JPWO2018155057A1 - Sensor device - Google Patents

Abstract

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sensor device whose damping is adjusted such that the detection element does not have a gain at a resonant frequency, wherein the response diagnosis of the detection element after shipment is suppressed while suppressing the cost for acquiring characteristics before shipment. Is to make it possible. In the sensor device 100 including the detection element 102 provided in the hermetically sealed cavity and including the vibrator, the response amplitude detection unit that detects the response amplitude of the detection element 102 with respect to the vibration of the vibrator is a frequency axis of the response amplitude. Response amplitude acquisition units 103, 104, and 108 that acquire the first response amplitude and the second response amplitude corresponding to the first frequency and the second frequency, or the first time and the second time, which are two different points on the upper or time axis. , 111 to 113 and a determination unit 114 that determines the presence or absence of pressure abnormality in the cavity 501 based on the relative relationship between the first response amplitude and the second response amplitude.

Description

  The present invention relates to a sensor device having a pressure-detecting sensor element for detecting a physical quantity, and relates to a technique for diagnosing responsiveness of a system including the sensor device.

  Applications that detect attitude, acceleration, pressure, etc., such as automotive safety support and automatic driving, robot control, and autonomous flight devices called UAV (Unmanned Aerial Vehicle), are becoming popular with the development of MEMS (MicroElectro Mechanical Systems) technology . The MEMS is a system including a sensor and an actuator in combination with a control unit configured by fabricating a minute mechanical device using a semiconductor microfabrication technology and configured by an application specific integrated circuit (ASIC) or the like. In the MEMS type sensor which detects a physical quantity, a detection element part can be manufactured using batch processing which is a feature of semiconductor manufacturing technology. For this reason, the MEMS type sensor plays an important role in the industry as realizing the cost reduction of the sensor itself and, at the same time, realizing the above-mentioned application requiring the utilization of the sensor at low cost. The

In the MEMS type sensor, since the detection element is processed on the order of microns (1e-6m: 1 × 10 ⁻⁶ m) or less, physical changes of the detection element after fabrication affect the characteristics of the sensor. Therefore, it is an issue in the industry to solve this physical change at low cost.

  In particular, in a detection element of an acceleration sensor where it is important to keep the pressure constant or a detection element of a pressure sensor, slight pressure fluctuation in the detection element affects the responsiveness and sensitivity as a sensor. Therefore, the ability of the sensor to self-diagnose that this pressure is maintained at the desired value after shipment is particularly important in applications where detection defects are not acceptable such as automotive safety support, automatic operation, robot control, and UAV. Become.

  As background art of this technical field, there exists Unexamined-Japanese-Patent No. 2016-170089 (patent document 1), for example. Patent Document 1 discloses a method of performing vibration in the vicinity of a resonance frequency of a detection element in a pressure detection element kept in vacuum, and detecting pressure fluctuation from this response (half-width or time constant of amplitude). There is.

  In addition, in Japanese Patent Application Laid-Open No. 2002-162413 (Patent Document 2), the frequency response of the detection element is obtained at various temperatures before shipment in the earthquake detection device, and is stored in the memory, and then the detection element is shipped. A method is disclosed for detecting pressure fluctuation by again acquiring the frequency response of the above and comparing the acquired frequency response with the frequency response before shipment stored in the memory.

JP, 2016-170089, A JP, 2002-162413, A

  In the case of the method as disclosed in Patent Document 1, a pressure fluctuation can not be diagnosed with a detection element having damping without a gain at a resonance frequency.

  In the technique of Patent Document 2, since it is necessary to acquire the frequency response of the detection element at various temperatures before shipping, the cost involved in acquiring this frequency response becomes an issue.

  SUMMARY OF THE INVENTION It is an object of the present invention to provide a sensor device whose damping is adjusted such that the detection element does not have a gain at a resonant frequency, wherein the response diagnosis of the detection element after shipment is suppressed while suppressing the cost for acquiring characteristics before shipment. In making it possible.

In order to achieve the above object, the sensor device of the present invention is
A sensor device comprising: a hermetically sealed cavity; and a detection element provided inside the cavity and having a vibrator.
And a response amplitude detection unit configured to detect a response amplitude of the detection element with respect to the vibration of the vibrator.
The response amplitude detection unit is configured to generate a first response amplitude and a second response corresponding to a first frequency and a second frequency, or a first time and a second time, which are two different points on the frequency axis or the time axis of the response amplitude. And a determination unit that determines the presence or absence of pressure abnormality in the cavity based on a relative relationship between the first response amplitude and the second response amplitude.

  According to the present invention, in a sensor or system whose damping is adjusted such that the detection element does not have gain at the resonance frequency, the responsiveness of the detection element after shipment is suppressed while suppressing the cost for acquiring characteristics before shipment. Diagnosis is possible. Problems, configurations, and effects other than those described above will be apparent from the description of the embodiments below.

It is a schematic diagram (plan view) which shows the structure of the acceleration detection element which has an electrode for generating the electrostatic force used for a diagnosis. It is sectional drawing which shows the structure of the acceleration detection element which has an electrode for producing | generating the electrostatic force used for a diagnosis. FIG. 2 is a view showing the configuration of an acceleration sensor device in Example 1, and a view showing the configuration of an acceleration detection element and its detection circuit. FIG. 7 is a diagram showing an example of the frequency response of an acceleration detection element to a plurality of pressures in Example 1; FIG. 7 is a diagram showing an example of a change in frequency response before and after leak of an acceleration detection element in Embodiment 1, and a diagram showing frequency points to be measured in response diagnosis. It is a figure which shows the processing flow of a detection circuit. FIG. 14 is a diagram showing an example of a change in frequency response before and after leak of an acceleration detection element in the first embodiment, and is a diagram showing an example of measurement frequency points different from FIG. 3 in response diagnosis. FIG. 6 is a diagram showing an example of a change in frequency response obtained by applying a plurality of Q values to Q in Equation 1. It is a figure which shows the relationship of the temperature and Q value of the detection element which fixed pressure to a certain value. In Example 1, it is a block diagram showing composition of an application system with which an acceleration sensor device and a plurality of systems were connected via a bus. It is a figure which shows the processing flow which determines the sustainability of each system with respect to an acceleration sensor apparatus. FIG. 14 is a diagram showing the configuration of an acceleration sensor device in Example 2, and is a diagram showing an example of performing correction or configuring a dual system using a pressure sensor device. FIG. 7 is a diagram showing a processing flow of a detection circuit in Embodiment 2. FIG. 17 is a diagram showing the configuration of an acceleration sensor device according to a third embodiment, and is a view showing a system configuration in the case of configuring a sensor device that controls the acceleration sensor with the same ASIC as the angular velocity sensor. FIG. 21 is a diagram according to a fourth embodiment and shows an application example in which a clock is input to the sensor device from an external clock source such as a microcomputer. FIG. 18 is a diagram illustrating a configuration example of a circuit of a sensor device (acceleration sensor device) that realizes a step response in the fifth embodiment. FIG. 18 is a diagram showing a process flow of a detection circuit in Embodiment 5. FIG. 21 is a diagram according to a fifth embodiment and shows an example in which the same diagnosis is realized by a step response.

  In the following embodiment, when it is necessary for the sake of convenience, it will be described by dividing into a plurality of sections or examples, but unless specifically stated otherwise, they are not mutually unrelated, one is the other Some or all of the variations, details, supplementary explanations, etc. are in a relation. Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, amount, range, etc.), unless otherwise specified or in principle when clearly limited to a specific number, etc. The number is not limited to the specific number, and may be more or less than the specific number. For example, the relationship between the resonance frequency and the damping coefficient with respect to pressure, and the frequency response are all determined by design, and the following embodiment merely shows an example of one design.

  Furthermore, in the following embodiments, it is needless to say that the constituent elements (including element steps and the like) are not necessarily essential unless specifically stated or considered to be obviously essential in principle. Yes. Similarly, in the following embodiments, when referring to the shapes, positional relationships and the like of components, etc., the shapes and the like are substantially excluded unless particularly clearly stated and where it is considered to be obviously not clear in principle. It includes those that are similar or similar to The same applies to the number of the above elements and the like.

Example 1
Referring to FIGS. 1A and 1B, detection elements of an acceleration sensor device according to an embodiment (Embodiment 1) of the present invention will be described. FIG. 1A is a schematic view (plan view) showing the structure of an acceleration detection element having an electrode for generating an electrostatic force used for diagnosis. FIG. 1B is a cross-sectional view showing the structure of an acceleration detection element having an electrode for generating an electrostatic force used for diagnosis.

  In the detection element of the acceleration sensor device 100 (see FIG. 1) shown in the first embodiment, the detection mass (weight) 502 is produced in a form suspended in the fixing portion 514 via the elastic deformation portion 507 in the cavity 501. . Also, the pressure in the sealed cavity 501 constitutes the damper 508 by the viscosity (air resistance) of air. Therefore, the detection element 102 (see FIG. 2) is a so-called spring mass system, and constitutes a vibrator including the detection mass 502 and the elastic deformation portion 507. The damper 508 may be considered as part of a transducer.

  When the acceleration detection element 102, which is a vibrator, receives the application of the acceleration, the detection mass 502 is displaced with the deformation of the elastic deformation portion 507. The detection principle of the acceleration sensor device 100 according to the present embodiment is that the applied acceleration is obtained by detecting this displacement as a change in capacitance on the positive side 503 and the negative side 504 of the capacitive detection electrode.

  In order to detect this change in capacitance, a DC voltage 505 and an AC voltage 506 are applied to the detection mass 502. As a result of the application of the alternating voltage, the capacitance on the positive side 503 and the negative side 504 of the capacitive detection electrode 503 is input to the capacitance-voltage converter (Capacitor-to-Voltage converter) 516 in the form of current through the wiring portion 515. As a result, the change in capacitance is output to the subsequent stage of the capacitance-voltage converter 516 as a change in voltage level 517.

  The diagnostic electrode positive side 509 and the negative side 510 receive voltage application from the diagnostic voltage application unit positive side 511 and the negative side 512, respectively, to generate electrostatic force. The electrostatic force causes the detection mass 502 to vibrate along the vibration direction 513. The displacement (displacement amount) due to the excitation is detected as a capacitance change on the positive side 503 and the negative side 504 of the capacitive detection electrode. Then, it is possible to determine whether the displacement amount due to the excitation is within the expected range from the relationship between the applied voltage and the frequency response, and diagnose the defect of the detection element 102. The diagnostic voltage application unit positive side 511 and the negative side 512 are electrodes for vibrating the detection mass 502, and may be referred to as a vibrating electrode positive side 511 and the negative side 512.

  In the present embodiment, the cavity 501 is constituted by the upper layer 518, the device layer 521, the oxide layer 520, and the handle layer 519, and is hermetically sealed in the absence of a failure. The cavity 501 of this embodiment may have any shape.

  Next, the detection circuit 130 will be described with reference to FIG. FIG. 2 is a view showing the configuration of the acceleration sensor device in Example 1, and is a view showing the configuration of an acceleration detection element and its detection circuit. Hereinafter, the acceleration detection element 102 will be described by being called the detection element 102. Here, the detection element 102 shows the entire detection element shown in FIG. 1A. Further, components excluding the detection element 102 in FIG. 2 constitute a detection circuit 130.

  In the detection circuit 130, the clock generated by the clock source 106 configured as an oscillator is adjusted to an appropriate frequency by the divider 107, and an AC signal (generally called a carrier) is output through a first DAC (Digital to Analog Converter) 118. To the detection mass 502 in the detection element 102. As a result, the capacitance change associated with the displacement of the detection mass 502 of the detection element 102 is obtained as a change in voltage through the capacitance-voltage converter 103 (equivalent to 516 in FIG. 5). Further, this voltage signal is converted into a digital value by an ADC (Analog to Digital Convertor) 104.

  A detection signal of the applied acceleration by the detection element 102 is converted into a digital value, and then an LPF (Low Pass Filter) 105, a correction unit 120 for correcting temperature, sensitivity and offset, and an output clip at upper and lower limits of the signal It is adjusted via the limiter 121 and transmitted to the upper system as an acceleration output 115. Here, using the temperature output from the temperature sensor 117, the correction unit 120 detects the temperature of the environment in which the sensor package 101 is placed, and performs correction of sensitivity and offset according to this. Thus, the output is corrected to satisfy the input / output specification of the acceleration sensor device 100.

  Next, referring to FIG. 3, the frequency response of the detection element 102 will be described. FIG. 3 is a diagram illustrating an example of the frequency response of the acceleration detection element to a plurality of pressures in the first embodiment. FIG. 3 shows the frequency response at the sensing element 102 of the acceleration sensor device 100 having a resonant frequency near 1 kHz as a mere example of the design for various sealing pressures. Here, the frequency response fluctuates according to the design of the resonance frequency and the damping, and the frequency response shown here is shown as an example.

  The frequency responses 201 to 206 are frequency responses of the detection element 102 shown for each sealing pressure. The frequency response 201 is a frequency response when sealed at 100 kPa (approximately atmospheric pressure), and further, in the order of the frequency responses 202, 203, 204, 205, and 206, the frequency response when the sealing pressure becomes higher vacuum is It shows.

  In the frequency responses 203 to 206, the gain in the vicinity of the resonant frequency exceeds 0 dB. This is because damping due to air resistance is not effective because the sealed pressure is low, and resonant vibration occurs at a frequency near the resonant frequency.

  However, when the detection element 102 has such a resonance-induced peak exceeding 0 dB, there is a problem in vibration resistance when the acceleration sensor device 100 is installed in an environment where disturbance vibration is applied.

  That is, when disturbance vibration is applied to the detection element 102 and a frequency component whose gain of the detection element 102 exceeds 0 dB is included in the vibration, the detection element 102 is detected by the mechanical gain (gain exceeding 0 dB) of the frequency component. The detection mass part of is largely displaced. This causes the saturation of the signal of the detection circuit 130 and the associated fluctuation of the offset.

  In order to prevent such a situation, in the acceleration sensor device 100 assumed to be installed in an environment with disturbance vibration, the sealing pressure of the detection element 102 is increased to strengthen damping and suppress a peak due to resonance exceeding 0 dB. Take the method. That is, the sealing pressure is designed so that the frequency response of the detection element 102 becomes a frequency response such as the frequency response 201 or 202.

  Next, a case will be considered in which a wide (e.g., direct current to 200 Hz) "sensor responsiveness" defined by a frequency (cutoff frequency) at which the gain is -3 dB is generally secured.

  “Sensor responsiveness” is wide (high) means that the frequency range in which the acceleration sensor device 100 operates (ie, the bandwidth of frequency: frequency band) is wide. In the present embodiment, the frequency range in which the acceleration sensor device 100 operates is from 0 Hz, which is the lower limit frequency of this frequency range, to the upper limit frequency (the aforementioned cutoff frequency: upper cutoff frequency). The lower limit frequency and the upper limit frequency can be set to various frequencies according to specifications.

  Although the detection element 102 can suppress the peak caused by the resonance by raising the pressure, there is a trade-off that the response becomes low, so that the response specification can not be satisfied by merely increasing the pressure. For example, in the design example shown in the present embodiment, the response when sealed at atmospheric pressure is about 100 Hz (as in the frequency response 201). Therefore, in order to ensure the vibration resistance while securing the response, the sealing pressure is set lower than the atmospheric pressure, and the sealing pressure is adjusted so that the frequency response of the detection element 102 does not have a peak. , It is important to maintain this.

  An example of the change in frequency response of the detection element 102 caused by pressure fluctuation will be described with reference to FIG. FIG. 4 is a diagram showing an example of a change in frequency response before and after leak of the acceleration detection element in the first embodiment, and is a diagram showing frequency points to be measured in response diagnosis.

  The frequency response 302 is the frequency response of the sensing element 102 sealed at a pressure less than atmospheric pressure. The acceleration sensor device 100 according to the present embodiment achieves a frequency response specification of 200 Hz (that is, the gain at 0 to 200 Hz is greater than -3 dB). It was designed to gain. Next, the frequency response 301 is a frequency response when the pressure of the cavity 501 becomes atmospheric pressure (about 100 kPa) in the same structure of the detection element 102. Such fluctuation in pressure of the cavity 501 (abnormality in pressure) may be caused, for example, by degassing in the cavity 501 even if leakage occurs in the cavity 501 of the detection element 102 or there is no problem in airtightness. It is generated by increase etc.

  When the pressure of the cavity 501 becomes atmospheric pressure, as shown in the frequency response 301, the frequency response of the detection element 102 can not realize "gain-3 dB at 200 Hz" of the frequency response specification. The present embodiment enables low-cost detection of such pressure fluctuation, in particular, responsiveness failure associated with vacuum leak.

  The operation of the detection circuit 130 of FIG. 2 will be described. Here, the processing flow of the detection circuit 130 will be described with reference to FIG. 5 in addition to FIG. FIG. 5 is a diagram showing a processing flow of the detection circuit.

  The frequency divider 107 generates at least two alternating current signals (first and second frequencies) used for diagnosis from the common clock source 106 by time division or frequency division, and generates a second alternating current signal for diagnosis. The voltage is applied to the diagnostic electrode positive side 509 and the negative side 510 of the detection element 102 shown in FIG. 1A through the DAC 119 (S101 in FIG. 5). Here, the diagnostic voltage application unit positive side 511 and the negative side 512 correspond to the second DAC 119 in FIG. The DAC may have outputs of a plurality of channels and may generate positive and negative AC voltages, may output AC voltage by one channel, may generate positive and negative AC voltages by an inverting circuit, or a diagnostic electrode positive side 509 Alternatively, the response failure can be similarly detected by applying an AC voltage only and applying only a DC voltage to the diagnostic electrode negative side 510.

  In addition, although it is generally difficult to generate an accurate sine wave signal in an integrated circuit, an LPF or BPF (Band Pass Filter) is added as hardware, or an output digital value of a sine wave is stored in a table. It is possible to generate a near-sinusoidal waveform at low cost by implementing a soft process that outputs this.

  The clock source 106, the frequency divider 107, the second DAC 119, the diagnostic electrode positive side 509, the negative side 510, the diagnostic voltage application unit positive side 511, the negative side 512, etc. A section (excitation circuit section) 130A is configured. In particular, the clock source 106, the frequency divider 107, and the like constitute an excitation signal generation unit (oscillation signal generation circuit unit) 130A1 that generates an excitation signal that excites a vibrator.

  The two frequencies will be described in more detail with reference to FIG.

  Here, 20 Hz (first frequency) and 200 Hz (second frequency) of FIG. 4 are selected as an example of the frequency of the AC signal (voltage) applied to the two diagnostic electrodes 509 and 510. At this time, the first frequency 20 Hz is a frequency at which the gain (first gain) does not fluctuate even if the pressure in the cavity 501 of the detection element 102 fluctuates to atmospheric pressure, and the second frequency 200 Hz corresponds to that of the detection element 102. When the pressure of the cavity 501 changes to the atmospheric pressure, the gain (second gain) changes. The former gain (first gain) is a common gain 401 before and after pressure fluctuation, and the latter gain (second gain) is a gain before pressure fluctuation called gain 402 and a gain after pressure fluctuation called gain 403. Do.

  The calculation procedure of each gain 401, 402, 403 will be described. In the detection circuit 130 of FIG. 2, as a result of applying an alternating current signal (voltage) for diagnosis, the capacitance fluctuation generated on the positive side 503 of the capacitive detection electrode on the same side as the negative side 504 is digitized via the CV converter 103 · ADC 104 It acquires as a signal (S102 of FIG. 5). The acquired capacity fluctuation is converted into amplitude components of in-phase and quadrature components through the demodulator 109, the phase delay unit 110, and the LPF 111 in the synchronous detection unit 108 (S103 in FIG. 5). The absolute value of the converted amplitude component is processed by the absolute value calculator 112 and the amplitude detector 113 to calculate the first gain 401 and the second gains 402 and 403, respectively (S104 in FIG. 5).

  The method of calculating the gain described in this specification is an example, and the gain may be calculated by any method other than that described.

  The comparator (comparison unit) 114 compares the gain 401 with the gain 402 or the gain 403 to determine whether the acceleration sensor device 100 is normal or abnormal (S105 in FIG. 5). In this sense, the comparator 114 may be called a determination unit. Here, in the following, comparison will be described as an example for calculating the ratio of the two, but it is not necessary to use the ratio.

  When the ratio is used for comparison, when there is no change in the pressure (cavity pressure) of the cavity 501 of the detection element 102, the ratio of the gain 401 and the gain 402 is ideally 1, and the disturbance component such as noise is considered. But it will be close to one. On the other hand, when there is a change in the pressure of the cavity 501, the gain 401 and the gain 403 are compared. However, since the gain 403 drops to about -5 dB, the ratio does not reach 1 or a value close thereto. Therefore, a predetermined threshold that divides the range of ratios that can be considered normal and the range of ratios that should be determined as abnormal is set, and the acceleration sensor device 100 is determined to be in a normal state when the value of the ratio is larger than this threshold. If the value of the ratio is smaller than this threshold, the acceleration sensor device 100 determines that it is in an abnormal state. If the value of the ratio is equal to the threshold value, it may be determined as normal or as abnormal. This threshold is set to a value close to one.

  In the present embodiment, the detection circuit 130 is composed of the above-described vibration unit (vibration circuit unit) 130A and a response amplitude detection unit (response amplitude detection circuit unit) 130B. The response amplitude detection unit 130B is a part (circuit unit) that detects the response amplitude (gain) of the detection element 102, and the CV converter 103, the ADC 104, and the synchronization detection unit 108 (demodulator 109, phase delay 110, LPF 111). And an absolute value calculation unit 112, an amplitude detection unit 113, a comparator 114, and a temperature sensor 117. In particular, CV converter 103, ADC 104, synchronous detection unit 108 (demodulator 109, phase delay unit 110, LPF 111), absolute value calculation unit 112 and amplitude detection unit 113 are two different points on the frequency axis of response amplitude. A response amplitude acquisition unit (response amplitude acquisition circuit unit) 130B1 configured to acquire a first response amplitude and a second response amplitude corresponding to the first frequency and the second frequency is configured. The comparator 114 and the temperature sensor 117 constitute a determination unit (determination circuit unit) 130B2 that determines the presence or absence of pressure abnormality in the cavity 501 based on the relative relationship between the first response amplitude and the second response amplitude.

  In FIG. 2, the CV converter 103, the ADC 104, the LPF 105, the correction unit 120, and the limiter 121 constitute an acceleration detection unit 130C that detects an acceleration.

  As described above, one of the at least two frequencies used for diagnosis (the first frequency) is a frequency at which the gain of the frequency response does not change when the cavity pressure of the detection element 102 becomes atmospheric pressure, By setting the frequency (second frequency) to the frequency at which the gain of the frequency response changes when the cavity pressure of the detection element 102 becomes atmospheric pressure, the frequency response of the cavity 501 is simply compared. Pressure changes can be detected. Usually, the first frequency is referred to as the low frequency side because it is on the low frequency side, and the second frequency may be referred to as the high frequency side because it is on the high frequency side. In particular, even if the absolute values of various gains change depending on the temperature characteristics of the detection element 102 and the temperature characteristics of the detection circuit 130, diagnosis is performed with the gain ratio of the frequency response, and the gain of 0 dB is Since this is used as a reference using the frequency that it has, diagnosis can be performed without considering previously acquired data and temperature characteristics.

  By performing diagnosis according to the above-described procedure, it is possible to diagnose the responsiveness of the detection element 102 such that the gain at the resonance frequency does not exceed 0 dB without acquiring the frequency response of the detection element 102 in advance and storing it in the memory. It can be implemented regardless of the temperature of the installation environment.

  As an example of the frequency of the voltage applied to the two diagnostic electrodes 509 and 510, at least one is an example where the gain does not fluctuate even if the pressure of the cavity 501 of the detection element 102 fluctuates to atmospheric pressure. Although shown, it does not necessarily have to be atmospheric pressure, and may be, for example, the pressure of the environment where use is expected, or the maximum pressure generated by degassing.

  Further, the latter frequency (frequency for obtaining gains 402 and 403) should be set near the frequency response specification (upper limit value of bandwidth) of the acceleration sensor device 100 (for example, frequency at which the gain is 0 dB to −60 dB). Is useful because the frequency response specification of the acceleration sensor device 100 can be diagnosed. The previous example corresponds to setting the latter frequency to 200 Hz, which is the frequency response specification. At this time, since the gain 401 is a gain of 0 dB, the value obtained by dividing the gain 402 by the gain 401 directly indicates the absolute value gain of the gain 402. For example, when this is −3 dB or less Since the frequency response specification (gain of 3 dB or more at 200 Hz) is not satisfied, it can be determined as a failure (pressure abnormality).

  Next, diagnosis of the detection element 102 which can not be diagnosed as a defect at normal temperature will be described with reference to FIG. FIG. 6 is a diagram showing an example of change in frequency response before and after leak of the acceleration detection element in the first embodiment, and is a diagram showing an example of measurement frequency points different from those in FIG. 4 in response diagnosis.

  In FIG. 6, frequency responses 406 and 407 are frequency responses that simulate the case where there is a pressure increase after fabrication in the detection element 102 sealed at a pressure lower than the atmospheric pressure. Here, the frequency response 407 is a normal temperature, and the frequency response 406 is a frequency response at 125 ° C.

  When the pressure of the cavity 501 is maintained at the initial pressure, the frequency response can be maintained at a predetermined specification even if the environmental temperature changes. However, if the pressure in the cavity 501 is increased, the frequency response may be reduced and the predetermined frequency response specification may not be maintained when the environmental temperature is increased. In this case, if the diagnosis of the present embodiment is carried out at normal temperature, it may be judged as normal. The details will be described below.

  Now, it is assumed that the frequency response specification of the acceleration sensor device 100 is 1000 Hz (1 kHz), and the usage environment temperature is normal temperature to 125 ° C. In addition, two frequencies used for diagnosis have a first frequency (low frequency) of 100 Hz and a second frequency (high frequency) of 1000 Hz. In this case, gain (first gain) 408 at 100 Hz is constant regardless of temperature, but gain (second gain) at 1000 Hz is approximately 0 dB at gain 409 at normal temperature, while gain 410 at 125 ° C. Changes to less than -3 dB. This change occurs because the pressure of the cavity 501 is increasing as described above.

  When the acceleration sensor device 100 is diagnosed in a room temperature environment, the gain 408 of the first frequency and the gain 409 of the second frequency are both 0 dB, and the diagnosis result is “normal”. However, when the environmental temperature of the acceleration sensor device 100 changes to 125 ° C., the gain 410 becomes less than −3 dB, so the acceleration sensor device 100 can not achieve the frequency response specification. Thus, even in the case of an individual diagnosed as normal at normal temperature, a leak may occur in the cavity 501, and there may be an individual who should be diagnosed as abnormal. Such a situation is likely to occur when the degree of leakage of the cavity 501 is mild.

  With respect to such a phenomenon, it is desirable that when the acceleration sensor device 100 is diagnosed in a room temperature environment, it is possible to predict a failure that may occur in the 125 ° C. environment and detect the failure as the failure of the acceleration sensor device 100 itself. .

  Equation 1 shows the transfer function of the detection element.

G (s) = K ω _n ² / (s ² + (s ω _n / Q (P, T)) + ω _n ² ) (Equation 1)
Here, ω _n is a natural frequency of the detection element 102, Q is a mechanical quality factor (Q value) determined by the sealing atmosphere (ie, pressure P and temperature T) of the detection element 102, and K is a value of the detection element 102. It is a gain obtained by the scale factor (sensitivity) and the detection circuit 130. In addition, since Q is related to the pressure P, it is a coefficient related to damping.

  Referring to FIGS. 7A and 7B, a plurality of Q values are applied to Equation 1 to show the frequency response.

  FIG. 7A is a diagram showing an example of change in frequency response obtained by applying a plurality of Q values to Q in Equation 1.

  A1 to A4 show frequency responses under the condition of low Q value to high Q value respectively in order. Generally, the higher the temperature, the lower the Q value.

Now, since K is a constant and the natural frequency ω _n is determined by the structure, the frequency response is determined only by the Q value. Therefore, using gains at room temperature at 100 Hz and 3000 Hz as shown in A5 and A6, using equation 1 with K and ω _n fixed in equation 1, Q value at room temperature can be obtained by the method of data fitting it can. That is, Q that satisfies Equation 1 can be solved numerically through A5 and A6.

  FIG. 7B is a view showing the relationship between the temperature and the Q value of the detection element in which the pressure is fixed to a certain value.

  Since the relationship of FIG. 7B can be obtained in advance by design or measurement, the gain at any frequency and temperature can be estimated by Equation 1 from which the constant is obtained and the relationship between the temperature and the Q value shown in FIG. 7B.

  According to the method described above, the gain of 1000 Hz at 125 ° C. can be estimated by the gain of 100 Hz at normal temperature and the gain of 3000 Hz.

  By determining a failure (pressure abnormality) when the gain at 1000 Hz in a 125 ° C. environment is less than or equal to −3 dB according to this calculation, it is possible to prevent the erroneous determination of the condition which should be determined as the above-mentioned failure as normal. be able to.

  Also, unlike the previous examples, at least two of the at least two frequencies (first and second frequencies) used for diagnosis have a gain of frequency response when the cavity pressure of the detection element 102 becomes atmospheric pressure. It may be a changing frequency. For example, in the example using 200 Hz (first frequency) and 600 Hz (second frequency) in FIG. 4, the ratio of gain 402 to gain 404 and the ratio of gain 403 to gain 405 are obviously different. It is also possible to detect the pressure change of the cavity 501 from the change of the ratio of gain.

  That is, in a normal state, while the ratio of gain 402 to gain 404 is a value close to 1, the ratio of gain 403 to gain 405 (absolute value of gain 405 / gain 403) is much more than 1 Become a big value. Therefore, when an appropriate threshold is set and the ratio of gain 403 to gain 405 (absolute value of gain 405 / gain 403) becomes equal to or larger than the threshold, the cavity 501 leaks. It can be determined that a pressure abnormality in the cavity 501 has occurred.

  In this case, the change of the ratio of the gains may be determined by the comparator 114 instead of the step S105 of FIG. 5 described above.

  The change in the ratio of the gains is detected and determined by the comparator 114 in FIG.

  If both the gain of the first frequency (first gain) and the gain of the second frequency (second gain) in the frequency response change when the cavity pressure of the detection element 102 becomes atmospheric pressure, the gain according to the temperature Although it is necessary to correct the gain ratio according to temperature (using the relationship of temperature to damping coefficient), there is no need for the process step of acquiring the frequency response of the detection element 102 in advance and storing it in memory. There is no cost for the work process.

  Next, with reference to FIG. 8, a configuration in which the acceleration sensor device 100 described in the first embodiment is linked with another system will be described. FIG. 8 is a block diagram showing the configuration of an application system in which an acceleration sensor device and a plurality of systems are connected via a bus in the first embodiment. In FIG. 8, the acceleration sensor device 100 is configured to cooperate with another system, but not limited to the acceleration sensor device 100, another sensor device to which the present invention is applied may be linked with another system. You may configure it.

  In FIG. 8, the application (system) not related to the safety system at the time of failure occurrence continues the use of the sensor, and the application (system) of the safety system is notified of the occurrence of the failure in the sensor to stop the use of the sensor. An example application is shown. Here, the acceleration sensor device 100 is connected to a plurality of devices such as an electronic control unit (ECU) 602, a navigation system 603, and a vehicle control system 604 via a communication bus 601, and the output of the acceleration sensor device 100 is an error of the navigation system 603. And the attitude detection of the vehicle in the vehicle control system 604.

  A process flow of determining whether each system can maintain the acceleration sensor device 100 will be described with reference to FIG. FIG. 9 is a diagram showing a processing flow for determining whether or not each system can be sustained with respect to the acceleration sensor device.

  In step S201, the self-diagnosis of the above-mentioned acceleration sensor device 100 is performed. As a result of the self-diagnosis of the acceleration sensor device 100, when the pressure in the cavity 501 is detected as abnormal in the comparator 114 of the detection circuit 130 (S202), the acceleration sensor device 100 transmits the ECU 602 via the communication bus 601. This is notified (S203). The ECU 602 that has received the notification of step S203 issues an instruction to stop using the output of the acceleration sensor device 100 or a failure flag of the acceleration sensor device 100 to a system sensitive to the failure of any sensor like the vehicle control system 604. (S204). On the other hand, the ECU 602 does not issue an instruction to stop the use of the output of the acceleration sensor device 100 and continues the output of the acceleration sensor device 100 for a system not sensitive to sensor failure, such as the navigation system 603 and other entertainment systems. To use (S205). That is, the ECU 602 determines whether or not each system can be sustained with respect to the acceleration sensor device 100 in accordance with the importance of the function. The process of step S204 has a higher priority than the process of step S205, and is performed prior to the process of step S205.

  The ECU 602 is not necessarily required to realize the process flow of FIG. 9, and the acceleration sensor device 100 detects its own failure and sends a signal with a failure flag to the communication bus 601 or uses a transmission ID that doubles as a failure flag. Alternatively, another system may be notified of the failure, and each system may determine itself whether or not the output of the acceleration sensor device 100 can be used.

  As described above, the method for diagnosing responsiveness of the detection element 102 obtained in the present embodiment can diagnose the pressure state from the gains at at least two different frequencies at the moment when the diagnosis is performed. For this reason, it is not necessary to obtain in advance the frequency response of the detection element 102 and store it in the memory. In addition, it is possible to carry out a response diagnosis of the detection element 102 such that the gain at the resonance frequency does not exceed 0 dB, regardless of the temperature of the installation environment.

  Further, although the example of the acceleration sensor device has been described in the present embodiment, a spring-mass based vibrator is configured in a cavity of a pressure state different from atmospheric pressure, like the pressure detection element or the acceleration detection element 102, for example. , And other physical quantity detection elements.

Example 2
The configuration of an acceleration sensor device 100 according to an embodiment (second embodiment) of the present invention will be described with reference to FIGS. 10 and 11. FIG. FIG. 10 is a diagram showing the configuration of the acceleration sensor device in the second embodiment, and is a diagram showing an example of performing correction or configuring a double system using a pressure sensor device. FIG. 11 is a diagram showing a processing flow of the detection circuit in the second embodiment. About the part which has the function same as the content as described in FIG. 2 and FIG. 5, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In this embodiment, a system configuration example in the case of correcting the atmospheric pressure using the pressure sensor 701 or creating a double system for diagnosing a failure from the contradiction between the atmospheric pressure and the sealing pressure of the acceleration detection element 102 Explain.

  In the present embodiment, the pressure sensor 701 is incorporated in the acceleration sensor device 100.

  If the sealing pressure of the acceleration detection element 102 is 80 kPa, even if a leak occurs in the cavity 501 of the detection element 102, the leak may not be detected. For example, in the Takayama region, since the atmospheric pressure may be 80 kPa, the configuration of the first embodiment can not detect a leak. Such problems do not occur if the detection element 102 is sealed at a low pressure that can not occur in a normal environment. In this embodiment, the case where a sealing pressure that can be generated in a normal environment such as 80 kPa is selected will be described.

  In the present embodiment, when the pressure of the installation environment of the acceleration sensor device 100 detected by the pressure sensor 701 is close to the sealing pressure of the detection element 102, a flag indicating the failure of the comparator 701 in the diagnosis of the acceleration sensor device 100. Output For this purpose, the pressure of the installation environment detected by the pressure sensor 701 is input to the comparator 701, and the comparator 701 compares the pressure of the installation environment with the sealing pressure in step 106. The comparator 701 stores a pressure range threshold value for determining that the differential pressure is zero or close to the differential pressure between the pressure of the installation environment and the sealing pressure. The comparator 701 compares the differential pressure with the threshold of the pressure range (S106), and outputs a failure flag if the differential pressure is smaller than the threshold (S107), and proceeds to step 101 if the differential pressure is larger than the threshold. If the value of the differential pressure is equal to the threshold value, the process may proceed to step 107 to output a failure flag, or may proceed to step 101.

  As described above, even if a leak occurs in the cavity 501 of the detection element 102, the acceleration sensor device 100 is installed in an environment where the leak can not be detected. When a close situation is detected, the output as the acceleration sensor device 100 is notified not to be used in various systems regardless of whether a leak actually occurs. This keeps each system on the safe side.

  Note that when this notification is received, a system that is sensitive to the failure of any sensor, such as the vehicle control system 604, stops using the output of the acceleration sensor device 100, and the navigation system 603, other entertainment systems, etc. A system not sensitive to sensor failure may continue to use the output of the acceleration sensor device 100.

  In the present embodiment, the pressure sensor 701 is included in the determination unit (determination circuit unit) 130B2.

[Example 3]
The configuration of an acceleration sensor device 100 according to an embodiment (third embodiment) of the present invention will be described with reference to FIG. FIG. 12 is a diagram showing the configuration of an acceleration sensor device according to a third embodiment, and is a diagram showing a system configuration in the case of configuring a sensor device that controls the acceleration sensor with the same ASIC as the angular velocity sensor. Here, parts having the same functions as the contents described in FIG. 2 are assigned the same reference numerals and descriptions thereof will be omitted.

  In general, when angular velocity and acceleration are controlled by one ASIC, the clock of the ASIC is synchronized with the angular velocity detection element 802. Therefore, the ASIC itself can not know the oscillating frequency by itself (depending on the resonance frequency of the connected angular velocity detection element 802). Therefore, the value of the resonance frequency of the angular velocity detection element 802 is stored in the memory, and the system configuration is configured to perform vibration based on this. The details will be described below.

  In the present embodiment, a vibration type angular velocity sensor device 800 for detecting an angular velocity is incorporated in the sensor package 801.

  The vibration type angular velocity sensor device 800 employs the detection principle of detecting the Coriolis force generated in proportion to the angular velocity when vibrating the angular velocity detection element 802 at a predetermined amplitude at a resonance frequency, and obtaining the angular velocity.

  Here, the drive control unit 805 that controls the drive amplitude and frequency through the CV converter 803 and the ADC 804 to maintain the vibration amplitude and maintain the vibration at the resonance frequency is an oscillator (PLL, Phase Locked Loop, or VCO, Voltage Controlled Oscillator) ) Is connected to 814. The oscillator 814 is connected to the DAC 815, and the output of the oscillator 814 is input to the DAC 815. The DAC 815 outputs a drive voltage having the frequency of the output signal of the oscillator 814. The DAC 815 is connected to the divider 107 of the detection circuit 130 of the acceleration sensor device 100, and the drive voltage output from the DAC 815 is input to the divider 107.

  By this control loop, the angular velocity detection element 802 maintains the resonance frequency and the vibration of the predetermined amplitude.

  Further, since the Coriolis force caused by the application of the angular velocity appears as a displacement of the angular velocity detection element 802, the displacement is output through the CV converter 806, the ADC 807, the displacement detection circuit 808, the LPF 809, the correction unit 810 and the limiter 811, and the vibration type angular velocity sensor device The angular velocity output 812 detected at 800 is notified to the host system.

  In the acceleration sensor device 100 mounted on the sensor package 801, the output of the oscillator 814 for vibrating the angular velocity detection element 802 is input to the frequency divider 107, and the same operation as that of the first embodiment is performed. To achieve.

  With this configuration, the size of the detection circuit 130 can be reduced because it is not necessary to have two oscillators in the sensor package 801.

  Note that in the configuration in which the oscillation frequency of the oscillator (PLL) 814 is locked to the resonance frequency of the angular velocity detection element 802 as in the configuration shown here, the oscillator (PLL) 814 generates when the resonance frequency of the angular velocity detection element 802 varies. The frequency also varies according to the variation of the angular velocity detection element 802. In this embodiment, since the frequency of the oscillator (PLL) 814 is divided (or multiplied) by the frequency divider 107, the frequency of the diagnostic signal generated for diagnosis of the acceleration sensor device 100 is also an angular velocity detection element. It fluctuates according to the resonance frequency dispersion of 802.

  Here, although the oscillator (PLL) 814 can determine whether it is locked to the resonance frequency of the angular velocity detection element 802, it can not know the frequency of the signal generated by itself. Therefore, the frequency of the diagnostic signal generated for diagnosis of the acceleration sensor device 100 can not be known by the detection circuit 130 alone.

  In order to solve this problem, in the present embodiment, the detection circuit 130 is provided with the non-volatile memory 813, and the resonance frequency of the angular velocity detection element 802 is stored therein. After the oscillator (PLL) 814 is locked to the resonance frequency of the angular velocity detection element 802, the oscillator (PLL) 814 generates the resonance frequency of the angular velocity detection element 802 (or its frequency divided wave). Therefore, based on the resonance frequency stored in the non-volatile memory 813, the division ratio of the divider 107 is changed, and at least two diagnostic frequency signals determined for responsiveness diagnosis of the acceleration detection element 102 are obtained. Generate

  With such a configuration, the output of the oscillator 814 locked to the resonance frequency of the angular velocity detection element 802 can be used for the responsiveness diagnosis of the acceleration detection element 102.

  In this embodiment, the vibration signal generation unit (vibration signal generation circuit unit) 130A1 described in the first embodiment includes a non-volatile memory 813 and an oscillator (PLL) 814. Instead, the excitation signal generator does not include the clock source 106.

  In the present embodiment, the acceleration sensor device 100 is configured as described in the first embodiment, but may be configured as described in the second embodiment.

Example 4
The configuration of an acceleration sensor device 100 according to an embodiment (fourth embodiment) of the present invention will be described with reference to FIG. FIG. 13 is a diagram according to the fourth embodiment and shows an application example in which a clock is input to the sensor device from an external clock source such as a microcomputer. Here, the acceleration sensor package 101 is mounted on the substrate 901 and connected to the microcomputer 902 through the wire 904. The microcomputer 902 is supplied with a clock from a crystal external oscillator 903.

  In this embodiment, the crystal external oscillator 903 is responsible for the function of the clock source 106 in the first and second embodiments, and the microcomputer 902 is responsible for the function of the frequency divider 107. That is, the crystal external oscillator 903 is a component of the vibration signal generation unit (vibration signal generation circuit unit) 130A1.

  An alternating current signal (which may be a clock or a sine wave signal directly driving the detection mass 502) for diagnosis of the acceleration detection element 102 is provided through the wiring 904. For this reason, generally, a high precision crystal external oscillator can be used to realize the same configuration as that of the first embodiment, and high frequency accuracy can further improve the accuracy of diagnosis.

  Although this embodiment shows an example using a microcomputer and a crystal external oscillator, a configuration using an oscillator provided outside the sensor package may be used.

[Example 5]
The configuration of an acceleration sensor device 100 according to an embodiment (fifth embodiment) of the present invention will be described with reference to FIGS. 14, 15, and 16. FIG.

  FIG. 14 is a diagram showing a configuration example of a circuit of a sensor device (acceleration sensor device) which realizes a step response in the fifth embodiment. FIG. 15 is a diagram showing a process flow of the detection circuit in the fifth embodiment. About the part which has the function same as the content as described in FIG. 2 and FIG. 5, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the present embodiment, different from the first embodiment, the step input is used for the responsiveness diagnosis of the acceleration detection element 102. The step input is generated by the DAC 1101 triggered by the step trigger 1102 and applied to the diagnostic electrode positive side 509 or the negative side 510 of the detection element 102 (see FIG. 2) described in FIG. 1A (step S301 in FIG. 15). ). The electrostatic force generated by this step input gives a step response displacement to the detection mass 502 of the acceleration detection element 102. The step response displacement is detected by the CV converter 103, and the detected step response displacement is converted into a digital value through the ADC 104 (step S302 in FIG. 15). The step response displacement converted into the digital value is sampled by the sampler 1103 in synchronization with the step input timing of the step trigger 1102 (step S303 in FIG. 15).

  The DAC 1101, the diagnostic electrode positive side 509, the negative side 510, the diagnostic voltage application part positive side 511, the negative side 512 and the like constitute an excitation part (excitation circuit part) 130 that excites a vibrator. The step trigger 1102 is also included in the components of the excitation unit 130. In particular, the step trigger 1102 constitutes an excitation signal generation unit (oscillation signal generation circuit unit) 130A1 that generates an excitation signal for exciting a vibrator.

  FIG. 16 is a diagram according to the fifth embodiment and shows an example in which the same diagnosis is realized by the step response. FIG. 16 shows time-series signals obtained by the sampler 1103.

  The step response 1001 shows the step response in the state where the cavity pressure of the acceleration detection element 102 is normal and satisfies the response specification. A step response 1002 shows a step response in a state where the cavity pressure of the acceleration detection element 102 is increased due to a leak or the like, and the response specification is insufficient. The sampler 1103 starts sampling the output of the ADC 104 in synchronization with the input of the step trigger 1102. In addition, the step response output after a predetermined time elapses from the sampling start time, which is determined in advance, is sent to the amplitude comparator (amplitude comparison unit) 1104 in the subsequent stage (step S304 in FIG. 15). Here, for example, the step response (second step response, second normalized amplitude) at the point of time (second time) with a normalization time of 1 second and the point of time (first time) with a normalization time of 1.8 seconds The example which obtains step response (1st step response, 1st normalization amplitude) is shown. That is, the step response value 1004 or the step response value 1005 at the time of 1 second which is the second step response, and the step response value 1003 at the time of 1.8 seconds which is the first step response It is sent to the container 1104. The first step response value 1004 is a step response value when there is no abnormality in the cavity pressure, and the second step response value 1005 is a step response value when there is an abnormality in the cavity pressure. Further, the first step response value 1003 at the time of 1.8 seconds is a constant value regardless of the presence or absence of an abnormality in the cavity pressure, and the normalized amplitude value is 1.

  The amplitude comparator 1104 calculates the ratio between the second step response value 1004 or the second step response value 1005 and the first step response value 1003 (step S305 in FIG. 15). Here, similarly to the comparison of the gains of the plurality of frequency responses shown in the first embodiment, the principle is that the ratio is 1 when there is no cavity pressure abnormality, and the ratio deviates from 1 when there is a cavity pressure abnormality. Diagnosis (determination of normality / abnormality) is performed (step S306 in FIG. 15).

  In the present embodiment, the detection circuit 130 is composed of the above-described vibration unit (vibration circuit unit) 130A and a response amplitude detection unit (response amplitude detection circuit unit) 130B. The response amplitude detection unit 130B is a part (circuit unit) that detects the response amplitude (normalized amplitude) of the detection element 102, and the CV converter 103, the ADC 104, the step trigger 1102, the sampler 1103, the amplitude comparator 1104, and the temperature sensor It consists of 117. In particular, the CV converter 103, the ADC 104, the step trigger 1102, and the sampler 1103 obtain the first response amplitude and the second response amplitude corresponding to the first time and the second time which are two different points on the frequency axis of the response amplitude. The response amplitude acquisition unit (response amplitude acquisition circuit unit) 130B1 is configured. The amplitude comparator 114 and the temperature sensor 117 constitute a determination unit (determination circuit unit) 130B2 that determines the presence or absence of pressure abnormality in the cavity 501 based on the relative relationship between the first response amplitude and the second response amplitude.

  In FIG. 14, the CV converter 103, the ADC 104, the LPF 105, the correction unit 120, and the limiter 121 constitute an acceleration detection unit 130C that detects an acceleration.

  With this configuration, the diagnosis can be performed from the output of at least two step responses at the moment when the diagnosis is performed, so it is not necessary to obtain the step response of the detection element 102 in advance and store it in the memory. It is possible to carry out the responsiveness diagnosis of the detection element 102 such that the gain of the signal does not exceed 0 dB regardless of the temperature of the installation environment.

  In the embodiments described above, there are an embodiment using frequency responses 301, 302, 406, and 407, and an embodiment using step responses 1001 and 1002. In the embodiment using the frequency responses 301, 302, 406 and 407, the response amplitude (i.e., gain) of the detection element 102 (or the transducers 502 and 507) to the vibration of the transducers 502 and 507 is obtained. That is, in the gain characteristics in the Bode diagram representing the frequency response, first response amplitudes (first gains) 401, 402, 403 and second response amplitudes (second gains) 402, corresponding to the first frequency and the second frequency. Acquire 403, 405, 405. In the embodiment using the step responses 1001 and 1002, the response amplitude (that is, normalized amplitude) of the detection element 102 (or the transducers 502 and 507) to the vibration of the transducers 502 and 507 by the step input is acquired. That is, in the step response, the first response amplitude (first normalized amplitude) 1003 and the second response amplitude (second normalized amplitude) 1003 and 1005 corresponding to the first time and the second time are acquired. Then, the presence or absence of pressure abnormality in the cavity 501 is determined based on the relative relationship between the first response amplitude and the second response amplitude.

  The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the embodiments described above are described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. In addition, with respect to a part of the configuration of each embodiment, it is possible to add, delete, and replace other configurations.

  DESCRIPTION OF SYMBOLS 100 ... Acceleration sensor apparatus, 101 ... Sensor package, 102 ... Detection element, 103 ... Capacity-voltage converter, 104 ... ADC, 105 ... LPF, 106 ... Clock source, 107 ... Divider, 108 ... Synchronous detection part, 109 ... Demodulator 110 Phase delay 111 111 LPF Absolute value calculator 113 Amplitude detector 114 Comparator 117 Temperature sensor 118 First DAC 119 Second DAC 120 correction unit 121 limiter 130 detection circuit 130A excitation unit (excitation circuit unit) 130A1 excitation signal generation unit (excitation signal generation circuit unit) 130B response amplitude detection unit 130B1 ... Response amplitude acquisition unit (response amplitude acquisition circuit unit), 130B2 ... determination unit (determination circuit unit), 130C ... acceleration detection unit, 201 to 206, 301, 302 ... frequency response , 401 to 405, frequency response, 408, first gain, 409, 410, second gain, 501, cavity, 502, detection mass, 503, capacitance type detection electrode positive side, 504,. Capacitive detection electrode negative side, 505: DC voltage, 506: AC voltage, 507: elastic deformation portion, 508: damper, 509: diagnostic electrode positive side, 510: diagnostic electrode negative side, 511: diagnostic voltage application part positive Side 512: diagnostic voltage application unit negative side 514: fixed unit 515: wiring unit 516: capacitance voltage converter 601: communication bus 602: ECU 603: navigation system 604: vehicle control system 701 Pressure sensor 800 vibration type angular velocity sensor device 801 sensor package 802 angular velocity detection element 803 CV converter 804 ADC 80 ... Drive control unit, 806 ... CV converter, 807 ... ADC, 808 ... Displacement detection circuit, 809 ... LPF, 810 ... Correction unit, 811 ... Limiter, 814 ... Oscillator, 815 ... DAC, 901 ... Substrate, 902 ... Microcomputer, 903 ... Crystal external oscillator, 904 ... Wiring, 1001, 1002, 1003 ... Step response, 1102 ... Step trigger, 1103 ... Sampler, 1104 ... Amplitude comparator.

Claims (12)

A sensor device comprising: a hermetically sealed cavity; and a detection element provided inside the cavity and having a vibrator.
And a response amplitude detection unit configured to detect a response amplitude of the detection element with respect to the vibration of the vibrator.
The response amplitude detection unit is configured to generate a first response amplitude and a second response corresponding to a first frequency and a second frequency, or a first time and a second time, which are two different points on the frequency axis or the time axis of the response amplitude. A response amplitude acquiring unit that acquires an amplitude, and a determination unit that determines the presence or absence of pressure abnormality in the cavity based on a relative relationship between the first response amplitude and the second response amplitude. Sensor device. In the sensor device according to claim 1,
Among the first frequency and the second frequency or the first time and the second time, the first frequency or the first time corresponds to a change in the sealing pressure of the cavity to atmospheric pressure. The first response amplitude is a frequency or time at which no change occurs, and the second frequency or the second time corresponds to the second response amplitude of the detection element when the sealing pressure of the cavity changes to atmospheric pressure. Sensor device characterized in that it is a frequency or time at which a change occurs. In the sensor device according to claim 2,
The first response amplitude and the second response amplitude are respectively response amplitudes corresponding to the first frequency and the second frequency for vibrating the vibrator,
The first frequency is a frequency having a gain characteristic based on the response amplitude of the detection element of -3 dB or more, and the second frequency is a gain characteristic based on the response amplitude of the detection element of 0 dB or less and -60 dB A sensor device characterized by having a frequency having the above. In the sensor device according to claim 1,
A sensor characterized in that the detection element is sealed at a pressure at which amplification of vibration amplitude due to a resonance phenomenon does not occur when excited at the resonance frequency of the detection element in a state where the pressure of the cavity is normal. apparatus. In the sensor device according to claim 1,
The first response amplitude and the second response amplitude are response amplitudes corresponding to the first frequency and the second frequency, respectively.
The sensor device, wherein the first frequency and the second frequency are generated using output signals output from the same oscillator. In the sensor device according to claim 5,
The sensor device, wherein the detection element detects an acceleration. In the sensor device according to claim 6,
An angular velocity detection element; and an oscillator for driving the angular velocity detection element,
A sensor device characterized in that an oscillator for driving the angular velocity detection element doubles as the oscillator for generating the first frequency and the second frequency. In the sensor device according to claim 7,
A memory for storing a value of a resonant frequency of the angular velocity detection element;
A sensor device characterized in that while the oscillator is locked to the resonant frequency and synchronized with the resonant frequency, the resonant frequency is divided or multiplied to obtain the first frequency and the second frequency. In the sensor device according to claim 1,
Using a coefficient related to temperature and damping, calculate the change in responsiveness of the detection element when the temperature rises, and diagnose the detection element based on the calculation result of the change in responsiveness. Sensor device. In the sensor device according to claim 5,
A sensor device characterized in that the oscillator is configured by an oscillator installed outside the sensor device. In the sensor device according to claim 5,
It has a pressure sensor that detects the environmental pressure at which the sensor device is installed,
The sensor device characterized by outputting a flag which shows a fault, when the pressure difference with the pressure by which the environmental pressure was sealed airtightly of the said cavity is smaller than predetermined value. A system comprising the sensor device according to claim 1 and a plurality of devices using the output of the sensor device.
A system comprising: an apparatus for continuing the output use of the sensor device and an apparatus for stopping the output use of the sensor device when the determination unit determines that there is pressure abnormality in the cavity.

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