JPS60213813A - Angular speed sensor - Google Patents

Abstract

PURPOSE:To prevent the generation of an offset voltage and to perform accurate detection of angular speed, by providing an electric conductor at a connecting part between a driving part and a detecting part, grounding the conductor, and shielding the capacitive coupling between the driving part and the detecting part. CONSTITUTION:A piezoelectric bimorph 1 for driving is fixed to a metal coupling 6 through an insulator 7. A piezoelectric bimorph 2 for detection is fixed to the metal coupling 6 through an insulator 8. One piezoelectric body of the driving piezoelectric bimorph 1 and one piezoelectric body of the detecting piezoelectric bimorph 2 are connected by lead wires 9 and 10. Similarly, a driving piezoelectric bimorph 1' and a detecting piezoelectric bimorph 2' are connected to a metal coupling 6' through insulators 7' and 8'. In this case, respective capacities Ca are grounded through the metal couplings 6 and 6'. Therefore, capacitive coupling between the driving piezoelectric bimorph 1 (1') and the detecting piezoelectric bimorph 2 (2') is eliminated. The offset voltage between the terminals on the detecting side is reduced, and the accurate measurement of the angular speed can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a piezoelectric vibration type angular velocity sensor.

[Prior art]

Conventionally, as this type of device, there is a piezoelectric vibration type angular velocity sensor shown in FIG.

To explain the structure of this product, there is a drive piezoelectric bimorph 1.1' (driver) made by bonding two piezoelectric bodies together, and a drive piezoelectric bimorph 1,1' which is made by bonding two piezoelectric bodies together. Detection piezoelectric bimorphs 2 and 2' (sensing portions) are bonded with adhesives 3 and 3' so as to be orthogonal to each other. In addition, the piezoelectric body inside the drive piezoelectric bimorphs 1, 1' is fixed to a metal terminal 4 with adhesive 1, solder, etc., and an AC drive voltage is applied to the drive piezoelectric bimorph 1°1' via this metal terminal 4. is applied. When an AC drive voltage is applied to the drive piezoelectric bimorph 1.1', the drive piezoelectric bimorph 1.1' vibrates with a phase shift of 180 degrees in the direction of the arrow in the figure, and at the time of this vibration, detection is detected. The angular velocity is obtained by detecting the bending state of the piezoelectric bimorph 2.2' in the vertical direction. That is, when an angular velocity occurs around the measurement axis A, the detection piezoelectric bimorph 2.2' bends due to the Coriolis force.
The bending state is detected to obtain the angular velocity.

However, in this case, the driving voltage leaks through the adhesive 3.3' from the driving piezoelectric bimorphs 1, 1' to the sensing piezoelectric bimorph 2.2' due to capacitive coupling, so that it is very sensitive to the angular velocity detection signal. A large offset voltage is generated and accurate angular velocity detection cannot be performed. To explain this in detail, the equivalent circuit of one of the vibrating bodies shown in FIG. 1 is as shown in FIG. Capacitive coupling is performed between them by a capacitance C3 caused by the adhesive 3 (3'). Therefore, the AC drive voltage leaks from the AC drive power supply 5 to the detection side through the capacitor C3.

An offset voltage is generated between the b terminals.

[Purpose of the invention]

The present invention has been made in view of the above problems, and an object of the present invention is to provide an angular velocity sensor that can accurately detect angular velocity by preventing the generation of offset voltage due to capacitive coupling between the driving section and the sensing section. It is about providing.

[Structure of the invention]

In order to achieve the above object, the present invention has the following steps: A drive section of a plate-shaped piezoelectric body and a detection section of a plate-shaped piezoelectric body are coupled to be orthogonal to each other, and the drive section is driven to vibrate by applying an AC drive voltage. In the angular velocity sensor, the angular velocity is obtained by detecting the bending state of the detecting section in a direction perpendicular to the vibration direction when the sensor is bent, the angular velocity sensor comprising: providing an electric conductor at a connecting portion between the driving section and the detecting section; It is characterized in that it is grounded to interrupt capacitive coupling between the drive section and the detection section.

〔Effect of the invention〕

As described above, in the present invention, a grounded electric conductor is provided at the coupling part between the drive part and the detection part to cut off the capacitive coupling between the drive part and the detection part. By eliminating the influence of the alternating current drive voltage that reaches the section, there is an excellent effect that offset voltage can be prevented from occurring and accurate angular velocity detection can be performed.

〔Example〕

The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 3 is a block diagram showing one embodiment of the present invention, which differs from that shown in FIG. 1 in that metal joints 6, 6' are provided instead of adhesives 3, 3'. That is, the drive piezoelectric bimorph 1 is fixed to the metal joint 6 via the insulator 7, and the detection piezoelectric bimorph 2 is fixed to the metal joint 6 via the insulator 8, and the drive piezoelectric One piezoelectric beam of the bimorph 1 and one piezoelectric beam of the sensing bimorph 2 are connected by a Y wire at 9°10. Similarly, the drive piezoelectric bimorph 1' and the detection piezoelectric bimorph 2' are also made of an insulator 7'.
8' to the metal joint 6', and one piezoelectric body of each is connected to the metal joint 6'.

Further, the piezoelectric bodies inside the driving piezoelectric bimorphs 1, 1' are fixed to a metal terminal 4 by welding, soldering, etc., and this metal terminal 4 is grounded. And drive piezoelectric bimorph 1
．． An alternating current driving voltage is applied to 1' through lead wires 11 and 11'. In addition, the detection signal due to the bending of the piezoelectric bimorphs 2 and 2' for detection is generated by the lead wires 12 and 12.
' is taken from '.

Therefore, according to the above configuration, the equivalent circuit of one of the vibrating bodies is as shown in FIG. In this equivalent circuit, Ca is the capacitance caused by the insulators '1f (7') and 8 (8'). As can be seen from this figure, since each capacitance Ca is grounded through the metal joint 6 (6'), the capacitive coupling between the drive piezoelectric bimorph 1 (1') and the detection piezoelectric bimorph 2 (2') is Therefore, the offset voltage generated between the detection side terminals a and b can be significantly reduced.

In the above embodiment, the drive piezoelectric bimorph 1, 1' and the detection piezoelectric bimorph 2.2' are fixed using a metal joint 6.6', but as shown in FIG. The adhesive 13 and the adhesive 13 are fixed with a metal conductor 14 that completely divides the adhesive 13 into two parts, and the lead wires 9 (9') and 10 are connected to each other.
The drive piezoelectric bimorph 1 (1') and the detection piezoelectric bimorph 2 (2') may be connected at (10') and grounded.

Further, as shown in FIG. 6, each vibrating body is integrally formed with a metal plate 15.15', and the metal plate 15.1
Vibration piezoelectric bodies 16, 16' and detection piezoelectric bodies 17, 17' may be provided on the metal plate 15, 15', and the metal plate 15, 15' may be grounded via the metal terminal 4. In this case, the driving piezoelectric body 16°16' and the sensing piezoelectric body 17.17'
may be provided not only on one side of the metal plate 15, 15' but also on the opposite side, and driving or sensing may be performed using the two piezoelectric bodies.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional angular velocity sensor, Fig. 2 is an equivalent circuit diagram of the one shown in Fig. 1, Fig. 3 is a block diagram of an angular velocity sensor according to the present invention, and Fig. 4 is a block diagram of the one shown in Fig. 3. Equivalent circuit diagram, Fig. 5 is a partial configuration diagram showing the main parts of another embodiment, Fig. 6
The figure is a configuration diagram showing still another embodiment. 1.1'...Piezoelectric bimorph for driving, 2.2'...
Piezoelectric bimorph for detection, 6,6'...metal joint, 7°? ', 8.8'...Insulator. Representative Patent Attorney Takashi OkabeFigure 3Figure 4Figure 5Figure 6

Claims (1)

[Claims] The drive part of the plate-shaped piezoelectric body and the detection part of the plate-shaped piezoelectric body are coupled so as to be perpendicular to each other! 11! In the angular velocity sensor, the angular velocity is obtained by detecting the bending state of the sensing portion in a direction perpendicular to the vibration direction when the driving portion is vibrated by applying an AC driving voltage. An angular velocity sensor, characterized in that an electric conductor is provided at a coupling portion between the drive section and the detection section, and the electrical conductor is grounded to interrupt capacitive coupling between the drive section and the detection section.