JPH08261767A - Structure of angle velocity sensor - Google Patents

Abstract

PURPOSE: To easily position and to fix a piezoelectric element for detecting an angle velocity and for exitation to an angle velocity sensor having a weight for detecting the angle velocity in the center of a disk-shaped flexible member. CONSTITUTION: An angle velocity sensor comprises a piezoelectric element 12 having electrodes formed on a flexible member 11 and a weight 13 disposed in the central section of the flexible member 11. The flexible member 11 and piezoelectric element 12 are distorted by energy generated on the weight 13 owing to the angle velocity, so that the angle velocity can be measured based on a quantity of electric charge generated by the piezoelectric element 12 by utilizing an angle velocity sensor. In the angle velocity sensor, the piezoelectric element 12 and a part of the weight 13 are provided on the same surface of the flexible member 11. The piezoelectric element 12 is positioned by virtue of the weight 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an angular velocity sensor using a piezoelectric element.

[0002]

2. Description of the Related Art An angular velocity sensor capable of attitude control and position control has been developed to have a smaller size and higher performance for the purpose of preventing camera shake of a video camera and being used for car navigation. Although there are various angular velocity sensors, the piezoelectric vibration type angular velocity sensor is advantageous in terms of size and cost, and tuning fork type, tuning piece type (square column), columnar type, triangular prism type and the like have been commercialized.

As a prior art related to the present invention, there is an international publication WO94 / 23272. FIG. 1 is a front sectional view of a typical example of a conventional angular velocity sensor. FIG. 2 is a plan view seen from the piezoelectric element side. On the upper surface of the flexible disk-shaped substrate 1, upper electrode layers L1 to L16 for detection and excitation are formed on the upper surface, and lower electrode layers M1 to M16 for detection and excitation are formed on the lower surface. The applied piezoelectric element 2 is attached, and a weight 3 for replacing the movement of the sensor with the strain of the flexible disk-shaped substrate is attached to the central portion of the lower surface.

The relative position of the weight and the flexible member shifts due to the angular velocity, so that the piezoelectric element attached to the flexible member is distorted and an electric charge is generated. The electric charges are collected by electrodes formed on the surface and measured as a certain electric potential (voltage). The amount of electric charges generated in the piezoelectric element changes depending on the amount of strain. Further, the amount of electric charge generated also changes depending on the area and volume of the piezoelectric element.

The above-mentioned International Publication No. WO94 / 23272 discloses a multi-axis angular velocity sensor for detecting an angular velocity around each coordinate axis in a three-dimensional coordinate system, in which an upper surface of a flexible disc-shaped substrate 1 is provided. In this example, the lower surface side of the piezoelectric element 2 is attached, a vibrator (weight) is fixed to the lower surface, and the peripheral portion of the flexible disk-shaped substrate 1 is fixedly supported by the sensor housing 4. . Here, the three-dimensional coordinate system is X with the central position Ο of the flexible disk-shaped substrate 1 as the origin.
Considering the YZ directions, the X axis is to the right in FIG. 2, the Y axis is to the down,
Define the Z axis in the vertical direction. The piezoelectric element 2 has a so-called donut shape, and upper electrode layers L1 to L16 are formed on the upper surface side at the positions shown in the drawing, and lower electrode layers Μ1 to M16 are opposed to the upper electrode layers L1 to L16 on the lower surface side. The upper electrode layer and the lower electrode layer are formed at the positions where the so-called sandwich is formed. The piezoelectric element 2 is polarized, and when a predetermined voltage is applied between a certain pair of electrode layers, a predetermined pressure is generated inside the piezoelectric element. Conversely, when a predetermined force is applied to the piezoelectric element 2, a gap between the pair of electrodes is generated. A predetermined voltage is generated at.

[0006]

If the uniformity of the flexible member and the uniformity of the piezoelectric element and the attachment position of the weight and the piezoelectric element are not accurate, the generated voltage due to the angular velocity will not be uniform depending on the direction of the angular velocity. It is important to match the center position of the flexible member with the center of gravity of the weight and to assemble the position of the piezoelectric element in point symmetry with respect to the center position of the flexible member. When the weight is placed on the lower surface of the flexible member and the piezoelectric element is placed on the upper surface as in the conventional case, the alignment is not easy. Further, unless the weight and the flexible member are firmly fixed, the energy generated in the weight cannot be transmitted reliably, and the conventional bonding method has a loss of energy.

[0007]

A flexible member has a piezoelectric element on the surface of which an electrode is formed, a central portion of the flexible member has a weight, and the flexible member and the piezoelectric element are separated by an angular velocity. In an angular velocity sensor that measures an angular velocity by the amount of electric charges generated by the piezoelectric element due to distortion, the piezoelectric element is positioned by a weight.

A hole is formed in the flexible member, a protrusion is provided on the weight so as to engage with the hole of the flexible member, and mechanical coupling such as press fitting, caulking, or physical coupling such as welding or adhesion can be used together. Fix the flexible member and the weight.

A hole is formed in the flexible member, and a protrusion is provided on the weight so as to engage with the hole of the flexible member. The protrusion is formed longer than the thickness of the flexible member, and the protrusion is protruded from the flexible member. Engage the fixing member. The weight fixing member is used for positioning the piezoelectric element.

[0010]

FIG. 3 is a sectional view showing an embodiment of the present invention. A hole 14 is provided in the center of the flexible member 11, and the weight 13
A protruding portion 13a is formed on this and is inserted and fixed in the hole 14. The fixing may be done by welding, press-fitting, caulking or the like as long as the positioning is accurate and can be firmly fixed. It is more reliable when used together with adhesion. The piezoelectric element 12 has a hole formed at the center thereof that matches the outer shape of the weight 13, and is bonded to the flexible member 11 using the weight 13 as a guide. Electrode L21 for detection and excitation
˜L36 (upper electrode layer) and Μ21 to Μ36 (lower electrode layer) are formed at predetermined positions on the upper surface side and the lower surface side of the piezoelectric element.

FIGS. 4 and 5 show another embodiment of the present invention.
It is a fragmentary sectional view which assembled a flexible member and a weight. In FIG. 4, the protrusion 15a of the weight 15 is elongated to guide the flexible member 16 and the piezoelectric element 17. FIG. 5 shows the protrusion 18 a of the weight 18.
This is an example in which a weight fixing member 20 that fixes the weight and guides the piezoelectric element 21 at the outer periphery is provided. The weight fixing member may have an outer diameter that matches the inner diameter of the piezoelectric element 21.

[0012]

Since the present invention is configured as described above, it has the following effects.

1. Since the piezoelectric element is positioned by the weight or the weight fixing member, the piezoelectric element can be attached easily and accurately without requiring a special jig. 2. No special material is required as it is positioned by a part of the weight. 3. Since the flexible member and the weight are fixed by engaging with each other, the fixation is firm and the angular velocity of the weight can be reliably transmitted to the flexible member.

[Brief description of drawings]

FIG. 1 is a front sectional view of an angular velocity sensor according to a conventional technique.

FIG. 2 is a plan view of an angular velocity sensor according to the related art.

FIG. 3 is a sectional view of an embodiment of the present invention.

FIG. 4 is a partial sectional view of an embodiment of the present invention.

FIG. 5 is a partial sectional view of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible member 2 Piezoelectric elements L1 to L16 Upper electrode layers for detection and excitation Μ1 to Μ16 Lower electrode layer for detection and excitation 3 Weight 4 Sensor housing 11 Flexible member 12 Piezoelectric element L21 to L24 For detection and excitation Upper electrode layer Μ21 to Μ24 Lower electrode layer for detection and excitation 13 Weight 13a Projection part 14 Hole 15 Weight 16 Flexible member 17 Piezoelectric element 18 Weight 18a Projection part 20 Weight fixing member 21 Piezoelectric element

Front page continued (72) Inventor Tomio Namiki 4107 Miyota, Miyota, Kitadaku-cho, Kitasaku-gun, Nagano Within Miyota Co., Ltd. (72) Minor Hatakeyama Minoru Hatakeyama 4107, Miyota, Miyota-cho, Kitasaku-gun, Nagano 5 Miyota Co., Ltd. (72) Inventor Kazuhiro Okada 4-73, Sugaya, Ageo City, Saitama Prefecture

Claims (4)

[Claims] 1. A flexible member has a piezoelectric element on the surface of which an electrode is formed, and a weight is provided at the center of the flexible member, and energy is generated in the weight due to an angular velocity so that the flexible member is connected to the flexible member. In the structure of the angular velocity sensor that measures the angular velocity by the amount of electric charge generated by the piezoelectric element due to the distortion of the piezoelectric element, a hole is made in the flexible member, and a part of the weight is engaged with the hole to fix the weight. The structure of the angular velocity sensor characterized in that 2. The structure of the angular velocity sensor according to claim 1, wherein a weight fixing member is used for fixing the weight, and the weight fixing member is used for positioning the piezoelectric element. 3. A flexible member has a piezoelectric element on the surface of which an electrode is formed, a weight is provided at the center of the flexible member, and energy is generated in the weight due to an angular velocity so that the flexible member is connected to the flexible member. Due to the distortion of the piezoelectric element, in the structure of the angular velocity sensor that measures the angular velocity by the amount of electric charge generated by the piezoelectric element, the piezoelectric element and a part of the weight are on the same surface of the flexible member, and the piezoelectric element is positioned by the weight. The structure of the angular velocity sensor characterized in that 4. The structure of the angular velocity sensor according to claim 3, wherein a hole is bored in the flexible member, and a part of the weight is engaged with the hole to fix the weight.