JPH10232133A - Excitation type angular velocity sensor - Google Patents

Abstract

(57) [Problem] In a conventional excitation vibration type angular velocity sensor, a piezoelectric element is formed on a semiconductor substrate to excite a vibrator and detect a vibration state. For this reason, variations in sensor characteristics are caused due to variations in characteristics of the piezoelectric elements, causing deterioration in sensor accuracy. Further, since the piezoelectric element must be formed with a thick piezoelectric material, it takes a long time to manufacture a conventional excitation type angular velocity sensor. The excitation type angular velocity sensor includes a light emitting element for exciting the vibrator, a light emitting element for detecting a vibration state of the vibrator, and a light receiving element corresponding to the light emitting element for detecting the vibration state.
These are used to excite the vibrator and detect the vibration state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excitation type angular velocity sensor, and more particularly, to an excitation type angular velocity sensor which detects the state of excitation and vibration using photons.

[0002]

2. Description of the Related Art Conventionally, a sensor having a vibrator formed of a semiconductor substrate has been used as an excitation type angular velocity sensor. FIG. 13 is a perspective view of a conventional excitation type angular velocity sensor. A vibrator 1, a stator 2, and a support 3 connecting the vibrator 1 and the stator 2 are integrally formed from a semiconductor substrate. As the semiconductor substrate, for example, a planar substrate of Si is used, and the vibrator 1, the stator 2, and the support 3 are formed by anisotropic etching. A large Si substrate is used as a substrate, and a large number of sets of transducers 1, stators 2, and supports 3 are formed at the same time, and then separated one by one, whereby a large number of sensors can be efficiently formed. Here, as shown in FIG. 13, the XY axis is taken along the plane of the semiconductor substrate, and the Z axis is taken in the thickness direction of the semiconductor substrate. The vibrator 1 has the shape of a prism having a long axis in the X-axis direction, which is a hexagonal prism in FIG.
For example, a quadrangular prism may be used. Further, FIG.
FIG. 14 shows a cross section along a line AA parallel to the Y axis. As can be seen from FIGS. 13 and 14, the driving piezoelectric element 11 and the detecting piezoelectric elements 13 and 15 are formed on the surface of the vibrator 1. These piezoelectric elements are typically made of ferroelectrics such as Zn
O, PLZT. The driving piezoelectric element 11 and the detecting piezoelectric elements 13 and 15 are respectively provided with the driving piezoelectric element electrode 12 and the detecting piezoelectric element electrodes 14 and 1 for applying a voltage.
6 are formed, and these electrodes are often made of metal such as Au, Al.

Although not shown, an oscillation circuit is connected to the driving piezoelectric element electrode 12 and a detection circuit is connected to the detecting piezoelectric element electrodes 14 and 16. The driving piezoelectric element 11 periodically expands and contracts in the Z-axis direction by a periodically changing voltage generated by the oscillation circuit. As a result, the bending vibration in the Z-axis direction with the connecting portion of the support 3 on the vibrator 1 as a fulcrum. Is excited. Here, it is assumed that a rotational motion having an angular velocity Ω having a rotation axis in the X-axis direction is applied to the vibrator 1 through the semiconductor substrate.
At this time, a Coriolis force F is generated on the vibrator 1 in the Y-axis direction. As a result, the vibrator 1 bends and vibrates also in the Y-axis direction with the connection point with the support 3 as a fulcrum. Since the intensity of the vibration in the Y-axis direction is proportional to the angular velocity Ω,
The angular velocity Ω can be measured by detecting the vibration in the Y-axis direction by the detecting piezoelectric elements 13 and 15. In addition, since the cross-sectional shape of the vibrator 1 is hexagonal in FIGS. 13 and 14, the detecting piezoelectric elements 13 and 15 are provided on the surfaces of the vibrator that have angles with respect to the Y-axis direction and the Z-axis direction, respectively. Have been. As a result, the detection piezoelectric elements 13 and 15 serve not only the vibration in the Y-axis direction but also the vibration monitor in the Z-axis direction. The voltage appearing on the detection piezoelectric element electrodes 14 and 16 is calculated by a detection circuit, so that excitation vibration in the Z-axis direction can be obtained.
Vibration due to Coriolis force in the Y-axis method can be detected at the same time.

[0004]

As described above, in the conventional excitation vibration type angular velocity sensor, the piezoelectric element is formed on the semiconductor substrate to excite the vibrator and detect the vibration state. However, it has not been easy to make the characteristics of the piezoelectric element uniform. In order to make the characteristics of the piezoelectric element uniform, it is necessary to make the shape such as the thickness of the piezoelectric element uniform, and also make the characteristics of the ferroelectric material itself constituting the piezoelectric element uniform. In particular, a ferroelectric material is a material whose characteristics, for example, piezoelectric characteristics and temperature characteristics, are difficult to make uniform. For example, even between the detecting piezoelectric elements 13 and 15 formed simultaneously by the same process, the characteristics are likely to be inconsistent. It is. As a result, variations in sensor characteristics, for example, output bias, bias stability, linearity, and the like are caused, and as a result, sensor accuracy is deteriorated. Also, since the piezoelectric material must be formed thick as the piezoelectric element,
This causes a long time to manufacture the conventional excitation type angular velocity sensor.

It is an object of the present invention to eliminate the need for a piezoelectric element and prevent variations in sensor characteristics and deterioration in accuracy due to variations in piezoelectric materials. Another object of the present invention is to eliminate the need for forming a thick film of a piezoelectric material and to shorten the manufacturing time.

[0006]

According to the present invention, in an excitation vibration type angular velocity sensor, a light emitting element for exciting a vibrator, a light emitting element for detecting a vibration state of the vibration element, and a light receiving element corresponding to a light emitting element for detecting a vibration state are provided. With photons.

[0007]

According to the present invention, the vibration excitation of the vibrator and the detection of the vibration state are performed in a non-contact manner by light without using a piezoelectric element. Therefore, there is no need to use a piezoelectric material having unstable characteristics, and it is not necessary to form the piezoelectric material over a long period of time.

[0008]

FIG. 1 shows a first embodiment of the present invention. A vibrator 1, a stator 2, and a support 3 connecting the vibrator 1 and the stator 2 are integrally formed from a semiconductor substrate. The vibrator 1 is connected to the stator 2 by a support 3 at two points in the X-axis direction. This formation is performed by anisotropic etching of the semiconductor substrate, so that a large number of sets of the vibrator 1, the stator 2, and the support 3 can be easily formed at the same time. For example, Si or GaAs is used as the semiconductor. When the substrate is GaAs, for example, AlGaAs is formed and patterned, and the substrate is etched using the etch stop layer of the GaAs substrate. Here, an X axis and a Y axis are set along a plane of the semiconductor substrate, and a Z axis is set in a thickness direction of the semiconductor substrate. The vibrator 1 has the shape of a prism having a long axis in the X-axis direction. Here, the shape of the vibrator 1 is a quadrangular prism, but other shapes such as a hexagonal prism may be used, and the cross section of the prism may not necessarily be a constant shape.

On the stator 2, an excitation light emitter 4, a monitor light emitter 8, a monitor light receiver 10, a detection light emitter 5, and a detection light receiver 7 are installed. The vibrator 1 has a reflecting surface 9 for monitoring the light emitted from the monitoring light emitting element 8 on a side surface in the Y-axis direction, and a reflecting surface 9 for reflecting the light emitted from the detecting light emitting element 5 on an end surface in the X-axis direction. Each of the detection reflection surfaces 6 is provided. The excitation light emitting element 4 is provided on the stator 2 so as to be able to irradiate light in the Y-axis direction, facing the center of the surface of the vibrator 1 facing the reflection surface 9 for monitoring. As a result, the excitation light emitter 4 and the monitor light emitter 8 irradiate different surfaces of the vibrator 1 in the Y-axis direction. Here, the excitation light emitting element 4 is installed facing the side surface of the oscillator 1 on which the monitor reflection surface 9 is installed, and the excitation light emitting element 4 and the monitoring light emitting element 8 are arranged in the Y-axis direction of the oscillator 1. It is also possible to configure so as to irradiate the same side surface with light, and it is possible to further reduce the size of the sensor. At this time, the same side surface of the vibrator 1 is irradiated with light such that the positions on the side surface where the light from the excitation light emitter 4 and the light from the monitor light emitter 8 are irradiated are different from each other. In this case, it is preferable not to provide the monitor reflection surface 9 in a portion of the side surface to which the light from the excitation light emitter 4 is irradiated, in order to efficiently perform excitation by light described later.
In this embodiment, a groove is formed in the stator 2 so that the excitation light-emitting element 4 is formed.
Is provided so that the irradiation light is efficiently irradiated on the side surface of the vibrator 1. The excitation light emitter 4 is, for example, L
An ED or a semiconductor laser diode (LD) is used. Although not shown in FIG. 1, the excitation light emitter 4 is periodically driven by the oscillation circuit 22. As a result, one side surface of the vibrator 1 is periodically irradiated with light. Due to the periodic irradiation of light, periodic thermal strain acts on the vibrator 1 along the Y-axis direction. Thus, the vibrator 1 bends and vibrates in the Y-axis direction with the joint with the support 3 as a fulcrum. Here, if the driving cycle is set to the natural frequency of the vibrator 1, a large excitation can be caused, and the angular velocity can be detected with high sensitivity.

Further, vibrations excited by the monitor light-emitting element 8 and the monitor light-receiving element 10 are monitored. The monitor light-emitting element 8 and the monitor light-receiving element 10 are respectively installed on the stator 2 at an angle in the X-axis direction. Light emitted from the monitor light emitter 8 to the vibrator 1 is reflected on the monitor reflection surface 9.
And is received by the monitoring photodetector 10. Here, the monitor light-emitting element 8 and the monitor light-receiving element 10 are installed in grooves formed in the stator 2 so that light can be used efficiently. Due to the vibration of the vibrator 1,
The monitor reflection surface 9 vibrates in the Y-axis direction. For this reason, the amount of light incident on the monitoring light-receiving element 10 changes, and the vibration state of the vibrator 1 can be monitored. If the reflecting surface 9 for monitoring is set perpendicular to the Y-axis direction, Z caused by the input of the angular velocity
The axial vibration does not appear as a change in the amount of light incident on the monitoring light-receiving element 10, and the excitation state in the Y-axis direction can be accurately detected. Here, the drive of the excitation light emitting element 4 can be controlled using the excitation state output. This is shown in FIG. A detection circuit 21 detects an output from the monitoring photodetector 10
To detect the excitation state in the Y-axis direction. The oscillation circuit 22 that drives the excitation light-emitting element 4 is controlled by the excitation state output from the detection circuit 21 to perform light irradiation for exciting the vibrator 1. The excitation light-emitting element 4 and the monitoring light-receiving element 10 are connected via the vibrator 1 as excitation and monitoring thereof. That is, the monitoring light-receiving element 10, the detection circuit 21, the oscillation circuit 22, and the excitation light-emitting element 4 form a positive feedback loop as a whole. As a result, the amplitude of the vibrator 1 to be excited is always kept at the maximum, and the excitation light emitting element 4 is automatically set at a frequency corresponding to the natural frequency of the vibrator 1.
Is driven.

A vibration in the Z-axis direction generated in the vibrator 1 by the input of the angular velocity in the X-axis direction is detected by the detecting light emitting element 5 and the detecting light receiving element 7. The light-emitting element 5 for detection and the light-receiving element 7 for detection are opposed to the end surface of the vibrator 1 in the X-axis direction, and are respectively installed at an angle in the Y-axis direction. The light is reflected by the reflection surface 6 for detection provided on the end face of the photodetector 7 and reaches the photodetector 7 for detection. Here, the light-emitting element 5 for detection and the light-emitting element 5 for detection are installed in grooves formed in the stator 2, and an input of an angular velocity with the X-axis as an axial direction is applied to the vibrator 1 which can efficiently use light. The vibrator 1 forms a combined vibration of the bending vibration in the Y-axis direction due to the excitation and the bending vibration in the Z-axis direction due to the Coriolis force, with the connection point with the support 3 as a fulcrum. For this reason, the reflection surface 6 for detection is oscillating in an elliptical shape that rotates at an angle around the X axis. Accordingly, the amount of light incident on the photodetector 7 for detection is Y axis,
This reflects the vibrations in both Z axes. In order to detect the angular velocity, it is necessary to extract only the vibration component in the Y-axis direction from this output. For this purpose, the fact that the vibration in the Z-axis direction is out of phase by + 90 ° or −90 ° with respect to the vibration in the Y-axis direction can be used. Although the detailed description is omitted, the vibration in the Z-axis direction is caused by the excitation vibration in the X-axis direction and Coriolis force caused by the input angular velocity. Therefore, based on the vibration in the Y-axis direction detected by the output of the monitoring photoreceptor 10, components having a phase different by + −90 ° are extracted from the output of the detection photoreceptor 7. Can be detected.

FIG. 3 schematically shows a second embodiment of the present invention. FIG. 3 shows that the light emitting element 5 for detection and the light receiving element 7 for detection are the stator 2
1 in that they are not on the same plane but are shifted in the Z-axis direction, and that the detection reflecting surface 6 is installed so as to have a tilt component in the Z-axis direction. The other points are the same as those in FIG. With such an arrangement, the vibration in the Z-axis direction can be detected more largely as a change in the amount of light incident on the photodetector 7 for detection. That is, the angular velocity can be detected with higher sensitivity.

FIG. 4 schematically shows a third embodiment of the present invention. FIG. 5 shows a cross section taken along line AA of FIG. In this embodiment, the monitor light-emitting element 8
The light emitting element 5 for detection is a light source having an internal resonator, for example, a semiconductor laser (LD). And the monitor light-emitting element 8
Is installed on the stator 2 so as to face the reflection surface 9 for the monitor,
An external resonator is formed between the light emitting end face of the light emitting element 8 and the reflection surface 9 for monitoring. The light emitting element 5 for detection is provided with a reflecting surface 6 for detection.
And an external resonator is configured between the light emitting end face of the light emitting element for detection 5 and the reflecting surface 6 for detection. On the other hand, the monitoring photodetector 10 and the detection photodetector 7
The light emitted from the monitor light-emitting element 8 and the detection light-emitting element 5 is disposed opposite to the monitor light-emitting element 8 and the detection light-emitting element 5 and opposite to the monitor reflection surface 9 and the detection light-reflecting surface 6, respectively. Respectively can be directly received.
Here, the excitation light-emitting element 4, the monitoring light-emitting element 8, the monitoring light-receiving element 10, the detection light-emitting element 5, and the detection light-receiving element 7 are all set in grooves formed on the stator 2, Can be used efficiently. Excitation of the vibrator 1 is performed by periodic light emission from the excitation light emitting element 4 as in the first and second embodiments. The excitation state monitor in the Y-axis direction utilizes the fact that the light emission intensity of the monitor light emitting element 8 changes due to a change in the length of the external resonator between the light emitting end face of the light emitting element 5 for detection and the reflecting surface 6 for detection. Done. This is shown in FIG. In the graph of FIG. 6, the horizontal axis represents the length of the external resonator formed between the end face of the monitor light-emitting element 8 and the reflection surface 6 for detection, and the vertical axis represents the output of the light-emitting element 5 for detection. When the length of the external resonator formed between the end face of the monitoring light emitting element 8 and the detecting reflecting surface 6 changes, the light output of the monitoring light emitting element 8 periodically fluctuates at half the emission wavelength λ. I have. This is because the interference relationship between the resonance of the internal resonator and the resonance of the external resonator in the monitor light-emitting element 8 varies depending on the length of the external resonator. Then, the fluctuation range of the external resonator length is set to の of the period of the output vibration, for example, Δh in FIG.
In this case, the external resonator length and the optical output correspond one to one. In this manner, the vibration of the vibrator 1 in the Y-axis direction can be detected as the optical output of the monitor light-emitting element 8 incident on the monitor light-receiving element 10.

The detection of the vibration of the vibrator 1 in the Z-axis direction is performed by receiving the light output of the light emitting element 5 for detection by the light receiving element 7 for detection. As described in the first embodiment, as a result of the combined vibration in the Y-axis direction and the Z-axis direction, the detection reflecting surface 6 makes an elliptical motion that rotates at an angle around the X-axis. From this, the fluctuation of the length of the external resonator formed by the end face of the detection light emitting element 5 and the reflection surface 6 for detection, and the fluctuation of the amount of light reflected back to the light emitting element 5 for detection due to the change in the angle of the reflection surface 6 for detection Occurs.
As a result, the light output of the light emitting element for detection 5 fluctuates by reflecting both the vibrations in the Y-axis direction and the Z-axis direction. From this, as described in the first embodiment, the vibration component in the Z-axis direction can be extracted by utilizing the fact that the vibration due to the Coriolis force in the Z-axis direction has a phase difference of + -90 ° with the vibration in the Y-axis direction. .

In the third embodiment, as in the second embodiment, the detecting reflection surface 6 can be provided on the vibrator 1 at an angle to the Z axis. At this time, it is necessary to face the detection light-emitting elements 5 in accordance with the direction of the detection reflection surface 6 which is inclined. By doing so, the detection sensitivity of vibration in the Z-axis direction can be increased.

FIG. 7 shows a fourth embodiment of the present invention. Here, unlike the third embodiment, the vibrator 1 is cantilevered in that the support 3 is not interposed between the vibrator 1 and the stator 2 and is directly coupled to the stator 2 at the end face of the vibrator 1. It becomes a beam. Here, even if the configuration of FIG. 8 is adopted instead of FIG. 7, the same cantilever structure of the vibrator 1 is obtained. FIG. 9 shows a cross section along the line AA in FIG. Here, the structure in which the stator 2 is not removed in the Z-axis direction of the vibrator 1 is adopted, and the vibrator 1 as a movable structure is provided on one surface in the Z-axis direction of the semiconductor substrate forming the vibrator 1 and the stator 2. Are formed, which is a so-called surface micromachining structure. At this time, if the thickness of the semiconductor substrate is sufficiently large, there is an advantage that the thickness of the vibrator 1 can be freely formed irrespective of the thickness, which leads to easiness of manufacturing the sensor.
It is known that such a surface micromachining structure can be formed by various methods. For example, a technique of forming an easily-etchable layer inside the substrate by using ion implantation can be used. The vibrator 1 having the cantilever structure has the following advantages. Example 3 is the support 3
Vibrates around the joint with the stator 2, but vibrates around the joint with the stator 2, and the distance between the end face of the vibrator 1 and the fulcrum of vibration increases. For this reason,
This contributes to increasing the amplitude of the vibration of the detecting reflection surface 6 and improving the detection sensitivity of the vibration. However, this difference is not essential from the measurement principle. Therefore, in this embodiment, a configuration using the support 3 shown in the third embodiment may be adopted. In all the embodiments in this specification, any of the configuration using the support 3 and the configuration not using the support 3 can be appropriately adopted. In this embodiment, the monitor light-emitting element 8 is omitted, the excitation light-emitting element 4 also serves as the monitor light-emitting element 8, and the excitation light-emitting element 4 end face and the monitor reflection surface 9
The third embodiment differs from the third embodiment in that an external resonator is formed between the first and second embodiments. As a result, the size of the sensor can be reduced compared to the third embodiment. The excitation light emitter 4 has an internal resonator, for example, L
D is used. Then, the excitation light-emitting element 4 is periodically driven to excite the vibrator 1. Here, the detection of the vibration of the vibrator 1 in the Y-axis direction is performed by monitoring both the driving force applied to the excitation light emitter 4 and the optical output of the excitation light emitter 4. That is, since the light output of the excitation light emitter 4 is a function of the driving force applied thereto and the external resonator length, the external resonator length can be obtained by knowing the driving force applied to the excitation light emitter 4. It is. The other points are not essentially different from the third embodiment, and the description is omitted.

FIG. 10 is a schematic diagram of a fifth embodiment of the present invention, and FIG. 11 is a cross-sectional view taken along line AA of FIG. Although this corresponds in principle to the third embodiment,
Excitation light emitter 4, monitor light emitter 8, monitor light receiver 1
0, in that the light emitting element 7 for detection and the light receiving element 7 for detection are formed integrally with the vibrator 1 and the stator 2 from a semiconductor substrate.
In this formation, for example, after forming the vibrator 1 and the stator 2 by etching a semiconductor substrate, a light emitting unit and a light receiving unit are formed on the vibrator 1 and the stator 2 by using a semiconductor technology.
Can be easily performed. In this embodiment, the alignment can be performed simultaneously with the formation of the light-emitting elements 1, 5, and 8 and the light-receiving elements 7 and 8 by using a one-piece mask. As a result, it contributes to simplifying the manufacturing process and improving the yield.

FIG. 12 is a schematic diagram of a sixth embodiment of the present invention. In this example, the light emitting element 5 for detection is not formed on the stator 2 but is formed on the end face of the vibrator 1 so as to face the light receiving element 7 for detecting light. 7
The fifth embodiment is different from the fifth embodiment in that the light is directly incident on the light source and that the reflecting surface 6 for detection is not provided. Here, the light emitting element 5 for detection
Is different from the fifth embodiment in that it does not require an LD internal resonator and does not need to be an LD. From these differences, Z
The method of detecting vibration in the axial direction is different from that of the fifth embodiment. Although the end face of the vibrator 1 oscillates in an elliptical shape, the angle of the light emitted from the light emitting element 5 for detection changes with respect to the light receiving element 7 for detection. That is, the detection photodetector 7
The light amount of the light incident on the vibrator 1 corresponds to the vibration of the vibrator 1. Then, the angular velocity can be detected by extracting the vibration component in the Z-axis direction from the output fluctuation of the detection light-receiving element 7 due to the change in the light amount, as in the other embodiments.

[0019]

As described above, according to the present invention, it is possible to provide an excitation type angular velocity sensor which does not use a piezoelectric element. As a result, it is possible to prevent variations in sensor characteristics and deterioration in accuracy due to variations in piezoelectric materials.
In addition, there is an effect that the formation of a thick film of a piezoelectric material is unnecessary, and the manufacturing time can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a block diagram for controlling an excitation light emitting element using an output of a monitoring light receiving element in the present invention.

FIG. 3 is a perspective view showing a second embodiment of the present invention.

FIG. 4 is a perspective view showing a third embodiment of the present invention.

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

FIG. 6 is a graph showing the relationship between the external resonator length and the light output of the light emitter in a light emitter having both an internal resonator and an external resonator.

FIG. 7 is a perspective view showing a fourth embodiment of the present invention.

FIG. 8 is a perspective view showing a modification of the fourth embodiment of the present invention.

FIG. 9 is a sectional view showing a modification of the fourth embodiment of the present invention.

FIG. 10 is a perspective view showing a fifth embodiment of the present invention.

FIG. 11 is a sectional view showing a fifth embodiment of the present invention.

FIG. 12 is a perspective view showing a sixth embodiment of the present invention.

FIG. 13 is a perspective view showing a conventional excitation type angular velocity sensor.

FIG. 14 is a sectional view showing a conventional excitation type angular velocity sensor.

[Description of Signs] 1: Vibrator 2: Stator 3: Supporter 4: Excitation light emitter 5: Detection light emitter 6: Detection reflection surface 7: Detection light receiver 8: Monitor light emitter 9: Monitor Reflecting surface 10: Monitor photodetector 11: Driving piezoelectric element 12: Driving piezoelectric element electrode 13: Detection piezoelectric element 14: Detection piezoelectric element electrode 15: Detection piezoelectric element 16: Detection piezoelectric element electrode 21: Detection circuit 22: Oscillation circuit

Claims (6)

[Claims] 1. An excitation-type angular velocity sensor comprising: a vibrator; and a semiconductor substrate formed integrally with a stator supporting the vibrator, comprising: a light-emitting element for exciting the vibrator; Further, an excitation type angular velocity sensor, comprising: at least one set of: a light emitting element for detecting the vibration state of the vibrator; and a light receiving element corresponding to the light emitting element for detecting the vibration state. 2. The exciting vibration type angular velocity sensor according to claim 1, wherein a reflecting surface for reflecting light emitted from the light emitting element for detecting the vibration state is provided on the vibrator, and the light receiving element for detecting the vibration state is provided. A photoreceptor that receives light reflected from the reflection surface, an excitation-vibration-type angular velocity sensor, 3. The excitation type angular velocity sensor according to claim 1, wherein a reflecting surface for reflecting light emitted from the light emitting element for detecting the vibration state is provided on the vibrator, and the light emitting element for detecting the vibration state is provided. An excitation-vibration type angular velocity sensor, which is arranged to face the reflection surface, and wherein a photodetector is a photodetector that receives light emitted from the light-emitting element for detecting the vibration state. 4. The excitation type angular velocity sensor according to claim 1, wherein a light emitting element for detecting a vibration state is provided on the vibrator, and a light receiving element is provided for emitting light emitted from the light emitting element for detecting the vibration state. An excitation type angular velocity sensor characterized in that it is a photoreceptor to be received. 5. An excitation type angular velocity sensor according to claim 1, wherein a light emitting element for excitation is controlled by an output of a photodetector. 6. The excitation type angular velocity sensor according to claim 5, wherein at least one of the light emitting element and the light receiving element is made of the same semiconductor material as the semiconductor substrate.