JP2010261889A - Inertial sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inertial sensor attenuating efficiently vibration of a spring-weight vibration system. <P>SOLUTION: This inertial sensor 100 includes: a base 12, an elastic part 14 in succession to the base 12; a substrate 10 in succession to the elastic part 14, supported by the elastic part 14, and having a mass part 16 displaceable by an inertial force; a piezoelectric conversion constitution 20 for converting strain of the elastic part 14 into an electric field; an electricity-heat conversion part 30 for converting the electric field into heat; and a displacement detection part 40 reacting on a force generated between the base 12 and the mass part 16. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an inertial sensor.

  Inertial sensors such as an acceleration sensor and an angular velocity sensor (gyro sensor) are used to control the position and orientation of, for example, an automobile, an aircraft, a rocket, a camera, and a game machine. For example, in a car navigation apparatus, when detecting the current position of a vehicle, an inertial sensor is used to autonomously measure the moving direction and moving distance of the vehicle. In recent years, the demand for increasing the accuracy of inertial sensors has become very strong.

  One example of an inertial sensor is one that senses the displacement of a weight (cone) supported by a spring (beam). As a method of detecting the displacement of the cone, a method using the resonance frequency of the vibrator (vibration type), a method using a change in electric capacitance (capacitance type), a method using a change in electric resistance (resistance type) )and so on.

  For example, Japanese Patent Application Laid-Open No. 2008-261839 discloses an acceleration detection unit (acceleration sensor) that detects a displacement by detecting a displacement of a cone supported in a cantilever shape with a double tuning fork vibrator. . The acceleration sensor disclosed in the publication has a structure in which when the acceleration is received, the cone receives an inertial force in a direction opposite to the direction of the acceleration, whereby a spring (beam) supporting the cone is bent. Due to the bending of the beam, the double tuning fork vibrator receives a compression force and an extension force, and the vibration frequency changes. The acceleration sensor disclosed in the publication detects the applied acceleration by detecting a change in the vibration frequency.

JP 2008-261839 A

  As described above, a general inertial sensor uses the inertial force of a cone. Therefore, the cone is supported by a member having a restoring force such as a spring. Therefore, the inertial sensor has a vibration system (spring / cone vibration system) composed of a spring and a cone.

  If the physical quantity such as acceleration input to such an inertial sensor is impulse-like, the resonance mode of the spring / cone vibration system may be excited. When the resonance mode of the spring / cone vibration system is excited, an unnecessary signal based on this (a signal of the resonance frequency of the spring / cone vibration system) may be superimposed on the signal for detecting the physical quantity. is there. When an unnecessary signal is superimposed on a signal for detecting a physical quantity, the measurement accuracy of the physical quantity measured by the inertial sensor may be lowered. An unnecessary signal based on the resonance mode of the spring / cone vibration system has a reverberation. For this reason, the measurement accuracy of the inertial sensor may be further reduced by the reverberation. In addition, when the input (physical quantity) for exciting the resonance mode of the spring / cone vibration system continues to enter the inertial sensor, the amplitude of the spring / cone vibration system increases. As a result, the inertial sensor may be destroyed or the output signal may be saturated.

  Particularly in a vibration type inertial sensor, there is a technical difficulty that it is necessary to suppress the vibration of the spring / cone vibration system while maintaining a good vibration state of a vibrator or the like that senses the displacement of the cone.

  One of the objects according to some embodiments of the present invention is to provide an inertial sensor that can efficiently attenuate the vibration of a spring-cone vibration system.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the inertial sensor according to the present invention is:
A base, an elastic part continuous to the base, and a base having a mass part that is continuous with the elastic part and supported by the elastic part and is displaceable by an inertial force;
A piezoelectric conversion structure for converting the distortion of the elastic portion into an electric field;
An electrothermal conversion section for converting the electric field into heat;
A detection unit that reacts to a force generated between the base and the mass unit;
including.

  Such an inertial sensor can efficiently dissipate the vibration energy of the spring / cone vibration system formed on the base as heat energy, and can attenuate the vibration of the spring / cone vibration system. Thereby, generation | occurrence | production of an unnecessary signal is suppressed and the precision of measurement, such as an acceleration and an angular velocity, can be improved.

[Application Example 2]
In application example 1,
Including a resistance layer formed on the elastic portion;
The elastic part has piezoelectricity,
The piezoelectric conversion configuration converts the strain into the electric field by the piezoelectricity of the elastic part,
The electrothermal conversion unit is an inertial sensor that converts the electric field into the heat by an electric resistance of the resistance layer.

  Such an inertial sensor can efficiently dissipate the vibration energy of the spring / cone vibration system as thermal energy, and can attenuate the vibration of the spring / cone vibration system. In addition, the inertial sensor of this application example has a relatively simple structure because a resistance layer is formed on the elastic portion, and thus, for example, manufacturing can be facilitated.

[Application Example 3]
In application example 1,
A piezoelectric film formed on the elastic portion;
A resistance layer formed on the piezoelectric film;
Including
The piezoelectric conversion configuration converts the strain into the electric field by the piezoelectricity of the piezoelectric film,
The electrothermal conversion unit is an inertial sensor that converts the electric field into the heat by an electric resistance of the resistance layer.

  Such an inertial sensor can efficiently dissipate the vibration energy of the spring / cone vibration system as thermal energy, and can attenuate the vibration of the spring / cone vibration system.

[Application Example 4]
In application example 1,
A pair of conductive layers formed on the elastic portion and spaced apart from each other;
A resistance element electrically connected to the pair of conductive layers;
Including
The elastic part has piezoelectricity,
The piezoelectric conversion configuration converts the strain into the electric field by the piezoelectricity of the elastic part,
The electrothermal conversion unit is an inertial sensor that converts the electric field into the heat by an electric resistance of the resistance element.

  Such an inertial sensor can efficiently dissipate the vibration energy of the spring / cone vibration system as thermal energy, and can attenuate the vibration of the spring / cone vibration system.

  In the present specification, the term “electrically connected” refers to, for example, another specific member (hereinafter referred to as “B member”) that is “electrically connected” to a “specific member (hereinafter referred to as“ A member ”)”. ")"). In this specification, in the case of this example, the case where the A member and the B member are directly connected and electrically connected, and the A member and the B member are connected via other members. The term “electrically connected” is used to include cases where the terminals are electrically connected.

[Application Example 5]
In application example 4,
The closest part between the pair of conductive layers is an inertial sensor in a region where the strain is concentrated in the elastic part when the mass part is displaced with respect to the base part.

  Such an inertial sensor can more efficiently dissipate the vibration energy of the spring / cone vibration system as thermal energy, and can attenuate the vibration of the spring / cone vibration system.

[Application Example 6]
In application example 1,
A piezoelectric element formed on the elastic part;
A resistive element electrically connected to the piezoelectric element;
Including
The piezoelectric conversion configuration converts the strain into the electric field by the piezoelectricity of the piezoelectric element,
The electrothermal conversion unit is an inertial sensor that converts the electric field into the heat by an electric resistance of the resistance element.

  Such an inertial sensor can efficiently dissipate the vibration energy of the spring / cone vibration system as thermal energy, and can attenuate the vibration of the spring / cone vibration system.

[Application Example 7]
In any one of Application Example 4 to Application Example 6,
In addition, a package for storing the inertial sensor,
The resistance element is an inertial sensor provided outside the package.

  Such an inertial sensor can efficiently dissipate the vibration energy of the spring / cone vibration system as thermal energy, and can attenuate the vibration of the spring / cone vibration system. In addition, since the inertial sensor of this application example can dissipate the vibration energy of the elastic portion as heat outside the package, the influence of the heat on the inertial sensor can be kept small, and the accuracy can be further improved. Can do. In addition, such an inertial sensor can attenuate the vibration of the spring / cone vibration system and reduce the pressure in the package, thereby suppressing thermal noise and member deterioration.

[Application Example 8]
In any one of Application Examples 1 to 7,
The detection unit includes a double tuning fork type vibration piece provided by bridging the base part and the mass part, and the resonance frequency of the double tuning fork type vibration piece is generated between the base part and the mass part. Inertial sensor that reacts to

  Such an inertial sensor can efficiently dissipate the vibration energy of the spring / cone vibration system as thermal energy, and can attenuate the vibration of the spring / cone vibration system. In addition, such an inertial sensor uses a change in the resonance frequency of the double tuning fork resonator element, and thus has a very high accuracy.

A top view showing typically inertial sensor 100 concerning an embodiment. The top view which shows typically the principal part of the inertial sensor 100 concerning embodiment. The schematic diagram of the cross section of the principal part of the inertial sensor 100 concerning embodiment. The schematic diagram of the cross section of the principal part of the inertial sensor 100 concerning embodiment. A top view showing typically inertial sensor 200 concerning an embodiment. The schematic diagram of the cross section of the inertial sensor 300 concerning embodiment. The schematic diagram of the cross section of the inertial sensor 100 concerning embodiment. The schematic diagram of the cross section of the inertial sensor 100 concerning embodiment. The top view which shows typically the principal part of the inertial sensor concerning a modification. The schematic diagram of the cross section of the principal part of the inertial sensor concerning a modification. The schematic diagram of the cross section of the principal part of the inertial sensor concerning a modification. The top view which shows typically the principal part of the inertial sensor 400 concerning embodiment. The schematic diagram of the cross section of the principal part of the inertial sensor 400 concerning embodiment. The top view which shows typically the principal part of the inertial sensor concerning a modification. The top view which shows typically the principal part of the inertial sensor concerning a modification. The top view which shows typically the principal part of the inertial sensor concerning a modification. The schematic diagram of the cross section of the principal part of the inertial sensor concerning a modification. The top view which shows typically the principal part of the inertial sensor concerning a modification. The schematic diagram of the cross section of the principal part of the inertial sensor concerning a modification. The schematic diagram of the cross section of the principal part of the inertial sensor concerning a modification. The top view which shows typically the principal part of the inertial sensor 500 concerning embodiment. The schematic diagram of the cross section of the principal part of the inertial sensor 500 concerning embodiment. The schematic diagram of the cross section of the principal part of the inertial sensor 500 concerning embodiment. The schematic diagram of the cross section of the principal part of the inertial sensor concerning a modification. The schematic diagram of the cross section of the principal part of the inertial sensor concerning a modification. The schematic diagram of the cross section of the principal part of the inertial sensor concerning a modification.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

  The inertial sensor according to the present invention includes a base body having a base portion, an elastic portion, and a mass portion, a piezoelectric conversion configuration, an electrothermal conversion portion, and a detection portion. The inertial sensor according to the present invention has many embodiments. The embodiments described below exemplify some preferred embodiments of the many embodiments. The detection unit responds to stress, and the following is an example in which a displacement detection unit that reacts to stress accompanying displacement is applied. In addition, this invention is not limited to the following embodiment, Various modifications implemented in the range which does not change the summary of this invention are included.

1. 1st Embodiment This embodiment is an example in case the elastic part of a base | substrate has piezoelectricity and an elastic part is a piezoelectric conversion structure. Moreover, this embodiment is an example in case an electrothermal conversion part is comprised by a resistance layer.

  The inertial sensor 100 as an example of the present embodiment includes a base body 10, a piezoelectric conversion configuration 20, an electrothermal conversion unit 30, and a displacement detection unit 40. FIG. 1 is a plan view schematically showing the inertial sensor 100. FIG. 2 is a plan view schematically showing the main part (near the elastic part 14) of the inertial sensor 100. FIG. In FIG. 2, the displacement detection unit 40 (double tuning fork type vibrating piece 42) is omitted. 3 and 4 are schematic views of the cross section of the main part of the inertial sensor 100. FIG. 3 and 4 correspond to a cross section taken along line AA and a cross section taken along line BB in FIG. 2, respectively. FIG. 5 is a plan view schematically showing an inertial sensor 200 according to a modification. FIG. 6 is a schematic diagram of a cross section of an inertial sensor 300 according to a modification.

1.1. Substrate The substrate 10 is a member that bends when a physical quantity such as acceleration or angular velocity is given to the inertial sensor 100. That is, the base body 10 can be bent by an inertial force acting on the mass portion 16 when a physical quantity such as acceleration is applied to the inertial sensor 100.

  The base body 10 includes a base portion 12, an elastic portion 14 that is continuous with the base portion 12, and a mass portion 16 that is continuous with the elastic portion 14 and supported by the elastic portion 14. The mass portion 16 can be displaced with respect to the base portion 12 by an inertial force.

  The shape of the base 10 is not limited as long as it has the base 12, the elastic part 14, and the mass part 16. The planar outer shape of the base 10 can be, for example, a rectangle, a circle, or the like, and may have a notch or a constriction. Moreover, the external shape of the base | substrate 10 can be made into plate shape, frame shape (refer FIG. 5), container shape (refer FIG. 6) etc., for example. In the example of the inertial sensor 100 shown in FIG. 1, the shape of the base body 10 is a plate shape having a rectangular outer shape when seen in a plan view. In the inertial sensor 200 shown in FIG. 5, the base body 10 has a shape including a frame-like base portion 12 and a mass portion 16 formed on the inner side when seen in a plan view. Further, in the inertial sensor 300 shown in FIG. 6, the base body 10 has a shape including a container-like base portion 12 that accommodates the mass portion 16 therein. The external shape of the base 10 illustrated here can be applied to other embodiments.

  In the present embodiment, the elastic portion 14 of the substrate 10 is formed of at least one of a piezoelectric material such as quartz, lithium tantalate, and lithium niobate, and a piezoelectric polymer material such as polyvinylidene fluoride. The base body 10 may be integrally formed of the same material as a whole, and each part may be formed of different materials. The material of the portion other than the elastic portion 14 of the base 10 is not particularly limited, but glass such as silicate glass, semiconductor material such as silicon and gallium arsenide, metal material such as stainless steel, various rubbers, polymer materials, A piezoelectric material such as quartz, lithium tantalate, or lithium niobate can be used. In the case where the entire base 10 is integrally formed of the same material, for example, manufacturing can be facilitated. In the example of the inertial sensor 100, the base body 10 is integrally formed of quartz with the base portion 12, the elastic portion 14, and the mass portion 16.

  The base 12 is a part that supports the base 10. The base 12 is a part that is mechanically fixed to the device when the inertial sensor is mounted on a device such as an automobile, an aircraft, a camera, or a game machine. The shape of the base 12 is not limited. The functions of the base portion 12 include supporting the mass portion 16 via the elastic portion 14 and serving as a reference for the displacement of the elastic portion 14 that occurs when a physical quantity such as acceleration is input to the inertial sensor 100. Can be mentioned. The materials that can be used for the base 12 are as described above. In the example of the inertial sensor 100, the base 12 is formed of quartz.

  The elastic portion 14 is a portion that connects the base portion 12 and the mass portion 16 so that the base portion 12 supports the mass portion 16. A plurality of elastic portions 14 may be provided on the base 10. For example, when the base portion 12 has a frame-like outer shape when seen in a plan view, a plurality of elastic portions 14 may exist so as to suspend the mass portion 16 inside the base portion 12. For example, in the inertial sensor 200 illustrated in FIG. 5, there are four elastic portions 14.

  The shape of the elastic part 14 is not particularly limited. Examples of the shape of the elastic portion 14 include a leaf spring shape, a string spring (coil) shape, and a bent shape. In the example of the inertial sensor 100, the elastic portion 14 corresponds to a portion where the thickness of the base 10 is small between the base portion 12 and the mass portion 16 (a portion where the thickness is narrow in a sectional view) in the plate-like base 10. . In the example of the inertial sensor 200 in FIG. 5, the elastic portion 14 corresponds to a portion connecting the frame-shaped base portion 12 and the mass portion 16. In the example of the inertial sensor 300 in FIG. 6, the elastic portion 14 corresponds to a portion in which the mass portion 16 is connected to the base portion 12 in a cantilever shape.

  The elastic part 14 has elasticity. That is, the elastic portion 14 is bent when the inertia force is generated in the mass portion 16, and flexibly displaces the mass portion 16, and when the mass portion 16 is displaced with respect to the base portion 12, It has a restoring force to return to the position before the displacement. The elastic modulus of the elastic portion 14 is not limited as long as the mass portion 16 can be supported. Further, the strain amount of the elastic portion 14 can be appropriately designed so as to be within the elastic limit of the elastic portion 14.

  In this embodiment, the elastic part 14 has piezoelectricity. Therefore, in the present embodiment, the elastic portion 14 corresponds to the piezoelectric conversion configuration 20. Therefore, in this embodiment, it is not always necessary to include another configuration for piezoelectric conversion (for example, a piezoelectric element). In the present embodiment, the piezoelectric conversion configuration 20 may include other configurations such as a piezoelectric element.

  In the present embodiment, the elastic portion 14 is made of the above-described piezoelectric material, and can convert strain generated in the elastic portion 14 into an electric field when acceleration or the like is input to the inertial sensor. Such an electric field can cause a potential difference in, for example, a conductive member formed in the elastic portion 14. Therefore, current (electric power) can be taken out through the member by appropriately arranging a member having conductivity.

  The piezoelectric material of the elastic portion 14 can be arranged by selecting the direction of the crystal axis and the like in consideration of the distortion of the elastic portion 14 and the arrangement of conductive members and the like. In the example of the inertial sensor 100, the elastic portion 14 is formed of quartz, and as indicated by arrows in FIGS. 1 to 4, along the direction from the base 12 toward the mass portion 16, the Y axis (mechanical axis) of the quartz And the X axis (electric axis) of quartz is arranged along the direction in which the elastic portion 14 extends. Thereby, when the base 10 is bent in the thickness direction (the Z-axis (optical axis) direction of the crystal), an electric field is generated in the X-axis (electric axis) direction of the crystal in the elastic portion 14. Since the inertial sensor 100 employs such a crystal axis arrangement, it is easy to take out current using an electric field. Similarly, when the elastic portion 14 is formed of another piezoelectric material, the arrangement of crystal axes and the like can be selected so that current can be easily taken out. Similarly, in the case of the inertial sensor 200 and the inertial sensor 300, the crystal axes can be appropriately arranged so that the electric field of the elastic portion 14 can be easily taken out as a current.

  The mass part 16 is a part that is continuous with the elastic part 14 and supported by the elastic part 14. The shape of the mass part 16 is not particularly limited. Examples of the form in which the mass part 16 is supported include a cantilever form, a doubly supported form, and a form suspended by the elastic part 14. The mass part 16 becomes an inertial resistance (mass) when acceleration or the like is applied to the inertial sensor. Therefore, when an inertial force is generated in the spring / cone vibration system, the elastic portion 14 can be distorted by the action of the mass portion 16. Further, when acceleration or the like is applied to the inertial sensor, the relative position of the mass portion 16 with respect to the base portion 12 changes due to the inertia of the mass portion 16. Therefore, the inertial sensor can measure applied acceleration or the like by detecting a change in the relative position of the mass portion 16 with respect to the base portion 12. In the example of the inertial sensor 100, the mass portion 16 is continuous with the elastic portion 14 and is held in a cantilever shape. In this example, when the acceleration is applied in the thickness direction of the base body 10, the elastic portion 14 is distorted, and the position of the mass portion 16 with respect to the base portion 12 is changed (see FIGS. 7 and 8, which will be described later).

  The mass of the mass unit 16 is not limited, and may be a suitable mass in consideration of at least one of the type and size of the physical quantity measured by the inertial sensor and the elasticity of the elastic unit 14. The material of the mass part 16 is as described above. The mass portion 16 may include a configuration corresponding to a weight formed of a material having a large specific gravity such as gold, platinum, lead, or iron in order to adjust the mass.

  As described above, the base 10 has the base portion 12, the elastic portion 14, and the mass portion 16. Therefore, the base 10 constitutes a spring / cone vibration system. As a result, the base body 10 is a position change of the mass portion 16 with respect to the base portion 12 such that an inertial force, which is a virtual force, can be converted into a stress in the Y-axis direction that acts on the displacement detection unit 40 in the inertial sensor. You can make it appear.

1.2. Piezoelectric Conversion Configuration The inertial sensor according to the present invention has a piezoelectric conversion configuration. In the present embodiment, the elastic portion 14 of the base body 10 is the piezoelectric conversion configuration 20. The piezoelectric conversion structure 20 can convert the strain generated in the elastic portion 14 of the base 10 into an electric field.

  When distortion occurs in the elastic portion 14 that is the piezoelectric conversion structure 20, an electric field is generated in the elastic portion 14. At this time, if a conductive member is provided on the surface of the elastic portion 14, a potential difference (including a potential difference in a minute section) according to the electric field of the piezoelectric body can be generated in the member. That is, the conductive member formed on the elastic portion 14 can generate portions having different potentials depending on the strain of the elastic portion 14. When these portions are electrically connected to each other, a current can be generated in the connection path.

  Here, the potential difference generated in the conductive member means a potential difference generated between a plurality of minute portions of the elastic member 14 when a single conductive member is provided in the elastic portion 14, and a plurality of potential differences in the elastic portion 14. When a conductive member is provided, it means at least one of potential differences generated between the members.

  In the example of the inertial sensor 100, one conductive member (in this embodiment, a resistance layer 32 (described later)) is provided on the surface of the elastic portion 14. When the elastic portion 14 is distorted, a potential difference is generated in a minute section of the member, and a current is generated inside the member. In the example of the inertial sensor 200 and the inertial sensor 300, a plurality of conductive members (in the present embodiment, the resistance layer 32) are provided on the surface of the elastic portion 14. When the elastic portion 14 is distorted, a potential difference is generated in a minute section of the member, and a current is generated inside the member.

1.3. Electrothermal Conversion Unit The inertial sensor according to the present invention includes an electrothermal conversion unit. In the present embodiment, the resistance layer 32 provided on the elastic portion 14 corresponds to the electrothermal conversion portion 30. The electrothermal conversion unit 30 is a means for converting an electric field based on distortion generated in the elastic portion 14 of the base 10 into heat. In the present embodiment, an electric field is converted into heat by a current flowing through the resistance layer 32 having electrical resistance.

  The inertial sensor of this embodiment includes a resistance layer 32 as the electrothermal conversion unit 30. The resistance layer 32 has an electrical resistance. The resistance layer 32 is provided on the surface of the elastic portion 14. In each portion of the resistance layer 32 (a minute portion may be assumed), a potential difference according to the electric field generated by the elastic portion 14 being distorted can be generated. A current is generated in the resistance layer 32 according to this potential difference. Thereby, the resistance layer 32 can generate so-called Joule heat. That is, the resistance layer 32 (the electrothermal conversion unit 30) can convert the electrical energy generated by the elastic unit 14 (the piezoelectric conversion configuration 20) into thermal energy.

  Examples of the material of the resistance layer 32 include inorganic materials such as carbon, metals such as tungsten, conductive alloys, conductive polymers, and the like. Moreover, even if it is a metal with small resistivity, such as copper, gold | metal | money, chromium, platinum, it can be set as the resistance layer 32 which has electrical resistance by reducing the thickness of the resistance layer 32, etc. If the resistance layer 32 is made of a material having a relatively low elastic modulus, such as a metal thin film or a conductive polymer, it is possible to make it difficult to restrain deformation of the elastic portion 14.

  The resistance layer 32 may be provided at a plurality of locations on the surface of the elastic portion 14. In the example of the inertial sensor 100, the resistance layer 32 is formed only on one main surface side of the base 10, but may be provided on at least one place on the other main surface and both side surfaces of the base 10. Further, the plurality of resistance layers 32 may be provided electrically independently from each other, or the plurality of resistance layers 32 may be electrically connected to each other. As described above, since a current according to the electric field generated in the elastic portion 14 is generated in the resistance layer 32, the resistance layer 32 having a large area can be realized by providing the plurality of resistance layers 32. Therefore, the efficiency as the electrothermal conversion unit 30 can be further increased. In addition, since the resistance layer 32 can be formed only at a necessary portion, in this case, the deformation of the elastic portion 14 is restrained as compared with the case where the resistance layer 32 is formed on the entire elastic portion 14. Can be difficult.

  The inertial sensor 100 shows an example in which the elastic portion 14 of the base 10 is formed of a piezoelectric body, and one resistance layer 32 is provided on the surface of the elastic portion 14. Further, in the examples of the inertial sensor 200 and the inertial sensor 300, a plurality of resistance layers 32 are provided on the side surface of the elastic portion 14.

1.4. Displacement Detection Unit The displacement detection unit 40 responds to the displacement of the mass unit 16 with respect to the base 12, for example, and is configured to detect a physical quantity according to the stress in the Y-axis direction caused by the displacement. As a configuration of the displacement detection unit 40, for example, a pair or a plurality of electrodes (electrodes 48 in the examples of FIGS. 5 and 6) provided such that the capacitance is changed by the displacement of the mass unit 16, Examples thereof include a vibrator (vibration piece) provided such that the vibration frequency changes according to the displacement, a resistance change element provided such that the electric resistance changes according to the displacement of the mass portion 16, and the like. Among these, when the displacement detection unit 40 is configured by a vibrator (vibrating piece), the displacement of the mass unit 16 can be detected with very high accuracy. In the example of the inertial sensor 100, the displacement detection unit 40 is configured by a double tuning fork type vibrating piece 42. Hereinafter, the inertial sensor 100 in which the displacement detection unit 40 includes the double tuning fork type vibrating piece 42 will be described as an example.

  The double tuning fork type vibrating piece 42 functions as the displacement detection unit 40. In the case where the double tuning fork type vibrating piece 42 is formed of a material having piezoelectricity, an excitation electrode or the like (not shown) is disposed so that the double tuning fork type vibrating piece 42 can be appropriately driven, thereby providing a double tuning fork type piece. The vibrating piece 42 can be vibrated. When the double tuning fork type vibrating piece 42 is formed of a material that does not have piezoelectricity, the double tuning fork type vibrating piece 42 may be vibrated by providing a piezoelectric element or the like to the double tuning fork type vibrating piece 42 as appropriate. it can.

  In the inertial sensor 100, both ends of the double tuning fork type vibrating piece 42 are supported by the base 10. That is, one end of the double tuning fork type vibrating piece 42 is fixed to the base portion 12 of the base body 10, and the other end is fixed to the mass portion 16 of the base body 10 to bridge the base portion 12 and the mass portion 16 of the base body 10. It is provided as follows. The double tuning fork type vibrating piece 42 may be formed separately from the base body 10 and then connected to the base body 10 or may be formed integrally with the base body 10. In the inertial sensor 100, the double tuning fork type vibrating piece 42 is formed integrally with the base body 10. Therefore, in the inertial sensor 100, the material of the double tuning fork type vibrating piece 42 is the same as the material of the base 10, and the extending direction of the double tuning fork type vibrating piece 42 is the Y-axis direction of the crystal of the crystal.

  On the base 10, the planar position where the double tuning fork type vibrating piece 42 is formed is the tensile or compressive stress in the longitudinal direction of the double tuning fork type vibrating piece 42 when the base 10 is bent due to acceleration or the like. It is not limited as long as it is arranged so as to generate. The double tuning fork type vibrating piece 42 is arranged so that tensile or compressive stress is generated in the longitudinal direction when the base 10 of the inertial sensor 100 is subjected to acceleration or the like and is bent in the thickness direction.

  7 and 8 are schematic views of a cross section of the inertial sensor 100. FIG. 7 and 8 correspond to a cross section taken along line CC in FIG. 7 and 8 schematically show the behavior when the inertial sensor 100 receives acceleration. As shown in FIG. 7, when the acceleration α in the −Z direction is applied to the inertial sensor 100, the base body 10 bends in the + Z direction due to the inertia of the mass portion 16. At this time, the double tuning fork vibrating piece 42 receives a compressive stress. Similarly, as shown in FIG. 8, when acceleration in the + Z direction is applied to the inertial sensor 100, the base body 10 bends in the −Z direction due to the inertia of the mass portion 16. At this time, the double tuning fork type vibrating piece 42 receives an elongation stress.

  When the tensile or compressive stress in the longitudinal direction is applied to the double tuning fork type vibrating piece 42, the frequency of vibration changes. Therefore, the amount of displacement of the mass portion 16 of the base body 10 with respect to the base portion 12 can be measured by detecting the change in frequency of the vibration.

  Thus, the double tuning fork type vibrating piece 42 that is the displacement detection unit 40 in the inertial sensor 100 vibrates at a specific frequency, and the displacement of the mass unit 16 can be signaled by the change of the frequency in this state. The change in the frequency of vibration of the double tuning fork type vibrating piece 42 can be measured, for example, by comparing with the reference frequency. Further, if the correlation between the difference between the vibration frequency of the double tuning fork type vibrating piece 42 and the reference frequency and the magnitude of acceleration or the like is calculated in advance and tabulated, the acceleration applied to the inertial sensor 100 can be more easily obtained. Can be measured.

1.5. As described above, the inertial sensor 100 of the present embodiment is formed on the base 12, the base 10 having the piezoelectric elastic portion 14 (piezoelectric conversion configuration 20) and the mass portion 16, and the elastic portion 14. A resistance layer 32 (electrothermal conversion unit 30) and a displacement detection unit 40 are included. As a result, when a physical quantity such as acceleration is applied to the inertial sensor, the mechanical energy related to the distortion generated in the elastic portion 14 can be reduced by the amount converted into the thermal energy, so that the vibration generated in the elastic portion 14 Can be suppressed. Therefore, in particular, when impulse-like acceleration is applied to the inertial sensor and the resonance mode of the spring / cone vibration system is excited, the vibration of the base 10 is suppressed, and the vibration energy of the spring / cone vibration system is used as thermal energy. It is possible to achieve at least one of dissipating and stopping excess vibration and suppressing the reverberation to be small. Thereby, it is possible to make it difficult to mix unnecessary signals due to the vibration of the spring / cone vibration system into the signal from the displacement detection unit 20, and it is possible to improve the measurement accuracy such as acceleration of the inertial sensor.

1.6. Modifications The inertial sensor of the present embodiment can be further modified as follows. FIG. 9 is a plan view of a main part of an inertial sensor according to a modification. FIG. 10 is a schematic diagram of a cross section of a main part of an inertial sensor according to a modification. FIG. 10 corresponds to a cross section taken along line AA in FIG.

  The inertial sensor 110 has a convex portion 14 a on the elastic portion 14. A resistance layer 32 is formed along the surface of the convex portion 14a (that is, the surface of the elastic portion 14). The cross-sectional shape of the convex portion 14a is not particularly limited, and may be a triangle, a quadrangle, an arc shape, or the like. In the example of FIG. 10, the convex portion 14a has a rectangular cross section. Further, the planar shape of the convex portion 14a is not particularly limited.

  The convex portion 14a has a function of increasing the current generated in the resistance layer 32 when the elastic portion 14 is distorted. That is, since the side surface of the convex portion 14a intersects the electric axis (X axis) of the elastic portion 14, the resistance layer 32 formed on the side surface can more efficiently extract the electric field generated in the elastic portion 14 ( The arrows in the figure schematically show the direction of the electric field.) Thereby, when the elastic part 14 is distorted, more current can be generated in the resistance layer 32.

  More preferably, the convex portion 14a has a side surface orthogonal to the direction of the electric field generated when the elastic portion 14 is distorted. Moreover, the efficiency which takes out the electric field of the elastic part 14 can be improved by forming the convex part 14a in multiple numbers.

  FIG. 11 is a schematic diagram of a cross section of the elastic portion 14 when a plurality of convex portions 14a are formed. As shown in FIG. 11, when the plurality of convex portions 14a are provided, the current according to the electric field of the elastic portion 14 can be taken out by each convex portion 14a. The planar shape of the convex portion 14a is more preferably a linear shape extending in a direction orthogonal to the direction of the electric field generated when the elastic portion 14 is distorted. That is, when a plurality of convex portions 14a are provided, the shape may be a stripe shape extending in a direction (Y-axis direction) orthogonal to the direction of the electric field (X-axis direction) generated when the elastic portion 14 is distorted. More preferred.

  By the above deformation, the efficiency of converting the strain energy of the elastic portion 14 into heat energy can be further increased. Such a modification can also be applied to other embodiments (for example, the second embodiment and the third embodiment (when the piezoelectric conversion configuration 20 is configured by the piezoelectric film 22)), and strain energy is reduced. The efficiency of conversion into thermal energy can be further increased.

2. 2nd Embodiment This embodiment is an example in case an electrothermal conversion part is comprised including a conductive layer and a resistive element. This embodiment is an example in which the elastic portion of the base body has piezoelectricity and the elastic portion has a piezoelectric conversion configuration. The present embodiment is different from the first embodiment in that the electrothermal conversion unit includes a conductive layer and a resistance element. About other points, it is the same as that of a 1st embodiment and its modification. Therefore, substantially the same members are denoted by the same reference numerals and detailed description thereof is omitted.

  An inertial sensor 400 that is an example of the present embodiment includes a base 10, a piezoelectric conversion configuration 20, an electrothermal conversion unit 30, a displacement detection unit 40, a conductive layer 34, and a resistance element 36. In the inertial sensor 400, the electrothermal conversion unit 30 includes the conductive layer 34 and the resistance element 34, and the elastic portion 14 of the base 10 has piezoelectricity. Hereinafter, detailed description of the configuration other than the electrothermal conversion unit 30 will be omitted.

  FIG. 12 is a plan view schematically showing the main part (near the elastic part 14) of the inertial sensor 400. FIG. FIG. 13 is a schematic diagram of a cross section of a main part of the inertial sensor 400. 13 corresponds to a cross section taken along line BB in FIG. 14 and 15 are plan views schematically showing main parts of an inertial sensor according to a modification.

2.1. Base Body The base body 10 is a member that bends when a physical quantity such as acceleration or angular velocity is given to the inertial sensor 400. The configuration, shape, function, material, deformation and the like of the base body 10 are the same as those described in the first embodiment.

2.2. Piezoelectric Conversion Configuration In this embodiment, the elastic portion 14 of the base body 10 corresponds to the piezoelectric conversion configuration 20 as in the first embodiment. The piezoelectric conversion structure 20 can convert the strain generated in the elastic portion 14 of the base 10 into an electric field. The configuration, shape, function, material, deformation and the like of the piezoelectric conversion configuration 20 are the same as those described in the first embodiment.

2.3. Electrothermal Conversion Unit In the inertial sensor 400, the electrothermal conversion unit 30 includes a pair of conductive layers 34 and a resistance element 36.

  The conductive layer 34 is provided on the elastic portion 14. A plurality of conductive layers 34 are provided electrically separated from each other. The conductive layer 34 has conductivity and can have a potential according to the electric field generated in the elastic portion 14. Accordingly, a potential difference can be generated between any two conductive layers 34 (a pair of conductive layers 34) of the plurality of conductive layers 34. That is, by electrically connecting the pair of conductive layers 34 formed on the elastic portion 14, a current can be generated in the connection path.

  A function of the conductive layer 34 is to extract an electric field generated in the elastic portion 14 as a current. The shape and arrangement of the conductive layer 34 are not particularly limited as long as the electric field generated in the elastic portion 14 can be taken out. For example, the conductive layer 34 can have a thin film shape. When the conductive layer 34 has a thin film shape, the conductive layer 34 may have a single layer structure or a multilayer structure. When the conductive layer 34 has a single layer structure, it can be formed of a chemically stable metal such as gold. When the conductive layer 34 has a multilayer structure, for example, a structure in which a chromium layer and a gold layer are stacked from the base 10 side can be employed. If the conductive layer 34 is a laminated structure of a chromium layer and a gold layer, the adhesion between the elastic portion 14 and the conductive layer 34 can be improved.

  The resistance element 36 is electrically connected to the pair of conductive layers 34. In order to configure such an electrical connection, a wiring or the like may be further formed. Since the resistance element 36 has an electric resistance, when the elastic portion 14 is distorted, a current flows through the resistance element 36 and heat can be generated. Examples of the resistive element 36 include fixed resistors such as carbon film resistors and metal film resistors, and resistors such as variable resistors and semi-fixed resistors. Moreover, as a form of the resistance element 34, an element type, a chip type, etc. are mentioned. Further, the resistance layer 32 described in the first embodiment may be applied as the resistance element 34.

  The position where the resistance element 36 is provided is not particularly limited as long as the connection can be realized by wiring (such as a conductive thin film or a wire). The resistance element 36 can be provided on the base portion 12 or the mass portion 16 of the base body 10, for example. Of these locations, when the resistance element 36 is provided on the base 12, heat generated by the electrothermal conversion unit 30 can be easily dissipated to the outside through the base 12 (see FIG. 12). In the inertial sensor 400 shown in FIG. 12 and FIG. 13, the wiring 35 is drawn out from the pair of conductive layers 34, and the resistance element 36 is provided on the surface of the base 12.

  Further, as shown in FIG. 14, the resistance element 36 is disposed outside the inertial sensor (at a position separated from the base body and outside the package when the inertial sensor is accommodated in the package). By using this, the influence of the heat generated by the resistance element 36 on the characteristics of the inertial sensor can be extremely reduced. That is, the strain energy of the elastic portion 14 can be dissipated as heat energy at a location sufficiently separated from the inertial sensor.

  A plurality of sets including the pair of conductive layers 34 and the resistance element 36 may be provided. In the example shown in FIGS. 12 and 13, one set of the pair of conductive layers 34 and resistance elements 36 is formed, but a plurality of sets may be formed as shown in FIG. 15. Further, although not shown, it may be provided on the back side of the elastic portion 14. In this way, the electric field generated in the elastic part 14 can be taken out more efficiently. In addition, as shown in FIG. 15, when a plurality of sets including a pair of conductive layers 34 and resistance elements 36 are formed, the size of one set approaches zero, and the number of sets is infinite. The increasing limit can be regarded as substantially the same as the resistance layer 32 described in the first embodiment.

2.4. Displacement Detection Unit The displacement detection unit 40 detects the displacement of the mass unit 16 relative to the base 12. The displacement detection unit 40 of this embodiment is the same as that of the first embodiment, and can be a vibrating piece, an electrode provided such that the capacitance changes, a resistance change element, or the like.

2.5. Effects and the like The inertial sensor of the present embodiment includes a base 10, a base 10 having a piezoelectric elastic part 14 (piezoelectric conversion configuration 20) and a mass part 16, a pair of conductive layers 34 and a resistance element 36 (electrothermal conversion part). 30) and a displacement detector 40. Thereby, when a physical quantity such as acceleration is applied to the inertial sensor, the strain generated in the elastic portion 14 can be released outside the spring / cone vibration system as thermal energy. Thereby, it is possible to make it difficult to mix unnecessary signals due to the vibration of the spring / cone vibration system into the signal from the displacement detection unit 20, and it is possible to improve the measurement accuracy such as acceleration of the inertial sensor. In addition to this, in the present embodiment, the electrothermal conversion unit 30 includes a pair of conductive layers 34 and a resistance element 36. Therefore, heat energy can be discharged out of the spring / cone vibration system. Thereby, the thermal stability of the inertial sensor can be improved.

  Although not shown, examples of the package that accommodates the inertial sensor include a ceramic package base (container) provided with a lid (lid). According to such a package, the inertial sensor can be sealed in the decompression space. According to this, when the displacement detection unit 20 is the double tuning fork type vibrating piece 42, the Q value of the vibrating piece can be increased, and thermal noise and member deterioration can be suppressed. Here, if the inside of the package is a decompressed space, the frictional resistance with the gas molecules for damping the spring / cone vibration system will also decrease, but according to the inertial sensor of this embodiment, the double tuning fork type vibration The Q value of the piece 42 can be increased, and at the same time, only the vibration energy of the spring / cone vibration system can be discharged out of the system.

2.6. Modifications The inertial sensor of the present embodiment can be further modified as follows. FIG. 16 is a plan view schematically showing the main part of an inertial sensor according to a modification. FIG. 17 is a schematic diagram of a cross section of a main part of an inertial sensor according to a modification. FIG. 17 corresponds to a cross section taken along line AA of FIG.

  In the present embodiment, the conductive layer 34 can have a planar shape in order to efficiently extract the electric field of the elastic portion 14. FIG. 16 shows an example in which the shape of the conductive layer 34 is modified. The pair of conductive layers 34 illustrated in FIG. 16 has a triangular shape when seen in a plan view. A pair of triangular vertices 34a face each other in a region near the center of the elastic portion 14 in the Y direction. This makes it easier to take out the electric field of the elastic portion 14. That is, as shown in FIGS. 16 and 17, when the elastic portion 14 is distorted, a stress concentration region 14b (region surrounded by a broken line in the figure) exists near the center of the elastic portion 14 in the Y direction. In this example, the portion where the pair of conductive layers 34 are closest to each other (between the triangular apexes 34a in the illustrated example) is concentrated in the elastic portion 14 when the mass portion 16 is displaced with respect to the base portion 12. The stress concentration region 14b is arranged. Thereby, the electric field produced in the elastic part 14 can be taken out very efficiently. Here, the planar shape of the conductive layer 34 is exemplified by a triangular shape. However, the shape is not limited to this, and the portion where the pair of conductive layers 34 are closest to each other is disposed in the stress concentration region 14 b of the elastic portion 14. As long as the same effect can be achieved.

  FIG. 18 is a plan view schematically showing the main part of an inertial sensor according to a modification. FIG. 19 is a schematic diagram of a cross section of a main part of an inertial sensor according to a modification. FIG. 19 corresponds to a cross section taken along line BB in FIG.

  FIG. 18 is another example in which the shape of the conductive layer 34 is modified. The pair of conductive layers 34 illustrated in FIG. 18 has a comb shape when seen in a plan view. The pair of conductive layers 34 are arranged so as to mesh with each other in a comb shape. This makes it easier to take out the electric field of the elastic portion 14. The comb-shaped pitch and number of the conductive layers 34 are not limited. In this modification, the modifications described in “1.6. Modifications” of the first embodiment are further combined. That is, as shown in FIG. 19, the shape of the conductive layer 34 is modified by forming a convex portion 14 a on the elastic portion 14 as in the example of FIG. 11. In this way, the electric field of the elastic portion 14 can be further easily taken out by the conductive layer 34.

  A plurality of conductive layers 34 may be provided. In the example of the inertial sensor 400 and the modifications shown in FIGS. 14 and 16, the conductive layer 34 is formed only on one side of the base 10, but is also provided on the other side of the base 10. May be. Further, the conductive layer 34 may be provided on the side surface of the base 10. When a plurality of conductive layers 34 are provided, the conductive layers 34 are provided separately from each other. The resistance element 36 can be connected to at least one pair of the conductive layers 34 among the plurality of conductive layers 34. Thereby, the efficiency as the electrothermal conversion part 30 can further be improved.

  FIG. 20 is a schematic diagram of a cross section of the elastic portion 14 of the inertial sensor according to the modification. An example in which two conductive layers 34 are provided on both the upper and lower surfaces of the elastic portion 14 is shown. In the example shown in FIG. 20, two conductive layers 34 a, 34 b, 34 c, 34 d are provided on each of the upper surface side and the lower surface side of the base 10. The illustrated example shows a state where the elastic portion 14 is distorted, and an arrow in the figure schematically shows an electric field generated in the elastic portion 14 at a certain moment. At this time, in the elastic portion 14, distortions that are opposite to each other occur on the upper surface side and the lower surface side, so that the electric fields that are generated are also in the opposite directions. Each conductive layer has a potential according to the electric field of the elastic portion 14. That is, in the illustrated example, the conductive layer 34b has a high potential with respect to the conductive layer 34a, and the conductive layer 34d has a high potential with respect to the conductive layer 34c. Accordingly, when the conductive layer is electrically connected to the resistance element 36, heat can be generated in the resistance element 36 by selecting the conductive layer 34a and the conductive layer 34b as a pair of conductive layers. Similarly, heat can be generated in the resistance element 36 by selecting the conductive layer 34d and the conductive layer 34c as the pair of conductive layers. The resistance element 36 can also generate heat by selecting the conductive layer 34a and the conductive layer 34c as the pair of conductive layers, or by selecting the conductive layer 34d and the conductive layer 34b. It will be readily understood that the connections of the exemplified conductive layers 34 may be combined as appropriate.

3. Third Embodiment This embodiment is an example in which the elastic portion of the substrate does not have piezoelectricity and the piezoelectric film has a piezoelectric conversion configuration. This embodiment is different from the first and second embodiments in that the elastic part of the base body does not have piezoelectricity. About other points, it is the same as that of 1st Embodiment, 2nd Embodiment, and those modifications. Therefore, substantially the same members are denoted by the same reference numerals and description thereof is omitted.

  The inertial sensor 500 of the present embodiment includes a base body 10, a piezoelectric conversion configuration 20, an electrothermal conversion unit 30, and a displacement detection unit 40. The inertial sensor 500 includes the piezoelectric conversion configuration 20 including the piezoelectric film 22. Hereinafter, a detailed description of the configuration other than the piezoelectric conversion configuration 20 will be omitted. FIG. 21 is a plan view schematically showing the main part (near the elastic part 14) of the inertial sensor 500. 22 and 23 are schematic views of a cross section of a main part of the inertial sensor 500. FIG. 22 and FIG. 23 correspond to a cross section taken along line AA and a cross section taken along line BB in FIG. 21, respectively.

3.1. Base In this embodiment, the elastic portion 14 of the base 10 does not have piezoelectricity. Other configurations, shapes, functions, deformations, etc. of the substrate 10 are the same as those described in the first embodiment. The elastic portion 14 of the base 10 can be made of, for example, glass such as silicate glass, semiconductor material such as silicon and gallium arsenide, metal material such as stainless steel, various rubbers, and polymer material. In the example of the inertial sensor 500, the base body 10 is an example in which the base portion 12, the elastic portion 14, and the mass portion 16 are integrally formed of silicon. The outer shape and the like of the base 10 can be the same as described in the first embodiment.

3.2. Piezoelectric Conversion Configuration In the inertial sensor 500, the piezoelectric conversion configuration 20 includes a piezoelectric film 22.

  The piezoelectric film 22 is provided on the surface of the elastic portion 14. The position where the piezoelectric film 22 is provided is not limited as long as the distortion of the elastic portion 14 is transmitted. The thickness of the piezoelectric film 22 is not particularly limited, but can be 0.1 μm or more and 10 μm or less. The planar shape of the piezoelectric film 22 is not particularly limited.

  Examples of the piezoelectric film 22 include thin films such as PZT (lead zirconate titanate), ZnO (zinc oxide), and AlN (aluminum nitride). The piezoelectric film 22 has piezoelectricity and can generate an electric field by being distorted by receiving stress. Then, when a conductive member is formed on the surface of the piezoelectric film 22, an electric current can be generated in the conductive member.

  In the inertial sensor 500, the piezoelectric film 22 is formed on the surface of the elastic portion 14. Accordingly, the piezoelectric film 22 can be distorted by receiving stress according to the deformation of the elastic portion 14. The piezoelectric film 22 can generate an electric field due to strain.

3.3. Electrothermal Conversion Unit The inertial sensor 500 has a resistance layer 32 in contact with the piezoelectric film 22. The resistance layer 32 can convert the strain energy of the elastic portion 14 into thermal energy, as described in the first embodiment.

  That is, in the present embodiment, the elastic film 14 is distorted, so that the piezoelectric film 22 is distorted by receiving stress. As a result, an electric field is generated in the piezoelectric film 22. A current is generated in the resistance layer 32 in accordance with the electric field generated in the piezoelectric film 22, and Joule heat is generated by the electric resistance of the resistance layer 32. In the present embodiment, the resistance layer 32 similar to that described in the first embodiment is the electrothermal conversion unit 30. However, as described in the second embodiment, the electrothermal conversion includes the pair of conductive layers 34 and the resistance element 36. The conversion unit 30 may be configured.

3.4. Operational Effect, etc. The inertial sensor of the present embodiment includes a base 10, a piezoelectric conversion configuration 20, an electrothermal conversion unit 30, and a displacement detection unit 40. In the inertial sensor of this embodiment, the piezoelectric conversion configuration 20 includes a piezoelectric film 22. Thereby, in addition to the features described in the first embodiment, in this embodiment, even if the elastic portion 14 of the base 10 does not have piezoelectricity, strain energy generated in the elastic portion 14 is efficiently discharged as thermal energy. can do.

3.5. Modification In the inertial sensor 500 of the present embodiment, a plurality of piezoelectric films 22 can be provided. FIG. 24 is a schematic diagram of a cross section of a main part of an inertial sensor according to a modification. In this example, the inertial sensor has two piezoelectric films 22. Each piezoelectric film 22 is electrically connected by a resistance layer 32. The direction of the electric field generated when each piezoelectric film 22 is distorted can be designed according to the direction of strain and the crystal orientation of each piezoelectric film 22. In the inertial sensor of this example, when the elastic portion 14 is distorted, the piezoelectric film 22 is distorted and a current flows through the resistance layer 32. By providing a plurality of piezoelectric films 22, the distortion of the elastic portion 14 can be more efficiently converted into heat. Although not shown in the drawing, if unevenness is formed on the surface of the piezoelectric film 22, it is possible to easily extract the electric field as described in the modification of the first embodiment.

  Further, the piezoelectric film 22 can be sandwiched between a pair of conductive layers 38. FIG. 25 and FIG. 26 are schematic views of a cross section of a main part of an inertial sensor according to another modification. The elastic portion 14 of the inertial sensor of this example is provided with a piezoelectric element 24 in which the piezoelectric film 22 is sandwiched between a pair of conductive layers 38. Also in this modification, the piezoelectric film 22 corresponds to the piezoelectric conversion configuration 20. The piezoelectric film 22 can be distorted by distortion of the conductive layer 38 due to distortion of the conductive layer 38 due to distortion of the elastic portion 14. Thereby, an electric field is generated in the piezoelectric film 22, and a potential difference can be generated between the pair of conductive layers 38 that sandwich the piezoelectric film 22. In the illustrated example, the resistance element 36 is electrically connected to the pair of conductive layers 38, and current generated by the potential difference between the pair of conductive layers 38 is converted into heat by the resistance element 36.

  Thus, by providing the conductive layer 38 so as to sandwich the piezoelectric film 22, that is, by forming the piezoelectric element 24, the electric field generated in the piezoelectric film 22 can be taken out very efficiently. Thereby, the efficiency of the piezoelectric conversion structure 20 can further be improved. A plurality of piezoelectric elements 24 may be provided. Further, the planar shape of the piezoelectric element 24 is not limited.

  In the above description, the aspects and modifications exemplified in each embodiment can be applied to the inertial sensors of other embodiments singly or in combination with each other. Thereby, in the inertial sensor, a single effect of each deformation or a synergistic effect by a combination of each deformation can be obtained.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same purposes and effects). In addition, the present invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 10 ... Base | substrate, 12 ... Base part, 14 ... Elastic part, 14a ... Projection part, 14b ... Stress concentration area | region,
16 ... Mass part, 20 ... Piezoelectric conversion structure, 22 ... Piezoelectric film, 24 ... Piezoelectric element,
30: Electrothermal conversion section, 32: Resistance layer, 34, 38 ... Conductive layer, 35 ... Wiring, 36 ... Resistance element,
40: Displacement detection unit, 42: Double tuning fork type resonator element,
100, 200, 300, 400, 500 ... inertial sensor

Claims (8)

A base, an elastic part continuous to the base, and a base having a mass part that is continuous with the elastic part and supported by the elastic part and is displaceable by an inertial force;
A piezoelectric conversion structure for converting the distortion of the elastic portion into an electric field;
An electrothermal conversion section for converting the electric field into heat;
A detection unit that reacts to a force generated between the base and the mass unit;
Including inertial sensor. In claim 1,
Including a resistance layer formed on the elastic portion;
The elastic part has piezoelectricity,
The piezoelectric conversion configuration converts the strain into the electric field by the piezoelectricity of the elastic part,
The electrothermal conversion unit is an inertial sensor that converts the electric field into the heat by an electric resistance of the resistance layer. In claim 1,
A piezoelectric film formed on the elastic portion;
A resistance layer formed on the piezoelectric film;
Including
The piezoelectric conversion configuration converts the strain into the electric field by the piezoelectricity of the piezoelectric film,
The electrothermal conversion unit is an inertial sensor that converts the electric field into the heat by an electric resistance of the resistance layer. In claim 1,
A pair of conductive layers formed on the elastic portion and spaced apart from each other;
A resistance element electrically connected to the pair of conductive layers;
Including
The elastic part has piezoelectricity,
The piezoelectric conversion configuration converts the strain into the electric field by the piezoelectricity of the elastic part,
The electrothermal conversion unit is an inertial sensor that converts the electric field into the heat by an electric resistance of the resistance element. In claim 4,
The closest part between the pair of conductive layers is an inertial sensor in a region where the strain is concentrated in the elastic part when the mass part is displaced with respect to the base part. In claim 1,
A piezoelectric element formed on the elastic part;
A resistive element electrically connected to the piezoelectric element;
Including
The piezoelectric conversion configuration converts the strain into the electric field by the piezoelectricity of the piezoelectric element,
The electrothermal conversion unit is an inertial sensor that converts the electric field into the heat by an electric resistance of the resistance element. In any one of Claims 4 thru | or 6,
In addition, a package for storing the inertial sensor,
The resistance element is an inertial sensor provided outside the package. In any one of Claims 1 thru | or 7,
The detection unit includes a double tuning fork type vibration piece provided by bridging the base part and the mass part, and the resonance frequency of the double tuning fork type vibration piece is generated between the base part and the mass part. Inertial sensor that reacts to

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