JP4796790B2 - Inertial sensor element - Google Patents

Description

  The present invention detects a maximum of three axes and three directions of Coriolis force by mechanically joining an inertial sensor element that forms a crystal Z plate by etching and detects Coriolis force only in one axis direction. The present invention relates to an element shape that realizes an angular velocity detection sensor.

  When a vibrating piece oscillating along a predetermined direction, for example, a vibrating piece oscillating along the X axis in an orthogonal coordinate axis plane (XZ plane), rotates around the Y axis perpendicular to the XZ plane. The rotational angular velocity causes a Coriolis force in the Z-axis direction on the resonator element. Since this Coriolis force is determined in proportion to the angular velocity, the Coriolis force is measured directly as the deflection displacement amount of the resonator element or directly as the strain amount by the piezoelectric effect of the piezoelectric element, resistance change of the strain gauge, etc. By doing so, the rotational angular velocity acting around the Y-axis direction of the vibrating piece can be obtained. For this reason, a vibrating piece that vibrates is mounted as an angular velocity detection element in a vehicle, an aircraft, or the like, and its running or flight trajectory is recorded or yaw rate that occurs during turning is detected. This angular velocity detection element can be mounted on a robot and applied to posture control, etc. Recently, it has been developed in the field of camera shake detection for digital still cameras and video movies.

FIG. 3 is a front view showing a main part of a conventional inertial sensor element. A conventional inertial sensor element has a tuning fork shape. Generally, when the vibrator branch is oscillating in a predetermined direction, when the angular velocity sensor is rotated around the Y axis, the predetermined direction is By detecting the Coriolis force generated in the vertical direction, the magnitude of the rotational angular velocity acting around the Y axis of the angular velocity sensor can be obtained.
In addition, the applicant has not found any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the prior art document information described above.

  The inertial sensor element described above can only detect rotation in one direction with a single element. However, in consideration of the current situation of the posture control, it is necessary to detect at least two rotational directions (two axes). For example, taking the form control of an automobile as an example, the car body of the automobile is only acting in a linear motion in the forward direction during normal straight running, but when moving through a curved curve etc. It is influenced by the motion component in at least two directions of the external force in the radial direction due to the centrifugal force.

  On the other hand, when a braking force is applied to a running vehicle, the vehicle body of the vehicle is swayed in two directions, left and right, and back and forth due to the braking force, due to uneven braking force on the four wheels. You will receive rotational force.

  As another example, in the case of digital still cameras and video movies, which have recently become mainstream, the image incident on the subject from the lens is up and down and left and right as camera shake directions for the camera and movie. That is, the vibration component in the two directions is generated.

  Thus, recently, a detection element for maintaining a more stable natural state by detecting at least two rotational components is required, and for that purpose, three directions as shown in Patent Document 1 are required. Under the present circumstances, there is a demand for an element for detecting the Coriolis force component.

  However, in the technique disclosed in Patent Document 1, the detection elements are integrated, and it is very difficult to obtain all the axial components with the same detection accuracy in view of the characteristics of the materials of the detection elements. Conceivable. Recently, digital still cameras and video movies have been incorporated as functions of mobile phones, and devices and products themselves have become very small.

  Therefore, for example, in order to obtain a rotational component in two directions, a single inertial sensor element can be detected in two directions, that is, in the X-axis direction and the Y-axis direction. Although the components can be detected, the mounting of two detector elements is a big problem in miniaturization due to the progress of miniaturization of devices and products as described above. At present, there is a demand for an element that can detect rotational components in multiple directions with the upper element.

The present invention has been made in order to solve such problems, comprising a quartz crystal resonator element of the two tuning fork, base and one leg and the other quartz crystal resonator element tuning fork consists of two legs In an inertial sensor element for obtaining an angular velocity by detecting a Coriolis force generated by generating a rotational force of the rotating shaft by exciting the quartz crystal vibrating piece with a center line passing between the legs of the rotating shaft as an axis of rotation, the X axis And the Y-axis and the Z-axis are orthogonal coordinate systems, and one of the two tuning-fork-shaped crystal vibrating pieces has a length direction of one leg and the other leg of the tuning-fork-shaped crystal vibrating piece. For the remaining one of the two tuning-fork-shaped quartz crystal vibrating pieces, with the Y-axis and the direction straddling between one leg and the other leg parallel to the Z-axis. The length of one leg and the other leg of the quartz crystal vibrating piece X-axis direction, is the direction across between the one leg and the other leg is arranged parallel to the Z axis, the base of the quartz crystal resonator element of one tuning fork of the two, the one The L-shaped length of the portion farthest from the leg in the Z direction is approximately half the length in the Z direction of the portion connected to the one leg and the other leg, and the remaining one of the two In the tuning fork-shaped quartz crystal vibrating piece, the base in the Z direction on the side farthest from the one leg is approximately half the length in the Z direction of the portion connected to the one leg and the other leg. The base of one of the two tuning-fork-shaped crystal vibrating pieces and the base of the remaining one of the two tuning-fork-shaped crystal vibrating pieces are the one leg and the other. this constituted is joined with the leg and leads Z direction is maintained portion length of the part of Is an inertial sensor element characterized.

With the inertial sensor element of the present invention, it is possible to obtain rotational components in the three directions of the biaxial direction, the triaxial direction, the X-axis direction, the Y-axis direction, and the Z-axis direction from the detection based on Coriolis force in the uniaxial direction. .

Since the individual elements are connected by mechanical joining, it can be manufactured very efficiently compared to obtaining multi-axial inertial sensor elements, and the number of axial components to be detected can be reduced from one axis. By combining two or three axes and the number of inertial sensor elements as necessary, an inertial sensor element that can easily detect rotational components in multiple axes can be obtained.

As is apparent from the above description, according to the present invention, it is possible to detect two or more axial rotational components with a single element, while maintaining the high accuracy of manufacturing an inertial sensor element. Can be easily. In addition, an inertial sensor that can easily detect rotational components in multiple axes as needed by combining two crystal vibrating pieces by mechanical bonding and bonding to form a single inertial sensor element. An element can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same numerals indicate the same objects. FIG. 1 is a perspective view in which the inertial sensor elements of the present invention are combined in two axial directions. In the figure, reference numeral 1 denotes a quartz crystal vibrating piece, which is positioned in two directions, that is, has a shape that is combined at an angle in which both are orthogonal to each other. In addition, although the excitation and detection electrodes formed on each crystal vibrating piece (element) are not drawn, an excitation electrode is formed on one leg of the tuning-fork-shaped crystal vibrating piece and a detection electrode is provided on the other leg. Is forming.

According to the above-described embodiment, the Coriolis force is generated by generating the rotational force of the rotating shaft by exciting the crystal vibrating piece with the center line passing between one leg and the other leg of the tuning-fork-shaped quartz vibrating piece as the rotating axis. In the inertial sensor element that obtains the angular velocity by detecting the angular velocity, the X axis, the Y axis, and the Z axis are orthogonal coordinate systems, and one of the two tuning fork-shaped crystal vibrating pieces has the tuning-fork shape. The two tuning fork shapes are arranged so that the length direction of one leg and the other leg of the crystal vibrating piece is parallel to the Y axis and the direction between the one leg and the other leg is parallel to the Z axis. For the remaining one of the quartz crystal vibrating pieces, the length direction of one leg and the other leg of the tuning fork-shaped quartz crystal vibrating piece is the X-axis, and the direction between the one leg and the other leg is Z One of the two sounds arranged in parallel with the axis The base of the quartz crystal resonator element shape was approximately half the length in the Z direction of a portion where the length in the Z direction farthest side from said one leg is connected with the one leg and the other leg L The base of the remaining one of the two tuning-fork-shaped crystal vibrating pieces of the two is connected to the one leg and the other leg with the length in the Z direction on the side farthest from the one leg. An L-shape that is substantially half the length in the Z direction of the portion, and the base of one of the two tuning-fork-shaped crystal vibrating pieces and the other one of the two tuning-fork-shaped crystal vibrating pieces The base portion of the base plate is joined at the portion where the length in the Z direction of the portion connected to the one leg and the other leg is maintained, thereby obtaining an angular velocity in which biaxial Coriolis force is detected. Inertial sensor elements can be realized. The tuning fork-shaped quartz crystal vibrating piece is joined in a state in which approximately half of a part of the base portion 3 is cut into an L shape and both the quartz vibrating pieces 1 are assembled. In the drawings, the axial direction is provisionally defined for the sake of explanation.

  Each quartz crystal resonator element (element) described above is also a feature of the present invention in that elements can be freely combined depending on the number of detection direction components required by being mechanically integrated by direct bonding.

In short, two quartz crystal vibrating pieces are mechanically integrated by changing the direction in two directions (biaxial direction), and detecting the rotational component in the axial direction of the two axial directions as if in one element form. is there. As a result, the inertial sensor element can be manufactured with high accuracy, and by combining two crystal vibrating pieces in combination, the minimum is from the detection by the Coriolis force in the uniaxial direction, the biaxial direction, the triaxial direction, and the X axis. Three rotational components in the axial direction, the Y-axis direction, and the Z-axis direction can be obtained.

It is a perspective view which shows the conceptual diagram which combined the quartz crystal vibrating piece (element) in the biaxial direction of this invention. It is a perspective view of a tuning fork type inertial sensor element showing a conventional example.

Explanation of symbols

1 Crystal vibrating piece 2 Inertial sensor element 3 Base

Claims (1)

The quartz crystal resonator element including a tuning fork-shaped crystal resonator element including two tuning fork-shaped crystal resonator elements, the center line passing between one leg and the other leg of the tuning fork-shaped crystal resonator element including a base and two legs as a rotation axis In the inertial sensor element that obtains the angular velocity by detecting the Coriolis force generated by the generation of the rotational force of the rotating shaft by exciting
The X-axis, Y-axis, and Z-axis are orthogonal coordinate systems,
For one of the two tuning-fork-shaped crystal vibrating pieces, the length direction of one leg and the other leg of the tuning-fork-shaped crystal vibrating piece extends over the Y axis and between one leg and the other leg. While being arranged so that the direction is parallel to the Z axis,
For the remaining one of the two tuning-fork-shaped crystal vibrating pieces, the length direction of one leg and the other leg of the tuning-fork-shaped crystal vibrating piece is the X axis, and between the one leg and the other leg. Is arranged so that the direction across the Z axis is parallel to the Z axis,
The length of the base portion of one of the two tuning-fork-shaped quartz crystal vibrating pieces in the Z direction where the length in the Z direction on the side farthest from the one leg is connected to the one leg and the other leg It becomes an L shape that is about half of the length,
The base portion of the remaining one of the two tuning-fork-shaped quartz crystal vibrating pieces is the Z direction in which the length in the Z direction on the side farthest from the one leg is connected to the one leg and the other leg. L-shape that is approximately half the length of
The base of one of the two tuning-fork-shaped crystal vibrating pieces and the base of the remaining one of the two tuning-fork-shaped crystal vibrating pieces are connected to the one leg and the other leg . An inertial sensor element characterized by being joined at a portion where the length in the Z direction is maintained.

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