Sensor device

Abstract

This sensor device comprises a transmission part that faces the outside and a vibration source that is capable of vibrating the transmission part in one vibration mode from among a plurality of vibration modes. The plurality of vibration modes include a first mode and a second mode. A first frequency, which is the frequency of the vibration source for vibrating the transmission part in the first mode, is smaller than a second frequency, which is the frequency of the vibration source for vibrating the transmission part in the second mode. A first maximum displacement, which is the maximum displacement of the transmission part vibrated in the first mode, is greater than a second maximum displacement, which is the maximum displacement of the transmission part vibrated in the second mode. A first distance, which is the distance between the maximum displacement portion of the transmission part vibrated in the first mode and the center of the transmission part, is greater than a second distance, which is the distance between the maximum displacement portion of the transmission part vibrated in the second mode and the center of the transmission part.

Description

Sensor Device

[0001] The present disclosure relates to a sensor device.

[0002] Japanese Patent Application Laid-Open No. 2006-129999 discloses an optical device that vibrates a protective cover by selecting a cleaning mode or a heating mode. The cleaning mode is a mode for removing foreign matter adhering to the protective cover, and the heating mode is a mode for heating the protective cover.

[0003] WO2020 / 230419A1

[0004] The optical device of Patent Document 1 has room for improvement in terms of increasing both the efficiency of foreign matter removal in the cleaning mode and the heating efficiency in the heating mode.

[0005] An object of the present disclosure is to provide a sensor device that can improve both the efficiency of removing foreign matter adhering to a transmission portion and the efficiency of heating the transmission portion.

[0006] A sensor device according to a first aspect of the present disclosure comprises: a transmission section facing the outside; and a vibration source capable of vibrating the transmission section in one vibration mode among a plurality of vibration modes; the transmission section has a maximum displacement section where a displacement amount due to vibration of the vibration source is maximum, and a minimum displacement section where a displacement amount due to the vibration source is minimum; the plurality of vibration modes include a first mode where a maximum displacement amount that is the displacement amount of the maximum displacement section is maximum, and a second mode where a number of nodes that is the number of vibration nodes is greater than that of the first mode; a first frequency that is the frequency of the vibration source when vibrating the transmission section in the first mode is smaller than a second frequency that is the frequency of the vibration source when vibrating the transmission section in the second mode; and a first maximum displacement amount that is the maximum displacement amount when vibrating the transmission section in the first mode is larger than a second maximum displacement amount that is the maximum displacement amount when vibrating the transmission section in the second mode; A first distance, which is the distance between the maximum displacement portion and the center of the transmitting portion when the transmitting portion is vibrated in the first mode, is greater than a second distance, which is the distance between the maximum displacement portion and the center of the transmitting portion when the transmitting portion is vibrated in the second mode.

[0007] According to the present disclosure, it is possible to provide a sensor device that can improve both the efficiency of removing foreign matter adhering to a transmission portion and the efficiency of heating the transmission portion.

[0008] 5 is a perspective view showing a sensor device according to an example of the present disclosure. FIG. 1 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 1 is a diagram showing a simulation result of a lens displacement distribution by piezoelectric analysis when the lens of the sensor device of FIG. 1 is vibrated in a first mode. FIG. 1 is a diagram showing a simulation result of a lens displacement distribution by piezoelectric analysis when the lens of the sensor device of FIG. 1 is vibrated in a second mode. FIG. 5 is a cross-sectional view showing a first modified example of an external vibrator of the sensor device of FIG. 1. FIG. 6 is a plan view showing a second modified example of an external vibrator of the sensor device of FIG. 1. FIG. 7 is a cross-sectional view taken along line VIII-VIII in FIG. 5 showing a fourth modified example of an external vibrator of the sensor device of FIG. 1. FIG. 8 is a cross-sectional view showing a fifth modified example of an external vibrator of the sensor device of FIG. 1. FIG. 9 is a cross-sectional view showing a sixth modified example of an external vibrator of the sensor device of FIG. 1. FIG. 10 is a flowchart for explaining an example of a method for driving the sensor device of FIG. 1. FIG. 11 is a graph showing the relationship between the displacement gradient rate and the minimum displacement and the result of removing foreign matter of 1 μL or more. FIG. 12 is a diagram showing a foreign matter 100 of 1 μL or more. 17 is a graph showing the relationship between the displacement gradient rate and minimum displacement amount and the results of removing foreign matter of 1 μL or less. A diagram showing foreign matter 110 of 1 μL or less. A displacement contour diagram of the sensor device of FIG. 1. A stress contour diagram of the sensor device of FIG. 1 corresponding to FIG. 16. A partial enlarged view of FIG. 17. A graph showing the relationship between the stress applied to the sensor device of FIG. 1 and the maximum displacement amount of the lens. A graph showing the relationship between the maximum and minimum displacement amounts of the lens, the displacement gradient rate, and the failure range of the sensor device of FIG. 1. A graph showing the relationship between the displacement gradient rate and maximum displacement amount corresponding to the graph of FIG. 14, and the failure range of the sensor device of FIG. 1. A perspective view showing the sensor device of FIG. 1 in a state where the minimum displacement portion is located vertically above the maximum displacement portion.

[0009] Various aspects of the present disclosure will now be described.

[0010] A sensor device according to a first aspect of the present disclosure comprises: a transmission section facing the outside; and a vibration source capable of vibrating the transmission section in one vibration mode among a plurality of vibration modes; the transmission section has a maximum displacement section where a displacement amount due to vibration of the vibration source is maximum, and a minimum displacement section where a displacement amount due to the vibration source is minimum; the plurality of vibration modes include a first mode where a maximum displacement amount that is the displacement amount of the maximum displacement section is maximum, and a second mode where a number of nodes that is the number of vibration nodes is greater than that of the first mode; a first frequency that is the frequency of the vibration source when vibrating the transmission section in the first mode is smaller than a second frequency that is the frequency of the vibration source when vibrating the transmission section in the second mode; and a first maximum displacement amount that is the maximum displacement amount when vibrating the transmission section in the first mode is larger than a second maximum displacement amount that is the maximum displacement amount when vibrating the transmission section in the second mode; A first distance, which is the distance between the maximum displacement portion and the center of the transmitting portion when the transmitting portion is vibrated in the first mode, is greater than a second distance, which is the distance between the maximum displacement portion and the center of the transmitting portion when the transmitting portion is vibrated in the second mode.

[0011] A sensor device according to a second aspect of the present disclosure is the sensor device according to the first aspect, wherein the transmitting portion has a circular shape, the first distance is equal to a radius of the transmitting portion, and the second distance is zero.

[0012] A sensor device of a third aspect of the present disclosure is the sensor device of the first or second aspect, wherein in the first mode, the maximum displacement portion and the minimum displacement portion are respectively located at positions opposite to each other with respect to the center of the transmission portion.

[0013] A sensor device according to a fourth aspect of the present disclosure is the sensor device according to any one of the first to third aspects, wherein the transmission portion has a displacement gradient rate defined by the following formula (1): (A−B) / L formula (1) (in formula (1), A is the maximum displacement amount (μm) in the first mode, B is the minimum displacement amount (μm) that is the displacement amount of the minimum displacement portion in the first mode, and L is the distance (mm) between the maximum displacement portion and the minimum displacement portion in the first mode), and the displacement gradient rate is defined by the following formula (2): C≧2.3935e －０．１７６Ｂ It is defined by the following equation (2): [In equation (2), C is the displacement slope rate, B is the minimum displacement amount in the first mode, and e is Napier's constant].

[0014] A sensor device of a fifth aspect of the present disclosure is the sensor device of any of the first to fourth aspects, wherein the vibration of the transmitting portion in the first mode is a vibration that couples with an asymmetric piston motion of the vibration source, and the vibration of the transmitting portion in the second mode is a vibration that couples with an nth harmonic (n is a natural number) of the natural frequency of the transmitting portion.

[0015] A sensor device according to a sixth aspect of the present disclosure is the sensor device according to the fifth aspect, wherein the vibration of the transmission portion in the second mode is a vibration coupled with a third harmonic of a natural frequency of the transmission portion.

[0016] A sensor device of a seventh aspect of the present disclosure is the sensor device of any of the first to sixth aspects, further comprising: an internal vibrator having the transmitting portion connected to one end in a first direction and the vibration source connected to the other end in the first direction; and an external vibrator including a first connection portion connected to the transmitting portion and an attenuator portion extending from the first connection portion in a second direction intersecting the first direction and away from the transmitting portion, the attenuator portion being configured to attenuate vibrations; wherein the transmitting portion has an optical axis extending along the first direction, and the attenuator portion is non-axially symmetrical with respect to the optical axis.

[0017] A sensor device according to an eighth aspect of the present disclosure is the sensor device according to any one of the first to sixth aspects, further comprising: an internal vibrator having one end in a first direction to which the transmitting portion is connected and the other end in the first direction to which the vibration source is connected; and an external vibrator arranged to surround the internal vibrator, wherein the transmitting portion has an optical axis extending along the first direction, and the external vibrator includes: a first connection portion connected to the transmitting portion; an attenuator portion configured to extend from the first connection portion in a second direction intersecting the first direction and away from the transmitting portion to attenuate vibrations; and a cylinder portion extending in the first direction and connecting the first connection portion and the attenuator portion, wherein at least one of the attenuator portion and the cylinder portion is non-axially symmetrical with respect to the optical axis.

[0018] A driving method according to a ninth aspect of the present disclosure includes: a transmission section facing the outside; and a vibration source capable of vibrating the transmission section in one vibration mode among a plurality of vibration modes, wherein the transmission section has a maximum displacement section where a displacement amount due to vibration of the vibration source is maximum, and a minimum displacement section where a displacement amount due to the vibration source is minimum, the plurality of vibration modes including a first mode where a maximum displacement amount that is the displacement amount of the maximum displacement section is maximum, and a second mode having a larger number of nodes that is the number of vibration nodes than the first mode, wherein a first frequency that is the frequency of the vibration source when vibrating the transmission section in the first mode is smaller than a second frequency that is the frequency of the vibration source when vibrating the transmission section in the second mode, and a first maximum displacement amount that is the maximum displacement amount when vibrating the transmission section in the first mode is larger than a second maximum displacement amount that is the maximum displacement amount when vibrating the transmission section in the second mode, A method for driving a sensor device, wherein a first distance, which is the distance between the maximum displacement portion and the center of the transparent portion when the transparent portion is vibrated in the first mode, is greater than a second distance, which is the distance between the maximum displacement portion and the center of the transparent portion when the transparent portion is vibrated in the second mode, comprising: vibrating the transparent portion in the second mode to melt ice located on the transparent portion; and vibrating the transparent portion in the first mode to remove melted ice adhering to the transparent portion.

[0019] An example of the present disclosure will be described below with reference to the accompanying drawings. The following description is merely exemplary in nature and does not limit the present disclosure, its applications, and uses. The accompanying drawings are schematic drawings, and the illustrated configuration and actual products may differ in dimensional ratios, etc.

[0020] As shown in FIGS. 1 and 2 , a sensor device 1 according to an example of the present disclosure includes a lens 5 (an example of a transmission portion) and a vibration source 9 .

[0021] In this embodiment, as shown in FIG. 2 , the lens 5 has an optical axis L. The optical axis L passes through a center P0 of the lens 5 (an example of the center of the transmission portion) and extends along a first direction (e.g., the Z direction). The lens 5 has a circular shape when viewed along the optical axis L. The "circular shape" includes not only a perfect circle but also a shape that can be considered circular (e.g., a substantially circular shape). The lens 5 includes an exposed surface 51. The exposed surface 51 faces the outside of the sensor device 1 and is capable of receiving foreign matter (e.g., pure water). In this embodiment, the exposed surface 51 has a diameter that is substantially the same as the radius of the lens 5 relative to the optical axis L (hereinafter referred to as the radius).

[0022] 3 and 4, the lens 5 has a maximum displacement portion P1 and a minimum displacement portion P2. The maximum displacement portion P1 is the portion of the lens 5 where the amount of displacement due to vibration of the vibration source 9 is the largest, and the minimum displacement portion P2 is the portion of the lens 5 where the amount of displacement due to the vibration source 9 is the smallest.

[0023] The vibration source 9 is configured to be able to vibrate the lens 5 in one of a plurality of vibration modes. The vibration source 9 includes, for example, an element (a piezoelectric element, an electromagnetic vibrator, a magnetostrictive vibrator, etc.) or an actuator (an SMA actuator, an electromagnetic actuator, a motor, etc.).

[0024] The multiple vibration modes include a first mode and a second mode. The first mode is the mode among the multiple vibration modes in which the maximum displacement amount is the largest. The first mode is configured to be able to remove foreign matter adhering to the exposed surface 51 of the lens 5 by vibration, for example. The second mode is a mode in which the number of nodes, which is the number of vibration nodes, is greater than that of the first mode. The second mode is configured to be able to heat the lens 5 by heat generated at the maximum displacement point P1, for example.

[0025] The first mode and the second mode have the following relationship. The vibration frequency of the vibration source 9 when vibrating the lens 5 in the first mode is set to a first frequency f1 (e.g., 20 to 30 kHz), and the vibration frequency of the vibration source 9 when vibrating the lens 5 in the second mode is set to a second frequency f2 (e.g., 370 kHz). In this case, the first frequency f1 is smaller than the second frequency f2 (f1<f2). The vibration of the lens 5 in the first mode is, for example, a vibration coupled with the asymmetric piston motion of the vibration source 9. The vibration of the lens 5 in the second mode is, for example, a vibration coupled with the nth harmonic (n is a natural number) (e.g., the third harmonic) of the natural frequency of the lens 5. The maximum displacement amount when the lens 5 is vibrated in the first mode is set to a first maximum displacement amount A1, and the maximum displacement amount when the lens 5 is vibrated in the second mode is set to a second maximum displacement amount A2. In this case, the first maximum displacement amount A1 is greater than the second maximum displacement amount A2 (A1 > A2). The distance between the maximum displacement point P1 and the center P0 of the lens 5 when the lens 5 is vibrated in the first mode is defined as the first distance D1, and the distance between the maximum displacement point P1 and the center P0 of the lens 5 when the lens 5 is vibrated in the second mode is defined as the second distance D2. In this case, the first distance D1 is greater than the second distance D2 (D1 > D2). The first distance D1 and the second distance D2 are calculated, for example, from the difference in coordinates (e.g., XYZ coordinates) assigned to the center P0 of the lens 5 and the maximum displacement point P1.

[0026] 3 and 4 show examples of simulation results of the displacement distribution of the lens 5 by piezoelectric analysis. FIG. 3 shows an example of simulation results when the lens 5 is vibrated in the first mode, and FIG. 4 shows an example of simulation results when the lens 5 is vibrated in the second mode. As shown in FIG. 3 , in the first mode, the maximum displacement portion P1 and the minimum displacement portion P2 are located at positions opposite each other with respect to the center P0 of the lens 5 (e.g., symmetrically with respect to the center P0). As shown in FIG. 3 , in the first mode, the maximum displacement portion P1 is located at the radially outer end of the lens 5. That is, the first distance D1 is equal to the radius of the lens 5 or is within a range that can be considered to be equal to the radius of the lens 5. As shown in FIG. 4 , in the second mode, the maximum displacement portion P1 approximately coincides with the center P0 of the lens 5. That is, the second distance D2 is zero or is within a range that can be considered to be zero. For example, if the second distance D2 is within 3% of the lens diameter, it is considered to be substantially zero. This range corresponds to the viewing angle of a 1-meter-long child positioned 10 meters away when using a fisheye lens with a viewing angle of 180°. The range in which the second distance D2 can be considered to be zero may be set to include the area in the center of the field of view of the lens 5 where it is desired to melt the ice most quickly.

[0027] 1 and 2 , the sensor device 1 includes an internal vibrator 7 and an external vibrator 3. A vibration source 9 is connected to one end of the internal vibrator 7 in the first direction Z. A lens 5 is connected to the other end of the internal vibrator 7 in the first direction Z. Vibrations generated by the vibration source 9 are transmitted to the lens 5 via the internal vibrator 7, causing the lens 5 to vibrate. This removes foreign matter such as water droplets or mud adhering to the lens 5.

[0028] The internal vibrator 7 is configured to be able to amplify vibrations generated by the vibration source 9. The internal vibrator 7 includes, for example, a metal material such as stainless steel, aluminum, iron, titanium, or duralumin, or ceramics. The surface of the internal vibrator 7 may be subjected to a surface treatment such as oxidation or alumite treatment to improve adhesive adhesion. For example, by blackening the surface of the internal vibrator 7 through surface treatment, it is possible to prevent degradation of optical performance due to diffuse reflection of light.

[0029] The internal vibrator 7 is, for example, a cylindrical body positioned symmetrically with respect to the optical axis L. The internal vibrator 7 includes a first portion 71 in contact with the lens 5, a second portion 72 to which the vibration source 9 is attached, and a third portion 73 connecting the first portion 71 and the second portion 72. The first portion 71 and the second portion 72 have, for example, a cylindrical shape extending along the first direction Z. The second portion 72 is configured to vibrate together with the vibration of the vibration source 9 and has a thickness (i.e., a dimension in the first direction Z) greater than those of the first portion 71 and the third portion 73. This facilitates more efficient transmission of the vibration of the vibration source 9 to the lens 5. The third portion 73 has a substantially S-shaped cross section and is configured to support the first portion 71 and transmit the vibration of the second portion 72 to the first portion 71.

[0030] The first portion 71, the second portion 72, and the third portion 73 may be formed integrally or separately. The maximum outer dimension of the third portion 73 (i.e., the maximum dimension in a second direction (e.g., the X direction) intersecting the first direction Z) is larger than the maximum outer dimension of the first portion 71, and the maximum outer dimension of the second portion 72 is larger than the maximum outer dimension of the third portion 73. This allows the vibration of the vibration source 9 to be efficiently transmitted to the lens 5.

[0031] The external vibrator 3 is configured to prevent the vibrations of the internal vibrator 7 from escaping to members other than the lens 5 and to efficiently transmit the vibrations of the internal vibrator 7 to the lens 5. As an example, the external vibrator 3 is configured to cover the entire internal vibrator 7 and protect the internal vibrator 7 from the outside. The external vibrator 3 includes, for example, a metal material such as stainless steel, aluminum, iron, titanium, or duralumin, or a resin.

[0032] As an example, the external vibrator 3 has a substantially rectangular prism shape and is configured to surround the internal vibrator 7 in a radial direction (e.g., the X direction) relative to the optical axis L. The external vibrator 3 of this embodiment includes a first connecting portion 31, a cylinder portion 32, an attenuator portion 33, a second connecting portion 34, and a fixing portion 35.

[0033] The first connecting portion 31 has, for example, a cylindrical shape extending in the first direction Z. A radially inner surface of the first connecting portion 31 relative to the optical axis L is in contact with a radially outer surface of the internal vibrator 7 relative to the optical axis L. In other words, the first connecting portion 31 is connected to the lens 5 via the internal vibrator 7. The first connecting portion 31 is not limited to being connected to the lens 5 via the internal vibrator 7, and may also be connected to the lens 5 without the internal vibrator 7 via, for example, an adhesive.

[0034] The outer surface of the first connection portion 31 is covered with a cover member 8. The cover member 8 includes, for example, a resin member or a metal member, and is configured to cover the first connection portion 31 and the outer end of the lens 5 in the radial direction with respect to the optical axis L. The cover member 8 more reliably connects the first connection portion 31 and the lens 5, and also prevents moisture and foreign matter on the lens 5 from entering the interior of the external vibrator 3.

[0035] The cylinder portion 32 extends from the first connection portion 31 in the first direction Z in a direction away from the lens 5, and connects the first connection portion 31 and the attenuator portion 33. The cylinder portion 32 has, for example, a cylindrical shape and is configured to have an inner diameter larger than that of the first connection portion 31. A step is formed between the first connection portion 31 and the cylinder portion 32, and a gap is formed between the cylinder portion 32 and the internal vibrator 7. The cylinder portion 32 may include an inclined portion whose diameter gradually increases as it approaches the attenuator portion 33.

[0036] The attenuator section 33 extends from one of the ends of the cylinder section 32 in the first direction Z that is farthest from the lens 5 toward the outside in the radial direction with respect to the optical axis L. The attenuator section 33 has spring characteristics and is configured to attenuate vibrations generated by the vibration source 9.

[0037] The second connecting portion 34 extends from one of the ends of the attenuator portion 33 in the radial direction relative to the optical axis L, the end farthest from the optical axis L, in a direction away from the lens 5 along the first direction Z, and connects the attenuator portion 33 and the fixed portion 35. The second connecting portion 34 is, for example, cylindrical and configured to have spring characteristics.

[0038] The fixing portion 35 extends from one of the ends of the second connection portion 34 in the first direction Z that is farthest from the attenuator portion 33 in a direction away from the lens 5 along the first direction Z. The fixing portion 35 is configured to be able to suppress vibrations propagated to members connected to the fixing portion 35 (for example, a case that houses the imaging element and a lens module). The fixing portion 35 is configured to have a thickness (i.e., a radial dimension relative to the optical axis L) that is greater than other portions of the external vibrator 3.

[0039] 1, the fixing portion 35 has a substantially rectangular prism-like outer shape. By configuring it in this manner, the volume of the fixing portion 35 can be increased without increasing the size of the sensor device 1.

[0040] The maximum width of the first connecting portion 31 in the radial direction relative to the optical axis L (hereinafter referred to as the maximum outer dimension) is smaller than the maximum outer dimension of the cylinder portion 32, which is smaller than the maximum outer dimension of the attenuator portion 33. The maximum outer dimensions of the attenuator portion 33 and the second connecting portion 34 are substantially the same and are smaller than the maximum outer dimension of the fixed portion 35. With this configuration, the portion of the external vibrator 3 located on the lens 5 side can vibrate more easily, while vibration of the fixed portion 35 can be suppressed.

[0041] In this embodiment, the external vibrator 3 is made of a material having a lower Young's modulus than the internal vibrator 7. By configuring it in this way, the attenuation of vibration by the attenuator section 33 can be increased.

[0042] The first connecting portion 31, the cylinder portion 32, the attenuator portion 33, the second connecting portion 34, and the fixed portion 35 may be integrally formed as a single member, or may be individually formed as different members. The first connecting portion 31, the cylinder portion 32, the attenuator portion 33, and the second connecting portion 34 may be integrally formed as a single member, and only the fixed portion 35 may be individually formed as a separate member.

[0043] The sensor device 1 can be realized, for example, by the following configuration.

[0044] The sensor device 1 includes an attenuator unit 33 that is asymmetrical with respect to the optical axis L. The asymmetrical nature of the attenuator unit 33 can be achieved, for example, in the following manner: The attenuator unit 33 includes a first attenuator unit 331 and a second attenuator unit 332 that are positioned symmetrically with respect to the optical axis L. The first attenuator unit 331 and the second attenuator unit 332 are formed of different materials. For example, the first attenuator unit 331 is formed of a material having a smaller Young's modulus than the second attenuator unit 332. The first attenuator unit 331 and the second attenuator unit 332 may be formed of materials that are not limited to having a different Young's modulus, but may also have a different density or mechanical Q value, for example. The first attenuator unit 331 and the second attenuator unit 332 are formed so that their dimensions in the first direction Z (i.e., the thickness dimension of the attenuator unit 33) are different. For example, in the external vibrator 3 shown in Fig. 5 , the first attenuator section 331 has a thin portion 3311 having the same thickness (= t2) as the second attenuator section 332, and a thick portion 3312 having a thickness (= t1) greater than that of the thin portion 3311. The first attenuator section 331 may be configured as shown in Figs. 6 and 7 . In the first attenuator section 331 of Fig. 6 , the thick portion 3312 has a crescent shape extending toward the second attenuator section 332 along the outer shape of the external vibrator 3 when viewed along the direction of arrow XV in Fig. 5 . In the first attenuator section 331 of Fig. 7 , the thick portion 3312 has a straight portion facing the optical axis L and an arc portion extending along the outer shape of the external vibrator 3 when viewed along the direction of arrow XV in Fig. 5 . The first attenuator section 331 and the second attenuator section 332 are formed so that their lengths u (see FIG. 5) in the radial direction relative to the optical axis L are different.

[0045] The sensor device 1 includes a cylinder portion 32 that is non-axially symmetric with respect to the optical axis L. The non-axial symmetry of the cylinder portion 32 can be achieved, for example, in the following manner: The cylinder portion 32 includes a first cylinder portion 321 and a second cylinder portion 322 that are positioned symmetrically with respect to the optical axis L. The first cylinder portion 321 and the second cylinder portion 322 are formed of different materials. For example, the first attenuator portion 331 is formed of a material having a smaller Young's modulus than the second attenuator portion 332. The first cylinder portion 321 and the second cylinder portion 322 may be formed of materials that are not limited to having a different Young's modulus, but may also have a different density or mechanical Q value, for example. The first cylinder portion 321 and the second cylinder portion 322 are formed so that their radial dimensions with respect to the optical axis L (i.e., the thickness dimension of the cylinder portion 32) are different. For example, in the external vibrator 3 shown in FIG. 8 , the second cylinder portion 322 has a thickness s2 that is greater than the thickness s1 of the first cylinder portion 321. In the external vibrator 3 shown in FIG. 9, the first cylinder portion 321 and the second cylinder portion 322 are formed to have the same thickness s1, and a weight member 325 is fixed to the second cylinder portion 322.

[0046] In the external vibrator 3 shown in Fig. 5, both the cylinder portion 32 and the attenuator portion 33 are non-axially symmetric, but this is not limiting. The external vibrator 3 may be configured so that only one of the cylinder portion 32 and the attenuator portion 33 is non-axially symmetric. For example, as shown in Fig. 10, the external vibrator 3 may be configured with a first connection portion 31 and an attenuator portion 33.

[0047] An example of a method for driving the sensor device 1 will be described with reference to Fig. 11 . Fig. 11 shows a flow chart for melting and removing ice located on the lens 5 using the method for driving the sensor device 1. The flow chart shown in Fig. 11 can be automatically performed by a user using an external device. For example, the external device includes a processor and a storage unit, and the method for driving the sensor device 1 shown in Fig. 11 is performed by the processor executing a predetermined program stored in the storage unit.

[0048] 11 , the external device drives the sensor device 1 to vibrate the lens 5 in the second mode (step S1), and determines whether to end the vibration of the lens 5 in the second mode (step S2). The external device determines to end the vibration of the lens 5 in the second mode, for example, when all or part of the ice located on the exposed surface 51 of the lens 5 has melted, or when a predetermined time has elapsed since the vibration of the lens 5 in the second mode was started.

[0049] If it is not determined that the vibration of the lens 5 in the second mode should be ended (step S2 = NO), the process returns to step S1, and the vibration of the lens 5 in the second mode is continued. If it is determined that the vibration of the lens 5 in the second mode should be ended (step S2 = YES), the external device drives the sensor device 1 to vibrate the lens 5 in the first mode (step S3), and determines whether or not to end the vibration of the lens 5 in the first mode (step S4). The external device determines that the vibration of the lens 5 in the first mode should be ended, for example, when all or part of the melted ice (= water) adhering to the exposed surface 51 of the lens 5 has been removed, or when a predetermined time has elapsed since the vibration of the lens 5 in the first mode was started.

[0050] If it is not determined that the vibration of the lens 5 in the first mode should be ended (step S4 = NO), the process returns to step S3, and the vibration of the lens 5 in the first mode is continued. If it is determined that the vibration of the lens 5 in the first mode should be ended (step S4 = YES), the external device stops the sensor device 1, and the driving method of the sensor device 1 is ended.

[0051] The sensor device 1 can achieve the following effects.

[0052] The sensor device 1 includes a lens 5 facing the outside and a vibration source 9 capable of vibrating the lens 5 in one of multiple vibration modes. The lens 5 has a maximum displacement portion P1 and a minimum displacement portion P2. The multiple vibration modes include a first mode having the largest maximum displacement amount and a second mode having a greater number of vibration nodes than the first mode. The first frequency f1 is smaller than the second frequency f2, the first maximum displacement amount A1 is larger than the second maximum displacement amount A2, and the first distance D1 is larger than the second distance D2. Generally, when vibration is applied to liquids such as raindrops, they tend to move toward a direction where vibration is greater and they become more hydrophilic. Furthermore, positions farther from the center P0 of the lens 5 are closer to the component that secures the lens 5. Because the component that secures the lens 5 is made of a metal such as aluminum with high thermal conductivity, if the maximum displacement portion P1, which is a heat source in the second mode, is farther from the center P0 of the lens 5, the generated heat is more likely to escape to the component that secures the lens 5. According to the above configuration, in the first mode, the maximum displacement point P1 is positioned farther from the center P0 of the lens 5 than in the second mode, thereby improving both the efficiency of removing foreign matter adhering to the lens 5 and the heating efficiency of the lens 5.

[0053] The lens 5 has a circular shape, the first distance D1 is equal to the radius of the lens 5, and the second distance D2 is zero. With this configuration, it is possible to more reliably increase both the efficiency of removing foreign matter adhering to the lens 5 and the efficiency of heating the lens 5.

[0054] In the first mode, the maximum displacement portion P1 and the minimum displacement portion P2 are located at positions opposite each other with respect to the center of the lens 5. With this configuration, it is possible to more reliably improve both the efficiency of removing foreign matter adhering to the lens 5 and the efficiency of heating the lens 5.

[0055] The vibration of the lens 5 in the first mode is a vibration that is coupled with the asymmetric piston motion of the vibration source 9, and the vibration of the lens 5 in the second mode is a vibration that is coupled with the nth harmonic (n is a natural number) of the natural frequency of the lens 5. With this configuration, it is possible to more reliably improve both the efficiency of removing foreign matter adhering to the lens 5 and the efficiency of heating the lens 5. For example, by making the vibration of the lens 5 in the second mode the third harmonic of the natural frequency of the lens 5, it is possible to reduce the current required to drive the sensor device 1 in the second mode, thereby minimizing the wiring of the sensor device 1.

[0056] The sensor device 1 includes an internal vibrator 7 and an external vibrator 3. The internal vibrator 7 has one end in a first direction Z connected to a lens 5 and the other end in the first direction Z connected to a vibration source 9. The external vibrator 3 includes a first connector 31 connected to the lens 5 and an attenuator unit 33 extending from the first connector 31 in a second direction away from the lens 5 to attenuate vibrations. The lens 5 has an optical axis L extending along the first direction Z. The attenuator unit 33 is asymmetric with respect to the optical axis L. This configuration more reliably realizes a sensor device 1 that can improve both the efficiency of removing foreign matter adhering to the lens 5 and the heating efficiency of the lens 5. Furthermore, this configuration can impart a gradient to the vibration amplitude of the lens 5 and reduce uneven stress applied to the internal vibrator 7 during vibration.

[0057] The sensor device 1 includes an internal vibrator 7 having a lens 5 connected to one end in a first direction Z and a vibration source 9 connected to the other end in the first direction Z, and an external vibrator 3 arranged to surround the internal vibrator 7. The lens 5 has an optical axis L extending along the first direction Z. The external vibrator 3 includes a first connection portion 31 connected to the lens 5, a cylinder portion 32, and an attenuator portion 33. The attenuator portion 33 is configured to extend from the first connection portion 31 in the second direction and away from the lens 5 to attenuate vibrations. The cylinder portion 32 extends in the first direction Z and connects the first connection portion 31 and the attenuator portion 33. At least one of the attenuator portion 33 and the cylinder portion 32 is asymmetric with respect to the optical axis L. This configuration more reliably realizes a sensor device 1 that can improve both the efficiency of removing foreign matter adhering to the lens 5 and the heating efficiency of the lens 5. Furthermore, with the above-described configuration, the amplitude of the vibration of the surface of the lens 5 can be inclined during vibration, and the uneven distribution of stress applied to the internal vibrator 7 during vibration can be suppressed.

[0058] The method for driving the sensor device 1 has the following configuration. With this configuration, even if melted ice remains on the exposed surface 51 of the lens 5 after melting the ice located on the lens 5, the melted ice is removed from the exposed surface 51, so the field of view of the lens 5 can be easily restored. - The lens 5 is vibrated in the second mode to melt the ice located on the lens 5. - The lens 5 is vibrated in the first mode to remove the melted ice adhering to the lens 5.

[0059] The sensor device 1 can be configured as follows.

[0060] The lens 5 may be configured to have a displacement gradient rate defined by, for example, the following formula 1 and formula 2, or to have a displacement gradient rate defined by the following formula 1 and formula 3, or the following formula 4. In formula 1 below, A is the maximum displacement amount (μm) that is the displacement amount of the maximum displacement portion P1, B is the minimum displacement amount (μm) that is the displacement amount of the minimum displacement portion P2, and L is the distance (mm) between the maximum displacement portion P1 and the minimum displacement portion P2. L is calculated, for example, from the difference in coordinates (e.g., XYZ coordinates) assigned to the maximum displacement portion P1 and the minimum displacement portion P2. In formulas 2 to 4 below, C is the displacement gradient rate, B is the minimum displacement amount, and e is Napier's constant.

[0061] 12 shows the relationship between the displacement gradient rate C and the minimum displacement amount B and the result of removing foreign matter of 1 μL or more. FIG. 13 shows an example of a foreign matter 100 of 1 μL or more. The dotted line R1 in FIG. 12 corresponds to C=2.3935e －０．１７６Ｂ 12 is an approximation curve of the above. A circle (●) indicates a result in which the foreign matter 100 was successfully removed. A cross (×) indicates a result in which the foreign matter 100 was not successfully removed. In FIG. 12, the displacement of the lens 5 was measured in a room temperature (25±5 degrees Celsius) environment using a laser Doppler displacement meter (LV1800 manufactured by Ono Keisokuki) and a gain phase analyzer (FRA51602 manufactured by NF Corporation).

[0062] As shown in FIG. 12, the area on the dotted line R1 and the area to the upper right of the dotted line R1 (C≧2.3935e －０．１７６Ｂ ), only circles are shown, while the area below and to the left of the dotted line R1 (C<2.3935e －０．１７６Ｂ ) has multiple crosses. In other words, it has been found that by configuring the sensor device 1 so that the lens 5 has a displacement gradient rate defined by the mathematical expressions 1 and 2, foreign matter 100 of 1 μL or more can be more reliably removed.

[0063] 14 shows the relationship between the displacement gradient rate C and the minimum displacement amount B and the result of removing foreign matter of 1 μL or less. FIG. 15 shows an example of a foreign matter 110 of 1 μL or less. The dotted line R2 in FIG. 14 corresponds to C=3.6203 e－０．１３２Ｂ The dotted line R3 is an approximate curve of 3.2337e －０．０９３Ｂ 14 is an approximation curve of the above. Circles (●) indicate results in which the foreign matter 110 was removed quickly (for example, within 10 seconds). Triangles (▲) indicate results in which the foreign matter 110 was removed but not quickly. Crosses (×) indicate results in which the foreign matter was not removed. In FIG. 14, the displacement of the lens 5 was measured in a room temperature (25±5°C) environment using a laser Doppler displacement meter (LV1800 manufactured by Ono Keisokuki) and a gain phase analyzer (FRA51602 manufactured by NF Corporation).

[0064] As shown in FIG. 14, the area on the dotted line R2 and the area to the upper right of the dotted line R2 (C≧3.6203e －０．１３２Ｂ ), only circles and triangles are shown, while the area below and to the left of the dotted line R2 (C<3.6203e －０．１３２Ｂ ) has multiple crosses. In other words, it has been found that the sensor device 1 (hereinafter referred to as the first sensor device 1) including the lens 5 configured to have the displacement gradient rate defined by the mathematical expressions 1 and 3 can more reliably remove foreign matter 110 of 1 μL or less.

[0065] The area above the dotted line R3 and the area to the upper right of the dotted line R3 (C≧3.2337e －０．０９３Ｂ ) shows only a circle. That is, it was found that the sensor device 1 (hereinafter referred to as the second sensor device 1) including the lens 5 configured to have the displacement gradient rate defined by the mathematical expressions 1 and 4 can remove foreign matter 110 of 1 μL or less more reliably and quickly (for example, within 10 seconds) than the first sensor device 1.

[0066] It was found that, for the same minimum displacement amount B, the removal speed of the foreign matter 110 increases as the displacement gradient rate C increases. The removal speed of the foreign matter 110 was fastest when the displacement gradient rate C and the minimum displacement amount B were within the range of the first region 201, followed by when the displacement gradient rate C and the minimum displacement amount B were within the range of the second region 202, and slowest when the displacement gradient rate C and the minimum displacement amount B were within the range of the third region 203. In other words, it was found that the second sensor device 1 can sometimes remove foreign matter 110 of 1 μL or less faster than the first sensor device 1. For example, when the displacement gradient rate C and the minimum displacement amount B were within the range of the first region 201, removal of the foreign matter 110 was sometimes completed within one second. On the other hand, when the displacement gradient rate C and the minimum displacement amount B were within the range of the third region 203, it sometimes took 10 seconds to complete removal of the foreign matter 110.

[0067] For example, let us assume that the sensor device 1 includes a lens 5 configured to have a displacement gradient C and a minimum displacement B within the range of the region 200 shown by the dashed line in Fig. 14 (i.e., the minimum displacement B is 15 µm or more and the displacement gradient C is 1.0 µm / mm or more). It has been found that the sensor device 1 in this case can sometimes remove foreign matter 110 of 1 µL or less more quickly than the second sensor device 1.

[0068] FIG. 16 shows an example of a displacement contour diagram of the sensor device 1, and FIG. 17 shows an example of a stress contour diagram of the sensor device 1 corresponding to FIG. 16. FIG. 18 is an enlarged view showing the lens 5 portion of the stress contour diagram of FIG. 17. FIG. 19 shows an example of the relationship between the stress applied to the sensor device 1 and the maximum displacement amount A of the lens 5. As shown in FIGS. 16 to 18, the stress applied to the sensor device 1 tends to concentrate at the maximum displacement point P1. As shown in FIG. 19, as the maximum displacement amount A of the lens 5 increases, the stress applied to the sensor device 1 also increases. Therefore, the upper limit of the displacement amount of the lens 5 (i.e., the upper limit of the maximum displacement amount A) is determined from the stress value within the range in which the sensor device 1 will not break.

[0069] 20 shows an example of the relationship between the maximum displacement amount A and minimum displacement amount B of the lens 5, the displacement gradient rate C, and the failure range 300 of the sensor device 1. In the example of Fig. 20, when the maximum displacement amount A of the lens 5 exceeds 35 µm, the sensor device 1 tends to fail. The displacement gradient rate C is set within a range that does not fall within the failure range 300.

[0070] 21 shows an example of the relationship between the displacement gradient rate C and the maximum displacement amount A corresponding to the graph of FIG. 14 and the failure range 300 of the sensor device 1. As shown in FIG. 21, the smaller the maximum displacement amount A, the smaller the failure risk of the sensor device 1.

[0071] From the above, when the lens 5 is configured to have a displacement gradient rate defined by the following formula 1 and formula 2, a gradient can be provided in the vibration displacement of the lens 5, thereby preventing foreign matter from concentrating at the center of the lens 5 and facilitating removal of the foreign matter. For example, foreign matter of 1 μL or more can be more reliably removed in a room temperature environment. When the lens 5 is configured to have a displacement gradient rate defined by the following formula 1 and formula 3 or formula 4, a gradient can be provided in the vibration displacement of the lens 5, preventing foreign matter from concentrating at the center of the lens 5 and facilitating removal of the foreign matter. For example, foreign matter of 1 μL or less can be more reliably (and more quickly (e.g., within 1 second)) removed in a room temperature environment. When the sensor device 1 is configured so that the minimum displacement amount B is 15 μm or more and the displacement gradient rate C is 1.0 μm / mm or more, foreign matter of 1 μL or less can be more reliably and more quickly (e.g., within 1 second) removed in a room temperature environment.

[0072] 22, the sensor device 1 may be configured so that the minimum displacement part P2 is positioned vertically above the maximum displacement part P1. With such a configuration, removal of foreign matter from the lens 5 can be facilitated.

[0073] The exposed surface 51 of the lens 5 may be water-repellent. This configuration can facilitate removal of foreign matter from the lens 5.

[0074] The transmitting portion is not limited to the lens 5, and may be another transmitting portion, or may be a flat plate or metal plate that does not have light transmission. For example, when the sensor device 1 is applied to a millimeter-wave radar, the transmitting portion may be made of a low-dielectric-constant material or a low-dielectric-tangent material (such as PPE). For example, when the sensor device 1 is applied to an infrared camera for nighttime surveillance, the transmitting portion may be made of germanium (i.e., a germanium lens is used as the transmitting portion).

[0075] The internal vibrator 7 and the vibration source 9 may or may not be positioned symmetrically with respect to the optical axis L.

[0076] The cylinder portion 32 and / or the attenuator portion 33 are not limited to the above-described embodiment, and any configuration that can achieve non-axisymmetricity can be adopted. For example, the cylinder portion 32 and / or the attenuator portion 33 having non-axisymmetricity may be achieved by fixing a separate member to the cylinder portion 32 and / or the attenuator portion 33.

[0077] The sensor device 1 can be used in any manner. For example, the sensor device 1 can be used in a state where the minimum displacement portion P2 is located vertically lower than the maximum displacement portion P1, or in a state where the maximum displacement portion P1 and the minimum displacement portion P2 are located at the same position in the vertical direction.

[0078] 11 may be performed by a user manually driving the sensor device 1. In this case, the determinations in steps S2 and S4 are made by the user visually, for example.

[0079] The present disclosure is not limited to the sensor device 1 of the above embodiment, but can also be applied to other sensor devices 1 that include a transmission section and a vibration source 9 that can vibrate the transmission section in one of a plurality of vibration modes, and the plurality of vibration modes include a first mode and a second mode that have the following relationships: First frequency f1<second frequency f2 First maximum displacement A1>second maximum displacement A2 First distance D1>second distance D2

[0080] The embodiments and modifications of the present disclosure can be combined with each other, or with modifications, or with each other. Features included in the embodiments and modifications of the present disclosure can also be combined with each other.

[0081] The disclosure of the present disclosure may vary in structural details, and changes in the combination and order of elements in each embodiment may be made without departing from the scope and spirit of the claimed disclosure.

[0082] REFERENCE SIGNS LIST 1 Sensor device 3 External vibrator 5 Lens 7 Internal vibrator 71 First part 72 Second part 73 Third part 8 Cover member 9 Vibration source 31 First connection part 32 Cylinder part 321 First cylinder part 322 Second cylinder part 325 Weight member 33 Attenuator part 331 First attenuator part 3311 Thin part 3312 Thick part 332 Second attenuator part 34 Second connection part 35 Fixing part 51 Exposed surface 100, 110 Foreign matter 200, 201, 202, 203 Area 300 Failure range

Claims

1. A device comprising: a transparent portion facing the outside; and a vibration source capable of vibrating the transparent portion in one of a plurality of vibration modes, wherein the transparent portion has a maximum displacement portion where the displacement amount due to vibration of the vibration source is maximum, and a minimum displacement portion where the displacement amount due to the vibration source is minimum, the plurality of vibration modes including a first mode where the maximum displacement amount, which is the displacement amount of the maximum displacement portion, is maximum, and a second mode where the number of nodes, which is the number of vibration nodes, is greater than that of the first mode, wherein a first frequency, which is the frequency of the vibration source when vibrating the transparent portion in the first mode, is smaller than a second frequency, which is the frequency of the vibration source when vibrating the transparent portion in the second mode, and a first maximum displacement amount, which is the maximum displacement amount when vibrating the transparent portion in the first mode, is larger than a second maximum displacement amount, which is the maximum displacement amount when vibrating the transparent portion in the second mode, a first distance, which is the distance between the maximum displacement portion and the center of the transmission portion when the transmission portion is vibrated in the first mode, is greater than a second distance, which is the distance between the maximum displacement portion and the center of the transmission portion when the transmission portion is vibrated in the second mode.

2. The sensor device according to claim 1, wherein the transparent portion has a circular shape, the first distance is equal to a radius of the transparent portion, and the second distance is zero.

3. The sensor device according to claim 1 or 2, wherein in the first mode, the maximum displacement portion and the minimum displacement portion are located at positions opposite each other with respect to the center of the transmission portion.

4. The transmission portion has a displacement gradient rate defined by the following formula (1): (A-B) / L formula (1) [In formula (1), A is the maximum displacement amount (μm) in the first mode, B is the minimum displacement amount (μm) that is the displacement amount of the minimum displacement portion in the first mode, and L is the distance (mm) between the maximum displacement portion and the minimum displacement portion in the first mode], and the displacement gradient rate satisfies the following formula (2): C≧2.3935e －０．１７６Ｂ The sensor device according to any one of claims 1 to 3, defined by the following equation (2): [In equation (2), C is the displacement slope rate, B is the minimum displacement amount in the first mode, and e is Napier's constant].

5. A sensor device according to any one of claims 1 to 4, wherein the vibration of the transmitting part in the first mode is a vibration that is coupled with the asymmetric piston motion of the vibration source, and the vibration of the transmitting part in the second mode is a vibration that is coupled with the nth harmonic (n is a natural number) of the natural frequency of the transmitting part.

6. The sensor device according to claim 5, wherein the vibration of the transmission portion in the second mode is a vibration coupled with a third harmonic of the natural frequency of the transmission portion.

7. A sensor device according to any one of claims 1 to 6, comprising: an internal vibrator having one end in a first direction connected to the transmitting section and the vibration source connected to the other end in the first direction; and an external vibrator including a first connection section connected to the transmitting section, and an attenuator section extending from the first connection section in a second direction intersecting the first direction and away from the transmitting section, and configured to attenuate vibrations, wherein the transmitting section has an optical axis extending along the first direction, and the attenuator section is asymmetrical with respect to the optical axis.

8. A sensor device according to any one of claims 1 to 6, comprising: an internal vibrator having one end in a first direction connected to the transmitting section and the vibration source connected to the other end in the first direction; and an external vibrator arranged to surround the internal vibrator, wherein the transmitting section has an optical axis extending along the first direction, and the external vibrator includes: a first connection section connected to the transmitting section; an attenuator section extending from the first connection section in a second direction intersecting the first direction and away from the transmitting section, and configured to attenuate vibrations; and a cylinder section extending in the first direction and connecting the first connection section and the attenuator section, wherein at least one of the attenuator section and the cylinder section is non-axially symmetrical with respect to the optical axis.

9. A device comprising: a transmitting section facing the outside; and a vibration source capable of vibrating the transmitting section in one of a plurality of vibration modes, wherein the transmitting section has a maximum displacement section where the displacement amount due to vibration of the vibration source is maximum, and a minimum displacement section where the displacement amount due to the vibration source is minimum, the plurality of vibration modes including a first mode where the maximum displacement amount, which is the displacement amount of the maximum displacement section, is maximum, and a second mode where the number of nodes, which is the number of vibration nodes, is greater than that of the first mode, wherein a first frequency, which is the frequency of the vibration source when vibrating the transmitting section in the first mode, is smaller than a second frequency, which is the frequency of the vibration source when vibrating the transmitting section in the second mode, and a first maximum displacement amount, which is the maximum displacement amount when vibrating the transmitting section in the first mode, is larger than a second maximum displacement amount, which is the maximum displacement amount when vibrating the transmitting section in the second mode, A method for driving a sensor device, wherein a first distance, which is the distance between the maximum displacement part and the center of the transmitting part when the transmitting part is vibrated in the first mode, is greater than a second distance, which is the distance between the maximum displacement part and the center of the transmitting part when the transmitting part is vibrated in the second mode; the method comprises vibrating the transmitting part in the second mode to melt ice located on the transmitting part; and vibrating the transmitting part in the first mode to remove melted ice adhering to the transmitting part.

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