Supporting structure of vibrator

Abstract: A vibrating gyroscope having a supporting structure of a vibrator according to the present invention comprises, the vibrator. The vibrator includes, for example, a substantially regular triangular prism-shaped vibrating body. The vibrating body is formed with materials generally generating a mechanical vibration such as a constant-elastic materials. On three side faces of the vibrating body, three piezoelectric elements are formed respectively. On a ridge-line portion of the vicinity of two nodal points of the vibrating body, for example, a substantially rectangular frame-shaped supporting member is secured. The supporting member is formed into a body by means of etching or press molding. In this case, long sides of the supporting member are formed so as to extend in an axial direction of the vibrating body. Short sides of the supporting member are bonded to the vibrating body by securing means such as welding, adhesives or soldering.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a supporting structure of a vibrator, and more particularly, to the supporting structure of the vibrator used in a vibrating gyroscope applicable in a navigation system, which detects a rotational angular velocity to locate a moving body for adequate guidance, or in a damping system such as an anti-hand-vibration device which detects an external vibration for adequate vibration control. Description of the Prior Art Fig. 5(A) is a perspective view showing an example of a conventional vibrating gyroscope which is a background of the present invention, and Fig. 5(B) is a sectional view taken along a line VB-VB of Fig. 5(A). The vibrating gyroscope 1 comprises a vibrator 2. The vibrator 2 includes, for example, a substantially regular triangular prism-shaped vibrating body 3. On three side faces of the vibrating body 3, piezoelectric elements 4a, 4b and 4c are formed respectively. The three piezoelectric elements 4a, 4b and 4c include piezoelectric layers 5 respectively consisting of ceramics and the like. On both faces of the piezoelectric layers 5, electrodes 6 are formed respectively. One side of the electrode 6 is bonded to the vibrating body 3 by means of adhesives and the like. Meanwhile, on a ridge-line portion in the vicinity of two nodal points of the vibrating body 3, two supporting members 7a and 7b are secured respectively. The two supporting members 7a and 7b are formed with, for example, a substantially U-shaped metal wire, and are secured to the vibrating body 3 by means of welding or adhesives. The supporting members 7a and 7b are arranged such that, their end portions extend in a direction perpendicular to an axis of the vibrating body 3. The end portions of the supporting members 7a and 7b are fixed to a supporting base plate (not shown). In the vibrating gyroscope 1, an oscillation circuit (not shown) is connected between the piezoelectric elements 4a, 4b and the piezoelectric element 4c. The vibrating body 3 is bent and vibrated in a direction perpendicular to a face of the piezoelectric element 4c by the oscillation circuit. When the vibrating body 3 rotates about its axis in this state, the bending and vibrating directions change due to a Coriolis force. Thereby, a difference between output signals of the piezoelectric elements 4a and 4b is produced. Thus, a rotational angular velocity can be detected by measuring the output voltage difference between the piezoelectric elements 4a and 4b. When applying the vibrating gyroscope 1 to a navigation system of an automobile, the vibrating body 3 is arranged such that its axis is directed in a perpendicular direction, as shown in Fig. 6, to detect a rotational direction of the automobile. However, due to uneven road conditions, the automobile tends to vibrate in the perpendicular direction. In the case of arranging the axis of the vibrating body 3 in the perpendicular direction, the two supporting members 7a and 7b are arranged in a horizontal direction. And hence, the strength of the two supporting members 7a and 7b becomes weaker against a vibration in the perpendicular direction. Since the two supporting members 7a and 7b are fixed respectively to the vibrating body 3 or the supporting base plate, fixing works tend to increase. A conventional vibrating gyroscope as described above with respect to Figures 5(A), 5(B) and 6 is disclosed, for example, in EP-A-0563762. It is the object of the present invention to provide a vibrating gyroscope having an improved strength even when vibrations are applied in an axial direction of the vibrating body. This object is achieved by a vibrating gyroscope according to claim 1. The supporting member is preferably formed into a frame. In this case, the supporting member is preferably formed into a substantially rectangular frame. The supporting member may be formed such that, long sides of the substantially rectangular frame extend in the axial direction of the vibrating body from vertexes of the frame. It is also possible to form the supporting member such that, short sides of the substantially rectangular frame extend in a widthwise direction of the vibrating body from vertexes of the frame. The vibrating body is preferably formed into a regular triangular prism-shaped configuration. According to an above-mentioned configuration, since the supporting member is formed into a body and is fixed to the vibrating body, even when the vibration is applied in the axial direction of the vibrating body, a vibrating force is relaxed in a lengthwise direction of the supporting member. According to the present invention, when vibration is applied in an axial direction of the vibrating body, since the vibrating force is relaxed in the lengthwise direction of the supporting member, a large strength can be obtained as compared with the case of supporting in a perpendicular direction of the supporting member. And hence, the strength of the supporting member is not deteriorated against a vibration in the perpendicular direction of an automobile, thus it is suitable in a navigation system of the automobile. It is also possible to manufacture easily in a large quantity at low cost, by forming the supporting member in a body. Furthermore, the fixing works can be reduced, results in a partial cost down and eventually in cutting the cost of the vibrating gyroscope. The above and other objects, features, aspects and advantages of the present invention will become more apparent by the following detailed descriptions of the embodiments made with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1(A) is a perspective view showing an example of a vibrating gyroscope of the present invention, and Fig. 1(B) is a sectional view taken along a line IB-IB of Fig. 1(A). Fig. 2 is a perspective view showing a state where a vibrating gyroscope shown in Fig. 1 is fixed in a perpendicular direction. Fig. 3 is a perspective view showing another embodiment of the present invention. Fig. 4 is a perspective view showing still another embodiment of the present invention. Fig. 5(A) is a perspective view showing an example of vibrating gyroscope using a conventional supporting structure of a vibrator which is a background of the present invention, and Fig. 5(B) is a sectional view taken along a line VB-VB of Fig. 5(A). Fig. 6 is a perspective view showing a state where a vibrating gyroscope shown in Fig. 5 is fixed in a perpendicular direction. DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1(A) is a perspective view showing an example of a vibrating gyroscope of the present invention, and Fig. 1(B) is a sectional view taken along a line IB-IB of Fig. 1(A). The vibrating gyroscope 10 comprises, a vibrator 11. The vibrator 11 includes, for example, a substantially regular triangular prism-shaped vibrating body 12. The vibrating body 12 is formed with, for example, a constant-elastic metal materials such as elinvar, or materials generally generating a mechanical vibration such as quartz, glass, crystal, ceramics and the like. On three side faces of the vibrating body 12, piezoelectric elements 14a, 14b and 14c are formed respectively. The piezoelectric element 14a includes, a piezoelectric layer 16a consisting of, for example, ceramics and the like. On both faces of the piezoelectric layer 16a, electrodes 18a and 20a are formed. One electrode 18a is bonded to the side face of the vibrating body 12. Similarly, the piezoelectric elements 14b and 14c include piezoelectric layers 16b and 16c, respectively. On both faces of the piezoelectric element 16b, electrodes 18b and 20b are formed, and on both faces of the piezoelectric element 16c, electrodes 18c and 20c are formed. The electrodes 18b and 18c on one face of the piezoelectric elements 14b and 14c are bonded to the side faces of the vibrating body 12. On a ridge-line portion of the vicinity of two nodal points of the vibrating body 12, a supporting member 21 is fixed. The supporting member 21 is formed into a substantially rectangular frame in a body by means of etching or press molding. Long sides of the supporting member 21 are formed so as to extend in an axial direction of the vibrating body 12. Short sides of the supporting member 21 are fixed to the vibrating body 12 by securing means such as welding, adhesives or soldering. The long sides of the supporting member are fixed to a supporting base plate (not shown) mounted on a case (not shown). The vibrating gyroscope 10 is used, for example, in a navigation system installed on an automobile and the like. In this case, in order to measure a rotational direction of the automobile, as shown in Fig. 2, the vibrating gyroscope 10 is arranged such that an axis of the vibrating body 12 is directed in a perpendicular direction. An oscillation circuit (not shown) is connected between the piezoelectric elements 14a, 14b and the piezoelectric element 14c. The vibrating body 12 is bent and vibrated in a direction perpendicular to a face of the piezoelectric element 14c by the oscillation circuit. When the automobile is moved in the rotational direction in this state, a rotational angular velocity about the axis of the vibrating body 12 is applied on the vibrating body 12. Thereby, a Coriolis force functions on the vibrating body 12, and the bending and vibrating direction of the vibrating body 12 changes. And hence, a difference between output signals of the piezoelectric elements 14a and 14b is produced. Thus, the rotational angular velocity applied on the vibrating body 12 can be detected by measuring the output signal difference of the piezoelectric elements 14a and 14b. When applying the vibrating gyroscope 10 to the navigation system of the automobile, by a vibration of the automobile in the perpendicular direction due to uneven road conditions, the vibrating body 12 vibrates in an axial direction. In the vibrating gyroscope 10, since the long sides of the supporting member 21 are formed in a body so as to extend in the axial direction of the vibrating body 12, the axial vibration of the vibrating body 12 is relaxed in a lengthwise direction of the supporting member 21. And hence, a large strength can be obtained against the axial vibration of the vibrating body 12 as compared with the conventional vibration gyroscope, in which the vibrating body 12 is supporting by separate supporting members at respective nodal points. Since the supporting member 21 is formed in a body by means of etching or press molding, it can be manufactured easily in a large quantity at low cost. Besides, as compared with the case of fixing the separate two supporting members respectively to the vibrating body 12 as in the past, fixing works can be reduced. As a structure of the supporting member 21, as shown in Fig. 3, the long sides of the substantially rectangular frame may be formed to extend in the axial direction of the vibrating body 12, from vertexes portions 21a, 21b, 21c and 21d of the frame, and fixed to a supporting base plate and the like at their end portions. As a structure of the supporting member 21, as shown in Fig. 4, the short sides of the substantially rectangular frame may be formed to extend in the widthwise direction of the vibrating body 12, from the vertexes portions 21a, 21b, 21c, and 21d of the frame, and fixed to the supporting base plate and the like at their end portions. In the above-mentioned embodiments, though the substantially regular triangular prism-shaped vibrating body 12 is used, as a shape of the vibrating body 12, other columnar shapes such as a quadrangular prismatic shape or a cylindrical shape may be used. The number of piezoelectric elements is not restricted to three, it may be increased or decreased when necessary.

Claims: A vibrating gyroscope (10) comprising: a vibrator (11) having a columnar vibrating body (12), said vibrating body (12) having ridge-line portions and two nodal points, a single supporting member (21) formed as a frame-like unitary body and having two longitudinal portions extending in a longitudinal direction of said columnar vibrating body (12) and two lateral portions extending in a lateral direction of said columnar vibrating body (12) wherein an intermediate portion of one of said lateral portions is mounted in the vicinity of one of said nodal points and an intermediate portion of the other of said lateral portions is mounted in the vicinity of the other of said nodal points, wherein said vibrator (11) is supported solely by said single supporting member (21). A vibrating gyroscope in accordance with claim 1, wherein said supporting member (21) is formed into a frame. A vibrating gyroscope in accordance with claim 2, wherein said supporting member (21) is formed into a substantially rectangular frame. A vibrating gyroscope in accordance with claim 3, wherein said supporting member is formed such that long sides of said substantially rectangular frame extend in an axial direction of said vibrating body from vertexes of said frame. A vibrating gyroscpe in accordance with claim 3, wherein said supporting member (21) is formed such that short sides of said substantially rectangular frame extend in a widthwise direction of said vibrating body (12) from vertexes of said frame. A vibrating gyroscope in accordance with one of claims 3 to 5, wherein said vibrating body (12) is formed into a regular triangular prism-shaped configuration.

Inventors: YAMAMOTO SHIGETO, YAMAMOTO, SHIGETO, YAMAMOTO, SHIGETO, C/O MURATA MANUFAC. CO., LTD.
Applicants: MURATA MANUFACTURING CO, MURATA MANUFACTURING CO., LTD.
Application year: 1995
Main classification: G01C19
IPC codes: G01P9, G01C19