Sensor device, adjustment method and adjusting device

Abstract

To improve oscillation stability.SOLUTION: A sensor device comprises an oscillator and a variable voltage source. The variable voltage source includes at least one of a first variable voltage source that supplies voltage to the oscillator and a second variable voltage source that supplies voltage to a circuit for maintaining oscillation of the oscillator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a sensor device, an adjustment method, and an adjustment device. [Background technology]

[0002] For example, Patent Document 1 discloses a sensor device that includes a sensor including an oscillator and a circuit for causing the oscillator to self-oscillate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-158557 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the important performance characteristics of a sensor is its oscillation stability. Even if the design is the same, the oscillation stability can be reduced due to individual variations.

[0005] One aspect of the present disclosure improves oscillation stability. [Means for solving the problem]

[0006] A sensor device according to one aspect of the present disclosure includes a vibrator and a variable voltage source, the variable voltage source including at least one of a first variable voltage source that supplies voltage to the vibrator and a second variable voltage source that supplies voltage to a circuit for maintaining vibration of the vibrator.

[0007] An adjustment method according to one aspect of the present disclosure includes measuring an oscillation frequency corresponding to the vibration of a vibrator, evaluating the stability of the oscillation frequency based on the measurement result, and adjusting the voltage value of a variable voltage source based on the evaluation result, wherein the variable voltage source includes at least one of a first variable voltage source that supplies voltage to the vibrator and a second variable voltage source that supplies voltage to a circuit for maintaining the vibration of the vibrator.

[0008] An adjustment device according to one aspect of the present disclosure is an adjustment device for adjusting a sensor device including a vibrator and a variable voltage source, and includes a measurement device that measures an oscillation frequency corresponding to the vibration of the vibrator, and an evaluation device that evaluates the stability of the oscillation frequency based on the measurement results of the measurement device, wherein the adjustment device adjusts the voltage value of the variable voltage source based on the evaluation results of the evaluation device, and the variable voltage source includes at least one of a first variable voltage source that supplies voltage to the vibrator and a second variable voltage source that supplies voltage to a circuit for maintaining the vibration of the vibrator. [Effects of the Invention]

[0009] According to the present invention, it is possible to improve the oscillation stability. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of a schematic configuration of a sensor device 1. FIG. [Figure 2] 1 is a diagram illustrating an example of a schematic configuration of a sensor device 1. FIG. [Figure 3] 10A and 10B are diagrams illustrating an example of measurement of oscillation frequency f and evaluation of stability. [Figure 4] 10 is a flowchart showing an example of a process (adjustment method) executed for adjusting an operating point. [Figure 5] FIG. 2 is a diagram illustrating an example of a schematic configuration of an adjustment device 7. [Figure 6] FIG. 2 is a diagram illustrating an example of a schematic configuration of an adjustment device 7. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described with reference to the drawings. The same elements are denoted by the same reference numerals, and duplicated descriptions will be omitted where appropriate.

[0012] FIG. 1 is a diagram showing an example of the schematic configuration of a sensor device 1. The sensor device 1 includes a sensor 2, a circuit 3, a variable voltage source 4, and a storage device 5. Note that the term "circuit" may be interpreted as meaning a "device," "apparatus," "module," or the like configured to have similar functions, and may be interpreted accordingly. Some or all of the functions may be realized by software.

[0013] The sensor 2 is a vibration sensor. Various known vibration sensors may be used as the sensor 2. The following description will be given taking as an example a case where the sensor 2 is an electrostatically driven vibration sensor. As shown in FIG. 1 , the sensor 2 includes a vibrator 21, an input electrode 22, and an output electrode 23.

[0014] The vibrator 21 has a natural frequency that changes depending on the state of the vibrator 21. An example of the state of the vibrator 21 is distortion of the vibrator 21. The distortion is caused by, for example, pressure applied to the vibrator 21, and in this case, the natural frequency of the vibrator 21 changes depending on the pressure. A sensor 2 including such a vibrator 21 can be used as a pressure sensor.

[0015] In one embodiment, the oscillator 21 may be made of silicon. The sensor 2 may be a silicon resonant pressure sensor, in which case the sensor device 1 may also be called a silicon resonant pressure sensor device.

[0016] The input electrode 22 and the output electrode 23 are provided with respect to the vibrator 21, more specifically, on opposite sides of the vibrator 21. An attenuated voltage signal αVs, which will be described later, is input to the input electrode 22. The output electrode 23 outputs an AC current signal Is having a frequency corresponding to the vibration of the vibrator 21 (for example, the same frequency as the natural frequency of the vibrator 21). The frequency corresponding to this vibration is referred to as an oscillation frequency f. The current signal Is from the output electrode 23 is input to a circuit 3 (more specifically, a conversion circuit 31, which will be described later).

[0017] The circuit 3 is a circuit for maintaining the oscillation of the oscillator 21 of the sensor 2. The circuit 3 operates to maintain the oscillation of an AC electrical signal having an oscillation frequency f.

[0018] The circuit 3 has a feedback loop for self-oscillation. The sensor 2 and the circuit 3 may be collectively referred to as an oscillator circuit, a self-oscillation circuit, or the like. Various known circuit configurations may be employed. In the example shown in FIG. 1 , the circuit 3 includes a conversion circuit 31, a damping circuit 32, a detection circuit 33, and an integration circuit 34.

[0019] The conversion circuit 31 converts the current signal Is from the output electrode 23 of the sensor 2 into a voltage signal Vs. The conversion may be interpreted to include amplification of the voltage signal Vs. The frequency of the voltage signal Vs is the oscillation frequency f, just like the current signal Is.

[0020] The attenuation circuit 32 attenuates the voltage signal Vs from the conversion circuit 31. The attenuation rate is referred to as the attenuation rate α. The attenuation rate α is determined based on the voltage from the integration circuit 34. The voltage signal Vs after attenuation by the attenuation circuit 32 is referred to as the attenuated voltage signal αVs. As described above, the attenuated voltage signal αVs is input (feedback) to the input electrode 22 of the sensor 2.

[0021] The detection circuit 33 detects the amplitude of the voltage signal Vs from the conversion circuit 31. In this example, the detection circuit 33 outputs a detection voltage signal Vdet that indicates the amplitude value of the voltage signal Vs. The detection voltage signal Vdet is a DC voltage.

[0022] The integrating circuit 34 includes an input terminal T1-1, an input terminal T1-2, and an output terminal T2. The input terminal T1-1 and the input terminal T1-2 form a pair of input terminals.

[0023] A detection voltage signal Vdet from detection circuit 33 is input to input terminal T1-1. A voltage from variable voltage source 4, more specifically, an amplitude command voltage Vc from variable voltage source 42 (described later), is input to input terminal T1-2. Output terminal T2 outputs a voltage corresponding to the difference between the voltage at input terminal T1-1 and the voltage at input terminal T1-2, i.e., the difference between the detection voltage signal Vdet and the amplitude command voltage Vc. Such an integration circuit 34 can also be called an error amplifier circuit, which outputs the error of the detection voltage signal Vdet when the amplitude command voltage Vc is used as a reference voltage.

[0024] The specific circuit configuration of the integrating circuit 34 is not particularly limited, and various known circuit configurations may be employed. In the example shown in Fig. 1, the integrating circuit 34 includes an operational amplifier circuit 341 and a capacitor 342. One input terminal of the operational amplifier circuit 341 corresponds to the input terminal T1-1 of the integrating circuit 34. The other input terminal of the operational amplifier circuit 341 corresponds to the input terminal T1-2 of the integrating circuit 34. The output terminal of the operational amplifier circuit 341 corresponds to the output terminal T2 of the integrating circuit 34. The capacitor 342 is connected between the input terminal T1-1 and the output terminal T2.

[0025] The voltage from the output terminal T2 of the integrating circuit 34 is input to the attenuation circuit 32. The attenuation factor α of the integrating circuit 34 is determined so that the feedback loop formed by the sensor 2, the conversion circuit 31, and the attenuation circuit 32 maintains the amplitude of the voltage signal Vs.

[0026] The variable voltage source 4 supplies voltage to several elements within the sensor device 1. The specific configuration of the variable voltage source 4 is not particularly limited, and various known configurations may be employed. Examples of components of the variable voltage source 4 include a digital potentiometer and a digital-to-analog converter (DAC). In the example shown in FIG. 1, the variable voltage source 4 includes two variable voltage sources. The first variable voltage source is illustrated as variable voltage source 41. The second variable voltage source is illustrated as variable voltage source 42.

[0027] The variable voltage source 41 supplies a voltage to the vibrator 21 of the sensor 2. This voltage is referred to as a bias voltage Vb. The variable voltage source 42 supplies a voltage to the circuit 3, more specifically, to the input terminal T1-2 of the operational amplifier circuit 341. This voltage is referred to as an amplitude command voltage Vc.

[0028] The storage device 5 stores a voltage value 50. The voltage value 50 indicates the value of the voltage to be generated by the variable voltage source 4. The variable voltage source 4 supplies the voltage of the voltage value 50 stored in the storage device 5. Specifically, the voltage value 50 includes a voltage value V1 and a voltage value V2.

[0029] The voltage value V1 indicates the value of the voltage to be generated by the variable voltage source 41, that is, the bias voltage Vb. The variable voltage source 41 generates the bias voltage Vb with the voltage value V1 and supplies it to the vibrator 21 of the sensor 2.

[0030] The voltage value V2 indicates the value of the voltage to be generated by the variable voltage source 42, i.e., the value of the amplitude command voltage Vc. The variable voltage source 42 generates the amplitude command voltage Vc of the voltage value V2 and supplies it to the input terminal T1-2 of the integration circuit 34. The storage device 5 may be a non-volatile storage device such as a ROM (Read Only Memory).

[0031] In the present disclosure, the combination of the bias voltage Vb and the amplitude command voltage Vc is also referred to as the "operating point." The operating point is a parameter related to the performance of the sensor device 1 and defines the operation of the sensor device 1. Examples of the performance of the sensor device 1 include oscillation stability and resolution. Oscillation stability indicates the stability of the value of the oscillation frequency f. Since resolution is equal to the self-noise level of the sensor device 1, higher oscillation stability also increases the resolution. This is because the higher the oscillation stability, the lower the self-noise level. It can be said that improving oscillation stability is important for improving the performance of the sensor device 1.

[0032] The sensor device 1 may be one of many sensor devices mass-produced according to the same design, in which case, due to individual variations (e.g., manufacturing variations, etc.), the optimal operating point may differ for each sensor device 1. The optimal operating point means the operating point for obtaining high (e.g., highest) oscillation stability.

[0033] In the sensor device 1 including the variable voltage source 4 described above, the bias voltage Vb and the amplitude command voltage Vc are variable, so the operating point can be adjusted and optimized. Therefore, for example, the operating point can be brought closer to the optimal operating point than in a case where the operating point cannot be adjusted and the sensor device 1 can only operate at one fixed operating point. As a result, the oscillation stability of the sensor device 1 can be improved. The resolution, noise resistance, etc. of the sensor device 1 can also be improved.

[0034] An example of adjusting the driving point is setting a voltage value 50 in the storage device 5. The voltage value 50 is set based on the results of a stability evaluation of the oscillation frequency f. The stability evaluation may be performed inside the sensor device 1 or outside the sensor device 1. An example of the configuration of the sensor device 1 when the stability evaluation is performed inside the sensor device 1 will be described with reference to FIG. 2.

[0035] 2 is a diagram showing an example of a schematic configuration of the sensor device 1. The sensor device 1 further includes an adjustment circuit 6. The adjustment circuit 6 adjusts the operating point of the sensor device 1 based on the voltage signal Vs from the conversion circuit 31. The adjustment circuit 6 may be realized using, for example, one or more chips (integrated circuits) and incorporated into the sensor device 1.

[0036] The adjustment circuit 6 includes a measurement circuit 61 and an evaluation circuit 62. Note that other elements (not shown) may also be included in the adjustment circuit 6. Examples of other elements include a control circuit that controls the entire adjustment circuit 6, the variable voltage source 4, the storage device 5, etc.

[0037] The measurement circuit 61 measures the oscillation frequency f based on the voltage signal Vs from the conversion circuit 31. From the waveform of the voltage signal Vs in the sensor device 1 operating at a given operating point, the frequency of the voltage signal Vs is calculated and acquired as (data of) the oscillation frequency f.

[0038] The acquired data may be time-series data. For example, a plurality of oscillation frequencies f acquired within a certain period of time are acquired as time-series data.

[0039] The evaluation circuit 62 evaluates the stability of the oscillation frequency f based on the measurement results of the measurement circuit 61. Various known indicators may be used as the stability. Examples of stability include the variance of the oscillation frequency f, the range of change in the oscillation frequency f (peak-to-peak frequency value), and the standard deviation of the oscillation frequency f. The smaller these values are, the higher the stability is.

[0040] The Allan variance may be used as the variance of the oscillation frequency f. For example, the oscillation frequency f is measured using appropriate parameters according to the product specifications, etc., and the Allan variance is calculated. Examples of parameters include the acquisition interval (gate time) of the oscillation frequency f, the number of oscillation frequencies f to be acquired (number of data), etc. An example of the gate time is about several tens of ms, and an example of the number of data is about several tens.

[0041] For example, the adjustment circuit 6 scans the bias voltage Vb of the variable voltage source 41 and the amplitude command voltage Vc of the variable voltage source 42 within a variable range. The specific scanning procedure is not particularly limited. The voltage values may be scanned in ascending or descending order, or according to any other algorithm. The scanning resolution (voltage value interval) may be fixed or variable. In the latter case, for example, scanning may be performed with a relatively high resolution (fine voltage value interval) within a voltage range that is likely to be used, and with a relatively low resolution (coarse voltage value interval) within a voltage range that is unlikely to be used. The measurement circuit 61 measures the oscillation frequency f, and the evaluation circuit 62 evaluates the stability for all combinations of the bias voltage Vb and the amplitude command voltage Vc within the scanning range, i.e., for all operating points. This description will also be made with reference to FIG. 3.

[0042] 3 is a diagram showing an example of measurement of oscillation frequency f and evaluation of stability. The scanned values of bias voltage Vb are shown schematically as xx1, xx2, xx3, etc. The scanned values of amplitude command voltage Vc are shown schematically as yy1, yy2, yy3, etc. The stability of oscillation frequency f at each combination of bias voltage Vb and amplitude command voltage Vc, i.e., each operating point, is shown schematically as z11, z12, z13, z21, z22, z23, z31, z32, z33, etc.

[0043] For example, the adjustment circuit 6 (FIG. 2) selects the bias voltage Vb and amplitude command voltage Vc corresponding to the highest stability among the stabilities z11 to z33, etc. as the optimal operating point. The adjustment circuit 6 writes the voltage values that give the optimal operating point into the storage device 5 as the voltage value V1 and the voltage value V2.

[0044] FIG. 4 is a flowchart showing an example of a process (adjustment method) executed for adjusting the operating point.

[0045] In step S1, the oscillation frequency f is measured. For example, a control circuit of the adjustment circuit 6 scans the bias voltage Vb and the amplitude instruction voltage Vc. The measurement circuit 61 of the adjustment circuit 6 measures the oscillation frequency f at each operating point.

[0046] In step S2, the stability of the oscillation frequency f is evaluated. Based on the measurement results in the previous step S1, the evaluation circuit 62 of the adjustment circuit 6 evaluates the stability of the oscillation frequency f at each operating point.

[0047] In step S3, the voltage value 50 of the variable voltage source 4 is adjusted. Based on the evaluation result in the previous step S2, a control circuit, for example, of the adjustment circuit 6 selects an optimal operating point and writes the corresponding values of the bias voltage Vb and amplitude command voltage Vc into the storage device 5 as the voltage value V1 and the voltage value V2.

[0048] For example, in the manner described above, the operating point of the sensor device 1 is adjusted. As described above, the variable voltage source 41 generates a voltage of voltage value V1 as the bias voltage Vb and supplies it to the vibrator 21 of the sensor 2. The variable voltage source 42 generates a voltage of voltage value V2 as the amplitude command voltage Vc and supplies it to the input terminal T1-2 of the integrating circuit 34. This allows the sensor device 1 to operate at the optimal operating point, achieving high oscillation stability.

[0049] The improved oscillation stability also brings about various benefits. For example, the resolution can be improved by reducing the self-noise. The sensitivity to accidental noise is reduced, resulting in improved noise resistance.

[0050] This makes it possible to manage the oscillation stability of the sensor device 1 using a unified standard, leading to improved product quality control. By setting grades according to the oscillation stability of the sensor device 1, it is also possible to expand the product lineup.

[0051] Even if the operating point changes due to long-term drift and the performance of the sensor device 1 deteriorates, this can be addressed by readjusting the operating point. There is no need to replace hardware, which improves maintainability.

[0052] The timing for adjusting the operating point is not particularly limited. For example, the operating point may be adjusted before shipping the sensor device 1 (at the manufacturing, inspection, etc. stage). A sensor device 1 with improved oscillation stability can be provided to the user from the start. Since the sensor device 1 includes an adjustment circuit 6, it is also possible to adjust the operating point after shipping. For example, the state of the sensor device 1 may change over time, causing the optimal operating point to shift. In such a case, the operating point of the sensor device 1 can be optimized again in the sensor device 1.

[0053] In addition, conventional technologies use a fixed voltage source instead of a variable voltage source 4, such as a voltage source that divides a reference voltage using a fixed resistor or the like and supplies the voltage, and the voltage value of the voltage source must be determined at the design stage. Since multiple sensor devices with the same design can only operate at the same operating point, individual variations can cause the operating point to deviate from the optimal operating point, potentially resulting in reduced oscillation stability. This problem can become particularly apparent when high resolution is required. In contrast, in this embodiment, the operating point is adjusted for each sensor device 1 using the variable voltage source 4, thereby suppressing the reduction in oscillation stability due to individual variations. Therefore, oscillation stability can be improved compared to conventional sensor devices.

[0054] <Modification> The disclosed technology is not limited to the above-described embodiment, and several modifications will be described below.

[0055] In the above embodiment, an example has been described in which both of the two power supplies, variable voltage source 41 that supplies bias voltage Vb and variable voltage source 42 that supplies amplitude command voltage Vc, are variable voltage sources. However, only one of the two power supplies may be a variable voltage source, and the other may be a fixed voltage source. In other words, variable voltage source 4 may include at least one of variable voltage source 41 and variable voltage source 42.

[0056] The operating point can be adjusted even if only one of the bias voltage Vb and the amplitude command voltage Vc is made variable, thereby improving oscillation stability. Furthermore, by making only one voltage variable, the functions and configuration can be simplified compared to when both voltages are made variable, leading to cost reductions, etc.

[0057] <Application example> Some application examples of the techniques described above will now be described. In one embodiment, the operating point of the sensor device 1 may be adjusted from outside the sensor device 1. A device for this purpose is referred to as an adjustment device. This will be described with reference to FIG. 5.

[0058] 5 is a diagram showing an example of a schematic configuration of the adjustment device 7. The adjustment device 7 is provided outside the sensor device 1 and adjusts the operating point of the sensor device 1. The sensor device 1 may have the configuration shown in FIG. 1 described above, or may have the configuration shown in FIG. 2. Here, it is assumed that the sensor device 1 has the configuration shown in FIG. 1.

[0059] The adjustment device 7 has the same functions as the adjustment circuit 6 (FIG. 2) described above, and is configured to be able to communicate data with the sensor device 1. The method of data communication is not particularly limited, and various known methods may be used. Communication may be wired communication or wireless communication.

[0060] The adjustment device 7 includes a measurement device 71 and an evaluation device 72. The measurement device 71 and the evaluation device 72 have the same functions as the measurement circuit 61 and the evaluation circuit 62 (FIG. 2) of the adjustment circuit 6 described above. A description of specific operations, etc. will not be repeated as they would be redundant. The flow of the process (adjustment method) executed to adjust the operating point of the sensor device 1 can be explained by appropriately replacing the adjustment circuit 6, the measurement circuit 61, and the evaluation circuit 62 in the flowchart of FIG. 4 described above with the adjustment device 7, the measurement device 71, and the evaluation device 72.

[0061] The adjustment device 7 provided externally to the sensor device 1 has the advantage of being less subject to various limitations, such as size, calculation power, and power consumption, compared to the adjustment circuit 6 (Fig. 2). For example, even if the sensor device 1 has an extremely large number of operating point combinations and it is difficult for the adjustment circuit 6 in the sensor device 1 to measure and evaluate the oscillation frequency f for all of the operating points, this can be achieved by using the adjustment device 7. It is possible to use a complex algorithm to reduce the number of operating points to be evaluated, but even in this case, the adjustment device 7, which may have higher calculation power than the adjustment circuit 6, is advantageous. Another advantage of using the adjustment device 7 is that it can provide a frequency counter with higher performance than the adjustment circuit 6, thereby improving the accuracy of operating point adjustment.

[0062] Furthermore, by using the adjustment device 7, it is possible to adjust the operating point of the sensor device 1 even if the sensor device 1 does not include the adjustment circuit 6. Since the sensor device 1 does not include the adjustment circuit 6, the configuration can be simplified, which contributes to miniaturization, cost reduction, etc.

[0063] In one embodiment, the operating points of a plurality of sensor devices 1 may be collectively adjusted by one adjustment device 7. This will be described with reference to FIG.

[0064] 6 is a diagram showing an example of a schematic configuration of the adjustment device 7. The adjustment device 7 performs data communication with each of the multiple sensor devices 1 and adjusts the operating point of each sensor device 1. The communication may be parallel communication in which the adjustment device 7 communicates with the multiple sensor devices 1 simultaneously, or serial communication in which the adjustment device 7 communicates with each sensor device 1 in turn.

[0065] One sensor device 1 may include a plurality of sensors 2, i.e., a plurality of vibrators 21. The operating points of the plurality of vibrators 21 in one sensor device 1 can be adjusted together by the adjustment device 7.

[0066] <Small conclusion> The techniques described above can be specified, for example, as follows. One of the techniques disclosed is a sensor device 1. As described with reference to Figs. 1 and 2 etc., the sensor device 1 includes a vibrator 21 and a variable voltage source 4. The variable voltage source 4 includes at least one of a variable voltage source 41 (first variable voltage source) that supplies a voltage (bias voltage Vb) to the vibrator 21, and a variable voltage source 42 (second variable voltage source) that supplies a voltage (amplitude command voltage Vc) to a circuit 3 that maintains the vibration of the vibrator 21.

[0067] According to the sensor device 1 described above, variable voltage source 4 includes at least one of variable voltage source 41 and variable voltage source 42, making it possible to adjust the operating point (combination of bias voltage Vb and amplitude command voltage Vc) of sensor device 1. This allows the operating point of sensor device 1 to approach the optimal operating point, thereby improving the oscillation stability of sensor device 1.

[0068] As described with reference to FIGS. 1 to 3, the sensor device 1 includes a storage device 5 that stores voltage values 50 (voltage value V1, voltage value V2), and the variable voltage source 4 may supply voltages (bias voltage Vb, amplitude command voltage Vc) of the voltage values 50 stored in the storage device 5. The voltage values 50 may be voltage values (for example, voltage values corresponding to an optimal operating point) that are set based on the evaluation results of the stability of the oscillation frequency f corresponding to the vibration of the vibrator 21. For example, in this way, the operating point of the sensor device 1 can be brought closer to the optimal operating point.

[0069] 2 and 3, the stability may include at least one of the variance of the oscillation frequency f (e.g., Allan variance), the variation range of the oscillation frequency f (peak-to-peak), and the standard deviation of the oscillation frequency f. For example, the stability of the oscillation frequency f can be evaluated using such an index.

[0070] 2 and 3, the sensor device 1 may include a measurement circuit 61 that measures the oscillation frequency f and an evaluation circuit 62 that evaluates the stability of the oscillation frequency f based on the measurement result of the measurement circuit 61. This allows the sensor device 1 to adjust its own operating point value.

[0071] 1 etc., the circuit 3 includes an integration circuit 34, which may include an input terminal T1-1 (one input terminal) to which a voltage signal (detection voltage signal Vdet) indicating the amplitude value of an electrical signal having an oscillation frequency f corresponding to the vibration of the vibrator 21 is input, an input terminal T1-2 (the other input terminal) to which an amplitude instruction voltage Vc from a variable voltage source 42 is input, and an output terminal T2 that outputs a voltage corresponding to the difference between the voltage at the input terminal T1-1 and the voltage at the input terminal T1-2. The sensor device 1 includes an output electrode 23 provided for the vibrator 21 and outputting a current signal Is having an oscillation frequency f corresponding to the vibration of the vibrator 21, a conversion circuit 31 that converts the current signal Is from the output electrode 23 into a voltage signal Vs, and a detection circuit 33 that outputs a detection voltage signal Vdet indicating the amplitude value of the voltage signal Vs from the conversion circuit 31. The detection voltage signal Vdet from the detection circuit 33 may be input to the input terminal T1-1 of the integration circuit 34. The sensor device 1 may include an attenuation circuit 32 that attenuates the voltage signal Vs from the conversion circuit 31 with an attenuation rate α set based on the voltage from the output terminal T2 of the integration circuit 34, and an input electrode 22 that is provided on the opposite side of the vibrator 21 from the output electrode 23 and to which the voltage signal Vs (attenuated voltage signal αVs) after attenuation by the attenuation circuit 32 is input. For example, in the sensor device 1 that includes such a self-oscillating circuit, the operating point can be adjusted to improve oscillation stability.

[0072] 1 and 2, etc., variable voltage source 4 may include both variable voltage source 41 and variable voltage source 42. This widens the adjustment range of the operating point compared to when variable voltage source 4 includes only one of variable voltage source 41 and variable voltage source 42, which may further improve the oscillation stability of sensor device 1.

[0073] 1 and other figures, the vibrator 21 has a natural vibration frequency that changes depending on the state of the vibrator 21, and the state of the vibrator 21 may include distortion of the vibrator. An example of the sensor device may be a silicon resonator pressure sensor device in which the vibrator 21 is made of silicon. By improving the oscillation stability of such a sensor device 1, it is possible to improve, for example, the accuracy of pressure detection.

[0074] The adjustment method described with reference to Figures 1 to 6 etc. is also one of the techniques disclosed. The adjustment method includes measuring oscillation frequency f corresponding to the vibration of vibrator 21 (step S1), evaluating the stability of oscillation frequency f based on the measurement result of the measurement (step S1) (step S2), and adjusting the voltage value of variable voltage source 4 based on the evaluation result of the evaluation (step S2) (step S3). Variable voltage source 4 includes at least one of variable voltage source 41 (first variable voltage source) that supplies a voltage to vibrator 21 and variable voltage source 42 (second variable voltage source) that supplies a voltage to circuit 3 that maintains the vibration of vibrator 21. As described above, such an adjustment method can also improve oscillation stability.

[0075] The adjustment device 7 described with reference to FIGS. 1 to 6 is also one of the disclosed techniques. The adjustment device 7 is an adjustment device for adjusting the sensor device 1 including the vibrator 21 and the variable voltage source 4. The adjustment device 7 includes a measurement device 71 that measures an oscillation frequency f corresponding to the oscillation of the vibrator 21, and an evaluation device 72 that evaluates the stability of the oscillation frequency f based on the measurement result of the measurement device 71. The adjustment device 7 adjusts the voltage value of the variable voltage source 4 based on the evaluation result of the evaluation device 72. The variable voltage source 4 includes at least one of a variable voltage source 41 (first variable voltage source) that supplies a voltage to the vibrator 21, and a variable voltage source 42 (second variable voltage source) that supplies a voltage to the circuit 3 that maintains the oscillation of the vibrator 21. As described above, such an adjustment device 7 can also improve the oscillation stability of the sensor device 1.

[0076] Some examples of combinations of the disclosed technical features are set out below. (1) A vibrator and a variable voltage source; Equipped with the variable voltage source includes at least one of a first variable voltage source that supplies a voltage to the vibrator and a second variable voltage source that supplies a voltage to a circuit for maintaining the vibration of the vibrator; Sensor device. (2) a storage device that stores a voltage value; the variable voltage source supplies a voltage having a voltage value stored in the storage device; The sensor device according to (1). (3) the voltage value is a voltage value set based on an evaluation result of stability of an oscillation frequency corresponding to the vibration of the vibrator. The sensor device according to (2). (4) The stability includes at least one of a dispersion of the oscillation frequency, a change range of the oscillation frequency, and a standard deviation of the oscillation frequency. The sensor device according to (3). (5) The dispersion comprises an Allan dispersion. The sensor device according to (4). (6) a measurement circuit for measuring the oscillation frequency; an evaluation circuit that evaluates the stability of the oscillation frequency based on the measurement result of the measurement circuit; Equipped with The sensor device according to (5). (7) the circuit includes an integrating circuit; The integrating circuit one input terminal to which a voltage signal indicating the amplitude value of an electrical signal having an oscillation frequency corresponding to the vibration of the vibrator is input; another input terminal to which a voltage from the second variable voltage source is input; an output terminal that outputs a voltage corresponding to a difference between a voltage at the one input terminal and a voltage at the other input terminal; Including, The sensor device according to any one of (1) to (6). (8) an output electrode provided for the vibrator and configured to output a current signal having an oscillation frequency corresponding to the vibration of the vibrator; a conversion circuit that converts the current signal from the output electrode into a voltage signal; a detection circuit that outputs a detection voltage signal indicating the amplitude value of the voltage signal from the conversion circuit; Equipped with the detection voltage signal from the detection circuit is input to the one input terminal of the integration circuit; The sensor device according to (7). (9) an attenuation circuit that attenuates the voltage signal from the conversion circuit at an attenuation rate set based on the voltage from the output terminal of the integration circuit; an input electrode that is provided on the opposite side of the vibrator from the output electrode and to which the voltage signal attenuated by the attenuation circuit is input; Equipped with The sensor device according to (8). (10) the variable voltage source includes both the first variable voltage source and the second variable voltage source; The sensor device according to any one of (1) to (9). (11) the vibrator has a natural vibration frequency that changes depending on the state of the vibrator; The state of the vibrator includes a distortion of the vibrator. The sensor device according to any one of (1) to (10). (12) The oscillator is a silicon resonant pressure sensor device made of silicon. The sensor device according to any one of (1) to (11). (13) measuring an oscillation frequency corresponding to the vibration of the oscillator; Evaluating the stability of the oscillation frequency based on the measurement result of the measurement; adjusting a voltage value of the variable voltage source based on the evaluation result; Including, the variable voltage source includes at least one of a first variable voltage source that supplies a voltage to the vibrator and a second variable voltage source that supplies a voltage to a circuit for maintaining the vibration of the vibrator; Adjustment method. (14) 1. An adjustment device for adjusting a sensor device including a vibrator and a variable voltage source, a measuring device that measures an oscillation frequency corresponding to the vibration of the vibrator; an evaluation device that evaluates the stability of the oscillation frequency based on the measurement results of the measurement device; Equipped with the adjusting device adjusts the voltage value of the variable voltage source based on the evaluation result of the evaluating device; the variable voltage source includes at least one of a first variable voltage source that supplies a voltage to the vibrator and a second variable voltage source that supplies a voltage to a circuit for maintaining the vibration of the vibrator; Adjustment device. [Explanation of symbols]

[0077] 1. Sensor device 2 sensors 21 Oscillator 22 input electrode 23 Output electrode 3 circuits 31 Conversion circuit 32 Attenuation circuit 33 Detection circuit 34 Integrator circuit 341 Operational Amplifier Circuit 342 Capacitor 4 Variable Voltage Source 41 Variable voltage source 42 Variable Voltage Source 5 Storage device 50 Voltage Value 6 Adjustment circuit 61 Measurement circuit 62 Evaluation circuit 7 Adjustment device 71 Measuring Equipment 72 Evaluation equipment f oscillation frequency Is current signal T1 input terminal T1-1 input terminal T1-2 input terminal T2 output terminal V1 voltage value V2 voltage value Vb bias voltage Vc amplitude indication voltage Vdet detection voltage signal Vs voltage signal α Decay rate αVs Attenuated voltage signal

Claims

1. A vibrator and a variable voltage source; Equipped with the variable voltage source includes at least one of a first variable voltage source that supplies a voltage to the vibrator and a second variable voltage source that supplies a voltage to a circuit for maintaining the vibration of the vibrator; Sensor device.

2. a storage device that stores a voltage value; the variable voltage source supplies a voltage having a voltage value stored in the storage device; The sensor device according to claim 1 .

3. the voltage value is a voltage value set based on an evaluation result of stability of an oscillation frequency corresponding to the vibration of the vibrator. The sensor device according to claim 2 .

4. the stability includes at least one of a dispersion of the oscillation frequency, a change range of the oscillation frequency, and a standard deviation of the oscillation frequency; The sensor device according to claim 3 .

5. The dispersion comprises an Allan dispersion. The sensor device according to claim 4 .

6. a measurement circuit for measuring the oscillation frequency; an evaluation circuit that evaluates the stability of the oscillation frequency based on the measurement result of the measurement circuit; Equipped with The sensor device according to claim 5 .

7. the circuit includes an integrating circuit; The integrating circuit one input terminal to which a voltage signal indicating the amplitude value of an electrical signal having an oscillation frequency corresponding to the vibration of the vibrator is input; another input terminal to which a voltage from the second variable voltage source is input; an output terminal that outputs a voltage corresponding to a difference between a voltage at the one input terminal and a voltage at the other input terminal; Including, The sensor device according to any one of claims 1 to 6.

8. an output electrode provided for the vibrator and configured to output a current signal having an oscillation frequency corresponding to the vibration of the vibrator; a conversion circuit that converts the current signal from the output electrode into a voltage signal; a detection circuit that outputs a detection voltage signal indicating the amplitude value of the voltage signal from the conversion circuit; Equipped with the detection voltage signal from the detection circuit is input to the one input terminal of the integration circuit; The sensor device according to claim 7.

9. an attenuation circuit that attenuates the voltage signal from the conversion circuit at an attenuation rate set based on the voltage from the output terminal of the integration circuit; an input electrode that is provided on the opposite side of the vibrator from the output electrode and to which the voltage signal attenuated by the attenuation circuit is input; Equipped with The sensor device according to claim 8 .

10. the variable voltage source includes both the first variable voltage source and the second variable voltage source; The sensor device according to any one of claims 1 to 5.

11. the vibrator has a natural vibration frequency that changes depending on the state of the vibrator; The state of the vibrator includes a distortion of the vibrator. The sensor device according to any one of claims 1 to 5.

12. The oscillator is a silicon resonant pressure sensor device made of silicon. The sensor device according to any one of claims 1 to 5.

13. measuring an oscillation frequency corresponding to the vibration of the oscillator; Evaluating the stability of the oscillation frequency based on the measurement result of the measurement; adjusting a voltage value of the variable voltage source based on the evaluation result; Including, the variable voltage source includes at least one of a first variable voltage source that supplies a voltage to the vibrator and a second variable voltage source that supplies a voltage to a circuit for maintaining the vibration of the vibrator; Adjustment method.

14. 1. An adjustment device for adjusting a sensor device including a vibrator and a variable voltage source, a measuring device that measures an oscillation frequency corresponding to the vibration of the vibrator; an evaluation device that evaluates the stability of the oscillation frequency based on the measurement results of the measurement device; Equipped with the adjusting device adjusts the voltage value of the variable voltage source based on the evaluation result of the evaluating device; the variable voltage source includes at least one of a first variable voltage source that supplies a voltage to the vibrator and a second variable voltage source that supplies a voltage to a circuit for maintaining the vibration of the vibrator; Adjustment device.

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