JP4428079B2 - Angular velocity sensor - Google Patents

Description

  The present invention relates to an angular velocity sensor used for attitude control, navigation, and the like of a moving body such as an aircraft, an automobile, a robot, a ship, and a vehicle.

  Hereinafter, a conventional angular velocity sensor will be described with reference to the drawings.

  9 is a plan view of a vibrator of a conventional angular velocity sensor, FIG. 10 is a block diagram of the angular velocity sensor, and FIG. 11 is a waveform diagram of a drive signal, a monitor signal, and a sense signal of the angular velocity sensor.

  9 and 10, the conventional angular velocity sensor has a pair of arm portions 2 on a shaft portion 1, and a tuning fork type vibrator 3 made of a piezoelectric element, and the vibrator 3 are driven. And a control circuit unit 4 for detecting a given angular velocity.

  First, the vibrator 3 includes a drive electrode section 6 that inputs a drive signal 5 for vibrating the vibrator 3 at a specific frequency, and a monitor electrode section 8 that detects the vibration frequency of the vibrator 3 and outputs it as a monitor signal 7. And a sense electrode unit 10 that detects a synchronization frequency synchronized with the monitor signal 7 due to the angular velocity applied to the vibrator 3 and outputs it as a sense signal 9. The drive electrode portion 6 and the sense electrode portion 10 are formed on the arm portion 2, and the monitor electrode portion 8 is formed near the boundary between the shaft portion 1 and the arm portion 2.

  Next, the control circuit unit 4 includes a monitor circuit unit 11 connected to the monitor electrode unit 8 of the vibrator 3, an AGC circuit unit 12 connected to the monitor circuit unit 11, and a drive circuit unit connected to the AGC circuit unit 12. 13. An angular velocity detection circuit unit 14 connected to the sense electrode unit 10 of the vibrator 3 is provided.

  The monitor circuit unit 11 receives an amplifier that receives the monitor signal 7 output from the monitor electrode unit 8, a bandpass filter that receives the output signal of the amplifier, a rectifier that receives the output signal of the bandpass filter, And a smoothing circuit for inputting the output signal of the rectifier.

  The AGC circuit unit 12 has a function of inputting an output signal of the smoothing circuit in the monitor circuit unit 11 and amplifying or attenuating the output signal of the bandpass filter in the monitor circuit unit 11.

  The drive circuit unit 13 outputs the amplified or attenuated output signal of the bandpass filter to the drive electrode unit 6 as a drive signal 5 for driving the vibrator 3.

  The angular velocity detection circuit unit 14 detects the value of the angular velocity from the sense signal 9 output from the sense electrode unit 10.

  The vibrator 3 is driven to vibrate when a drive signal 5 is input from the drive electrode unit 6, and the vibration is output as a monitor signal 7 from the monitor electrode unit 8. When the amplitude of the drive signal 5 (sine wave of a specific frequency) is different from the amplitude of the monitor signal 7 (sine wave of vibration frequency caused by vibration of the vibrator 3), the monitor signal 7 Control is performed so that the amplitude and the amplitude of the drive signal 5 coincide with each other. Specifically, when the amplitude of the monitor signal 7 is smaller than the amplitude of the drive signal 5, a correction signal for increasing the amplitude of the drive signal 5 is added to the drive signal 5, and the amplitude of the monitor signal 7 is the drive signal. When the amplitude is larger than 5, the correction signal for decreasing the amplitude of the drive signal 5 is added to the drive signal 5. These functions are performed by the AGC circuit unit 12 and the drive circuit unit 13, and the vibration of the vibrator 3 is held at a constant amplitude.

  In the angular velocity sensor, the relationship between the drive signal 5, the monitor signal 7, and the sense signal 9 is as shown in FIG. That is, as shown in FIG. 11A, with respect to the drive signal 5 consisting of a sine wave having a specific frequency, as shown in FIG. The monitor signal 7 is output in the same phase as the drive signal 5 and, as shown in FIG. 11C, a sine whose phase is advanced by 90 degrees in synchronization with the monitor signal 7 according to the angular velocity applied to the vibrator 3 A sense signal 9 composed of waves is output.

For example, Patent Document 1 is known as prior art document information related to the invention of this application.
JP 2000-193459 A

  In the above conventional configuration, as shown in FIG. 12, when the amplitude of the monitor signal 7 becomes smaller than the amplitude of the drive signal 5, the correction signal for increasing the amplitude of the drive signal 5 by the AGC circuit unit 12 is provided. Is output to the drive circuit unit 13 and added to the drive signal 5.

  The drive voltage for driving the AGC circuit unit 12 and the drive circuit unit 13 is supplied from a power supply circuit unit (not shown) connected to the control circuit unit 4, and the drive voltage is supplied from the power supply circuit unit. When stopped, for example, when the engine is stopped, the drive signal 5 output from the drive circuit unit 13 is also stopped.

  At this time, it is generally difficult for all circuits including the drive circuit unit 13 and other circuit units of the control circuit unit 4 to stop instantaneously. In other words, during the time until the stop of the drive signal 5 is completely completed, the amplitude of the drive signal 5 also rapidly decreases in accordance with the rapid decrease of the voltage supplied to the drive circuit unit 13, and vibration of the vibrator 3 is caused. The amplitude of the accompanying monitor signal 7 is also very small. On the other hand, the correction signal for correcting this becomes very large, and a correction signal for greatly increasing the amplitude of the drive signal 5 is output from the drive circuit unit 13 to the drive electrode unit 6 of the vibrator 3.

  In such a state, the vibrator 3 is driven more than necessary, and there is a problem that the vibrator 3 may be destroyed.

  The present invention solves the above problem, and even if the supply of drive voltage from the power supply circuit unit is stopped, the angular velocity sensor suppresses the possibility of destruction of the vibrator without increasing the correction signal more than necessary. The purpose is to provide.

In order to solve the above-described conventional problems, the present invention particularly stops the supply of the drive voltage from the power supply circuit unit , and the additional circuit unit causes the difference between the amplitude of the monitor signal and the amplitude of the drive signal. Preset the maximum value of the amplitude difference that causes the transducer to break down when the correction signal that is generated becomes too large, and if there is an amplitude difference that exceeds the maximum value, provide a judgment circuit that does not add the correction signal to the drive signal It is a configuration.

As described above, according to the present invention, the supply of the drive voltage from the power supply circuit unit is stopped, and the correction signal generated from the additional circuit unit due to the amplitude difference between the amplitude of the monitor signal and the amplitude of the drive signal is large. The maximum value of the amplitude difference that destroys the vibrator due to being too large is set in advance, and if there is an amplitude difference that exceeds the maximum value, a judgment circuit is provided that does not input a correction signal to the drive signal. Even if the correction signal is very large due to a sudden drop in the voltage supplied to the drive circuit unit when the supply of the drive voltage from the unit is stopped, Since the correction signal is not added to the drive signal, it is possible to suppress the possibility of destruction of the vibrator.

  Hereinafter, an angular velocity sensor according to an embodiment of the present invention will be described with reference to the drawings.

  1 is a block diagram of an angular velocity sensor according to an embodiment of the present invention, FIG. 2 is a plan view of a vibrator used in the angular velocity sensor, and FIG. 3 is a waveform of input / output signals of each electrode section in the operating state of the angular velocity sensor. 4 is a waveform diagram of a drive signal and a monitor signal in which a phase shift of the angular velocity sensor occurs, FIG. 5 is a waveform diagram of a drive signal and a monitor signal of the angular velocity sensor, and FIG. 6 is an H-shaped identical angular velocity sensor. It is a top view of the vibrator to be used.

  1 and 2, an angular velocity sensor according to an embodiment of the present invention has a pair of arm portions 22 on a shaft portion 21, a tuning fork type vibrator 23 made of a piezoelectric element, and drives the vibrator 23. And a control circuit unit 24 that detects the angular velocity applied to the vibrator 23.

  First, the vibrator 23 has a drive electrode section 26 for inputting a drive signal 25 for vibrating the vibrator 23 at a specific frequency, and a monitor electrode section 28 for detecting the vibration frequency of the vibrator 23 and outputting it as a monitor signal 27. And a sense electrode unit 30 that detects a synchronization frequency synchronized with the monitor signal 27 due to the angular velocity applied to the vibrator 23 and outputs it as a sense signal 29. The drive electrode portion 26 and the sense electrode portion 30 are formed on the arm portion 22, and the monitor electrode portion 28 is formed near the boundary between the shaft portion 21 and the arm portion 22.

  Next, the control circuit unit 24 includes a monitor circuit unit 31 connected to the monitor electrode unit 28 of the vibrator 23, an AGC circuit unit 32 connected to the monitor circuit unit 31, and a drive circuit unit connected to the AGC circuit unit 32. 33, an angular velocity detection circuit unit 34 connected to the sense electrode unit 30 of the vibrator 23 is provided.

  The monitor circuit unit 31 includes an amplifier that receives the monitor signal 27 output from the monitor electrode unit 28, a bandpass filter that receives the output signal of the amplifier, a rectifier that receives the output signal of the bandpass filter, And a smoothing circuit for inputting the output signal of the rectifier.

  The AGC circuit unit 32 has a function of inputting the output signal of the smoothing circuit in the monitor circuit unit 31 and amplifying or attenuating the output signal of the bandpass filter in the monitor circuit unit 31.

  The drive circuit unit 33 outputs the amplified or attenuated output signal of the bandpass filter to the drive electrode unit 26 as the drive signal 25 for driving the vibrator 23.

  The angular velocity detection circuit unit 34 detects the value of the angular velocity from the sense signal 29 output from the sense electrode unit 30.

  In the angular velocity sensor, the relationship among the drive signal 25, the monitor signal 27, and the sense signal 29 is as shown in FIG. That is, as shown in FIG. 3A, a drive signal 25 consisting of a sine wave having a specific frequency is changed from a sine wave having a vibration frequency caused by the vibration of the vibrator 23 as shown in FIG. The monitor signal 27 is output in the same phase as the drive signal 25, and in accordance with the angular velocity applied to the vibrator 23, as shown in FIG. A sense signal 29 composed of waves is output.

  The vibrator 23 is driven to vibrate when a drive signal 25 is input from the drive electrode unit 26, and the vibration is output as a monitor signal 27 from the monitor electrode unit 28. If the amplitude of the drive signal 25 (sine wave of a specific frequency) is different from the amplitude of the monitor signal 27 (sine wave of vibration frequency caused by vibration of the vibrator 23), the monitor signal 27 Control is performed so that the amplitude and the amplitude of the drive signal 25 coincide with each other.

  Specifically, as shown in FIG. 4, when the amplitude of the monitor signal 27 is smaller than the amplitude of the drive signal 25, a correction signal for increasing the amplitude of the drive signal 25 is added to the drive signal 25. As shown in FIG. 5, when the amplitude of the monitor signal 27 is larger than the amplitude of the drive signal 25, a correction signal for reducing the amplitude of the drive signal 25 is added to the drive signal 25. These functions are performed by an additional circuit unit 43 including an AGC circuit unit 32 and a drive circuit unit 33, and the vibration of the vibrator 23 is held at a constant amplitude.

  Further, in the additional circuit unit 43, a maximum value of an amplitude difference between the amplitude of the monitor signal 27 (vibration frequency) and the amplitude of the drive signal 25 (specific frequency) is set in advance, and an amplitude difference exceeding the maximum value is generated. In such a case, a determination circuit unit 42 that does not add a correction signal to the drive signal 25 is connected.

  In addition, the control circuit unit 24 uses the signal component of the sense signal 29 erroneously detected that the angular velocity is generated as the noise signal component when the angular velocity is not generated in the vibrator 23, from the signal component of the sense signal 29. A correction circuit unit 35 for removing noise signal components is provided.

  The noise signal component includes a first noise signal component and a second noise signal component. As shown in FIGS. 3A and 3B, the first noise signal component is generated in a state where the phase of the sense signal 29 is not shifted from the phase of the monitor signal 27.

  This first noise signal component is generated by the mass balance of the vibrator 23. For example, in the case of a U-shaped or H-shaped tuning fork type vibrator 23, a first noise signal component is generated if the mass of each arm portion 22 varies. Further, even in a columnar or cone-shaped vibrator 23 that is not a tuning fork type, if there is a mass difference with respect to the center of gravity, a first noise signal component is generated. An example of the H-shaped tuning fork vibrator 23 is shown in FIG. In this vibrator 23, there are four arm portions 22 with respect to the shaft portion 21, and a drive electrode portion 26, a monitor electrode portion 28, and a sense electrode portion 30 are formed on the shaft portion 21 and the arm portion 22, respectively.

  The second noise signal component is obtained by removing the first noise signal component. In the monitor signal 27 and the sense signal 29 shown in FIGS. This is caused by a state in which the phases of 29 are shifted from each other, and is caused by a phase shift (W) as shown in FIGS. 7 (a) and 7 (b). Such a state in which the phases are shifted from each other is due to a temperature increase in the control circuit unit 24.

  As shown in FIG. 8, the correction circuit unit 35 includes a first noise correction circuit 36 for removing the first noise signal component and a second noise correction circuit 37 for removing the second noise signal component. And connected to the amplifier of the monitor circuit unit 31.

  The first noise correction circuit 36 and the second noise correction circuit 37 are connected to a memory unit 38 in which the first noise signal component and the second noise signal component are stored in advance. The noise signal component and the second noise signal component are constantly removed from the signal component of the sense signal 29. In particular, the first noise correction circuit 36 and the second noise correction circuit 37 are formed by combining a switch 39 having an internal resistance and a ladder resistor 40, and the resistance value of the ladder resistor 40 is changed to a switch 39 such as a transistor. The resistance value of the internal resistance is set to 100 times or more.

  The monitor signal 27 and the sense signal 29 are amplified with each other in the amplifier of FIG. The reason that there are two amplifiers of the sense signal 29 output from the sense electrode unit 30 is that two sense electrode units 30 are provided.

  With the above-described configuration, even if the vibrator 23 has a mass balance, the sense signal 29 component generated due to the mass balance is provided as a noise signal component, so that a correct angular velocity is calculated. can do.

  In addition, since the memory unit 38 in which the noise signal component is stored in advance is connected to the correction circuit unit 35 and the noise signal component stored in the memory unit 38 is steadily removed from the signal component in the sense signal 29, the angular velocity sensor In the operating state, it is possible to calculate an accurate angular velocity constantly. The memory unit 38 uses an EEPROM or the like.

  Further, the correction circuit unit 35 is provided with a circuit formed by combining a switch 39 having an internal resistance and a ladder resistor 40, and the resistance value of the ladder resistor 40 is 100 times or more the resistance value of the internal resistance of the switch 39. Therefore, when the switch 39 is switched from the off state to the on state, the on resistance is reduced and impedance matching is improved.

  The noise signal component is a first noise signal component generated when the phase of the sense signal 29 is not shifted from the phase of the monitor signal 27, and the correction circuit unit 35 is dedicated to removing the first noise signal component. Since the first noise correction circuit 36 is provided, the first noise signal component can be reliably removed from the plurality of noise signal components.

  The noise signal component is obtained by removing the first noise signal component generated in a state where the phases of the sense signals 29 are not shifted from each other with respect to the phase of the monitor signal 27. The correction circuit unit 35 is provided with a dedicated second noise correction circuit 37 for removing the second noise signal component as a second noise signal component generated due to the phase of the sense signal 29 being shifted from each other. Therefore, the second noise signal component can be reliably removed from the plurality of noise signal components.

  In addition, the monitor signal 27 and the sense signal 29 are amplified with each other by an amplifier, and the amplification degree is made substantially equal, so that the second noise signal component can be easily removed.

  In the present embodiment, the noise signal component is extracted and the noise signal terminal 41 for storing the noise signal component in the memory unit 38 is provided. After the noise signal component is stored in the memory unit 38, the noise signal is stored. The terminal 41 may be turned off. In this case, since the noise signal terminal 41 is non-conducting, it is possible to suppress the current from flowing unnecessarily to the noise signal terminal 41 during the manufacturing process or after mounting on the mounting substrate, and to adversely affect the angular velocity sensor.

  As described above, the angular velocity sensor according to the present invention includes the correction circuit unit that removes the sense signal component generated due to the mass balance as a noise signal component even if the vibrator has a mass balance. Therefore, it is possible to calculate an accurate angular velocity, and it can be applied to applications such as attitude control and navigation of moving bodies such as airplanes, automobiles, robots, ships and vehicles.

The block diagram of the angular velocity sensor in one embodiment of this invention Top view of the vibrator used in the same angular velocity sensor Waveform diagram of drive signal, monitor signal and sense signal of the same angular velocity sensor Waveform diagram of drive signal and monitor signal of same angular velocity sensor Waveform diagram of drive signal and monitor signal of same angular velocity sensor Plan view of H-shaped tuning fork type vibrator Waveform diagram of drive signal and monitor signal in which phase shift of same angular velocity sensor occurred Circuit diagram showing correction circuit section of same angular velocity sensor and amplifier connected thereto Plan view of transducer of conventional angular velocity sensor Block diagram of the same angular velocity sensor Waveform diagram of drive signal, monitor signal and sense signal of the same angular velocity sensor Waveform diagram of drive signal and monitor signal of same angular velocity sensor

DESCRIPTION OF SYMBOLS 21 Axis part 22 Arm part 23 Vibrator 24 Control circuit part 25 Drive signal 26 Drive electrode part 27 Monitor signal 28 Monitor electrode part 29 Sense signal 30 Sense electrode part 31 Monitor circuit part 32 AGC circuit part 33 Drive circuit part 34 Angular velocity detection circuit Unit 35 correction circuit unit 36 first noise correction circuit 37 second noise correction circuit 38 memory unit 39 switch 40 ladder resistor 41 noise signal terminal 42 determination circuit unit 43 additional circuit unit

Claims (1)

A vibrator and a control circuit unit that drives the vibrator and detects an angular velocity applied to the vibrator, and inputs a drive signal for vibrating the vibrator at a specific frequency. Drive electrode section, a monitor electrode section that detects a vibration amplitude of the vibrator and outputs it as a monitor signal, a sense signal that detects a synchronization frequency synchronized with the monitor signal due to an angular velocity applied to the vibrator When the amplitude of the monitor signal is different from the amplitude of the drive signal, the monitor signal is output so that the amplitude of the monitor signal is the same as the amplitude of the drive signal. When the amplitude is smaller than the amplitude of the drive signal, a correction signal for increasing the amplitude of the drive signal is added to the drive signal, and the monitor signal If the amplitude is greater than the amplitude of the drive signal has an additional circuit portion for adding a corrective signal to reduce the amplitude of the drive signal to the drive signal, the supply of the drive voltage from the power supply circuit is stopped, the Preset and set the maximum value of the amplitude difference that causes the vibrator to break down when the correction signal generated from the additional circuit section becomes too large due to the amplitude difference between the amplitude of the monitor signal and the drive signal. An angular velocity sensor provided with a determination circuit unit that does not input the correction signal to the drive signal when an amplitude difference exceeding 1 occurs.

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