Optical module and optical device

Abstract

This optical module comprises a light transmitting body, a vibrating body that has a cylindrical shape and supports the light transmitting body, a piezoelectric element that is disposed in the vibrating body and vibrates the vibrating body, and an inner layer optical component that is disposed within the vibrating body. A first gap is provided between the light transmitting body and the inner layer optical component, and a second gap is provided between the piezoelectric element and the inner layer optical component. A first size of the first gap in the vibration direction of the light transmitting body and / or a second size of the second gap in the vibration direction of the vibrating body is set in the range of [(n×λ / 2)+0.1 mm] to [{(n+1)×λ / 2)}-0.1 mm] inclusive, where n is an integer of 0 or more and λ is the wavelength of a sound wave generated by vibration.

Description

[Technical field]

[0001] The present invention relates to an optical module and an optical device that removes droplets and the like by vibration. [Background technology]

[0002] Patent Document 1 discloses a droplet removal device that includes a vibration member that is connected to the end of the curved surface that forms the dome part of an optical element and generates bending vibration in the dome part. In the droplet removal device described in Patent Document 1, a drip-proof cover and a piezoelectric element are bonded and fixed, and the drip-proof cover is subjected to bending vibration by vibration of the piezoelectric element, thereby removing droplets and the like that are attached to the surface of the drip-proof cover. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-170303 A Summary of the Invention [Problem to be solved by the invention]

[0004] The device described in Patent Document 1 still has room for improvement in terms of suppressing vibration damping. [Means for solving the problem]

[0005] An optical module according to one aspect of the present invention includes: A transparent body; A vibrating body formed in a cylindrical shape and supporting the light-transmitting body; A piezoelectric element is disposed on the vibrating body and vibrates the vibrating body; An inner layer optical component disposed inside the vibrating body; Equipped with A first gap is provided between the light-transmitting body and the inner layer optical component, A second gap is provided between the piezoelectric element and the inner layer optical component, At least one of a first dimension of the first gap in the vibration direction of the transparent body and a second dimension of the second gap in the vibration direction of the vibrating body is determined in a range of [(n×λ / 2)+0.1 mm] or more and [{(n+1)×λ / 2}−0.1 mm] or less; n is an integer greater than or equal to 0, and λ is the wavelength of the sound wave produced by the vibration.

[0006] An optical device according to one aspect of the present invention comprises: The optical module according to the above aspect; an optical element disposed in the optical module; Equipped with. Effect of the Invention

[0007] According to the present invention, it is possible to provide an optical module and an optical device capable of suppressing vibration damping. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic perspective view showing an example of an optical device according to a first embodiment of the present invention. [Diagram 2] 1 is a schematic cross-sectional view showing an example of a configuration of an optical device according to a first embodiment of the present invention. [Diagram 3] 1 is a block diagram showing an example of a functional configuration of an optical device according to a first embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram for explaining a first gap. [Diagram 5] FIG. 4 is a schematic diagram for explaining a second gap and a third gap. [Figure 6] 5 is a schematic diagram for explaining the relationship between the dimension of a first gap and sound waves. FIG. [Figure 7] 13 is a graph showing an example of an analysis result of the relationship between the displacement of a light-transmitting body and sound pressure. [Figure 8] 8 is an enlarged graph of the graph in FIG. 7. [Figure 9A] FIG. 4 is a schematic diagram for explaining a first vibration mode. [Figure 9B]FIG. 4 is a schematic diagram for explaining a second vibration mode. [Figure 10] 11 is a graph showing an example of the relationship between the displacement of a light-transmitting body and sound pressure when the gap dimension is used as a parameter in the first vibration mode and the second vibration mode. [Figure 11] 1 is a table showing an example of the relationship between acoustic impedance and reflectance for each material. [Figure 12] 10 is a schematic cross-sectional view showing a main configuration of an optical module according to a first modified example. [Figure 13] 11 is a schematic cross-sectional view showing a main configuration of an optical module according to a second modified example. FIG. [Figure 14] 11 is a schematic cross-sectional view showing a main configuration of an optical module according to a third modified example. FIG. [Figure 15] 13 is a graph showing a displacement attenuation rate when a space inside the vibrating body is made negative pressure. [Figure 16] FIG. 11 is a schematic cross-sectional view showing an example of an optical device according to a second embodiment of the present invention. [Figure 17] 4 is a schematic diagram showing the relationship between the voltage applied to a piezoelectric element and the displacement of a light-transmitting body. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (How the present invention was arrived at) In vehicles equipped with an imaging unit equipped with an imaging element or the like at the front or rear of the vehicle, images acquired by the imaging unit are used to control safety devices or perform automatic driving control. Such imaging units may be placed outside the vehicle. In this case, a protective cover or a transparent body such as a lens is placed on the exterior of the imaging unit.

[0010] For this reason, foreign matter such as raindrops (liquid droplets), mud, dust, etc. may adhere to the transparent body. If foreign matter adheres to the transparent body, the foreign matter may be reflected in the image captured by the imaging unit, making it difficult to obtain a clear image.

[0011] In recent years, devices have been developed that remove foreign matter adhering to a transparent body by vibrating the transparent body. In such devices, the transparent body is placed on a cylindrical vibrating body, and the vibrating body is vibrated by a piezoelectric element or the like, thereby vibrating the transparent body. In addition, an inner layer optical component is placed inside the vibrating body.

[0012] However, depending on the position of the inner layer optical component disposed inside the vibrating body, the vibration of the light-transmitting body and / or the vibrating body may be attenuated. For example, a gap is provided between the light-transmitting body and the inner layer optical component, and vibration attenuation occurs depending on the size of the gap. This causes a problem that foreign matter attached to the light-transmitting body cannot be sufficiently removed. This is a new problem that the inventors have discovered.

[0013] For example, when a transparent body is vibrated, a sound wave is generated by the vibration. The sound wave generated from the transparent body is reflected by the inner layer optical component, and a standing wave including an antinode and a node of the sound wave is generated. At the antinode of the sound wave, the sound pressure is increased compared to other parts, and the air is in a more compressed state. Therefore, at the antinode of the sound wave, the compressed air acts as a damper, and vibration attenuation occurs. Therefore, in the gap between the transparent body and the inner layer optical component, when an antinode of the sound wave is formed at the position where the transparent body is placed, the vibration of the transparent body is attenuated. The same phenomenon occurs in the gap between the vibrating body and the inner layer optical component. As a result, there are cases where foreign matter attached to the transparent body cannot be sufficiently removed.

[0014] As a result of extensive research, the inventors have found a configuration that suppresses vibration attenuation by avoiding antinodes of sound waves generated by vibration, and have arrived at the following invention.

[0015] An optical module according to one aspect of the present invention includes: A transparent body; A vibrating body formed in a cylindrical shape and supporting the light-transmitting body; A piezoelectric element is disposed on the vibrating body and vibrates the vibrating body; An inner layer optical component disposed inside the vibrating body; Equipped with A first gap is provided between the light-transmitting body and the inner layer optical component, A second gap is provided between the piezoelectric element and the inner layer optical component, At least one of a first dimension of the first gap in the vibration direction of the transparent body and a second dimension of the second gap in the vibration direction of the vibrating body is determined in a range of [(n×λ / 2)+0.1 mm] or more and [{(n+1)×λ / 2}−0.1 mm] or less; n is an integer greater than or equal to 0, and λ is the wavelength of the sound wave produced by the vibration.

[0016] With this configuration, vibration damping can be suppressed.

[0017] At least one of the first dimension and the second dimension may be determined in the range of 0.1 mm or more and (λ / 2−0.1 mm) or less.

[0018] With this configuration, vibration damping can be further suppressed.

[0019] A third gap is provided between the vibration body and a sidewall of the inner optical component, The third dimension of the third gap may be greater than or equal to 0.1 mm.

[0020] With this configuration, vibration damping can be further suppressed.

[0021] The first dimension of the first gap may be a distance between a center of the optically transparent body and the inner layer optical component.

[0022] With this configuration, it is possible to suppress vibration damping in the central portion of the translucent body.

[0023] The vibrating body and the piezoelectric element may be configured so that the entire light-transmitting body vibrates approximately uniformly.

[0024] With this configuration, vibration damping can be further suppressed.

[0025] The vibrating body and the piezoelectric element may be configured so that a central portion of the light-transmitting body vibrates more strongly than the ends.

[0026] With this configuration, vibration damping can be further suppressed.

[0027] The inner layer optical component may be made of a material having a smaller acoustic impedance than the optically transparent body.

[0028] With this configuration, it is possible to suppress the reflection of sound waves at the inner optical components, and further suppress vibration attenuation.

[0029] The inner layer optical component may be made of resin.

[0030] With this configuration, it is possible to further suppress the reflection of sound waves at the inner optical components, and further suppress vibration attenuation.

[0031] The inner layer optical component is An inner lens; A lens holding portion that holds the inner layer lens; an inner layer flange extending outward from an outer wall of the lens holding portion; having The first gap is provided between the light-transmitting body and the inner layer lens, The second gap may be provided between the piezoelectric element and the inner layer flange.

[0032] With this configuration, vibration damping can be further suppressed.

[0033] The inner layer optical component has a first surface that defines the first gap and a second surface that defines the second gap; An acoustic wave suppressing member for suppressing reflection of acoustic waves may be disposed on at least one of the first surface and the second surface.

[0034] With this configuration, the sound wave suppressing member can suppress reflection of sound waves and suppress vibration attenuation.

[0035] The inner layer optical component has a first surface that defines the first gap and a second surface that defines the second gap; At least one of the first surface and the second surface may be coated with a resin.

[0036] With this configuration, the resin coating can suppress the reflection of sound waves and can suppress vibration attenuation.

[0037] The space inside the vibrating body may be a vacuum or a negative pressure.

[0038] With this configuration, vibration damping can be further suppressed.

[0039] The space inside the vibrating body may be filled with a gas having a density lower than that of air.

[0040] With this configuration, vibration damping can be further suppressed.

[0041] When the position of the light-transmitting body in a non-vibrated state is taken as a reference position, the direction away from the inner layer optical component with respect to the reference position in the thickness direction (Z direction) of the light-transmitting body is taken as a positive direction, and the direction approaching the inner layer optical component with respect to the reference position is taken as a negative direction, In the transparent body, the displacement in the positive direction may be greater than the displacement in the negative direction.

[0042] With this configuration, vibration damping can be further suppressed.

[0043] The optical module further includes a control unit that controls the piezoelectric element. The control unit may repeatedly apply a forward voltage and stop applying the voltage to the piezoelectric element.

[0044] With this configuration, vibration damping can be further suppressed.

[0045] An optical device according to one aspect of the present invention comprises: The optical module according to the above aspect; an optical element disposed in the optical module; Equipped with.

[0046] With this configuration, vibration damping can be suppressed.

[0047] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following description is merely illustrative in nature and is not intended to limit the present disclosure, its application, or its uses. Furthermore, the drawings are schematic, and the ratios of dimensions do not necessarily correspond to the real ones.

[0048] (Embodiment 1) [Optical device] Fig. 1 is a schematic perspective view showing an example of an optical device 100 according to a first embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing an example of a configuration of the optical device 100 according to the first embodiment of the present invention. The X, Y, and Z directions in the figure indicate the vertical, horizontal, and height directions of the optical device 100.

[0049] 1 and 2, the optical device 100 includes an optical module 1 and an optical element 2. The optical element 2 is disposed in the optical module 1. Specifically, the optical element 2 is disposed inside the optical module 1.

[0050] In this embodiment, an example will be described in which the optical device 100 is an imaging device. The optical device 100 is attached to, for example, the front or rear of a vehicle, and captures an image of an imaging target. Note that the location where the optical device 100 is attached is not limited to a vehicle, and the optical device 100 may be attached to other devices such as a ship or an aircraft.

[0051] The optical element 2 is an imaging element, and is, for example, a CMOS, a CCD, a bolometer, or a thermopile that receives light having a wavelength ranging from the visible region to the far infrared region.

[0052] When the optical device 100 is mounted on a vehicle or the like and used outdoors, foreign matter such as raindrops, mud, dust, etc. may adhere to the light-transmitting body 10 of the optical module 1 that is disposed in the viewing direction of the optical element 2 and covers the outside. The optical module 1 can generate vibrations to remove foreign matter such as raindrops that have adhered to the light-transmitting body 10.

[0053] [Optical module] 1 and 2, the optical module 1 includes a light-transmitting body 10, a vibrating body 20, a piezoelectric element 30, a fixing portion 40, and an inner layer optical component 50. Note that in the optical module 1, the fixing portion 40 is not an essential component.

[0054] <Translucent body> The light-transmitting body 10 has a light-transmitting property that transmits energy rays or light of a wavelength detected by the optical element 2. In this embodiment, the light-transmitting body 10 is a cover for protecting the optical element 2 and the inner layer optical component 50 from adhesion of foreign matter. In the optical device 100, the optical element 2 detects energy rays or light through the light-transmitting body 10.

[0055] Examples of materials that can be used to form the light-transmitting body 10 include light-transmitting plastic, quartz, glass such as borosilicate, light-transmitting ceramic, and synthetic resin. The strength of the light-transmitting body 10 can be increased by forming the light-transmitting body 10 from, for example, reinforced glass. In this embodiment, the light-transmitting body 10 is formed from BK-7 (borosilicate glass).

[0056] The light-transmitting body 10 has, for example, a dome shape. When viewed from the height direction (Z direction) of the optical module 1, the light-transmitting body 10 is formed in a circular shape, and the thickness of the light-transmitting body 10 decreases continuously from the center to the outer periphery of the light-transmitting body 10. Note that the shape of the light-transmitting body 10 is not limited to this.

[0057] In this embodiment, the translucent body 10 has a first main surface PS1 and a second main surface PS2 opposite to the first main surface PS1. The first main surface PS1 is a main surface located on the outside of the translucent body 10. The first main surface PS1 is formed of a continuous curved surface. Specifically, the first main surface PS1 is curved in a round shape. The second main surface PS2 is a main surface located on the inside of the translucent body 10. The second main surface PS2 is formed flat.

[0058] The outer peripheral end of the light-transmitting body 10 is joined to the vibration body 20. Specifically, along the outer periphery of the light-transmitting body 10, the second main surface PS2 of the light-transmitting body 10 and the vibration flange 21 of the vibration body 20 are joined. The light-transmitting body 10 and the vibration body 20 can be joined by using, for example, an adhesive or a brazing material. Alternatively, thermocompression bonding, anodic bonding, or the like can also be used.

[0059] <Vibration body> The vibrating body 20 is formed in a cylindrical shape and supports the light-transmitting body 10. The vibrating body 20 is vibrated by the piezoelectric element 30, thereby vibrating the light-transmitting body 10.

[0060] The vibrating body 20 has a vibrating flange 21, a first cylindrical body 22, a spring portion 23, a second cylindrical body 24, a vibration plate 25, and a connecting portion 26. It should be noted that in the vibrating body 20, the connecting portion 26 is not an essential component.

[0061] The vibrating flange 21 is formed of an annular plate member when viewed from the height direction (Z direction) of the optical module 1. The vibrating flange 21 is disposed along the outer periphery of the light-transmitting body 10 and joined to the light-transmitting body 10. The vibrating flange 21 stably supports the light-transmitting body 10 by being in surface contact with the light-transmitting body 10.

[0062] The first cylindrical body 22 is formed in a cylindrical shape having one end and the other end. The first cylindrical body 22 is made of a hollow member with a through hole provided therein. The through hole is provided in the height direction (Z direction) of the optical module 1, and the opening of the through hole is provided at one end and the other end of the first cylindrical body 22. The first cylindrical body 22 has, for example, a cylindrical shape. When viewed from the height direction of the optical module 1, the outer shape of the first cylindrical body 22 and the opening of the through hole are formed in a circular shape.

[0063] A vibration flange 21 is provided at one end of the first cylindrical body 22, and a spring portion 23 is provided at the other end of the first cylindrical body 22. The first cylindrical body 22 supports the vibration flange 21, while being supported by the spring portion 23.

[0064] The spring portion 23 is a leaf spring that supports the other end of the first cylindrical body 22. The spring portion 23 is configured to be elastically deformable. The spring portion 23 supports the other end of the cylindrical first cylindrical body 22 and extends from the supported position toward the outside of the first cylindrical body 22.

[0065] The spring portion 23 is formed in a plate shape. The spring portion 23 has a hollow circular shape with a through hole provided therein, and extends so as to surround the periphery of the first cylindrical body 22 in a circular shape. In other words, the spring portion 23 has an annular plate shape. The annular plate shape means a shape in which a plate-shaped member is formed in an annular shape. When viewed from the height direction (Z direction) of the optical module 1, the outer shape of the spring portion 23 and the opening of the through hole are formed in a circular shape.

[0066] The spring portion 23 connects the first cylindrical body 22 and the second cylindrical body 24. Specifically, the spring portion 23 is connected to the first cylindrical body 22 on the inner peripheral side of the spring portion 23, and is connected to the second cylindrical body 24 on the outer peripheral side of the spring portion 23.

[0067] The second cylindrical body 24 is formed in a cylindrical shape having one end and the other end. When viewed from the height direction (Z direction) of the optical module 1, the second cylindrical body 24 is located outside the first cylindrical body 22 and supports the spring portion 23. The spring portion 23 is connected to one end of the second cylindrical body 24. The vibration plate 25 is connected to the other end of the second cylindrical body 24.

[0068] The second cylindrical body 24 is made of a hollow member with a through hole provided therein. The through hole is provided in the height direction (Z direction) of the optical module 1, and the through hole opening is provided at one end and the other end of the second cylindrical body 24. The second cylindrical body 24 has, for example, a cylindrical shape. When viewed from the height direction of the optical module 1, the outer shape of the second cylindrical body 24 and the opening of the through hole are formed into a circle.

[0069] The diaphragm 25 is a plate-like member extending inward from the other end of the second cylindrical body 24. The diaphragm 25 supports the other end of the second cylindrical body 24 and extends toward the inside of the second cylindrical body 24 from the supported position.

[0070] The diaphragm 25 has a hollow circular shape with a through hole provided therein, and is provided along the inner circumference of the second cylindrical body 24. The diaphragm 25 has an annular plate shape.

[0071] The connection part 26 connects the diaphragm 25 and the fixed part 40. The connection part 26 extends outward from the outer peripheral end of the diaphragm 25 and is bent toward the fixed part 40. The connection part 26 is supported by the fixed part 40. The connection part 26 is configured to have a node, making it difficult for vibrations from the diaphragm 25 to be transmitted.

[0072] In this embodiment, the first cylindrical body 22, the spring portion 23, the second cylindrical body 24, the diaphragm 25, and the connection portion 26 are integrally formed. Note that the first cylindrical body 22, the spring portion 23, the second cylindrical body 24, the diaphragm 25, and the connection portion 26 may be formed as separate bodies or as separate members.

[0073] The elements constituting the vibrating body 20 described above are made of, for example, metal or ceramic. Examples of metals that can be used include stainless steel, 42 alloy, 50 alloy, invar, super invar, kovar, aluminum, and duralumin. Alternatively, the elements constituting the vibrating body 20 may be made of ceramics such as alumina and zirconia, or may be made of semiconductors such as Si. Furthermore, the elements constituting the vibrating body 20 may be covered with an insulating material. Furthermore, the elements constituting the vibrating body 20 may be subjected to blackbody treatment.

[0074] Furthermore, the shape and arrangement of the elements that make up the vibrating body 20 are not limited to the above example.

[0075] <Piezoelectric element> The piezoelectric element 30 is disposed on the vibrating body 20 and vibrates the vibrating body 20. The piezoelectric element 30 is provided on a main surface of the vibration plate 25. Specifically, the piezoelectric element 30 is provided on the main surface of the vibration plate 25 opposite to the side on which the translucent body 10 is located. The piezoelectric element 30 vibrates the vibration plate 25, thereby vibrating the second cylindrical body 24 in the penetration direction (Z direction). For example, the piezoelectric element 30 vibrates when a voltage is applied thereto.

[0076] The piezoelectric element 30 has a hollow circular shape with a through hole provided therein. In other words, the piezoelectric element 30 has a circular plate shape. When viewed from the height direction (Z direction) of the optical module 1, the outer shape of the piezoelectric element 30 and the opening of the through hole are formed in a circular shape.

[0077] The outer shape of the piezoelectric element 30 and the opening of the through hole are not limited to this.

[0078] The piezoelectric element 30 has a piezoelectric body and electrodes. Examples of materials for forming the piezoelectric body include barium titanate (BaTiO3), lead zirconate titanate (PZT: PbTiO3·PbZrO3), lead titanate (PbTiO3), lead metaniobate (PbNb2O6), bismuth titanate (Bi4Ti3O 12Suitable piezoelectric ceramics such as (K,Na)NbO3, or suitable piezoelectric single crystals such as LiTaO3, LiNbO3, etc. can be used. The electrodes may be, for example, Ni electrodes. The electrodes may be electrodes made of a thin metal film such as Ag or Au formed by a sputtering method. Alternatively, the electrodes can be formed by plating or vapor deposition in addition to sputtering.

[0079] The fixing portion 40 fixes the vibration body 20. The fixing portion 40 also fixes the inner layer optical component 50. The fixing portion 40 is formed in a tubular shape. For example, the fixing portion 40 has a cylindrical shape. The shape of the fixing portion 40 is not limited to a cylindrical shape. The fixing portion 40 may be formed integrally with the vibration body 20.

[0080] <Inner layer optical components> The inner layer optical component 50 is an optical component disposed inside the vibration body 20. For example, the inner layer optical component 50 is a lens module.

[0081] In this embodiment, the inner layer optical component 50 has an inner layer lens 51 , a lens holding portion 52 , and an inner layer flange 53 .

[0082] The inner layer lens 51 is composed of a plurality of lenses. The inner layer lens 51 is disposed on the optical path of the optical element 2 inside the vibration body 20, and faces the light-transmitting body 10. The inner layer lens 51 is held by a lens holding portion 52.

[0083] The lens holding portion 52 holds the inner layer lens 51. The lens holding portion 52 is formed in a tubular shape having one end and the other end. Specifically, the lens holding portion 52 has a cylindrical shape and holds the outer periphery of the inner layer lens 51.

[0084] The inner layer flange 53 extends outward from the outer wall of the lens holding portion 52. Specifically, the inner layer flange 53 is connected to the other end of the lens holding portion 52 and extends toward the fixed portion 40. The inner layer flange 53 is formed in a circular ring shape when viewed from the height direction (Z direction) of the optical module 1. The outer periphery of the inner layer flange 53 is connected to the fixed portion 40. The inner layer flange 53 is fixed to the inside of the vibrating body 20 by being supported by the fixed portion 40.

[0085] FIG. 3 is a block diagram showing an example of a functional configuration of the optical device 100 according to the first embodiment of the present invention. As shown in FIG. 3, the piezoelectric element 30 is controlled by a control unit 3. The control unit 3 applies a drive signal that generates vibration to the piezoelectric element 30. The control unit 3 is connected to the piezoelectric element 30 via, for example, a power supply conductor. The piezoelectric element 30 vibrates in the height direction (Z direction) of the optical module 1 based on the drive signal from the control unit 3. The vibration of the piezoelectric element 30 vibrates the vibrating body 20, and the vibration of the vibrating body 20 is transmitted to the light-transmitting body 10, causing the light-transmitting body 10 to vibrate. As a result, foreign matter such as raindrops attached to the light-transmitting body 10 is removed.

[0086] The control unit 3 can be realized, for example, by a semiconductor element. For example, the control unit 3 can be configured by a microcomputer, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit). The functions of the control unit 3 may be configured by hardware alone, or may be realized by combining hardware and software.

[0087] For example, the control unit 3 realizes a predetermined function by reading out data and programs stored in the storage unit and performing various arithmetic processing.

[0088] The control unit 3 may be included in the optical device 100, or may be included in a control device separate from the optical device 100. For example, when the control unit 3 is not included in the optical device 100, the optical device 100 may be controlled by a control device including the control unit 3. Alternatively, the control unit 3 may be included in the optical module 1.

[0089] [About Gap] Next, the gaps formed in the optical module 1 between the light-transmitting body 10, the vibrating body 20, and the piezoelectric element 30, and the inner layer optical component 50 will be described.

[0090] Returning to Figures 1 and 2, a first gap G1, a second gap G2 and a third gap G3 are formed between the translucent body 10 and the inner layer optical component 50, between the piezoelectric element 30 and the inner layer optical component 50, and between the vibrating body 20 and the inner layer optical component 50, respectively.

[0091] 4 is a schematic diagram for explaining the first gap G1. FIG. 4(a) shows a schematic diagram of the light-transmitting body 10 viewed from the first main surface PS1 side, and FIG. 4(b) shows a schematic cross-sectional view of the vicinity of the light-transmitting body 10. As shown in FIG. 4, the first gap G1 is formed between the light-transmitting body 10 and the inner layer optical component 50. Specifically, the first gap G1 is formed between the second main surface PS2 of the light-transmitting body 10 and the first surface 51a of the inner layer lens 51. Here, the first surface 51a of the inner layer lens 51 is a surface that defines the first gap G1 and is a surface that faces the second main surface PS2 of the light-transmitting body 10.

[0092] The first dimension L1 of the first gap G1 is determined within a range in which vibration attenuation does not occur. The "range in which vibration attenuation does not occur" will be described later. The first dimension L1 is a dimension in the vibration direction A1 of the translucent body 10. The "vibration direction A1" refers to vibration in a direction having a larger displacement component when the displacement distribution due to the vibration of the translucent body 10 is separated into the X and Z directions. In this embodiment, in the translucent body 10, the displacement component in the Z direction is larger than the displacement component in the X direction. Therefore, the vibration direction A1 is the Z direction.

[0093] The first dimension L1 is defined by the shortest distance between the light-transmitting body 10 and the inner layer lens 51 in the vibration direction A1. That is, the first dimension L1 is defined by the shortest distance between the second main surface PS2 of the light-transmitting body 10 and the first surface 51a of the inner layer lens 51 in the Z direction.

[0094] Preferably, the first dimension L1 is the distance between the center Z1 of the light-transmitting body 10 and the inner layer lens 51. The center Z1 means the central portion of the light-transmitting body 10 when the light-transmitting body 10 is viewed from the first main surface PS1 side. For example, when viewed from the first main surface PS1 side of the light-transmitting body 10, the center Z1 of the light-transmitting body 10 is a circular region centered on the center C1 of the light-transmitting body 10. For example, when viewed from the first main surface PS1 side, the center Z1 of the light-transmitting body 10 has a diameter D2 that is 2 / 3 times or less the outer diameter D1 of the light-transmitting body 10. Preferably, the diameter D2 may be 1 / 2 times or less the outer diameter D1 of the light-transmitting body 10. In addition, the diameter D2 may be 1 / 3 times or more the outer diameter D1 of the light-transmitting body 10. The first dimension L1 is determined as the dimension at which the distance between the second main surface PS2 of the light-transmitting body 10 and the first surface 51a of the inner layer lens 51 is the shortest within the range of the central portion Z1 of the light-transmitting body 10.

[0095] More preferably, the first dimension L1 is determined by the dimension that makes the distance between the second main surface PS2 at the center C1 of the light-transmitting body 10 and the first surface 51a of the inner layer lens 51 the shortest.

[0096] 5 is a schematic diagram for explaining the second gap G2 and the third gap G3. As shown in FIG. 5, the second gap G2 is formed between the piezoelectric element 30 and the inner layer optical component 50. Specifically, the second gap G2 is formed between the piezoelectric element 30 and the inner layer flange 53. More specifically, the second gap G2 is formed between the surface of the piezoelectric element 30 opposite to the side on which the vibration plate 25 is provided and the second surface 53a of the inner layer flange 53. Here, the second surface 53a of the inner layer flange 53 is a surface that defines the second gap G2 and is a surface that faces the piezoelectric element 30.

[0097] The second dimension L2 of the second gap G2 is determined within a range in which no vibration attenuation occurs, similar to the first dimension L1 of the first gap G1. The second dimension L2 is a dimension in the vibration direction A2 of the piezoelectric element 30. In this embodiment, the displacement component in the Z direction is larger than the displacement component in the X direction in the piezoelectric element 30. Therefore, the vibration direction A2 is the Z direction.

[0098] The second dimension L2 is defined by the shortest distance between the piezoelectric element 30 and the inner layer flange 53 in the vibration direction A2. That is, the second dimension L2 is defined by the shortest distance in the Z direction between the face of the piezoelectric element 30 opposite to the side on which the vibration plate 25 is provided and the second surface 53a of the inner layer flange 53.

[0099] 5, a third gap G3 is formed between the vibrating body 20 and the inner optical component 50. A third dimension L3 of the third gap G3 is determined within a range in which no vibration attenuation occurs. The third dimension L3 is defined by the shortest distance between the vibrating body 20 and the lens holding part 52. In this embodiment, the third dimension L3 is defined by the shortest distance between the vibrating body 20 and the outer wall 52a of the lens holding part 52 in the X and Y directions.

[0100] [Area where vibration damping does not occur] The range in which vibration attenuation does not occur will be described with reference to Fig. 6. Fig. 6 is a schematic diagram for explaining the relationship between the first dimension L1 of the first gap G1 and sound waves.

[0101] 6, when the transparent body 10 vibrates in the vibration direction A1, sound waves are generated from the transparent body 10 in the first gap G1. The sound waves generated from the transparent body 10 proceed toward the first surface 51a of the inner layer lens 51 and are reflected by the first surface 51a of the inner layer optical component 50 (inner layer lens 51). As a result, the sound waves proceeding from the transparent body 10 toward the first surface 51a of the inner layer optical component 50 and the sound waves reflected by the first surface 51a overlap each other, generating a standing wave Ws that includes antinodes and nodes.

[0102] In the standing wave Ws, in the region Z10 that is the antinode of the sound wave, the sound pressure is greater than in other regions, and the air is compressed. Therefore, in the region Z10 that is the antinode of the sound wave, the compressed air acts as a damper, and vibration attenuation (damping) is likely to occur. Therefore, when the transparent body 10 is located in the region Z10 that is the antinode of the sound wave, the vibration of the transparent body 10 is attenuated.

[0103] If the wavelength of a sound wave is "λ", then the antinode of the sound wave occurs at a position equivalent to λ / 2. The formula for calculating the wavelength λ is [wavelength (mm)] = [speed of sound (m / s) / frequency (Hz)].

[0104] When the sound pressure in area Z10 vibrating due to standing wave Ws increases, the air pressure increases, and the springiness of the air increases. The springiness of air is proportional to the air pressure and inversely proportional to the volume. This is clear from the formula for the spring constant of a bellows-type air spring: [air spring constant K] = 10 x γ (P + 0.1) A / V. Note that P is the internal pressure, A is the effective pressure-receiving area of ​​the air spring, and V is the internal volume of the air spring.

[0105] When considering damping in free vibration, the critical damping rate is calculated as Cc = 2√mk, where m is mass and k is spring constant. The larger this critical damping rate Cc is, the easier it is for vibration to be damped. For this reason, it is thought that an increase in the spring constant of air leads to vibration damping. From the above, it can be said that vibration damping occurs due to an increase in sound pressure in region Z10, which is the antinode of the standing wave Ws.

[0106] FIG. 7 is a graph showing an example of an analysis result of the relationship between the displacement of the light-transmitting body 10 and the sound pressure. FIG. 8 is a graph in which the graph in FIG. 7 is enlarged. The graphs shown in FIG. 7 and FIG. 8 were obtained by performing a piezoelectric / sound wave analysis (harmonic analysis, strong coupling) using Femtet manufactured by Murata Software Co., Ltd. In the analysis, a model in which a glass plate was arranged on the upper surface of the light-transmitting body 10 in the Z direction was used, and the distance between the glass plate and the upper surface of the light-transmitting body was changed. In addition, an air layer was inserted into the gap between the glass plate and the upper surface of the light-transmitting body 10. As for the materials of the model, the material forming the glass plate was borosilicate glass, the material forming the vibration body 20 was stainless steel, and the piezoelectric element 30 was PZT. In addition, the light-transmitting body 10 and the vibration body 20 were bonded with epoxy resin. In addition, the resonance frequency of the vibration body 20 used in the analysis was 27 kHz, and the wavelength λ of the sound wave was set to 9.2 mm from the sound speed of air.

[0107] 7 and 8, when the distance in the Z direction of the gap between the light-transmitting body 10 and the glass plate is changed, in regions P1 and P2 corresponding to an integer multiple of the half wavelength λ / 2 of the standing wave Ws, the sound pressure increases and vibration attenuation occurs, thereby reducing the displacement of the light-transmitting body 10. Specifically, in regions where the distance in the Z direction of the gap between the light-transmitting body 10 and the glass plate is in the vicinity of 4.6 mm and 9.6 mm, the sound pressure increases and the displacement of the light-transmitting body 10 decreases. Also in region P0 where the gap between the light-transmitting body 10 and the glass plate is in the vicinity of 0 mm, the displacement of the light-transmitting body 10 decreases.

[0108] From the above, it is considered that vibration damping of the light-transmitting body 10 can be suppressed by arranging the light-transmitting body 10 so as to avoid the region P0 where the gap is near 0 mm and the regions P1 and P2 which are half the wavelength of the standing wave Ws.

[0109] As an example, a value obtained by reducing the maximum displacement amount S0 of the light-transmitting body 10 by 60% is set as the lower limit value S1 of the displacement amount of the light-transmitting body 10. The lower limit value S1 may be set within a range in which droplets attached to the light-transmitting body 10 can be removed. In FIG. 8, the maximum displacement amount S0 is 7.4 μm, so the lower limit value S1 is set to 4.7 μm. In this case, in the region Pz in which the vibration damping of the light-transmitting body 10 is suppressed, the distance of the gap in the Z direction is 0.1 mm or more and 4.5 mm or less. Within this numerical range, the vibration damping of the light-transmitting body 10 can be suppressed.

[0110] Here, vibration damping of the transparent body 10 occurs at every integer multiple of half the wavelength λ / 2 of the standing wave Ws. Therefore, the gap size for suppressing vibration damping of the transparent body 10 is determined to be in the range of [(n×λ / 2)+0.1 mm] to [{(n+1)×λ / 2}-0.1 mm]. Here, "n" is an integer equal to or greater than 0, and "λ" is the wavelength of the sound wave generated by the vibration.

[0111] Therefore, in the optical module 1, the first dimension L1 of the first gap G1 between the light-transmitting body 10 and the inner layer optical component 50 is set in the range of [(n×λ / 2)+0.1 mm] to [{(n+1)×λ / 2}-0.1 mm]. In other words, when the first dimension L1 satisfies the relationship [(n×λ / 2)+0.1 mm]≦L1≦[{(n+1)×λ / 2}-0.1 mm], vibration damping of the light-transmitting body 10 can be suppressed.

[0112] Preferably, the first dimension L1 is set in the range of 0.1 mm or more and (λ / 2-0.1 mm) or less. That is, it is preferable that the first dimension L1 satisfies the relationship 0.1 mm≦L1≦(λ / 2-0.1 mm). This makes it possible to further suppress vibration damping of the light-transmitting body 10.

[0113] The second dimension L2 of the second gap G2 between the piezoelectric element 30 and the inner layer optical component 50 (the inner layer flange 53) is the same as the first dimension L1 of the first gap G1. That is, the second dimension L2 is greater than or equal to [(n×λ / 2)+0.1 mm] and less than or equal to [{(n+1)×λ / 2}−0.1 mm]. belowIn other words, when the second dimension L2 satisfies the relationship [(n×λ / 2)+0.1 mm]≦L2≦[{(n+1)×λ / 2}−0.1 mm], the vibration damping of the piezoelectric element 30 can be suppressed.

[0114] Preferably, the second dimension L2 is set in the range of 0.1 mm or more and (λ / 2-0.1 mm) or less. That is, it is preferable that the second dimension L2 has the relationship 0.1 mm≦L2≦(λ / 2-0.1 mm). This makes it possible to further suppress the vibration damping of the piezoelectric element 30.

[0115] In this embodiment, the first dimension L1 of the first gap G1 and the second dimension L2 of the second gap G2 are set to be equal to or larger than [(n×λ / 2)+0.1 mm] or [{(n+1)×λ / 2}−0.1 mm]. below Although an example in which the range is set within the range has been described, the present invention is not limited to this.

[0116] Moreover, the third dimension L3 of the third gap G3 between the vibrating body 20 and the side wall (outer wall) 52a of the inner layer optical component 50 (lens holding portion 52) is preferably 0.1 mm or more.

[0117] [About vibration modes] The optical module 1 vibrates in a plurality of vibration modes. In this embodiment, the optical module 1 vibrates in a first vibration mode and a second vibration mode. Figures 9A and 9B are schematic diagrams for explaining the first vibration mode and the second vibration mode, respectively.

[0118] 9A, the first vibration mode is a bending vibration mode in which the central part of the light-transmitting body 10 vibrates with a larger displacement amount than the end parts. That is, in the first vibration mode, the central part of the light-transmitting body 10 vibrates with a larger displacement amount than the end parts. In the first vibration mode, vibration occurs in which the displacement direction of the central part of the light-transmitting body 10 is opposite to the displacement direction of the end parts, and the light-transmitting body 10 bends and vibrates. For this reason, droplets attached to the light-transmitting body 10 gather at the central part of the light-transmitting body 10.

[0119] 9B, the second vibration mode is a piston vibration mode in which the entire light-transmitting body 10 vibrates substantially uniformly. In the second vibration mode, vibration occurs in which the entire light-transmitting body 10 is displaced in the same direction, and the light-transmitting body 10 vibrates like a piston. For this reason, liquid droplets attached to the light-transmitting body 10 slide off the light-transmitting body 10.

[0120] The vibrating body 20 and the piezoelectric element 30 are configured to vibrate in a first vibration mode and a second vibration mode. The first vibration mode and the second vibration mode are controlled by a control unit. For example, the control unit can switch between the first vibration mode and the second vibration mode by changing the frequency of a drive signal applied to the piezoelectric element 30. For example, in the optical module 1, the resonance frequency of the first vibration mode is 37 kHz, and the resonance frequency of the second vibration mode is 28 kHz. Note that these resonance frequencies are merely examples, and may be changed depending on the dimensions and materials of each element of the optical module 1.

[0121] 10 is a graph showing an example of the relationship between the displacement of the transparent body and the sound pressure when the gap size is used as a parameter in the first vibration mode and the second vibration mode. As shown in FIG. 10, the half wavelength λ of the sound wave in the first vibration mode b When the gap dimension is around 4.6 mm, vibration attenuation occurs, and the displacement is reduced by 75% from the maximum displacement. Also, the half wavelength λ of the sound wave in the second vibration mode p / 2 is 6 mm, and vibration attenuation occurs when the gap dimension is around 6 mm, and the displacement is reduced by 50% from the maximum displacement.

[0122] Thus, in both the first and second vibration modes, it can be seen that vibration attenuation occurs when the gap dimension is set to approximately half the wavelength λ of the sound wave. Therefore, in both the first and second vibration modes, when the gap dimension is set to approximately half the wavelength λ b / 2,λ p / 2, vibration damping can be suppressed. In particular, in the first vibration mode, vibration damping can be improved by as much as 75% from the maximum displacement, so it can be said that there is a great advantage in applying the configuration of the present application.

[0123] [Materials that form the inner layer optical components] The material forming the inner layer optical component 50 will be described. In this embodiment, the inner layer optical component 50 is made of a material having a smaller acoustic impedance than the translucent body 10. This makes it possible to suppress the sound waves generated in the first gap G1 between the translucent body 10 and the inner layer optical component 50 from being reflected by the first surface 51a of the inner layer optical component 50. As a result, the sound pressure of the standing wave Ws can be reduced.

[0124] The greater the difference between the acoustic impedance of the medium on which the sound wave is incident and the acoustic impedance of the medium on which the sound wave is reflected, the greater the reflection of the sound wave. Acoustic impedance can be calculated using the sound speed and density of the medium.

[0125] In this embodiment, the medium on the side of the incident sound waves is the air layer present in the first gap G1. The medium on the side where the sound waves are reflected is the inner layer optical component 50 (inner layer lens 51). Therefore, by reducing the difference in acoustic impedance between the air layer of the first gap G1 and the inner layer optical component 50, the sound pressure of the standing wave Ws can be suppressed.

[0126] FIG. 11 is a table showing an example of the relationship between the acoustic impedance and the reflectance of sound waves in each material. FIG. 11 shows the acoustic impedance of resin, glass, and air as an example. As shown in FIG. 11, resin has a smaller acoustic impedance than glass. Therefore, resin can suppress the reflection of sound waves more than glass. Therefore, by making the inner layer optical component 50 out of resin, it is possible to reduce the reflection of sound waves more than glass.

[0127] Examples of the resin include amorphous polyolefin resin, polycarbonate resin, acrylic resin, polystyrene resin, and urethane resin.

[0128] In the first embodiment, an example in which the inner layer optical component 50 is made of resin has been described, but the present invention is not limited to this. The inner layer optical component 50 may be made of a material that has an acoustic impedance smaller than that of the translucent body 10 and that can suppress reflection of sound waves. For example, the inner layer lens 51 may be made of glass that has an acoustic impedance smaller than that of the translucent body 10.

[0129] [effect] The optical module 1 and the optical device 100 according to the first embodiment can provide the following advantages.

[0130] The optical module 1 includes a light-transmitting body 10, a vibrating body 20, a piezoelectric element 30, and an inner layer optical component 50. The vibrating body 20 is formed in a cylindrical shape and supports the light-transmitting body 10. The piezoelectric element 30 is disposed on the vibrating body 20 and vibrates the vibrating body 20. The inner layer optical component 50 is disposed inside the vibrating body 20. A first gap G1 is provided between the light-transmitting body 10 and the inner layer optical component 50, and a second gap G2 is provided between the piezoelectric element 30 and the inner layer optical component 50. At least one of a first dimension L1 of the first gap G1 in the vibration direction (Z direction) of the light-transmitting body 10 and a second dimension L2 of the second gap G2 in the vibration direction (Z direction) of the vibrating body 20 is determined in the range of [(n×λ / 2)+0.1 mm] or more and [{(n+1)×λ / 2}−0.1 mm] or less. Here, n is an integer of 0 or more, and λ is a wavelength of a sound wave generated by vibration.

[0131] With this configuration, vibration attenuation can be suppressed. Specifically, in the first gap G1 and the second gap G2, a sound wave generated by the vibration of the light-transmitting body 10 and the piezoelectric element 30 is reflected by the inner layer optical component 50, generating a standing wave Ws. Therefore, in a range where the first dimension L1 of the first gap G1 and / or the second dimension L2 of the second gap G2 is close to half the wavelength (n×λ / 2) of the sound wave, the sound pressure increases and the air is compressed, causing vibration attenuation. Therefore, when the light-transmitting body 10 and / or the piezoelectric element 30 are located in this range, the displacement amount is reduced by vibration attenuation. In the optical module 1, the first dimension L1 of the first gap G1 and / or the second dimension L2 of the second gap G2 is [(n×λ / 2)+0.1 mm] or more [{(n+1)×λ / 2}-0.1 mm] below By setting the range within this range, the range in which vibration attenuation occurs in the light-transmitting body 10 and / or the piezoelectric element 30 is avoided. This makes it possible to efficiently vibrate the light-transmitting body 10 and efficiently remove droplets adhering to the light-transmitting body 10.

[0132] At least one of the first dimension L1 and the second dimension L2 is set in the range of 0.1 mm or more (λ / 2-0.1 mm) or less. With this configuration, it is possible to realize a reduction in the size of the optical module 1 while suppressing vibration damping.

[0133] A third gap G3 is provided between the vibrating body 20 and the side wall (outer wall) 52a of the inner layer optical component 50, and the third dimension L3 of the third gap G3 is 0.1 mm or more. With this configuration, vibration attenuation can be further suppressed.

[0134] A first dimension L1 of the first gap G1 is the distance between the center Z1 of the light-transmitting body 10 and the inner layer optical component 50. With this configuration, vibration attenuation in the center Z1 of the light-transmitting body 10 can be suppressed.

[0135] The vibrating body 20 and the piezoelectric element 30 are configured so that the entire light-transmitting body 10 vibrates substantially uniformly. With this configuration, even when the entire light-transmitting body 10 vibrates substantially uniformly, vibration attenuation of the light-transmitting body 10 can be suppressed.

[0136] The vibrating body 20 and the piezoelectric element 30 are configured so that the central part of the light-transmitting body 10 vibrates more strongly than the ends. With this configuration, even if the central part of the light-transmitting body 10 vibrates more strongly than the ends, vibration attenuation of the light-transmitting body 10 can be suppressed.

[0137] The inner layer optical component 50 is made of a material having a smaller acoustic impedance than the light-transmitting body 10. Preferably, the inner layer optical component 50 is made of a resin. With such a configuration, it is possible to suppress reflection of sound waves in the inner layer optical component 50 and further suppress vibration attenuation.

[0138] The inner layer optical component 50 has an inner layer lens 51, a lens holding part 52, and an inner layer flange 53. The lens holding part 52 holds the inner layer lens 51. The inner layer flange 53 extends outward from the outer wall 52a of the lens holding part 52. A first gap G1 is provided between the light-transmitting body 10 and the inner layer lens 51, and a second gap G2 is provided between the piezoelectric element 30 and the inner layer flange 53. With this configuration, vibration damping of the light-transmitting body 10 and / or the piezoelectric element 30 can be suppressed.

[0139] The optical device 100 includes an optical module 1 and an optical element 2 disposed in the optical module 1. With such a configuration, it is possible to achieve the same effects as the optical module 1 described above.

[0140] <Variation 1> Fig. 12 is a schematic cross-sectional view showing the main configuration of an optical module 1A of modified example 1. As shown in Fig. 12, the optical module 1A has an acoustic wave suppression member 60 disposed in an inner layer optical component 50. The acoustic wave suppression member 60 is disposed on a first surface 51a of the inner layer optical component 50. The first surface 51a is a surface that defines a first gap G1 between the light-transmitting body 10 and the inner layer optical component 50 (inner layer lens 51).

[0141] The sound wave suppressing member 60 suppresses the reflection of sound waves. The sound wave suppressing member 60 is a member formed of, for example, a foamed resin material or a porous body. Examples of the foamed resin material that can be used include polyurethane, polystyrene, polyolefin, polyethylene, polypropylene, phenolic resin, polyvinyl chloride, urea resin, silicone, polyimide, and melamine resin. Examples of the porous body that can be used include glass wool.

[0142] The sound wave suppressing member 60 is arranged in an annular shape when viewed from the Z direction of the optical module 1A. Specifically, the sound wave suppressing member 60 is arranged along the outer periphery of the first surface 51a of the inner layer optical component 50.

[0143] In this way, by disposing the sound wave suppressing member 60 in the inner layer optical component 50, it is possible to suppress the reflection of sound waves in the inner layer optical component 50. This makes it possible to reduce sound pressure and further suppress vibration attenuation.

[0144] In the first modification, the acoustic wave suppressing member 60 is disposed on the first surface 51a of the inner layer optical component 50, but the present invention is not limited thereto. For example, the acoustic wave suppressing member 60 may be disposed on the second surface 53a of the inner layer optical component 50 (the inner layer flange 53) that defines the second gap G2 between the piezoelectric element 30 and the inner layer optical component 50.

[0145] The inner layer optical component 50 has a first surface 51a that defines a first gap G1 and a second surface 53a that defines a second gap G2, and an acoustic wave suppression member 60 that suppresses reflection of acoustic waves may be disposed on at least one of the first surface 51a and the second surface 53a.

[0146] Alternatively, the sound wave suppressing member 60 may be disposed on a surface that defines the gap other than the first surface 51a and the second surface 53a. The sound wave suppressing member 60 may be disposed in a position that does not interfere with the optical path of the optical element 2.

[0147] <Variation 2> Fig. 13 is a schematic cross-sectional view showing the main configuration of an optical module 1B of Modification 2. As shown in Fig. 13, in the optical module 1B, a first surface 51a of an inner layer optical component 50 (inner layer lens 51) is coated with a translucent resin coating.

[0148] As the resin coating, for example, a fluorine-based coating material or a silicone-based coating material can be used. As the fluorine-based coating material, for example, a fluorine-based polymer, polytetrafluoroethylene (PTFE), etc. As the silicone-based coating material, for example, a material having a main chain portion formed of a direct bond between silicon (Si) and oxygen (O), such as silicone oil, can be used.

[0149] In this manner, by applying a resin coating to the first surface 51a of the inner layer optical component 50 (inner layer lens 51), it is possible to suppress reflection of sound waves at the first surface 51a.

[0150] In the second modification, the first surface 51a of the inner layer optical component 50 is coated with a resin, but the present invention is not limited to this. For example, the second surface 53a of the inner layer optical component 50 (the inner layer flange 53) may be coated with a resin.

[0151] The inner layer optical component 50 has a first surface 51a that defines a first gap G1 and a second surface 53a that defines a second gap G2, and a resin coating 61 may be applied to at least one of the first surface 51a and the second surface 53a.

[0152] Alternatively, the resin coating 61 may be applied to surfaces that define the gap other than the first surface 51a and the second surface 53a.

[0153] <Variation 3> Fig. 14 is a schematic cross-sectional view showing the main configuration of an optical module 1C of the third modified example. As shown in Fig. 14, in the optical module 1C, the space SP1 formed inside the vibrating body 20 is at negative pressure. Negative pressure means a state in which the air pressure is lower than atmospheric pressure. Preferably, the air pressure in the space SP1 is 1 / 2 or less of the atmospheric pressure. More preferably, the space SP1 is a vacuum.

[0154] The space SP1 inside the vibration body 20 is a space formed between the vibration body 20 and the inner layer optical component 50. In the optical module 1C, the vibration body 20 and the inner layer optical component 50 are joined to the fixed part 40. For example, the vibration body 20 and the fixed part 40 are integrally formed, and the inner layer optical component 50 is welded to the fixed part 40 by laser welding or the like. This forms a sealed space SP1 between the vibration body 20 and the inner layer optical component 50. Note that, in the manufacture of the optical module 1C, the space SP1 can be made negative pressure or vacuum by performing the manufacture in a negative pressure or vacuum environment.

[0155] 15 is a graph showing the displacement attenuation rate when the space SP1 inside the vibration body 20 is made negative pressure. In FIG. 15, Example 1 shows the displacement attenuation rate when the space SP1 is at atmospheric pressure. rate In Example 2, the displacement attenuation in the negative pressure state of the space SP1 is 1 / 10 of the atmospheric pressure. rate Shows.

[0156] As shown in FIG. 15, Example 2 has a smaller displacement attenuation than Example 1. rateIn this manner, by making the space SP1 inside the vibrating body 20 have a negative pressure, the reflection of sound waves can be suppressed, and the vibration attenuation of the light-transmitting body 10 and the piezoelectric element 30 can be suppressed.

[0157] In the third modification, the space SP1 inside the vibrating body 20 is made vacuum or negative pressure, but the present invention is not limited thereto. For example, the space SP1 inside the vibrating body 20 may be filled with a gas having a lower density than air. Examples of the gas include nitrogen, neon, helium, and ethylene. Even with such a configuration, it is possible to suppress reflection of sound waves and suppress vibration attenuation of the translucent body 10 and the piezoelectric element 30.

[0158] (Embodiment 2) A vibration device according to a second embodiment of the present invention will be described. Note that in the second embodiment, differences from the first embodiment will be mainly described. In the second embodiment, configurations that are the same as or similar to those in the first embodiment will be described with the same reference numerals. Also, in the second embodiment, descriptions that overlap with the first embodiment will be omitted.

[0159] Fig. 16 is a schematic cross-sectional view showing an example of an optical module 1D according to the second embodiment of the present invention. Fig. 17 is a schematic diagram showing the relationship between the voltage applied to the piezoelectric element 30 and the displacement of the light-transmitting body 10. Fig. 17(a) shows the voltage applied to the piezoelectric element 30, and Fig. 17(b) shows the displacement of the light-transmitting body 10 in the Z direction.

[0160] In embodiment 2, if the position of the light-transmitting body 10 when it is not vibrating is taken as the reference position H0, and the direction away from the inner layer optical component 50 in the thickness direction (Z direction) of the light-transmitting body with respect to the reference position H0 is taken as the positive direction, and the direction approaching the inner layer optical component 50 with respect to the reference position H0 is taken as the negative direction, the light-transmitting body 10 differs from embodiment 1 in that the displacement in the positive direction is greater than the displacement in the negative direction.

[0161] In the second embodiment, the optical module 1D has the same configuration as the optical module 1 in the first embodiment, unless otherwise specified.

[0162] 16, the position of the light-transmitting body 10 in a state where it is not vibrating is taken as the reference position H0. In the second embodiment, the reference position H0 refers to the position of the second main surface PS2 of the light-transmitting body 10 in the thickness direction (Z direction) of the light-transmitting body 10 in a state where the light-transmitting body 10 is not vibrating. In addition, in the thickness direction (Z direction) of the light-transmitting body 10, the direction away from the inner layer optical component 50 with respect to the reference position H0 is taken as the positive direction, and the direction approaching the inner layer optical component 50 with respect to the reference position H0 is taken as the negative direction.

[0163] In the optical module 1D, the light-transmitting body 10 vibrates so that the displacement in the positive direction is larger than the displacement in the negative direction. That is, in the light-transmitting body 10, the displacement in the positive direction is larger than the displacement in the negative direction. For example, the displacement in the negative direction is 1 / 3 or less than the displacement in the positive direction. Preferably, the displacement in the negative direction is 1 / 10 or less than the displacement in the positive direction. More preferably, the displacement in the negative direction is zero.

[0164] Furthermore, in the vibration of the light-transmitting body 10, the displacement in the positive direction is greater than the displacement in the negative direction. For example, in the vibration of the light-transmitting body 10, the ratio of the displacement in the positive direction to the displacement in the negative direction is 6:4 or more and 10:0 or less. Preferably, the ratio of the displacement in the positive direction to the displacement in the negative direction is 8:2 or more and 10:0 or less. More preferably, the vibration of the light-transmitting body 10 includes only the displacement in the positive direction.

[0165] 17, the control unit 3 realizes vibration of the light-transmitting body 10 such that the displacement in the positive direction is greater than the displacement in the negative direction by controlling the voltage applied to the piezoelectric element 30. For example, the control unit 3 repeatedly applies a positive voltage +V1 to the piezoelectric element 30 and stops applying the voltage.

[0166] Specifically, the control unit 3 applies a positive voltage +V1 to the piezoelectric element 30 for a predetermined time, then stops the application of the voltage and sets the applied voltage to zero. After the applied voltage is kept at zero for a predetermined time, the control unit 3 applies the positive voltage +V1 again for a predetermined time. For example, the voltage application and halt may be performed at equal intervals or randomly. In this manner, the control unit 3 repeats the application and halt of the positive voltage +V1. That is, the control unit 3 applies the positive voltage +V1 to the piezoelectric element 30 without applying a negative voltage.

[0167] 17, the displacement of the light-transmitting body 10 in the thickness direction (Z direction) is controlled by the voltage applied to the piezoelectric element 30. When the voltage application to the piezoelectric element 30 is stopped, the light-transmitting body 10 does not vibrate. When a forward voltage +V1 is applied to the piezoelectric element 30, the light-transmitting body 10 vibrates so as to be displaced in a direction away from the inner layer optical component 50, i.e., in the positive direction, relative to a reference position H0 in the thickness direction (Z direction) of the light-transmitting body 10. In other words, when a forward voltage +V1 is applied to the piezoelectric element 30, the light-transmitting body 10 vibrates with a positive displacement +H1.

[0168] In this manner, by repeatedly applying a positive voltage +V1 to the piezoelectric element 30 and then stopping the voltage application, the light-transmitting body 10 vibrates between a reference position H0 and a positive displacement +H1.

[0169] [effect] The optical module 1D according to the second embodiment can provide the following advantages.

[0170] If the position of the light-transmitting body 10 when it is not vibrating is taken as the reference position H0, and the direction away from the inner layer optical component 50 relative to the reference position H0 in the thickness direction (Z direction) of the light-transmitting body 10 is taken as the positive direction, and the direction approaching the inner layer optical component 50 relative to the reference position H0 is taken as the negative direction, then in the light-transmitting body 10, displacement in the positive direction is greater than displacement in the negative direction.

[0171] With this configuration, it is possible to suppress displacement in the negative direction when the light-transmitting body 10 is vibrating. This makes it possible to suppress compression of the air between the light-transmitting body 10 and the inner layer optical component 50. As a result, it is possible to suppress vibration damping due to an increase in the air spring constant.

[0172] The optical module 1D further includes a control unit 3 that controls the piezoelectric element 30. The control unit 3 repeatedly applies a forward voltage to the piezoelectric element 30 and stops applying the voltage.

[0173] With this arrangement, the positive displacement can easily be made larger than the negative displacement.

[0174] In the second embodiment, the reference position H0 is the position of the second principal surface PS2 of the light-transmitting body 10 when the light-transmitting body 10 is not vibrating. However, the present invention is not limited to this. For example, the reference position H0 may be the position of the first principal surface PS1 of the light-transmitting body 10 when the light-transmitting body 10 is not vibrating.

[0175] In the second embodiment, an example has been described in which the control unit 3 repeatedly applies a positive voltage and stops applying the voltage to the piezoelectric element 30, but the present invention is not limited to this. For example, the control unit 3 may apply a negative voltage. In this case, the negative voltage may be smaller than the positive voltage. Alternatively, the application of the negative voltage may be smaller than the application of the positive voltage.

[0176] Although the present invention has been fully described in connection with the preferred embodiment with reference to the accompanying drawings, various changes and modifications will become apparent to those skilled in the art, and such changes and modifications are to be understood as being included within the scope of the present invention as defined by the appended claims, unless they depart therefrom. [Industrial Applicability]

[0177] The vibration device and vibration control method of the present invention can be applied to vehicle-mounted cameras, surveillance cameras, or optical sensors such as LiDAR used outdoors. [Explanation of symbols]

[0178] 1,1A,1B,1C,1D Optical Module 2. Optical elements 3. Control Unit 10 Translucent body 20 Vibration Body 21 Vibration flange 22 First cylindrical body 23 Spring section 24 Second cylindrical body 25 Diaphragm 26 Connection 30 Piezoelectric element 40 Fixed part 50 Inner layer optical components 51 Inner Lens 51a 1st surface 52 Lens holder 52a Outer wall 53 Inner layer flange 53a 2nd surface 60 Sound suppression material 61 Resin Coating 100 Optical equipment A1,A2 Vibration direction C1 center D1,D2 diameter G1 First Gap G2 2nd Gap G3 3rd Gap H0 reference position H1 Positive displacement L1 First dimension L2 Second dimension L3 3rd dimension PS1 First main surface PS2 2nd main surface SP1 Space V1 positive voltage Ws standing wave Z1 central part Z10 area P0,P1,P2,Pz area

Claims

1. A transparent body; A vibrating body formed in a cylindrical shape and supporting the light-transmitting body; A piezoelectric element is disposed on the vibrating body and vibrates the vibrating body; An inner layer optical component disposed inside the vibrating body; Equipped with A first gap is provided between the light-transmitting body and the inner layer optical component, A second gap is provided between the piezoelectric element and the inner layer optical component, At least one of a first dimension of the first gap in the vibration direction of the light-transmitting body and a second dimension of the second gap in the vibration direction of the vibrating body is determined in a range of [(n×λ / 2)+0.1 mm] or more and [{(n+1)×λ / 2}−0.1 mm] or less, n is an integer equal to or greater than 0, and λ is the wavelength of the sound wave generated by the vibration. Optical module.

2. At least one of the first dimension and the second dimension is determined in a range of 0.1 mm or more and (λ / 2-0.1 mm) or less. The optical module according to claim 1 .

3. A third gap is provided between the vibration body and a sidewall of the inner optical component, The third dimension of the third gap is 0.1 mm or more. The optical module according to claim 1 .

4. The first dimension of the first gap is the distance between the center of the transparent body and the inner layer optical component. The optical module according to claim 1 .

5. The vibrating body and the piezoelectric element are configured so that the entire light-transmitting body vibrates substantially uniformly. The optical module according to claim 1 .

6. The vibrator and the piezoelectric element are configured so that a central portion of the light-transmitting body vibrates more than an end portion of the light-transmitting body. The optical module according to claim 1 .

7. The inner layer optical component is made of a material having an acoustic impedance smaller than that of the transparent body. The optical module according to claim 1 .

8. The inner layer optical component is formed of a resin. The optical module according to claim 7.

9. The inner layer optical component is An inner lens; A lens holding portion that holds the inner layer lens; an inner layer flange extending outward from an outer wall of the lens holding portion; having The first gap is provided between the light-transmitting body and the inner layer lens, The second gap is provided between the piezoelectric element and the inner layer flange. The optical module according to claim 1 .

10. The inner layer optical component has a first surface that defines the first gap and a second surface that defines the second gap; An acoustic wave suppressing member that suppresses reflection of acoustic waves is disposed on at least one of the first surface and the second surface. The optical module according to claim 1 .

11. The inner layer optical component has a first surface that defines the first gap and a second surface that defines the second gap; At least one of the first surface and the second surface is coated with a resin. The optical module according to claim 1 .

12. The space inside the vibrating body is a vacuum or a negative pressure. The optical module according to claim 1 .

13. The space inside the vibrator is filled with a gas having a density lower than that of air. The optical module according to claim 1 .

14. When the position of the light-transmitting body in a non-vibrated state is taken as a reference position, the direction away from the inner layer optical component with respect to the reference position in the thickness direction (Z direction) of the light-transmitting body is taken as a positive direction, and the direction approaching the inner layer optical component with respect to the reference position is taken as a negative direction, In the transparent body, the displacement in the positive direction is greater than the displacement in the negative direction. The optical module according to claim 1 .

15. A control unit for controlling the piezoelectric element is further provided. the control unit repeatedly applies a positive voltage to the piezoelectric element and stops applying the voltage to the piezoelectric element.

15. The optical module according to claim 14.

16. An optical module according to any one of claims 1 to 15; an optical element disposed in the optical module; An optical device comprising:

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