JP2006126095A - Abnormality detection device for sensor, abnormality detection method for sensor, acceleration measuring device and acceleration measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality detection device for a sensor, an acceleration measuring device and detection methods therefor, capable of determining surely disconnection of a sensor cable 4 for connecting a piezoelectric sensor 3 to a charge amplifier 5. <P>SOLUTION: In the abnormality detection device for the sensor, its method, the acceleration measuring device and its method, a switch 9 is interposed in a sensor cable 4 for connecting the piezoelectric acceleration sensor 3 to a common terminal of an operation amplifier OP of the charge amplifier 5, and an alternating voltage is supplied from a voltage signal supply source 11, and an output from the operation amplifier OP is observed, to thereby enable determination of an abnormal state of the sensor cable 4 or the piezoelectric acceleration sensor 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piezoelectric sensor, a sensor abnormality detection device such as a disconnection of a cable connected to the piezoelectric sensor, a sensor abnormality detection method, an acceleration measurement device, and an acceleration measurement method. The present invention relates to a sensor abnormality detection device, a sensor abnormality detection method, an acceleration measurement device, and an acceleration measurement method that can easily detect cable disconnection, sensor deterioration, and the like.

  Conventionally, various sensor detection devices such as piezoelectric acceleration sensors and sensor detection methods have been proposed. FIG. 5 is a system diagram of the vibration sensor disconnection detection apparatus disclosed in Patent Document 1.

  In FIG. 5, a yaw rate sensor (Yow Rate Sensor) 50 detects an angular velocity acting on the yaw rate sensor 50. The yaw rate sensor 50 vibrates when the drive signal A is applied, and sends a pair of detection signals B and C to the respective lines 53 and 54 via the charge amplifiers 51 and 52. The differential amplifier 55 receives the detection signals B and C and outputs a signal D indicating the difference between the detection signals B and C. The AC amplifier 56 amplifies the signal D and outputs a signal E. The synchronous detector 57 inverts the signal E every half cycle of the drive signal A, forms a signal F, and outputs it. The integrator 58 integrates the signal F, forms a signal G, and outputs it.

  FIG. 6 is a timing chart showing the waveform of each signal in the apparatus of FIG. In FIG. 6, the drive signal A is a square wave and is applied to the yaw rate sensor 50 to vibrate the yaw rate sensor 50. A pair of detection signals B and C are sent from the yaw rate sensor 50 to the signal lines 53 and 54 through the charge amplifiers 51 and 52, respectively. These detection signals B and C include a component of the drive signal A caused by crosstalk. The components of the drive signal A included in these detection signals B and C are removed by the differential amplifier 55, and the signal D is obtained. This signal D includes a signal component of vibration leakage generated due to the structure of the yaw rate sensor 50. This signal D is amplified by the AC amplifier 55, the signal E is inverted every half cycle of the drive signal A by the synchronous detector 57, and when the signal F is integrated by the integrator 58, this causes the vibration included in the signal E. The leakage signal component is removed, and a signal G indicating only a component detected by the yaw rate sensor 50, that is, an angular velocity acting on the yaw rate sensor 50 can be obtained.

  Usually, the level of the signal G is in the range of −100 mV to +100 mV. The disconnection of each of the signal lines 53 and 54 is detected by comparing the output of the integrator 58 with a predetermined threshold value.

  FIG. 7 is a timing chart showing the waveform of each signal when the signal line 53 is disconnected. In FIG. 7, since the signal line 53 is disconnected, the level of the detection signal B on the signal line 53 is “0”. In this case, the level of the signal G becomes +500 mV or higher. As described above, since the level of the signal G is normally -100 mV to +100 mV, when the signal line 53 is disconnected and the level of the signal G becomes +500 mV or more, the level of the signal G is set to a predetermined threshold value. As a result, the disconnection of the signal line 53 can be determined.

  When the signal line 53 is disconnected, the detection signal B on the signal line 54 becomes a signal component fed back by the differential amplifier 55 by the feedback circuit. In this case, the level of the signal G is −100 mV to +100 mV. As described above, since the level of the signal G is normally −100 mV to +100 mV, the signal line 54 is disconnected and the level of the signal G becomes −100 mV to +100 mV. Although the disconnection of the signal line 54 cannot be determined, these problems are solved by another method in the above-mentioned Patent Document 1.

  An acceleration monitor that measures a bearing vibration of a rotating machine by combining a piezoelectric acceleration sensor and a charge amplifier is also well known. FIG. 8 shows an acceleration monitor disclosed in Non-Patent Document 1. In FIG. 8, reference numeral 70 denotes a rotating machine shaft or the like on which a piezoelectric acceleration sensor 72 is mounted to detect vibration on a bearing 71. A detection signal of a sensor cable 73 connected to an electrode of the acceleration sensor 72 is charged. The signal is given to the acceleration monitor 76 via the amplifier 74 via the extension cable 75. The acceleration monitor 76 includes a display unit 77 such as an LCD, and is configured to output an alarm stop signal when vibration level data or preset acceleration is generated by power supply from the power input terminal. .

  Now, even if the disconnection detection device of Patent Document 1 is applied to the acceleration monitor disclosed in Non-Patent Document 1, the configuration compares the detection outputs of the subsequent stages of the charge amplifiers 51 and 52 as shown in FIG. Therefore, the disconnection state of the sensor cable 73 from the yaw rate sensor 50 or the piezoelectric acceleration sensor 72 shown in FIG. 8 to the charge amplifier 74 (51, 52) cannot be detected. Therefore, there is a problem that the abnormal state of the yaw rate sensor 50 and the piezoelectric acceleration sensor 72 and the disconnection of the sensor cable cannot be detected.

  Furthermore, since the piezoelectric acceleration vibration type sensor 72 such as the disconnection detecting device described in Non-Patent Document 1 described above outputs the charge Q corresponding to the vibration of the measured object as shown in FIG. It is not possible to detect the disconnection state (indicated by x) of the sensor cable 73 between the type acceleration sensors 72, and it is possible to detect an abnormality such as disconnection of the voltage output line such as the extension cable 75 subsequent to the charge amplifier 74. It was only a disconnection.

In FIG. 9, the electric energy generated by the piezoelectric acceleration sensor 72 is supplied as the charge Q to the non-inverting input terminal and the inverting input terminal of the operational amplifier 78 of the charge amplifier 74. The operational amplifier 78 includes a feedback circuit including a capacitor C1 and a resistor R1 that are connected in parallel between the non-inverting input terminal and the output terminal. The charge Q from the piezoelectric acceleration sensor 72 and the output of the operational amplifier 78 are applied to the non-inverting input terminal of the operational amplifier 78, and the reference voltage Vo is applied to the inverting input terminal. The operational amplifier 78 always operates so that the voltage determined by the input charge Q of the non-inverting input terminal, the resistor R1, and the capacitor C1 appears at the output of the operational amplifier 78, and outputs the detection signal _VOUT to the output terminal T.

Therefore, the charge Q generated by the piezoelectric acceleration sensor resembles static electricity, and it is impossible to take out a current while maintaining the generated voltage. For example, when a voltmeter is connected, the generated voltage immediately drops to zero V, and the voltage cannot be taken out from the sensor cable 73.
JP 2000-146594 A (FIG. 8) Electronic Application 73-A Acceleration Monitor, Internet http // www.aec-jpn.com / seihinservice / moniter / 73-a / 73aindex.htm, 2004/10/13

  The present invention has been made to solve the above-described problems. The problem to be solved by the present invention is that the sensor cable 73 between the piezoelectric acceleration sensor and the charge amplifier is disconnected and the internal state of the piezoelectric sensor itself is disconnected. The present invention also provides a sensor abnormality detecting device, a sensor abnormality detecting method, an acceleration measuring device, and an acceleration measuring method capable of detecting an abnormality such as a deterioration state of a piezoelectric sensor.

  A sensor abnormality detection device according to a first aspect of the present invention is a sensor abnormality detection device in which a piezoelectric sensor and a charge amplifier are connected by a sensor cable and a sensor output signal is extracted from the charge amplifier. Switching means for detecting an abnormality interposed between the input common side of the charge amplifier and a voltage signal supply source for supplying an AC signal to the piezoelectric sensor via the switching means, and switching the switching means An AC signal is supplied from a voltage signal supply source to the piezoelectric sensor, and an abnormality of the sensor cable or the piezoelectric sensor is detected.

  According to a second aspect of the present invention, there is provided an acceleration measuring apparatus in which a piezoelectric sensor and a charge amplifier are connected by a sensor cable, and a sensor output signal is extracted from the charge amplifier. An abnormality detection switching means interposed between the input common sides, a voltage signal supply source for supplying an AC signal to the piezoelectric sensor via the switching means, and at least monitoring means connected to the subsequent stage of the charge amplifier An acceleration measuring device main body, switching the switching means and supplying an AC signal from a voltage signal supply source to the piezoelectric sensor, detecting an abnormality of the sensor cable or the piezoelectric acceleration sensor, and monitoring the monitoring means. Made.

  A sensor abnormality detection method according to a third aspect of the present invention is a sensor abnormality detection method in which a piezoelectric sensor and a charge amplifier are connected by a sensor cable and a sensor output signal is extracted from the charge amplifier. Switching the abnormality detection switching means interposed between the input common side of the charge amplifier to the abnormality detection mode, supplying an AC signal from the voltage signal supply source to the piezoelectric sensor via the switching means, An abnormality of the sensor cable or the piezoelectric sensor is detected via the.

  According to a fourth aspect of the present invention, there is provided an acceleration measuring method in which a piezoelectric sensor and a charge amplifier are connected by a sensor cable, and a sensor output signal is extracted from the charge amplifier. A step of switching an abnormality detection switching means interposed between the common sides to an abnormality detection mode; and a step of supplying an AC signal from the voltage signal supply source to the piezoelectric sensor via the switching means. At least the monitoring means connected to the subsequent stage, the switching means is switched by the main body of the acceleration measuring device, and an AC signal is supplied from the voltage signal supply source to the piezoelectric sensor to detect an abnormality in the sensor cable or the piezoelectric acceleration sensor. This is designed to be monitored by the monitoring means.

  Thus, according to the present invention, it is possible to detect the disconnection state of the sensor cable and determine whether the wire in the piezoelectric acceleration sensor is disconnected or whether the sensor body can be deteriorated. An abnormality detection device, a sensor abnormality detection method, an acceleration measurement device, and an acceleration measurement method can be obtained.

  A configuration of a sensor abnormality detecting device and an acceleration measuring device according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a system diagram showing an entire acceleration measuring apparatus incorporating a sensor detection device of the present invention, FIG. 2 is a principle diagram for explaining the principle of disconnection detection of the present invention, and FIG. 3 is a sensor detection of the present invention. FIG. 4 is a specific configuration diagram and principle explanatory diagram of a sensor used in the present invention.

  In FIG. 1, reference numeral 1 denotes a base on which a measurement object 2 is placed. A predetermined vibration is applied to the measurement object 2, and acceleration measurement for measuring the vibration speed and acceleration of the measurement object 2. The device 10 includes a piezoelectric sensor 3, a charge amplifier 5, an acceleration measuring device body 7, and the like.

The piezoelectric sensor 3 is provided with electrodes above and below a dielectric having a predetermined thickness, such as barium titanate, so as to cause electric polarization in an electric field, and a potential generated when vibration is applied to the piezoelectric sensor 3 is taken out. Various piezoelectric sensors are commercially available for measuring vibrations and accelerations such as dynamic vibration analysis of structures and drop tests of packages. The piezoelectric acceleration sensor 3a shown in FIG. 4 (A) is an ultra-sensitive sensor having a sensitivity of 400 pc / m / s ² and a measured acceleration of 2000 m / s ² .

  In the piezoelectric acceleration sensor 3a of FIG. 4A, 3b is a cylindrical casing made of metal such as aluminum, and a base 3c is provided on the lower surface of the casing 3b, and a coaxial cable such as BNC is provided on the upper surface. A sensor element 3d in which a receptacle 3c is provided and electrodes 3e and 3f [see FIG. 4B] are provided above and below a disk-like bulk body such as barium titanate in a casing 3b is a buffer member. Is disposed in the casing 3b so as to be swingable.

When electrodes 3e and 3f are provided above and below the bulk of the sensor element 3d as shown in FIG. 4B and voltage V is applied thereto, an electric field E is applied to the sensor element 3d. Now, assuming that the thickness d of the sensor element 3d is constant and the electric field E is uniform, the electric field E can be expressed by V / d (v / m). A current i equal to the charge Q of the sensor element 3d flows at the moment of application of the electric field, and the charge Q becomes equal to a value obtained by integrating the current idt from 0 to ∞. There induce electrical polarization occurring micro altered electric dipole 3g by application of an electric field E, plus this time, the negative polarization charge electrode 3e to neutralize the end of the electric dipole 3g Q _b and the electrode 3f polarization charge Q _f correspond to flow into the bulk. Here, charge Q = Q _b + Q _f , and Q is Q = ∫idt obtained by integrating idt from 0 to infinity. Such an electrically polarized sensor element 3d generates mechanical strain in proportion to the electrical polarization, and this phenomenon is reversible, and the electrical strain generated when mechanical strain is applied to the sensor element 3d. The potential generated during polarization is proportional to the magnitude of strain. The piezoelectric sensor 3 uses a sensor having such a piezoelectric effect.

As shown in FIG. 1, the plug seat 3 b of the piezoelectric sensor 3 is screwed with a plug (plug) attached to the tip of the sensor cable 4, and the other end of the sensor cable 4 is in the charge amplifier 5. Connected to the inverting input terminal of the operational amplifier OP, the other end of the sensor cable 4 is connected to the movable contact a of the switch 9 constituting the switching means. A parallel circuit comprising a feedback resistor R1 and an integrating capacitor C1 is connected between the output terminal and the inverting input terminal of the operational amplifier OP. A fixed contact b of the switch 9 is connected to the reference power supply V ₀ which non-inverting terminal and the charge amplifier 5 of the operational amplifier OP, a fixed contact c of the switch 9 is connected to a voltage signal source 11 for generating an AC signal.

The output of the operational amplifier OP of the charge amplifier 5 is supplied to the analog-digital conversion circuit (ADC) 12 of the acceleration measuring device 7 through the extension cable 5. The measurement speed data and acceleration data converted into digital data by the ADC 12 are output to the output terminal T ₁ via the computer (CPU) 13. The output of the deterioration state of the piezoelectric sensor 3 and the disconnection state of the sensor cable 4 is output to the output terminals T ₂ and T ₃ . Reference numeral 14 denotes an operation unit composed of a group of various operation keys attached to the casing of the acceleration measuring device main body 7. Reference numeral 15 denotes display means such as a monitor LCD attached to a predetermined position of the casing. Reference numerals 16 and 17 denote CPUs 13. Are the RAM and ROM for work normally possessed by.

  In the acceleration measuring apparatus 10 described above, the switch 9 and the voltage signal supply source 11 are separated from the charge amplifier 5 and are provided in the acceleration measuring apparatus main body 7. However, as shown in FIG. It is possible to arrange the source 11 in the charge amplifier 5. Further, a power supply terminal may be provided in the charge amplifier 5, the switch 9, and the voltage signal source 11 in the casing 3 b shown in FIG. 4A constituting the piezoelectric sensor 3.

Next, based on FIG. 2 (A) and FIG. 2 (B), the operation | movement in the case of detecting the disconnection state of the sensor cable 4 is demonstrated. In FIG. 2A, the common side of the non-inverting input terminal of the operational amplifier OP of the charge amplifier 5 is disconnected and connected to the reference voltage source V0 through the fixed contact b of the switch 9, and the movable piece a of the switch 9 is connected to one end of the acceleration sensor 3 through the sensor cable 4, the voltage signal supply source 11 fixed contacts connected switch 9 c is an acceleration sensor 3 a voltage signal V _s of known AC through a movable contact piece a To supply. That is, the movable contact piece a of the switch 9 is switched to the fixed contact C side from the acceleration measurement state in which the movable contact piece a of the switch 9 is connected to the fixed contact b, and an abnormality of the piezoelectric acceleration sensor 3 is detected. . Piezoelectric acceleration sensor 3 is equivalently to the parallel circuit of the capacitor C _s and a resistor R _s in parallel with the charge generator CG that generates charges Q as shown in FIG. 3 (A) is connected configuration, the piezoelectric effect charge Q generated by appears as a voltage stored in the capacitor C _s. Since the resistance R _s in the equivalent circuit is very large, if it does not leak to the outside, the value is maintained for a very long time, but the electric energy generated in the sensor element 3d is taken out as a current while maintaining the generated voltage once. I can't. Therefore, even if a load resistor is connected, the charge leaks as indicated by Q shown in FIG. 4B and gradually drops to zero volt. Therefore, the disconnection or abnormality of the sensor cable 4 or the piezoelectric acceleration sensor cannot be detected, and only the disconnection of the extension cable 75 is detected.

Therefore, in the present invention, when the value of the equivalent capacitor of the piezoelectric acceleration sensor 3 is C _s and a known alternating voltage signal V _s is supplied from the voltage signal supply source 11 to the piezoelectric acceleration sensor 3 via the switch 9. The known voltage signal V _s is converted into a charge Q by the piezoelectric acceleration sensor 3, and a voltage output V is output from the charge amplifier 5 by measuring the voltage of a charge signal similar to that during normal speed or acceleration measurement. It converts to _out .

Charge Q of the above relationship shown in the equation 1 between the capacitance values C _s and known voltage signal V _s of capacitor.

(Equation 1) Q = C _s × V _s (1)

Moreover, the charge Q is the capacitance of the integrating capacitor C1 of the charge amplifier 5 the output voltage V _out and the C ₀ can be expressed by the number 2.

(Expression 2) V _out = C _s / C ₀ (2)

  Therefore, Formula 3 is obtained from the equations (1) and (2).

(Expression 3) V _out = C _s × V _s / C ₀ (3)

Depending, the charge amplifier when the switch the movable contact piece a of the switch 9 to the fixed contact c side, and supplied from the voltage signal supply source 11 a voltage signal V _s to the piezoelectric type acceleration sensor 3, and operates the piezoelectric acceleration sensor 3 long as the fifth output terminal T2 (T3) is output output V _out is, from the non-inverting terminal of the operational amplifier OP of the charge amplifier 5 (common terminal) between the piezoelectric type acceleration sensor 3, the piezoelectric type acceleration sensor 3 and an operational amplifier OP It can be recognized that there is no disconnection or abnormality in the sensor cable 4 and the piezoelectric acceleration sensor 3 between the inversion terminals. Of course, if the output voltage _Vout is zero, it is possible to recognize the disconnection or sensor failure of the sensor cable 4 and the piezoelectric acceleration sensor 3 described above.

Further, the capacitance value of the piezoelectric acceleration sensor 3 is obtained from the expression 3 of the value of the output voltage V _out of the charge amplifier 5 and is compared with the standard capacitance value of the piezoelectric acceleration sensor 3 known in advance, thereby the piezoelectric acceleration sensor. 3 can also be judged. In this case, the detection means may be configured by hardware using an operational amplifier or the like, or may be configured by software by the CPU 13.

Output impedance of the piezoelectric type acceleration sensor 3 are used the transistor of FET or MOS structure as the input impedance of the operational amplifier OP constituting the charge amplifier because the equivalent resistance R _s is large as shown in FIG. 2 (B). In FIG. 2, the value of the common _{C s} of the piezoelectric type acceleration sensor is 1000PF～10000pF, capacitance value _{C 0} of the integrating capacitor C1 connected in parallel with the resistor R1 for feedback of the operational amplifier OP is small gain In the case of, tens of thousands pF, and in the case of a large gain, it is about several hundreds pF.

  The operation of the acceleration measuring apparatus 10 equipped with the abnormality detection apparatus for the piezoelectric acceleration sensor 3 will be described with reference to the flowchart of FIG. In FIG. 1, before measuring the acceleration and speed of the measurement object 2 arranged on the base 1, an abnormality detection is performed to check whether the piezoelectric acceleration sensor 3 is good or defective and the sensor cable 4 is disconnected. To do. When the power source of the acceleration measuring apparatus main body is turned on (step S1), in the next second step S2, the movable contact piece a of the switch 9 is switched to the fixed contact c side, so that the disconnection check mode of the piezoelectric acceleration sensor 3 is set. Made. The acceleration data of the DUT 2 is output to the output terminal T1 through the path of the piezoelectric acceleration sensor 3-sensor cable 4-charge amplifier 5-ADC12-CPU13.

The following provides a voltage signal V _s of the AC from the third step S3 the voltage signal supply source (several V about OSC) 11 to the piezoelectric type acceleration sensor 3 through a switch 9. If the sensor cable 4 or sensor 3 is not disconnected, the output signal amplified by the charge amplifier 5 is digitally converted by the ADC 12 of the acceleration measuring device body 7 via the extension cable 6, and the CPU 13 performs the fourth step S4 based on the three equations. If V _out is calculated and V _out can be measured, disconnection between the piezoelectric acceleration sensor 3 and the common terminal (non-inverting input terminal) of the charge amplifier 5 and between the piezoelectric acceleration sensor 3 and the inverting input terminal of the charge amplifier 5 is disconnected. I understand that there is no. Therefore, in this case, the sensor cable 4 is in a NO state where the cable is not disconnected, and the process proceeds to the fifth step S5 to output an OK signal to the LCD 15. On the other hand, if V _out is not output in the fourth step S4, the process proceeds to the sixth step S6, and the N0 signal is output to the LCD 15.

  In the state of the fifth step S5, the process proceeds to the next seventh step S7, where the movable piece a of the switch 9 is switched to the fixed contact b side to set the next acceleration or speed measurement state as the measurement mode. Measurements are taken to the end. In the state of the sixth step S6, the sensor cable 4 is repaired in the next eighth step S8 and the end is reached.

In the above description of the operation, the presence or absence of disconnection of the sensor cable 4 is detected. However, the CPU 13 obtains the equivalent capacitance C _s of the piezoelectric acceleration sensor 3 from the three types of _Vout , for example, the known piezoelectric acceleration sensor 3. An abnormality of the piezoelectric acceleration sensor 3 may be detected by detecting a significant change in the sensor in comparison with the standard capacitance values tabulated.

  According to the sensor abnormality detection device, the sensor abnormality detection method, the acceleration measurement device, and the acceleration measurement method of the present invention, it is possible to check the disconnection of the sensor cable without greatly changing the normal acceleration measurement device. Further, regarding the connection between the charge amplifier and the piezoelectric acceleration sensor, it is possible to confirm the abnormality in all sections, and the reliability can be greatly improved. Furthermore, there is an effect that the user can obtain a sensor that can detect disconnection and abnormality of the sensor and the sensor cable only by switching the switch without changing the connection of the piezoelectric sensor in the acceleration or speed measurement mode.

1 is a system diagram of a sensor abnormality detection device and an acceleration measurement device according to an embodiment of the present invention. 1 is a circuit diagram for explaining the principle of a sensor abnormality detection device and an acceleration measurement device according to the present invention and an equivalent circuit of a piezoelectric sensor. It is a flowchart at the time of the disconnection detection of the abnormality detection apparatus of the sensor of this invention, and an acceleration measuring apparatus. It is the external view which shows one Example of the piezoelectric acceleration sensor used for this invention, and operation | movement explanatory drawing of a piezoelectric sensor. It is a systematic diagram which shows the abnormality detection apparatus of the conventional sensor. It is operation | movement explanatory waveform (I) of the conventional abnormality detection apparatus of a sensor. It is operation | movement explanatory waveform (II) of the abnormality detection apparatus of the conventional sensor. It is a systematic diagram of the conventional acceleration measuring device. It is a circuit diagram of the charge amplifier used for the conventional acceleration measuring device.

Explanation of symbols

2 ... Measured object, 3 ... Piezoelectric acceleration sensor, 4 ... Sensor cable, 5 ... Charge amplifier, 6 ... Extension cable, 7 ... Accelerometer main unit, 9 ... Switch, 10 ... Acceleration Measuring device, 11 ... Voltage signal supply source, 13 ... CPU, 15 ... LCD, T1, T2, T3 ... Output terminal, OP ... Operational amplifier

Claims (8)

In the sensor abnormality detection device, wherein the piezoelectric sensor and the charge amplifier are connected by a sensor cable, and the sensor output signal is extracted from the charge amplifier.
Anomaly detection switching means interposed between the sensor cable and the input common side of the charge amplifier,
A voltage signal supply source for supplying an AC signal to the piezoelectric sensor via the switching means;
Comprising
Abnormality detection of the sensor characterized by switching the switching means and supplying the AC signal from the voltage signal supply source to the piezoelectric sensor to detect abnormality of the sensor cable or the piezoelectric sensor. apparatus.   2. The sensor abnormality detection device according to claim 1, wherein the switching means and the voltage signal supply source are built in the charge amplifier.   The capacitance value of the piezoelectric sensor is registered as a judgment value in advance, and an abnormality of the piezoelectric sensor is detected from the output voltage value of the charge amplifier. Sensor abnormality detection device. In an acceleration measuring apparatus configured to connect a piezoelectric sensor and a charge amplifier with a sensor cable and take out a sensor output signal from the charge amplifier.
Anomaly detection switching means interposed between the sensor cable and the input common side of the charge amplifier,
A voltage signal supply source for supplying an AC signal to the piezoelectric sensor via the switching means;
An acceleration measuring device main body having at least monitoring means connected to a subsequent stage of the charge amplifier,
The switching means is switched and the AC signal is supplied from the voltage signal supply source to the piezoelectric sensor, and an abnormality of the sensor cable or the piezoelectric acceleration sensor is detected and monitored by the monitoring means. An acceleration measuring device characterized by the above.   5. The acceleration measuring device according to claim 4, wherein the switching means and the voltage signal supply source are built in the charge amplifier or the acceleration measuring device main body.   The capacitance value of the piezoelectric sensor is registered as a judgment value in advance, and the abnormality of the piezoelectric sensor is detected from the output voltage value of the charge amplifier, and is monitored by the acceleration measuring device main body. 6. The acceleration measuring apparatus according to claim 4 or 5, characterized in that: In the sensor abnormality detection method in which the piezoelectric sensor and the charge amplifier are connected by a sensor cable and the sensor output signal is extracted from the charge amplifier.
Switching the abnormality detection switching means interposed between the sensor cable and the input common side of the charge amplifier to an abnormality detection mode;
Supplying an AC signal from the voltage signal supply source to the piezoelectric sensor via the switching means;
An abnormality detection method for a sensor, characterized in that an abnormality of the sensor cable or the piezoelectric sensor is detected via a cable. In the acceleration measuring method in which a piezoelectric sensor and a charge amplifier are connected by a sensor cable and a sensor output signal is taken out from the charge amplifier.
Switching the abnormality detection switching means interposed between the sensor cable and the input common side of the charge amplifier to an abnormality detection mode;
Supplying an AC signal from the voltage signal supply source to the piezoelectric sensor via the switching means;
Comprising
The accelerometer has at least a monitoring unit connected to the subsequent stage of the charge amplifier, and the switching unit is switched by an acceleration measuring apparatus body, and the AC signal is supplied from the voltage signal supply source to the piezoelectric sensor. An acceleration measuring method characterized in that an abnormality of a type acceleration sensor is detected and monitored by the monitoring means.

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