a third recess 311c that opens to the bottom surface of the second recess 311b and has a smaller opening than the second recess 311b. And a vibration element 6 is arranged on the bottom surface of the first recess 311a, and the heat-generating IC 7 and the oscillation IC 8 are arranged side by side in the X-axis direction on the bottom surface of the third recess 311c.

[0017] The inner lid 32 is joined to the lower surface 31b of the inner base 31 via a sealing member 33 such as a seal ring or a low-melting-point glass so as to close the opening of the recess 311. Thereby, the recess 311 is hermetically sealed, and an inner accommodation space S3 is formed within the inner package 3. And the vibration element 6, the heat-generating IC 7, and the oscillation IC 8 are accommodated in the inner accommodation space S3.

[0018] Such an inner accommodation space S3 is airtight and in a decompressed state, preferably a state closer to a vacuum. This reduces the viscous resistance of the inner accommodation space S3 and improves the vibration characteristics of the vibration element 6. However, the atmosphere in the inner accommodation space S3 is not particularly limited.

[0019] On the inner base 31, a plurality of internal terminals 341 arranged on the bottom surface of the first recess 311a, a plurality of internal terminals 342 and 343 arranged on the bottom surface of the second recess 311b, and a plurality of external terminals 344 arranged on the upper surface 31a of the inner base 31 are arranged. Each internal terminal 341 is electrically connected to the vibration element 6 via a conductive bonding member B2 and a bonding wire BW3, each internal terminal 342 is electrically connected to the heat-generating IC7 via a bonding wire BW4, and each internal terminal 343 is electrically connected to the oscillation IC8 via a bonding wire BW5.

[0020] These terminals 341, 342, 343, and 344 are appropriately electrically connected via internal wirings (not shown) formed in the inner package 3, electrically connecting the vibration element 6, the heat-generating IC7, the oscillation IC8, and the external terminal 344. In such an inner package 3, the inside and outside are electrically connected via the external terminal 344.

[0021] The inner package 3 as described above is fixed to the bottom surface of the third upper recess 211c via a bonding member B3 having a sufficiently low thermal conductivity in the inner lid 32.

[0022] As shown in FIG. 3, the heat-generating IC7 is arranged on the bottom surface of the third recess 311c with the active surface facing downward (toward the inner lid 32 side) and is electrically connected to a plurality of internal terminals 342 via a bonding wire BW4. The oscillation IC8 is arranged on the bottom surface of the third recess 311c with the active surface facing downward (toward the inner lid 32 side) and is electrically connected to a plurality of internal terminals 343 via a bonding wire BW5.

[0023] As shown in FIG. 4, the vibrator 5 has a package 51 and a vibration element 55 housed in the package 51.

[0024] The package 51 has a base 52 and a lid 53. The base 52 has a recess 521 that opens to the lower surface 52b. And the vibration element 55 is disposed on the bottom surface of the recess 521.

[0025] The lid 53 is joined to the lower surface 52b of the base 52 via a sealing member 54 such as a seal ring or a low-melting-point glass so as to close the opening of the recess 521. Thereby, the recess 521 is hermetically sealed, and an accommodation space S5 is formed in the package 51. And the vibration element 55 is accommodated in the accommodation space S5. The accommodation space S5 is airtight and is in a depressurized state, preferably a state closer to a vacuum state. Thereby, the viscous resistance of the accommodation space S5 is reduced, and the vibration characteristics of the vibration element 55 are improved. However, the atmosphere of the accommodation space S5 is not particularly limited.

[0026] A plurality of internal terminals 561 disposed on the bottom surface of the recess 521 and a plurality of external terminals 564 disposed on the upper surface 52a of the base 52 are disposed on the base 52. Each internal terminal 561 is electrically connected to the vibration element 55 via a conductive joining member B4. These terminals 561 and 564 are electrically connected as appropriate via internal wirings (not shown) formed in the base 52, and electrically connect the vibration element 55 and the external terminal 564. In such a package 51, the inside and outside are electrically connected via the external terminal 564.

[0027] The vibration element 55 is an AT-cut crystal vibration element. However, the vibration element 55 does not have to be an AT-cut crystal vibration element, and for example, an SC-cut crystal vibration element, a BT-cut crystal vibration element, a tuning fork type crystal vibration element, a surface acoustic wave resonator, other piezoelectric vibration elements, MEMS resonator elements, etc. may be used.

[0028] As shown in Fig. 4, the vibrator 5 is fixed to the bottom surface of the lower recess 212 via a conductive joint member B1. Also, the external terminal 564 and the internal terminal 243 are electrically connected via the joint member B1.

[0029] 1-2. Functional Configuration of the Oscillator Fig. 5 is a functional block diagram of the oscillator 1 of the first embodiment. In Fig. 5, the same components as those shown in Figs. 1 to 4 are denoted by the same reference numerals. As shown in Fig. 5, the oscillator 1 of the first embodiment includes a control IC 4, a vibrator 5, a vibration element 6, a heat generating IC 7, and an oscillation IC 8.

[0030] The oscillation IC 8 includes an oscillation circuit 81 and a temperature sensor 82, and operates with a power supply voltage VOSC supplied from the control IC 4. The oscillation circuit 81 is electrically connected to both ends of the vibration element 6, and is a circuit that amplifies the output signal of the vibration element 6 and feeds it back to the vibration element 6 to oscillate the vibration element 6 and output an oscillation signal OSCO. For example, the oscillation circuit 81 may be an oscillation circuit using an inverter as an amplification element, or may be an oscillation circuit using a bipolar transistor as an amplification element. The oscillation signal OSCO output from the oscillation circuit 81 is input to the control IC 4.

[0031] The temperature sensor 82 is a temperature sensing element that detects temperature and outputs a temperature detection signal TS1 having a voltage level corresponding to the detected temperature. The temperature sensor 82 is built in the oscillation IC 8 and detects the temperature of the oscillation IC 8. Since the oscillation circuit 81 is also built in the oscillation IC 8, the temperature sensor 82 detects the temperature of the oscillation circuit 81. The temperature detection signal TS1 output from the temperature sensor 82 is input to the control IC 4. The temperature sensor 82 may be, for example, a sensor that utilizes the temperature dependence of the forward voltage of the PN junction of a diode.

[0032] The heating IC 7 includes a temperature control element 71 and a temperature sensor 72. The temperature control element 71 is an element that controls the temperature of the vibration element 6 based on the temperature control signal OVC output from the control IC 4, and may be a heating element. For example, the temperature control element 71 is a CMOS transistor, and the amount of heat generated changes according to the voltage of the temperature control signal OVC input to the gate. The higher the amount of heat generated by the temperature control element 71, the higher the temperature of the vibration element 6. The control IC 4 controls the amount of heat generated by the temperature control element 71 so that the temperature of the vibration element 6 becomes constant at the target set temperature. For example, the set temperature may be a fixed value such as 80°C, or may be arbitrarily set within a predetermined range such as a range of 70°C to 125°C.

[0033] The temperature sensor 72 is a temperature-sensitive element that detects temperature and outputs a temperature detection signal TS2 having a voltage level corresponding to the detected temperature. The temperature sensor 72 is built into the heating IC 7 and detects the temperature of the heating IC 7. Since the heating IC 7 also incorporates the temperature control element 71, the temperature sensor 72 detects the temperature of the temperature control element 71. The temperature detection signal TS2 output from the temperature sensor 72 is input to the control IC 4. The temperature sensor 72 may be, for example, a sensor that utilizes the temperature dependence of the forward voltage of the PN junction of a diode.

[0034] As shown in FIG. 3, the vibration element 6, the heating IC 7, and the oscillation IC 8 are housed in the inner package 3, and the heat generation of the heating IC 7 is controlled by the control IC 4 so that the temperature of the vibration element 6 is kept constant. Since the heating IC 7 is a heat source and the radiant heat from the heating IC 7 is transmitted to the vibration element 6 and the oscillation IC 8, a difference occurs between the temperatures of the vibration element 6 and the oscillation IC 8 and the temperature of the heating IC 7. On the other hand, the vibration element 6 and the oscillation IC 8 are arranged separately from the heating IC 7, and if it is considered that the thermal distance between the heating IC 7 and the vibration element 6 is substantially the same as the thermal distance between the heating IC 7 and the oscillation IC 8, it can be said that the temperature of the oscillation IC 8 is close to the temperature of the vibration element 6. That is, the temperature detected by the temperature sensor 82 built in the oscillation IC 8 is closer to the temperature of the vibration element 6 than the temperature detected by the temperature sensor 72 built in the heating IC 7. Therefore, as will be described later, the control IC 4 controls the heat generation of the heating IC 7 based on the temperature detection signal TS1 output from the temperature sensor 82. However, depending on the arrangement of the vibration element 6, the heating IC 7, and the oscillation IC 8, there may be a case where the temperature of the heating IC 7 is closer to the temperature of the vibration element 6 than the temperature of the oscillation IC 8. In that case, the control IC 4 may control the heat generation of the heating IC 7 based on the temperature detection signal TS2 output from the temperature sensor 72.

[0035] The control IC 4 includes a microcontroller 40, a selector 41, a temperature sensor 42, an A / D conversion circuit 43, a D / A conversion circuit 44, a fractional N-PLL circuit 45, a PLL circuit 46, a switch circuit 47, a power supply circuit 48, an interface circuit 49, a memory 90, and a register 94. PLL is the abbreviation of Phase Locked Loop.

[0036] Based on the power supply voltage VDD and the ground voltage VSS supplied from the outside of the oscillator 1, the power supply circuit 48 generates a power supply voltage VOSC which is a constant voltage lower than the power supply voltage VDD. For example, the power supply circuit 48 generates a power supply voltage VOSC which is a constant voltage based on the output voltage of the bandgap reference circuit. The power supply voltage VOSC is supplied to the oscillation IC 8.

[0037] The fractional-N PLL circuit 45 receives the oscillation signal OSCO output from the oscillation IC 8, and converts the frequency f of the oscillation signal OSCO into a frequency f OSCO according to the division ratio indicated by the division ratio control signal DIVC, and generates and outputs a clock signal CK1. The fractional-N PLL circuit 45 performs feedback control so that the phase of the oscillation signal OSCO matches the phase of the signal obtained by dividing the clock signal CK1 by the division ratio specified by the division ratio control signal DIVC, thereby generating the clock signal CK1. The division ratio control signal DIVC is delta-sigma modulated, and the division ratio specified by the division ratio control signal DIVC switches between a plurality of integer division ratios and becomes a fractional division ratio when averaged. Therefore, the frequency f CK1 is a non-integer multiple of the frequency f CK1 The fractional-N PLL circuit 45 may output a clock signal CK1 having a frequency f OSCO which is different from f and is substantially constant regardless of the outside air temperature. OSCO and outputs a clock signal CK1 having a frequency f CK1 which is different from f and is substantially constant regardless of the outside air temperature.

[0038] The PLL circuit 46 receives the clock signal CK1 output from the fractional-N PLL circuit 45, and generates and outputs a clock signal CK2 having the same frequency f as the frequency f CK1 of the clock signal CK1. The PLL circuit 46 generates the clock signal CK2 by performing feedback control on the oscillation frequency of the oscillator 5 so that the phase of the clock signal CK1 matches the phase of the clock signal CK2 based on the signal output from the oscillator 5. CK2 The PLL circuit 46 generates the clock signal CK2 by performing feedback control on the oscillation frequency of the oscillator 5 so that the phase of the clock signal CK1 matches the phase of the clock signal CK2 based on the signal output from the oscillator 5.

[0039] The clock signal CK1 output from the fractional-N PLL circuit 45 has a large jitter because its frequency f CK1 is a non-integer multiple of the frequency f of the oscillation signal OSCO OSCO In contrast, the clock signal CK2 output from the PLL circuit 46 has a frequency f CK2 which is the same as the frequency f of the clock signal CK1 CK1Since it is the same as [the above] and the oscillator 5 with high frequency stability is oscillated and generated, the jitter is smaller than that of the clock signal CK1.

[0040] The switch circuit 47 outputs a clock signal CK that selects either the clock signal CK1 or the clock signal CK2 according to the logic level of the switch control signal SWC output from the register 94. The clock signal CK is output to the outside of the oscillator 1. The clock signal CK may be supplied to the external device 100 or may be supplied to a device different from the external device 100. For example, during the normal operation of the oscillator 1, the clock signal CK2 with small jitter may be selected as the clock signal CK, and the clock signal CK1 may be selected as the clock signal CK during the inspection of the clock signal CK1.

[0041] The temperature sensor 42 is a temperature-sensitive element that detects the temperature and outputs a temperature detection signal TS3 having a voltage level corresponding to the detected temperature. The temperature sensor 42 is built into the control IC4 and detects the temperature of the control IC4. As shown in FIG. 1, the control IC4 is arranged at a location close to the outer lid 22, the distance between the vibrating element 6 and the temperature sensor 42 is larger than the distance between the vibrating element 6 and the temperature sensor 82 included in the oscillation IC8, and the temperature of the control IC4 is easily affected by the temperature of the outside air of the oscillator 1. Therefore, assuming that the heat generation amount of the control IC4 is substantially constant, the temperature sensor 42 can detect the temperature change of the outside air of the oscillator 1. The temperature detection signal TS2 output from the temperature sensor 72 is input to the control IC4. The temperature sensor 72 may be, for example, a sensor that utilizes the temperature dependence of the forward voltage of the PN junction of a diode.

[0042] Selector 41 selects and outputs any one of the temperature detection signal TS1 output from the oscillation IC8, the temperature detection signal TS2 output from the heat generating IC7, the temperature detection signal TS3 output from the temperature sensor 42, and the test voltage VIN output from the test voltage generation circuit 60. In the present embodiment, selector 41 selects the temperature detection signals TS1, TS2, and TS3 in a time-division manner and outputs them periodically. Also, as will be described later, when the self-test of the A / D conversion circuit 43 is executed, selector 41 selects and outputs the test voltage VIN.

[0043] The A / D conversion circuit 43 converts the voltages of the temperature detection signals TS1, TS2, and TS3, which are analog signals output from selector 41 in a time-division manner, and the test voltage VIN into temperature codes DTS1, DTS2, and DTS3 and a test code DVIN, which are digital signals, respectively. The A / D conversion circuit 43 may convert the temperature detection signals TS1, TS2, and TS3 and the test voltage VIN into the temperature codes DTS1, DTS2, and DTS3 and the test code DVIN after converting the voltage levels by means of resistor voltage division or the like.

[0044] The microcontroller 40 includes a CPU 10 and a memory 15. The CPU is an abbreviation for Central Processing Unit. The non-volatile memory 90 stores temperature control data 91 and temperature compensation data 92, which are transferred to the memory 15 when the oscillator 1 is started. Also, the non-volatile memory 90 stores a temperature control program, a temperature compensation program, and a failure detection program (not shown), which are transferred to the memory 15 when the oscillator 1 is started.

[0045] By executing the temperature control program transferred to the memory 15, the CPU 10 functions as the temperature control circuit 11. The temperature control circuit 11 controls the operation of the temperature control element 71 built into the heat-generating IC 7. Specifically, the temperature control circuit 11 outputs a temperature control code DOVC for controlling the heat generation amount of the temperature control element 71 based on the temperature code DTS1 and the stored temperature control data 91 transferred to the memory 15. For example, the temperature control data 91 may include information on the set temperature that is the target temperature of the vibration element 6 and information on the gain for controlling the heat generation amount of the temperature control element 71. Alternatively, when the set temperature that is the target temperature of the vibration element 6 varies depending on the outside air temperature, the temperature control data 91 may include information indicating the relationship between the temperature code DTS3 and the set temperature. In this case, the temperature control circuit 11 outputs the temperature control code DOVC based on the temperature codes DTS1, DTS3 and the temperature control data 91.

[0046] By executing the temperature compensation program transferred to the memory 15, the CPU 10 functions as the temperature compensation circuit 12. The temperature compensation circuit 12 temperature-compensates the frequency of the oscillation signal OSCO generated when the oscillation circuit 81 built into the oscillation IC 8 oscillates the vibration element 6. Specifically, the temperature compensation circuit 12 outputs a division ratio control signal DIVC for causing the fractional N-PLL circuit 45 to output a clock signal CK1 with a constant frequency regardless of temperature based on the temperature code DTS3 and the temperature compensation data 92 transferred to the memory 15. For example, the temperature compensation data 92 may be table information indicating the relationship between the temperature code DTS3 and the frequency of the oscillation signal OSCO, or may be information on the coefficient values of each order of the mathematical formula indicating the relationship. Alternatively, the temperature compensation data 92 may be information indicating the relationship between the temperature code DTS3 and the value of the fractional division ratio of the fractional N-PLL circuit 45 calculated from the relationship between the temperature code DTS3 and the frequency of the oscillation signal OSCO.

[0047] The CPU 10 functions as a failure detection circuit 13 by executing a failure detection program transferred to the memory 15. The failure detection circuit 13 performs failure detection of a plurality of temperature sensors 82, 72, 42 and the temperature control element 71 based on the output values of the plurality of temperature sensors 82, 72, 42 in a state where the temperature control element 71 is operating. Further, the failure detection circuit 13 performs a self-test of the A / D conversion circuit 43 if necessary according to the result of the failure detection. When performing the self-test of the A / D conversion circuit 43, the failure detection circuit 13 causes the test voltage generation circuit 60 to output a test voltage VIN. The test voltage VIN is a predetermined voltage determined in advance, and may be, for example, a voltage equal to the reference voltage of the A / D conversion circuit 43. The failure detection circuit 13 performs failure detection of the A / D conversion circuit 43 based on the test code DVIN obtained by converting the test voltage VIN by the A / D conversion circuit 43. Details of the processing of the failure detection circuit 13 will be described later.

[0048] The D / A conversion circuit 44 converts a temperature control code DOVC, which is a digital signal output from the temperature control circuit 11, into a temperature control signal OVC, which is an analog signal. The temperature control signal OVC is supplied to the temperature control element 71 of the heating IC 7.

[0049] The interface circuit 49 is a circuit for performing data communication between the external device 100 connected to the oscillator 1. Specifically, the interface circuit 49 writes and reads data to and from the memory 90, the register 94, or the memory 15 of the microcontroller 40 in response to a request from the external device 100. The interface circuit 49 may be, for example, an interface circuit corresponding to the I 2 C bus, or an interface circuit corresponding to the SPI bus. I 2 C is an abbreviation for Inter-Integrated Circuit. Also, SPI is an abbreviation for Serial Peripheral Interface.

[0050] In the inspection process during the manufacture of the oscillator 1, the inspection device, which is the external device 100, may set a switch control signal SWC for selecting the clock signal CK1 to the switch circuit 47 via the interface circuit 49 and inspect the clock signal CK1. Further, the inspection device, which is the external device 100, writes temperature control data 91 and temperature compensation data 92 into the memory 90 via the interface circuit 49, and further writes a temperature control program and a temperature compensation program. Note that the temperature control data 91 and the temperature compensation data 92 may be set by the external device 100 in the register 94 when the oscillator 1 is started up.

[0051] 1-3. Processing of the Fault Detection Circuit When the oscillator 1 starts up, the temperature control element 71 starts to operate, and due to the heat generation of the temperature control element 71, the internal temperature of the oscillator 1 rises with the passage of time. Since the internal temperature of the oscillator 1 rises as the temperature of the temperature control element 71 rises, the output values of the plurality of temperature sensors 82, 72, 42 also rise. Then, when the temperature of the temperature control element 71 stabilizes, the internal temperature of the oscillator 1 stabilizes, and the output values of the temperature sensors 82, 72, 42 also stabilize. In the present embodiment, the fault detection circuit 13 determines whether the output values of the temperature sensors 82, 72, 42 are within the normal range, and based on the determination result, performs fault detection of the temperature sensors 82, 72, 42 and the temperature control element 71. The normal range of each output value of the temperature sensors 82, 72, 42 may be, for example, the range between the upper limit and the lower limit of each output value of the temperature sensors 82, 72, 42 assumed when the outside air temperature changes within the temperature range in which the operation of the oscillator 1 guaranteed by the specifications is ensured.

[0052] As described above, the A / D conversion circuit 43 A / D-converts each of the output values of the plurality of temperature sensors 82, 72, 42 to generate temperature codes DTS1, DTS2, DTS3 which are a plurality of temperature data. Therefore, as the temperature of the temperature control element 71 rises, the values of the temperature codes DTS1, DTS2, DTS3 rise, and when the temperature of the temperature control element 71 stabilizes, the values of the temperature codes DTS1, DTS2, DTS3 also stabilize.

[0053] After the values of the temperature codes DTS1, DTS2, and DTS3 have stabilized, if the temperature sensors 82, 72, and 42 are normal, the value of the temperature code DTS1 is included in the normal range P1, if the temperature sensor 72 is normal, the value of the temperature code DTS2 is included in the normal range P2, and if the temperature sensor 42 is normal, the value of the temperature code DTS3 is included in the normal range P3. Therefore, after a predetermined time longer than the time when the output values of the temperature sensors 82, 72, and 42 are expected to stabilize has elapsed after the temperature control element 71 starts operating, the failure detection circuit 13 can determine whether the temperature sensors 82, 72, and 42 are normal or faulty based on whether the values of the temperature codes DTS1, DTS2, and DTS3 are within the normal ranges P1, P2, and P3, respectively. After starting the determination, the failure detection circuit 13 may repeat the determination at the cycle in which the temperature codes DTS1, DTS2, and DTS3 are updated, or may repeat the determination at a predetermined cycle determined in advance.

[0054] For example, as shown in FIG. 6, when the temperature codes DTS1, DTS2, and DTS3 are within the normal ranges P1, P2, and P3, respectively, the failure detection circuit 13 determines that all of the temperature sensors 82, 72, and 42 are normal.

[0055] Also, as shown in FIG. 7, when the temperature codes DTS2 and DTS3 are within the normal ranges P2 and P3, respectively, and the temperature code DTS1 is outside the normal range P1, the failure detection circuit 13 determines that the temperature sensors 72 and 42 are normal and the temperature sensor 82 is faulty. Generally speaking, when the value of the temperature code corresponding to the output value of at least one temperature sensor among the plurality of temperature sensors 82, 72, and 42 is normal and the values of the temperature codes corresponding to the output values of the other temperature sensors are abnormal, the failure detection circuit 13 determines that the other temperature sensors are faulty.

[0056] Also, as shown in FIG. 8, when the temperature codes DTS1, DTS2, and DTS3 are outside the normal ranges P1, P2, and P3 respectively, it is unlikely that the temperature sensors 82, 72, and 42 have all failed simultaneously, and it is highly likely that either the temperature control element 71 or the A / D conversion circuit 43 has failed. Therefore, when all of the plurality of temperature codes DTS1, DTS2, and DTS3 are outside the normal range, the failure detection circuit 13 determines that either the temperature control element 71 or the A / D conversion circuit 43 has failed. Specifically, when all of the temperature codes DTS1, DTS2, and DTS3 are outside the normal ranges P1, P2, and P3, the failure detection circuit 13 performs a self-test of the A / D conversion circuit 43, and determines which of the temperature control element 71 and the A / D conversion circuit 43 has failed based on the result of the self-test. That is, the failure detection circuit 13 causes the test voltage generation circuit 60 to output a test voltage VIN, and if the test code DVIN obtained by converting the test voltage VIN by the A / D conversion circuit 43 is within the normal range, it determines that the temperature control element 71 has failed, and if the test code DVIN is outside the normal range, it determines that the A / D conversion circuit 43 has failed.

[0057] FIG. 9 is a diagram showing an example of the procedure of the process of the failure detection circuit 13 in the first embodiment. As shown in FIG. 9, in step S1, when the temperature control element 71 is turned on and starts operating, in step S2, the failure detection circuit 13 waits until a predetermined time elapses. This predetermined time is set to be longer than the time expected for the output values of the temperature sensors 82, 72, and 42 to stabilize after the temperature control element 71 starts operating.

[0058] In step S2, when the predetermined time has elapsed, in step S3, the failure detection circuit 13 determines whether all of the temperature codes DTS1, DTS2, and DTS3 are within the normal range. Then, in step S3, if all of the temperature codes DTS1, DTS2, and DTS3 are within the normal range, in step S4, the failure detection circuit 13 determines that all of the temperature sensors 82, 72, and 42 are normal.

[0059] On the one hand, in step S3, if at least one of the temperature codes DTS1, DTS2, and DTS3 is outside the normal range, then in step S5, the failure detection circuit 13 determines whether all of the temperature codes DTS1, DTS2, and DTS3 are outside the normal range.

[0060] In step S5, if at least one of the temperature codes DTS1, DTS2, and DTS3 is within the normal range, then in step S10, if the temperature code DTS1 is outside the normal range, in step S11, the failure detection circuit 13 determines that the temperature sensor 82 is faulty. Also, in step S12, if the temperature code DTS2 is outside the normal range, in step S13, the failure detection circuit 13 determines that the temperature sensor 72 is faulty. Also, if the temperature code DTS2 is within the normal range, in step S14, if the temperature code DTS3 is outside the normal range, in step S15, the failure detection circuit 13 determines that the temperature sensor 42 is faulty. Also, the failure detection circuit 13 determines that the temperature sensors among 82, 72, and 42 that are not determined to be faulty are normal.

[0061] On the other hand, in step S5, if all of the temperature codes DTS1, DTS2, and DTS3 are outside the normal range, then in step S6, the failure detection circuit 13 executes a self-test of the A / D conversion circuit 43.

[0062] In step S7, if the self-test passes, then in step S8, the failure detection circuit 13 determines that the temperature control element 71 is faulty. On the one hand, in step S7, if the self-test fails, then in step S9, the failure detection circuit 13 determines that the A / D conversion circuit 43 is faulty.

[0063] Then, in step S16, every time the temperature codes DTS1, DTS2, and DTS3 are updated, the failure detection circuit 13 repeats the processing after step S3.

[0064] Note that the outer package 2 is an example of a "container". Also, the temperature sensor 82 is an example of a "first temperature sensor". Further, the temperature sensor 72 is an example of a "second temperature sensor". Additionally, the temperature sensor 42 is an example of a "third temperature sensor".

[0065] 1-4. Operational effects As described above, according to the oscillator 1 of the first embodiment, in the control IC 4, when the temperature control element 71 is operating, due to the positional relationship between the temperature control element 71 and the temperature sensors 82, 72, 42, a difference occurs in the output values of the temperature sensors 82, 72, 42, and the failure detection circuit 13 can detect the failures of the temperature sensors 82, 72, 42 and the temperature control element 71 based on the output values of the temperature sensors 82, 72, 42. In the oscillator 1 having the structure shown in FIGS. 1 to 4, when the temperature control element 71 is operating, among the temperature sensors 82, 72, 42, the difference between the temperature detected by the temperature sensor 72 and the temperature of the temperature control element 71 is the smallest, the difference between the temperature detected by the temperature sensor 82 and the temperature of the temperature control element 71 is the second smallest, and the difference between the temperature detected by the temperature sensor 42, which is the farthest from the temperature control element 71, and the temperature of the temperature control element 71 is the largest. Therefore, the failure detection circuit 13 can detect the failures of the temperature sensors 82, 72, 42 based on the output values of the temperature sensors 82, 72, 42. Specifically, if the temperature sensors 82, 72, 42 are each normal, then when the temperature control element 71 is operating, the temperature codes DTS1, DTS2, DTS3 will each be within different normal ranges of values from each other. Thus, the failure detection circuit 13 can determine whether the temperature codes DTS1, DTS2, DTS3 are within the normal ranges respectively, and detect the failures of the temperature sensors 82, 72, 42 based on the determination results.

[0066] Also, according to the oscillator 1 of the first embodiment, since the probability that all of the temperature sensors 82, 72, and 42 fail simultaneously is extremely low, when all of the temperature codes DTS1, DTS2, and DTS3 are outside the normal range, the failure detection circuit 13 can determine that the temperature control element 71 or the A / D conversion circuit 43 has failed. Specifically, when all of the temperature codes DTS1, DTS2, and DTS3 are outside the normal range, the failure detection circuit 13 executes a self-test of the A / D conversion circuit 43. If the self-test passes, it can be determined that the temperature control element 71 has failed; if the self-test fails, it can be determined that the A / D conversion circuit 43 has failed.

[0067] 2. Second Embodiment Hereinafter, for the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the same descriptions as those in the first embodiment are omitted or simplified, and mainly the contents different from those in the first embodiment will be described.

[0068] Since the structure of the oscillator 1 of the second embodiment is the same as that in FIGS. 1 to 4, the illustration and description thereof are omitted. Also, since the functional block diagram of the oscillator 1 of the second embodiment is the same as that in FIG. 5, the illustration and description thereof are omitted. However, in the second embodiment, the processing of the failure detection circuit 13 is different from that in the first embodiment.

[0069] When the oscillator 1 starts up, the temperature control element 71 starts to operate, and due to the heat generation of the temperature control element 71, the internal temperature of the oscillator 1 rises over time. Since the internal temperature of the oscillator 1 rises as the temperature of the temperature control element 71 rises, the output values of the plurality of temperature sensors 82, 72, and 42 also rise. Then, when the temperature of the temperature control element 71 stabilizes, the internal temperature of the oscillator 1 stabilizes, and the output values of the temperature sensors 82, 72, and 42 also stabilize. In this embodiment, the failure detection circuit 13 performs failure detection of the temperature sensors 82, 72, and 42 and the temperature control element 71 based on the change amounts of the output values of the plurality of temperature sensors 82, 72, and 42 during a predetermined period included in the period from when the temperature control element 71 starts to operate until the temperature of the temperature control element 71 stabilizes.

[0070] For example, the failure detection circuit 13 determines whether the amount of change in the output value of each of the temperature sensors 82, 72, and 42 within the predetermined period is within the normal range, and based on the determination result, may perform failure detection on the temperature sensors 82, 72, and 42 and the temperature control element 71. The normal range of the amount of change in the output value of each of the temperature sensors 82, 72, and 42 may be, for example, the range between the upper limit and the lower limit of the amount of change in the output value of each of the temperature sensors 82, 72, and 42 within a predetermined period assumed when the outside air temperature changes within the temperature range in which the operation of the oscillator 1 determined by the specification is guaranteed.

[0071] As described above, the A / D conversion circuit 43 A / D-converts each of the output values of the plurality of temperature sensors 82, 72, and 42 to generate temperature codes DTS1, DTS2, and DTS3 which are a plurality of temperature data. Therefore, as the temperature of the temperature control element 71 rises, the values of the temperature codes DTS1, DTS2, and DTS3 increase, and when the temperature of the temperature control element 71 stabilizes, the values of the temperature codes DTS1, DTS2, and DTS3 also stabilize.

[0072] If the temperature sensor 82 is normal, the amount of change ΔDTS1 in the value of the temperature code DTS1 within a predetermined period included in the period until the values of the temperature codes DTS1, DTS2, and DTS3 stabilize is within the normal range. If the temperature sensor 72 is normal, the amount of change ΔDTS2 in the value of the temperature code DTS2 within the predetermined period is within the normal range. If the temperature sensor 42 is normal, the amount of change ΔDTS3 in the value of the temperature code DTS3 within the predetermined period is within the normal range. Therefore, the failure detection circuit 13 can determine whether the temperature sensors 82, 72, and 42 are normal or faulty based on whether the amounts of change ΔDTS1, ΔDTS2, and ΔDTS3 in the values of the temperature codes DTS1, DTS2, and DTS3 within the predetermined period are respectively within the normal range.

[0073] For example, as shown in FIG. 10, when the amounts of change ΔDTS1, ΔDTS2, and ΔDTS3 are respectively within the normal range, the failure detection circuit 13 determines that all of the temperature sensors 82, 72, and 42 are normal.

[0074] Also, as shown in FIG. 11, when the change amounts ΔDTS2 and ΔDTS3 are within the normal ranges respectively and the change amount ΔDTS1 is outside the normal range, the failure detection circuit 13 determines that the temperature sensors 72 and 42 are normal and the temperature sensor 82 has failed. Generally speaking, when the value of the temperature code corresponding to the output value of at least one temperature sensor among the plurality of temperature sensors 82, 72, and 42 is normal and the values of the temperature codes corresponding to the output values of the other temperature sensors are abnormal, the failure detection circuit 13 determines that the other temperature sensors have failed.

[0075] Also, as shown in FIG. 12, when the change amounts ΔDTS1, ΔDTS2, and ΔDTS3 are all outside the normal ranges, it is unlikely that the temperature sensors 82, 72, and 42 have failed simultaneously, and it is highly likely that either the temperature control element 71 or the A / D conversion circuit 43 has failed. Therefore, when all of the plurality of temperature codes DTS1, DTS2, and DTS3 are outside the normal ranges, the failure detection circuit 13 determines that either the temperature control element 71 or the A / D conversion circuit 43 has failed. Specifically, when all of the temperature codes DTS1, DTS2, and DTS3 are outside the normal ranges, the failure detection circuit 13 performs a self-test on the A / D conversion circuit 43 and determines which of the temperature control element 71 and the A / D conversion circuit 43 has failed based on the result of the self-test. That is, the failure detection circuit 13 causes the test voltage generation circuit 60 to output a test voltage VIN. If the test code DVIN obtained by converting the test voltage VIN by the A / D conversion circuit 43 is within the normal range, the failure detection circuit 13 determines that the temperature control element 71 has failed. If the test code DVIN is outside the normal range, the failure detection circuit 13 determines that the A / D conversion circuit 43 has failed.

[0076] FIG. 13 is a diagram showing an example of the procedure of the processing of the failure detection circuit 13 in the second embodiment. As shown in FIG. 13, in step S21, when the temperature control element 71 is turned on and starts operating, in step S22, the failure detection circuit 13 waits until a predetermined time elapses. When the predetermined time elapses in step S22, in step S23, the failure detection circuit 13 acquires the temperature codes DTS1, DTS2, and DTS3. The point in time when this predetermined time elapses is the start point of the aforementioned predetermined period.

[0077] Then, in step S24, the failure detection circuit 13 waits until a predetermined time elapses. When the predetermined time elapses in step S24, in step S25, the failure detection circuit 13 acquires the temperature codes DTS1, DTS2, and DTS3. The point in time when this predetermined time elapses is the end point of the aforementioned predetermined period.

[0078] In step S26, the failure detection circuit 13 calculates the change amounts ΔDTS1, ΔDTS2, and ΔDTS3 of the respective values of the temperature codes DTS1, DTS2, and DTS3 during the predetermined period. Specifically, the failure detection circuit 13 calculates, as the change amounts ΔDTS1, ΔDTS2, and ΔDTS3, the differences between the respective values of the temperature codes DTS1, DTS2, and DTS3 acquired in step S25 and the respective values of the temperature codes DTS1, DTS2, and DTS3 acquired in step S23.

[0079] In step S27, the failure detection circuit 13 determines whether or not all of the change amounts ΔDTS1, ΔDTS2, and ΔDTS3 are within the normal range. And in step S27, if all of the change amounts ΔDTS1, ΔDTS2, and ΔDTS3 are within the normal range, in step S28, the failure detection circuit 13 determines that all of the temperature sensors 82, 72, and 42 are normal.

[0080] On the other hand, in step S27, if at least one of the change amounts ΔDTS1, ΔDTS2, and ΔDTS3 is outside the normal range, in step S29, the failure detection circuit 13 determines whether or not all of the change amounts ΔDTS1, ΔDTS2, and ΔDTS3 are outside the normal range.

[0081] In step S29, if at least one of the change amounts ΔDTS1, ΔDTS2, and ΔDTS3 is within the normal range, in step S34, if the change amount ΔDTS1 is outside the normal range, in step S35, the failure detection circuit 13 determines that the temperature sensor 82 has failed. Also, in step S36, if the change amount ΔDTS2 is outside the normal range, in step S37, the failure detection circuit 13 determines that the temperature sensor 72 has failed. Also, in step S38, if the change amount ΔDTS3 is outside the normal range, in step S39, the failure detection circuit 13 determines that the temperature sensor 42 has failed. Also, the failure detection circuit 13 determines that the temperature sensors among the temperature sensors 82, 72, and 42 that are not determined to have failed are normal.

[0082] On the other hand, in step S29, if all of the change amounts ΔDTS1, ΔDTS2, and ΔDTS3 are outside the normal range, in step S30, the failure detection circuit 13 executes a self-test of the A / D conversion circuit 43.

[0083] In step S31, if the self-test passes, in step S32, the failure detection circuit 13 determines that the temperature control element 71 has failed. On the other hand, in step S31, if the self-test fails, in step S33, the failure detection circuit 13 determines that the A / D conversion circuit 43 has failed.

[0084] According to the oscillator 1 of the second embodiment described above, the same effects as those of the oscillator 1 of the first embodiment are achieved.

[0085] Also, in the oscillator 1 of the second embodiment, in the control IC 4, if the temperature sensors 82, 72, and 42 are each normal, during a predetermined period included in the period from when the temperature control element 71 starts operating until the temperature of the temperature control element 71 stabilizes, the change amounts ΔDTS1, ΔDTS2, and ΔDTS3 of the temperature codes DTS1, DTS2, and DTS3 are each within the normal range. Therefore, the failure detection circuit 13 can detect failures of the temperature sensors 82, 72, and 42 based on the change amounts ΔDTS1, ΔDTS2, and ΔDTS3.

[0086] 3. Third Embodiment Hereinafter, for the third embodiment, the same components as those in the first or second embodiment are denoted by the same reference numerals, and the same explanations as those in the first or second embodiment are omitted or simplified, and mainly the contents different from those in the first and second embodiments will be described.

[0087] Since the structure of the oscillator 1 in the third embodiment is the same as that in FIGS. 1 to 4, the illustration and description thereof are omitted. Also, since the functional block diagram of the oscillator 1 in the third embodiment is the same as that in FIG. 5, the illustration and description thereof are omitted. However, in the third embodiment, the processing of the failure detection circuit 13 is different from that in the first and second embodiments.

[0088] In the first embodiment, when the temperature of the temperature control element 71 is stable, the failure detection circuit 13 determines whether the output values of the temperature sensors 82, 72, 42 are within the normal range, and when all the output values are within the normal range, it determines that the temperature sensors 82, 72, 42 are normal. Also, in the second embodiment, the failure detection circuit 13 determines whether the change amounts of the output values of the temperature sensors 82, 72, 42 within a predetermined period included in the period until the temperature of the temperature control element 71 stabilizes are within the normal range, and when all the change amounts are within the normal range, it determines that the temperature sensors 82, 72, 42 are normal.

[0089] However, even if all the output values or change amounts of the temperature sensors 82, 72, 42 are within the normal range, if the magnitude relationship thereof is not as expected, the operation of the oscillator 1 is as described above. Therefore, in this embodiment, the failure detection circuit 13 detects an abnormal state of the oscillator 1 based on the magnitude relationship of the output values of the plurality of temperature sensors 82, 72, 42. Specifically, the failure detection circuit 13 detects an abnormal state of the oscillator 1 based on the magnitude relationship of the temperature codes DTS1, DTS2, DTS3 obtained by converting the output values of the temperature sensors 82, 72, 42 by the A / D conversion circuit 43, respectively.

[0090] As is clear from FIGS. 1 to 5, the distance between the temperature sensor 72 and the temperature control element 71 is smaller than the distance between the temperature sensor 82 and the temperature control element 71 and the distance between the temperature sensor 42 and the temperature control element 71. Also, the distance between the temperature sensor 42 and the temperature control element 71 is larger than the distance between the temperature sensor 82 and the temperature control element 71 and the distance between the temperature sensor 72 and the temperature control element 71. That is, among the temperature sensors 82, 72, and 42, the temperature sensor 72 is arranged at the position closest to the temperature control element 71 which is the heat source, and the temperature sensor 42 is arranged at the position farthest from the temperature control element 71. Therefore, normally, "the value of temperature code DTS2 > the value of temperature code DTS1 > the value of temperature code DTS3" holds. Thus, when the values of the temperature codes DTS1, DTS2, and DTS3 do not satisfy this magnitude relationship, the failure detection circuit 13 can determine that the oscillator 1 is abnormal.

[0091] For example, in the example shown in FIG. 14, since the temperature codes DTS1, DTS2, and DTS3 are respectively within the normal ranges P1, P2, and P3 and "the value of temperature code DTS2 > the value of temperature code DTS1 > the value of temperature code DTS3", the failure detection circuit 13 determines that all of the temperature sensors 82, 72, and 42 are normal.

[0092] On the other hand, in the example shown in FIG. 15, although the temperature codes DTS1, DTS2, and DTS3 are respectively within the normal ranges P1, P2, and P3, since "the value of temperature code DTS2 > the value of temperature code DTS1 > the value of temperature code DTS3" does not hold, the failure detection circuit 13 determines that the oscillator 1 is abnormal. Examples of the abnormality of the oscillator 1 include defects related to the heat insulation property of the inner package 3 and the temperature of the outside air of the oscillator 1 becoming equal to or higher than the internal temperature of the inner package 3.

[0093] FIG. 16 is a diagram showing an example of the processing procedure of the failure detection circuit 13 in the third embodiment. In FIG. 16, the same steps as those in FIG. 9 are denoted by the same reference numerals. As shown in FIG. 16, in step S1, when the temperature control element 71 is turned on and starts operating, in step S2, the failure detection circuit 13 waits until a predetermined time elapses.

[0094] In step S2, when a predetermined time has elapsed, in step S3, the failure detection circuit 13 determines whether all of the temperature codes DTS1, DTS2, and DTS3 are within the normal range. Then, in step S3, if all of the temperature codes DTS1, DTS2, and DTS3 are within the normal range, in step S17, the failure detection circuit 13 determines whether "the value of temperature code DTS2 > the value of temperature code DTS1 > the value of temperature code DTS3".

[0095] In step S17, if "the value of temperature code DTS2 > the value of temperature code DTS1 > the value of temperature code DTS3", in step S4, the failure detection circuit 13 determines that all of the temperature sensors 82, 72, and 42 are normal. Also, in step S17, if "the value of temperature code DTS2 > the value of temperature code DTS1 > the value of temperature code DTS3" does not hold, in step S18, the failure detection circuit 13 determines that there is an abnormality in the oscillator 1.

[0096] The processing of the other steps in FIG. 16 is the same as the corresponding steps in FIG. 9, so the description thereof is omitted.

[0097] FIG. 17 is a diagram showing another example of the processing procedure of the failure detection circuit 13 in the third embodiment. In FIG. 17, the same steps as those in FIG. 13 are denoted by the same reference numerals. As shown in FIG. 17, in step S21, when the temperature control element 71 is turned on and starts operating, in step S22, the failure detection circuit 13 waits until a predetermined time has elapsed. In step S22, when the predetermined time has elapsed, in step S23, the failure detection circuit 13 acquires the temperature codes DTS1, DTS2, and DTS3.

[0098] Then, in step S24, the failure detection circuit 13 waits until a predetermined time has elapsed. In step S24, when the predetermined time has elapsed, in step S25, the failure detection circuit 13 acquires the temperature codes DTS1, DTS2, and DTS3.

[0099] In step S26, the failure detection circuit 13 calculates the amounts of change ΔDTS1, ΔDTS2, and ΔDTS3 of the values of the temperature codes DTS1, DTS2, and DTS3 over a predetermined period. Specifically, the failure detection circuit 13 calculates, as the amounts of change ΔDTS1, ΔDTS2, and ΔDTS3, the differences between the values of the temperature codes DTS1, DTS2, and DTS3 acquired in step S25 and the values of the temperature codes DTS1, DTS2, and DTS3 acquired in step S23, respectively.

[0100] In step S27, the failure detection circuit 13 determines whether all of the amounts of change ΔDTS1, ΔDTS2, and ΔDTS3 are within the normal range. And in step S27, if all of the amounts of change ΔDTS1, ΔDTS2, and ΔDTS3 are within the normal range, then in step S40, the failure detection circuit 13 determines whether "the value of temperature code DTS2 > the value of temperature code DTS1 > the value of temperature code DTS3".

[0101] In step S40, if "the value of temperature code DTS2 > the value of temperature code DTS1 > the value of temperature code DTS3", then in step S28, the failure detection circuit 13 determines that all of the temperature sensors 82, 72, and 42 are normal. Also, in step S41, if "the value of temperature code DTS2 > the value of temperature code DTS1 > the value of temperature code DTS3" does not hold, then in step S41, the failure detection circuit 13 determines that there is an abnormality in the oscillator 1.

[0102] Since the processing of each of the other steps in FIG. 17 is the same as the corresponding steps in FIG. 13, the description thereof is omitted.

[0103] According to the oscillator 1 of the third embodiment described above, the same effects as those of the oscillator 1 of the first embodiment or the second embodiment are achieved.

[0104] Also, in the oscillator 1 of the third embodiment, in the control IC 4, when the temperature control element 71 is operating, a predetermined magnitude relationship occurs among the temperature codes DTS1, DTS2, and DTS3 due to the positional relationship between the temperature control element 71 and the temperature sensors 82, 72, and 42. Therefore, the failure detection circuit 13 can detect an abnormal state of the oscillator 1 based on the magnitude relationship of the temperature codes DTS1, DTS2, and DTS3.

[0105] 4. Modification The present invention is not limited to this embodiment, and various modifications can be made within the scope of the gist of the present invention.

[0106] In each of the above embodiments, the oscillator 1 includes three temperature sensors 82, 72, and 42, and the failure detection circuit 13 performs failure detection based on the output values of the three temperature sensors 82, 72, and 42. However, the number of temperature sensors is not limited to three, and may be two or four or more.

[0107] Also, in each of the above embodiments, the temperature control element 71 and the temperature sensor 72 are incorporated in the heat generating IC 7, but the temperature control element 71 and the temperature sensor 72 may be provided separately. Also, in the above embodiment, the temperature sensor 82 is incorporated in the oscillation IC 8, but the temperature sensor 82 and the oscillation IC 8 may be provided separately. Also, in each of the above embodiments, the temperature sensor 42 is incorporated in the control IC 4, but the temperature sensor 42 and the control IC 4 may be provided separately. In these cases, for example, the temperature sensors 72, 82, and 42 may be thermistors or platinum resistors.

[0108] Also, in each of the above embodiments, the control IC4 includes one temperature sensor 42, but it may include a plurality of temperature sensors. In this case, for example, the A / D conversion circuit 43 converts a plurality of temperature detection signals output from the plurality of temperature sensors into a plurality of temperature codes, and the microcontroller 40 may perform temperature control and temperature compensation based on the plurality of temperature codes. For example, the microcontroller 40 may perform temperature control and temperature compensation using the average value of the plurality of temperature codes as the temperature code DTS3.

[0109] Also, in each of the above embodiments, temperature compensation is performed by controlling the division ratio of the fractional N-PLL circuit 45 based on the division ratio control signal DIVC output by the microcontroller 40, but the temperature compensation method is not limited to this. For example, the oscillation circuit 81 built in the oscillation IC8 has a capacitor array, and temperature compensation may be performed by selecting the capacitance value of the capacitor array based on the temperature compensation code DCMP calculated by the microcontroller 40. Also, for example, the oscillation circuit 81 has a variable capacitance element for adjusting the frequency, and the D / A conversion circuit converts the temperature compensation code DCMP calculated by the microcontroller 40 into an analog signal, and temperature compensation may be performed by controlling the capacitance value of the variable capacitance element based on the analog signal.

[0110] Also, in each of the above embodiments, one A / D conversion circuit 43 converts the voltages of the temperature detection signals TS1, TS2, TS3 and the test voltage VIN into the temperature codes DTS1, DTS2, DTS3 and the test code DVIN in a time-division manner. However, for example, the control IC4 may include a plurality of A / D conversion circuits, and the plurality of A / D conversion circuits may convert the voltages of the temperature detection signals TS1, TS2, TS3 and the test voltage VIN into the temperature codes DTS1, DTS2, DTS3 and the test code DVIN respectively.

[0111] Also, in each of the above embodiments, the temperature control element 71 is a heat-generating element such as a CMOS transistor. However, the temperature control element 71 may be any element that can control the temperature of the vibration element 6. Depending on the relationship between the set temperature that is the target temperature of the temperature of the vibration element 6 and the outside air temperature, it may be a heat-absorbing element such as a Peltier element.

[0112] The above-described embodiments and modifications are examples and are not necessarily limited thereto. For example, it is also possible to appropriately combine each embodiment and each modification.

[0113] The present invention includes configurations that are substantially the same as the configurations described in the embodiments, for example, configurations having the same functions, methods, and results, or configurations having the same objectives and effects. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that exhibit the same operational effects as the configurations described in the embodiments or configurations that can achieve the same objectives. The present invention also includes configurations in which known techniques are added to the configurations described in the embodiments.

[0114] The following content is derived from the above-described embodiments and modifications.

[0115] One aspect of the oscillator is a vibration element, an oscillation circuit that oscillates the vibration element, a temperature control element that controls the temperature of the vibration element, a plurality of temperature sensors, a failure detection circuit, and a container that houses the vibration element, the oscillation circuit, the temperature control element, the plurality of temperature sensors, and the failure detection circuit, The failure detection circuit performs failure detection of the plurality of temperature sensors and the temperature control element based on output values of the plurality of temperature sensors in a state where the temperature control element is operating.

[0116] According to this oscillator, when the temperature control element is operating, a difference occurs in the output values of the plurality of temperature sensors due to the positional relationship between the temperature control element and the plurality of temperature sensors, and the failure detection circuit can detect the failures of the plurality of temperature sensors based on the output values of the plurality of temperature sensors.

[0117] In one aspect of the oscillator, The failure detection circuit may determine whether the output values of the plurality of temperature sensors are within a normal range, and perform the failure detection based on the determination result.

[0118] In this oscillator, if the plurality of temperature sensors are each normal, then when the temperature control element is operating, the output values of the plurality of temperature sensors are each within the normal range. Therefore, according to this oscillator, the failure detection circuit can determine whether the output values of the plurality of temperature sensors are each within the normal range, and detect the failures of the plurality of temperature sensors based on the determination result.

[0119] In one aspect of the oscillator, The failure detection circuit may perform the failure detection based on the amount of change in the output values of the plurality of temperature sensors during a predetermined period included in the period from when the temperature control element starts operating until the temperature of the temperature control element stabilizes.

[0120] In this oscillator, if the plurality of temperature sensors are each normal, then during a predetermined period included in the period from when the temperature control element starts operating until the temperature of the temperature control element stabilizes, the amount of change in the output values of the plurality of temperature sensors is each within the normal range. Therefore, according to this oscillator, the failure detection circuit can detect the failures of the plurality of temperature sensors based on the amount of change in the output values of the plurality of temperature sensors during the said predetermined period.

[0121] One aspect of the oscillator is It may include an A / D conversion circuit that A / D converts each of the output values of the plurality of temperature sensors to generate a plurality of temperature data.

[0122] In one aspect of the oscillator, the fault detection circuit, when the value of the temperature data corresponding to the output value of at least one of the plurality of temperature sensors is normal and the values of the temperature data corresponding to the output values of the other temperature sensors are abnormal, determines that the other temperature sensors are faulty, when all of the plurality of temperature data are outside the normal range, may determine that the temperature control element or the A / D conversion circuit is faulty.

[0123] According to this oscillator, since the possibility that all of the plurality of temperature sensors fail simultaneously is extremely small, when all of the plurality of temperature data are outside the normal range, the fault detection circuit can determine that the temperature control element or the A / D conversion circuit is faulty.

[0124] In one aspect of the oscillator, when all of the temperature data are outside the normal range, the fault detection circuit performs a self-test of the A / D conversion circuit and determines which of the temperature control element and the A / D conversion circuit is faulty based on the result of the self-test.

[0125] In this oscillator, when all of the plurality of temperature data are outside the normal range, if the self-test of the A / D conversion circuit fails, the A / D conversion circuit is faulty, and if the self-test of the A / D conversion circuit passes, it is considered that the temperature control element is faulty. Therefore, according to this oscillator, the fault detection circuit can determine which of the temperature control element and the A / D conversion circuit is faulty.

[0126] In one aspect of the oscillator, the fault detection circuit may detect an abnormal state of the oscillator based on the magnitude relationship of the output values of the plurality of temperature sensors.

[0127] In this oscillator, when the temperature control element is operating, a difference occurs in the output values of the plurality of temperature sensors due to the positional relationship between the temperature control element and the plurality of temperature sensors, and a predetermined magnitude relationship occurs in the output values of the plurality of temperature sensors. Therefore, according to this oscillator, the failure detection circuit can detect the abnormal state of the oscillator based on the magnitude relationship of the output values of the plurality of temperature sensors.

[0128] In one aspect of the oscillator, the plurality of temperature sensors include a first temperature sensor, a second temperature sensor, and a third temperature sensor, the first temperature sensor detects the temperature of the oscillation circuit, the second temperature sensor detects the temperature of the temperature control element, the distance between the third temperature sensor and the temperature control element may be greater than the distance between the first temperature sensor and the temperature control element and the distance between the second temperature sensor and the temperature control element.

[0129] In this oscillator, when the temperature control element is operating, among the first temperature sensor, the second temperature sensor, and the third temperature sensor, the difference between the temperature detected by the second temperature sensor and the temperature of the temperature control element is the smallest, the difference between the temperature detected by the first temperature sensor and the temperature of the temperature control element is the second smallest, and the difference between the temperature detected by the third temperature sensor, which is the farthest from the temperature control element, and the temperature of the temperature control element is the largest. Therefore, according to this oscillator, the failure detection circuit can detect the failures of the first temperature sensor, the second temperature sensor, and the third temperature sensor based on the output values of the first temperature sensor, the second temperature sensor, and the third temperature sensor.

[0130] In one aspect of the oscillator, the temperature control element may be a heating element.

Description of Reference Numerals

[0131] 1... Oscillator, 2... Outer package, 3... Inner package, 4... Control IC, 5... Vibrator, 6... Vibration element, 7... Heat-generating IC, 8... Oscillation IC, 10... CPU, 11... Temperature control circuit, 12... Temperature compensation circuit, 13... Fault detection circuit, 14... Filter circuit, 15... Memory, 21... Outer base, 21a... Upper surface, 21b... Lower surface, 22... Outer lid, 23... Sealing member, 25... Internal wiring, 27... Substrate, 28... Wall portion, 29... Leg portion, 31... Inner base, 31a... Upper surface, 31b... Lower surface, 32... Inner lid, 33... Sealing member, 40... Microcontroller, 41... Selector, 42... Temperature sensor, 43... A / D conversion circuit, 44... D / A conversion circuit, 45... Fractional N-PLL circuit, 46... PLL circuit, 47... Switch circuit, 48... Power supply circuit, 49... Interface circuit, 51... Package, 52... Base, 52a... Upper surface, 52b... Lower surface, 53... Lid, 54... Sealing member, 55... Vibration element, 60... Test voltage generation circuit, 71... Temperature control element, 72... Temperature sensor, 81... Oscillation circuit, 82... Temperature sensor, 90... Memory, 91... Temperature control data, 92... Temperature compensation data, 94... Register, 100... External device, 211... Upper recess, 211a... First upper recess, 211b... Second upper recess, 211c... Third upper recess, 212... Lower recess, 241... Internal terminal, 242... Internal terminal, 243... Internal terminal, 244... External terminal, 245... Side terminal, 311... Recess, 311a... First recess, 311b... Second recess, 311c... Third recess, 341... Internal terminal, 342... Internal terminal, 343... Internal terminal, 344... External terminal, 521... Recess, 561... Internal terminal, 564... External terminal, B1... Bonding member, B2... Bonding member, B3... Bonding member, B4... Bonding member, BW1... Bonding wire, BW2... Bonding wire, BW3... Bonding wire, BW4... Bonding wire, BW5... Bonding wire, H... Solder, S2... Outer accommodation space, S3... Inner accommodation space, S5... Accommodation space

Claims

1. An oscillator element, an oscillation circuit for oscillating the oscillator element, a temperature control element for controlling the temperature of the oscillator element, a plurality of temperature sensors, a fault detection circuit, and a container for housing the oscillator element, the oscillation circuit, the temperature control element, the plurality of temperature sensors, and the fault detection circuit, wherein the fault detection circuit detects faults in the plurality of temperature sensors and the temperature control element based on output values of the plurality of temperature sensors in a state where the temperature control element is operating.

2. In Claim 1, the fault detection circuit determines whether output values of the plurality of temperature sensors are within a normal range, and performs the fault detection based on the determination result.

3. In Claim 1, the fault detection circuit performs the fault detection based on a change amount of output values of the plurality of temperature sensors in a predetermined period included in a period from when the temperature control element starts operating until the temperature of the temperature control element stabilizes.

4. In any one of Claims 1 to 3, the oscillator includes an A / D conversion circuit that A / D-converts each of the output values of the plurality of temperature sensors to generate a plurality of temperature data.

5. In Claim 4, the fault detection circuit when, among the plurality of temperature sensors, the value of the temperature data corresponding to the output value of at least one of the temperature sensors is normal and the values of the temperature data corresponding to the output values of the other temperature sensors are abnormal, determines that the other temperature sensors are faulty, and when all of the plurality of temperature data are outside the normal range, determines that the temperature control element or the A / D conversion circuit is faulty.

6. In Claim 5, when all of the temperature data are outside the normal range, the fault detection circuit performs a self-test of the A / D conversion circuit, and determines which of the temperature control element and the A / D conversion circuit is faulty based on the result of the self-test.

7. In Claim 1, the fault detection circuit detects an abnormal state of the oscillator based on a magnitude relationship of output values of the plurality of temperature sensors.

8. In Claim 1, the plurality of temperature sensors include a first temperature sensor, a second temperature sensor, and a third temperature sensor, the first temperature sensor detects the temperature of the oscillation circuit, The second temperature sensor detects the temperature of the temperature control element, The distance between the third temperature sensor and the temperature control element is greater than the distance between the first temperature sensor and the temperature control element and the distance between the second temperature sensor and the temperature control element, an oscillator.

9. In claim 1, The temperature control element is a heating element, an oscillator.

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