Optical device and imaging unit including optical device

Abstract

The present disclosure provides an optical device in which a vibrating body is less susceptible to stress concentration when foreign matter adhering to a light transmitting body covering the exterior thereof is removed by vibration, and an imaging unit provided with the optical device. An optical device (100) is provided with an outermost layer lens (1) (light transmitting body), a housing (2), a vibrating body (3), and a piezoelectric element (5). The outermost layer lens (1) transmits light of a predetermined wavelength. The housing (2) holds the outermost layer lens (1). The vibrating body (3) is in contact with the outermost layer lens (1) held by the housing (2). The piezoelectric element (5) is provided on the vibrating body (3) and vibrates the vibrating body (3). The vibrating body (3) is a cylindrical body, and the cross-sectional shape of a supporting portion (33) (third part) thereof connecting a connecting portion (31) (first part) that is in contact with the outermost layer lens (1) and a vibrating portion (32) (second part) on which the piezoelectric element (5) is provided is a curved shape.

Description

[Technical Field]

[0001] The present disclosure relates to an optical device and an imaging unit including the optical device. [Background technology]

[0002] Imaging units are installed at the front or rear of a vehicle, and images obtained by the imaging units are used to control safety devices and perform driving assistance control.Since such imaging units are often installed outside the vehicle, raindrops (water droplets), mud, dust, and other foreign matter can adhere to the transparent bodies (protective covers and lenses) that cover the exterior.

[0003] If foreign matter adheres to a light-transmitting body, the foreign matter will be reflected in the image obtained by the imaging unit, making it impossible to obtain a clear image. Therefore, in Japanese Patent Laid-Open No. 2017-170303 (Patent Document 1), a vibrator that vibrates the light-transmitting body in order to remove foreign matter adhered to the surface of the light-transmitting body is provided in the imaging unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-170303 Summary of the Invention [Problem to be solved by the invention]

[0005] In the imaging unit described in Patent Document 1, the transparent body (waterproof cover) is formed with a dome portion, a tubular portion, and a flange portion. The flange portion is formed around the periphery of the tubular portion near the connection portion between the base end of the dome portion and the tubular portion, extending from the connection portion toward the outer periphery, and has an annular surface that is perpendicular to the optical axis. A plate-shaped piezoelectric element is disposed on the back side of the flange portion.

[0006] Therefore, to vibrate the drip-proof cover using a piezoelectric element, the vibration of the piezoelectric element needs to be transmitted to the dome portion via the flange portion. In other words, the flange portion functions as a vibrating body that transmits the vibration of the piezoelectric element to the dome portion. However, vibrating the dome portion causes stress to concentrate at the connection between the flange portion and the dome portion, which could cause cracks in that area.

[0007] Therefore, an object of the present disclosure is to provide an optical device in which stress is less likely to be concentrated in the vibrating body when foreign matter adhering to a translucent body covering the exterior is removed by vibration, and an imaging unit equipped with the optical device. [Means for solving the problem]

[0008] An optical device according to an embodiment of the present disclosure includes a transparent body that transmits light of a predetermined wavelength, a housing that holds the transparent body, a vibrator that contacts the transparent body held by the housing, and a piezoelectric element that is provided on the vibrator and vibrates the vibrator. The vibrator is a cylindrical body, and has a first portion that contacts the transparent body and a third portion that connects the first portion and the second portion where the piezoelectric element is provided. On a plane parallel to the axial direction of the cylindrical body The cross section is curved.

[0009] An imaging unit according to one embodiment of the present disclosure includes the optical device described above and an imaging element arranged so that the light-transmitting body is in the field of view. [Effects of the Invention]

[0010] According to the present disclosure, the vibrating body is a cylindrical body, and the cross-sectional shape of the third part connecting the first part that contacts the translucent body and the second part where the piezoelectric element is provided is curved, so that stress is less likely to concentrate in the vibrating body, and the occurrence of cracks can be reduced. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a half cross-sectional view of an optical device according to an embodiment. [Figure 2] 1 is a schematic diagram of a vibrating body according to an embodiment. [Figure 3]5A and 5B are schematic diagrams for explaining displacements that occur in the optical device according to the embodiment. [Figure 4] 5A and 5B are schematic diagrams for explaining stresses generated in the optical device according to the embodiment. [Figure 5] 5A and 5B are schematic diagrams for explaining displacement due to vibration of the optical device according to the embodiment. [Figure 6] 5A and 5B are schematic diagrams for explaining the radius of curvature of a vibrating body according to an embodiment. [Figure 7] 10A and 10B are schematic diagrams for explaining stresses generated in an optical device in which the radius of curvature of the vibrating body is changed. [Figure 8] 10 is a half cross-sectional view of an optical device according to a first modified example. FIG. [Figure 9] 10 is a half cross-sectional view of an optical device according to a second modification. FIG. [Figure 10] FIG. 11 is a half cross-sectional view of an optical device according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] An optical device according to an embodiment and an imaging unit including the optical device will be described in detail below with reference to the drawings. Note that the same reference numerals in the drawings indicate the same or corresponding parts. The optical device described below is applied to, for example, an imaging unit for vehicle use, and can vibrate a transparent body (e.g., the outermost lens) to remove foreign matter adhering to the surface of the transparent body. The optical device is not limited to applications as an imaging unit for vehicle use. For example, the optical device can also be applied to a surveillance camera for security purposes, an imaging unit for a drone, etc.

[0013] (Embodiment) FIG. 1 is a half cross-sectional view of an optical device 100 according to an embodiment. The X and Z directions in the figure indicate the horizontal and vertical directions of the optical device 100, respectively. The dashed-dotted line in FIG. 1 indicates the portion passing through the central axis of the optical device 100. The optical device 100 has an outermost lens 1, a housing 2, a vibrating body 3, an inner lens 4, and a piezoelectric element 5.

[0014] After adjusting the alignment between the outermost lens 1 and the inner lens 4, a case including an imaging element 6 is attached to the optical device 100 to form an imaging unit. The imaging unit has the optical device 100 and the imaging element 6 arranged so that the outermost lens 1 and the inner lens 4 are in the field of view. The imaging element 6 is an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor, and is mounted on a circuit board (not shown).

[0015] The outermost lens 1 is a light-transmitting body that transmits light of a predetermined wavelength (for example, a wavelength of visible light or a wavelength that can be captured by an imaging element), and is, for example, a convex meniscus lens. Note that the optical device 100 may use a transparent member such as a protective cover instead of the outermost lens 1. The protective cover is made of glass or a resin such as transparent plastic.

[0016] An end of the outermost lens 1 is held by an end of a leaf spring 2a extending from the housing 2. An adhesive is filled between the outermost lens 1 and a retainer 2b, which is the end of the leaf spring 2a. Furthermore, the optical device 100 is provided with a vibrating body 3 at a position in contact with the outermost lens 1 in order to vibrate the outermost lens 1 held in the housing.

[0017] FIG. 2 is a schematic diagram of a vibrating body 3 according to an embodiment. FIG. 2(a) is a perspective view of the vibrating body 3, and FIG. 2(b) is a perspective cross-sectional view of the vibrating body 3. As shown in FIG. 2, the vibrating body 3 is a cylindrical body and is composed of a connection portion 31 (first portion) that contacts the outermost lens 1, a vibration portion 32 (second portion) that has a piezoelectric element 5, and a support portion 33 (third portion) that connects the connection portion 31 and the vibration portion 32. The cross-sectional shape of the support portion 33 is S-shaped. As shown in FIG. 1, the vibrating body 3 has a shape in which a connection point A1 between the outermost lens 1 and the connection portion 31, a connection point A2 between the connection portion 31 and the support portion 33, and a connection point A3 between the support portion 33 and the vibration portion 32 are arranged on a substantially straight line. An inner lens 4 is arranged inside the cylindrical vibrating body 3, as shown in FIG. 1.

[0018] The connecting portion 31 has a cylindrical shape that is elongated in the axial direction (Z direction) of the cylindrical body. Furthermore, by elongating the end of the connecting portion 31 in the radial direction (X and Y directions) of the cylindrical body, it can be stably connected to the peripheral portion of the outermost lens 1. The connecting portion 31 may be formed by only elongating the portion in the axial direction (Z direction) of the cylindrical body, or by only elongating the portion in the radial direction (X and Y directions) of the cylindrical body. The vibrating portion 32 is a portion that vibrates together with the vibration of the piezoelectric element 5, and has a thickness greater than that of the connecting portion 31 and the support portion 33. This facilitates more efficient transmission of the vibration of the piezoelectric element 5 to the outermost lens 1. The support portion 33 supports the connecting portion 31 and transmits the vibration of the vibrating portion 32 to the connecting portion 31. The connecting portion 31, the vibrating portion 32, and the support portion 33 may be formed integrally or separately. 2, the maximum outer dimension of support portion 33 (third portion) is larger than the maximum outer dimension of connection portion 31 (first portion), and the maximum outer dimension of vibrating portion 32 (second portion) is larger than the maximum outer dimension of support portion 33 (third portion). This allows the vibration of vibrating portion 32 (i.e., vibration of piezoelectric element 5) to be efficiently transmitted to outermost lens 1 (translucent body).

[0019] The piezoelectric element 5 is provided on the surface of the vibrating part 32 opposite to the side in contact with the outermost lens 1. The piezoelectric element 5 is hollow and circular, and vibrates, for example, by polarization in the thickness direction. The piezoelectric element 5 is made of lead zirconate titanate piezoelectric ceramics. However, other piezoelectric ceramics such as (K,Na)NbO3 may also be used. Furthermore, a piezoelectric single crystal such as LiTaO3 may also be used. The piezoelectric element 5 may also be provided on the surface of the vibrating part 32 on the same side as the side in contact with the outermost lens 1.

[0020] The hollow circular piezoelectric element 5 vibrates in the radial direction, and this vibration is converted into vibration in the Z direction (up and down in the figure) by the support part 33 of the vibrating body 3, causing the outermost lens 1 to vibrate in the Z direction. FIG. 3 is a schematic diagram for explaining displacement that occurs in the optical device 100 pertaining to the embodiment. As can be seen from FIG. 3, the vibrating body 3 displaces the outermost lens 1 in the Z direction as the support part 33 elastically deforms like a spring. The vibration of the vibrating body 3 also elastically deforms the leaf spring 2a of the housing 2 that holds the outermost lens 1.

[0021] As can be seen from Fig. 3, the vibrating body 3 has a vibration node N in the center of the S-shaped cross section of the support part 33. Here, the vibration node N is a part where the amplitude is approximately 1 / 50 or less of the maximum amplitude of the vibrating body 3. Therefore, while the displacement of the outermost lens 1 is maximized by the vibration of the vibrating body 3, the displacement of the vibration node N is small. Note that in Fig. 3, the magnitude of the displacement is indicated by the darkness of the hatching, with darker hatching indicating parts with greater displacement, and the displacement being greater in the outermost lens 1.

[0022] In this embodiment, the cross section of the support portion 33 is S-shaped, and a vibration node N is located at the center of the S-shaped portion. In other words, the support portion 33 is curved near the vibration node N. As a result, the vibrating body 3 has a shape that makes it difficult for stress to concentrate, and the occurrence of cracks can be significantly reduced. FIG. 4 is a schematic diagram illustrating stresses occurring in the optical device according to the embodiment. FIG. 4(a) is a schematic diagram illustrating stresses occurring in the optical device 100, and FIG. 4(b) is a schematic diagram illustrating stresses occurring in a comparative optical device 500.

[0023] 4(a) and 4(b) illustrate the stress generated in the vibrating body when the piezoelectric element 5 is vibrated and the vibrating body causes the outermost lens 1 to perform piston-like vibration in the Z direction. In a comparative optical device 500 shown in FIG. 4(b), the piezoelectric element 5 is vibrated and the vibrating body 3Z causes the outermost lens 1 to perform piston-like vibration in the Z direction. The vibrating body 3Z includes a first cylindrical portion 31Z that supports the outermost lens 1, a hollow circular spring portion 32Z, a second cylindrical portion 33Z, and a flange portion 34Z having a surface on which the piezoelectric element 5 is provided. In the optical device 500, stress is concentrated at a connection portion S1 between the first cylindrical portion 31Z and the spring portion 32Z, and at a connection portion S2 between the spring portion 32Z and the second cylindrical portion 33Z. It is. In FIG. 4(b), the intensity of the hatching indicates the magnitude of the stress, with darker hatching indicating areas where the stress is greater, and stress is concentrated at the connecting portions S1 and S2.

[0024] The comparative optical device 500 shown in FIG. 4(b) has a structure in which the vibrating body 3Z vibrates in a bending manner, causing the outermost lens 1 to piston-like vibrate in the Z direction, resulting in stress concentration at the connection parts S1 and S2. On the other hand, the optical device 100 shown in FIG. 4(a) has a structure in which the support part 33 vibrates like a spring in the Z direction, causing the outermost lens 1 to piston-like vibrate in the Z direction, resulting in no stress concentration at the vibration node N. In other words, the optical device 100 has an S-shaped cross section of the support part 33, thereby reducing the areas where stress concentrates in the support part 33 and reducing the overall stress. The comparative optical device 500 shown in FIG. 4(b) had a maximum stress per unit displacement of 56.4 MPa / um, whereas the optical device 100 shown in FIG. 4(a) had a maximum stress per unit displacement of 20.7 MPa / um. That is, in the optical device 100 shown in FIG. 4(a), the stress generated in the support portion 33 is reduced to 1 / 2 or less compared to the comparative optical device 500 shown in FIG. 4(b).

[0025] Next, displacement due to vibration of the optical device 500 and the optical device 100 for comparison will be described. Fig. 5 is a schematic diagram for explaining displacement due to vibration of the optical device according to the embodiment. Fig. 5(a) is a schematic diagram for explaining displacement due to vibration of the optical device 100, and Fig. 5(b) is a schematic diagram for explaining displacement due to vibration of the optical device 500 for comparison.

[0026] 5(b), when the vibrating body 3Z is vibrated at a natural frequency (for example, 29 kHz), a vibration node N is formed in the flange portion 34Z extending from the end of the second cylindrical portion 33Z, and the vibrating body 3Z vibrates in a bending manner starting from the node N. In other words, the vibrating body 3Z for comparison vibrates such that the spring portion 32Z and the flange portion 34Z bend like a seesaw starting from the node N.

[0027] As shown in Fig. 5(b), the first cylindrical portion 31Z provided on the upper part of the spring portion 32Z undergoes piston-like vibration in the Z direction due to the bending vibration of the vibrating body 3Z. While the first cylindrical portion 31Z itself does not deform and maintains its original shape due to this vibration, the end of the spring portion 32Z is ​​significantly displaced, and as explained in Fig. 4(b), stress is concentrated at the connection portion S1 between the first cylindrical portion 31Z and the spring portion 32Z. Note that in Fig. 5(b), the amount of displacement is indicated by the shade of hatching, with darker hatching indicating areas with greater displacement, and the displacement is greater in areas farther from the node N.

[0028] On the other hand, in the optical device 100, as shown in FIG. 5(a), when the vibrating body 3 is vibrated at a natural frequency (for example, 29 kHz), a vibration node N is formed at the center of the S-shaped support portion 33, but the vibrating body 3 does not vibrate in a bending manner starting from node N. The vibrating body 3 does not vibrate in a bending manner, but rather vibrates in a spring manner, expanding and contracting in the Z direction. The spring vibration of the vibrating body 3 eliminates areas where stress is applied locally, thereby reducing stress concentration. In the optical device 100, by reducing stress concentration due to vibration, failure modes such as cracks occurring in the vibrating body 3 can be reduced, improving reliability.

[0029] In the optical device 100, it has been explained that the cross-sectional shape of the support portion 33 is S-shaped to prevent stress concentration in the vibrating body 3. However, the cross-sectional shape of the support portion 33 connecting the connecting portion 31 and the vibrating portion 32 of the vibrating body 3 is not limited to an S-shape, and stress concentration can be reduced if the cross-sectional shape is a curved shape. Therefore, it will be described in detail how much stress concentration can be reduced when the radius of curvature of the vibrating body 3 is changed. Figure 6 is a schematic diagram for explaining the radius of curvature of the vibrating body according to the embodiment.

[0030] 6(a) shows the radius of curvature of the vibrating body 3 shown in FIG. 1. The curved shape K1 of the support part 33 on the upper side in the figure has an inner radius of curvature of 1 mm and an outer radius of curvature of 1.8 mm. The curved shape K2 of the support part 33 on the lower side in the figure has an inner radius of curvature of 1.2 mm and an outer radius of curvature of 2 mm. In other words, the radius of curvature of the support part 33 on the side closer to the vibrating part 32 is larger than the radius of curvature of the side closer to the connection part 31. By shaping the support part 33 in this way, the support part 33 is structured to vibrate more like a spring in the Z direction.

[0031] 6(b) shows the radius of curvature of vibrating body 3A, which has a larger radius of curvature near node N than vibrating body 3 shown in FIG. 1. Curved shape K1 of support portion 33A has an inner radius of curvature of 0.8 mm on the side closer to connection portion 31, an outer radius of curvature of 1.6 mm, an inner radius of curvature of 1.2 mm on the side farther from connection portion 31, and an outer radius of curvature of 2 mm. Curved shape K2 of support portion 33A has an inner radius of curvature of 1.5 mm on the side farther from vibrating portion 32, an outer radius of curvature of 2.3 mm, and an inner radius of curvature of 0.9 mm on the side closer to vibrating portion 32. In other words, the radius of curvature of support portion 33A on the side closer to node N is larger than the radius of curvature on the side farther from node N.

[0032] Fig. 7 is a schematic diagram for explaining stresses generated in an optical device 100A in which the radius of curvature of a vibrating body 3A is changed. In the optical device 100A shown in Fig. 7, the same components as those in the optical device 100 shown in Fig. 1 are denoted by the same reference numerals, and the description thereof will not be repeated.

[0033] In FIG. 7, the stress generated in the vibrating body 3A when the piezoelectric element 5 is vibrated and the outermost lens 1 is piston-vibrated in the Z direction by the vibrating body 3A is illustrated. In the optical device 100A, as shown in FIG. 7, in order to piston-vibrate the outermost lens 1 in the Z direction by the vibrating body 3A, the radius of curvature near the node N of the support portion 33A is increased. Therefore, the support portion 33 A when vibrated like a spring in the Z direction, the portion where stress concentrates in the support portion 33 A is further reduced to reduce the overall stress. In the optical device 100 shown in FIG. 4(a), the stress per unit displacement was at most 20.7 MPa / μm, whereas in the optical device 100A shown in FIG. 7, the stress per unit displacement is at most 17.3 MPa / μm. That is, in the optical device 100A shown in FIG. 7, the stress generated in the support portion 33A is further reduced compared to the optical device 100 shown in FIG. 4(a).

[0034] As described above, the optical device 100 according to the embodiment includes an outermost lens 1 (light-transmitting body), a housing 2, a vibrating body 3, and a piezoelectric element 5. The outermost lens 1 transmits light of a predetermined wavelength. The housing 2 holds the outermost lens 1. The vibrating body 3 contacts the outermost lens 1 held by the housing 2. The piezoelectric element 5 is provided on the vibrating body 3 and vibrates the vibrating body 3. The vibrating body 3 is a cylindrical body, and the cross-sectional shape of the support portion 33 (third portion) connecting the connection portion 31 (first portion) contacting the outermost lens 1 and the vibrating portion 32 (second portion) provided with the piezoelectric element 5 is a curved shape.

[0035] Thereby, in the optical device 100 according to the embodiment, since the vibrating body 3 is a cylindrical body and the cross-sectional shape of the support portion 33 (third portion) connecting the connection portion 31 (first portion) contacting the outermost lens 1 and the vibrating portion 32 (second portion) provided with the piezoelectric element 5 is a curved shape, stress concentration hardly occurs in the vibrating body 3, and the occurrence of cracks can be reduced.

[0036] (Modification 1)<00001In the optical device 100 according to the embodiment, the cross-sectional shape of the support portion 33 has been described as being S-shaped. However, the cross-sectional shape of the support portion is not limited to being S-shaped as long as it is a shape that does not cause stress concentration in the vibrating body. FIG. 8 is a half-sectional view of an optical device according to Modification 1. In the optical device 100B shown in FIG. 8, the same components as those in the optical device 100 shown in FIG. 1 are denoted by the same reference numerals, and their description will not be repeated. The X and Z directions in the figure indicate the lateral and height directions of the optical device 100B, respectively. The dashed dotted line in FIG. 8 indicates the portion that passes through the central axis of the optical device 100B.

[0037] As shown in Fig. 8, the optical device 100B has an outermost lens 1, a housing 2, a vibrating body 3B, an inner lens 4, and a piezoelectric element 5. The vibrating body 3B is a cylindrical body, and is composed of a connection part 31 (first part) that contacts the outermost lens 1, a vibrating part 32 (second part) that is provided with the piezoelectric element 5, and a support part 33B (third part) that connects the connection part 31 and the vibrating part 32. The cross-sectional shape of the support part 33B is a shape formed by connecting multiple S-shapes. The vibrating body 3 B An inner lens 4 is disposed inside the cylinder as shown in FIG.

[0038] The cross section of the support portion 33B is a shape made up of multiple S-shapes connected together, and therefore, by vibrating the piezoelectric element 5, the outermost lens 1 can be subjected to piston-like vibration in the Z direction. In the support portion 33B shown in Fig. 8, the cross section is a shape made up of two S-shapes connected together, but it may also be a shape made up of three or more S-shapes connected together. Furthermore, any cross section that reduces the areas where stress concentrates in the support portion may be used, and therefore the cross section may be a curved shape that is half of an S-shape.

[0039] Furthermore, it has been explained that the vibrating bodies 3, 3A, 3B are composed of the connecting portion 31 (first portion), the vibrating portion 32 (second portion), and the supporting portions 33, 33A, 33B (third portion). In order to further reduce the portions where stress concentrates in the vibrating bodies 3, 3A, 3B, it is preferable that not only the cross-sectional shapes of the supporting portions 33, 33A, 33B be curved, but also the connecting portions between the connecting portion 31 and the supporting portions 33, 33A, 33B and the connecting portions between the vibrating portion 32 and the supporting portions 33, 33A, 33B be curved.

[0040] (Variation 2) In the optical device 100 according to the embodiment, the vibrating portion 32 of the vibrating body 3 is thicker than the connecting portion 31 and the support portion 33. However, when manufacturing a vibrating body having portions with different thicknesses, it is difficult to use a press process or the like, which is less expensive than cutting. Therefore, in the optical device according to Modification 2, the configuration of the vibrating body that can be processed using a press process or the like will be described. FIG. 9 is a half-sectional view of the optical device 100C according to Modification 2. Note that in the optical device 100C shown in FIG. 9, the same components as those in the optical device 100 shown in FIG. 1 are designated by the same reference numerals, and their description will not be repeated. The X and Z directions in the figure indicate the horizontal and vertical directions of the optical device 100C, respectively. The dashed-dotted line in FIG. 9 indicates the portion passing through the central axis of the optical device 100C.

[0041] 9, the optical device 100C has an outermost lens 1, a housing 2, a vibrating body 3C, an inner lens 4, and a piezoelectric element 5. The vibrating body 3C is a cylindrical body, and has a connecting portion 31 (first portion) that contacts the outermost lens 1, a vibrating portion 32a (second portion) that is provided with the piezoelectric element 5, and a connecting portion 31 and a vibrating portion 32b. a The vibrating body 3C is made up of a support portion 33C (third portion) that connects the connecting portion 31 and the vibrating portion 32a, and a weight portion 32b. The thickness of the connecting portion 31, the vibrating portion 32a, and the support portion 33C is uniform so that the vibrating body 3C can be formed using inexpensive press work or the like. The connecting portion 31, the vibrating portion 32a, and the support portion 33C may be formed integrally or separately.

[0042] However, because the thickness of the vibrating portion 32a is reduced, its function as a weight, like the vibrating portion 32 of the vibrating body 3, is reduced. Therefore, in the vibrating body 3C, a weight portion 32b, which is processed separately from the vibrating portion 32a, is provided between the vibrating portion 32a and the piezoelectric element 5 to add a weight function to the vibrating portion. The vibrating portion 32a and the weight portion 32b are joined together using adhesive, screws, or the like. Furthermore, the piezoelectric element 5 is provided on the surface of the weight portion 32b opposite the surface that contacts the vibrating portion 32a. However, this is not a limitation; the piezoelectric element 5 may also be provided on the surface of the vibrating portion 32a opposite the surface that contacts the weight portion 32b. Furthermore, the piezoelectric element 5 may also be provided on the same surface as the surface that contacts the vibrating portion 32a. By carefully arranging the piezoelectric element 5 and the weight portion 32b relative to the vibrating portion 32a, the height of the vibrating body 3C can be reduced, thereby enabling a low-profile optical device 100C and increasing the design flexibility of the optical device 100C. The radial lengths of weight portion 32b and piezoelectric element 5 may be approximately the same.

[0043] (Variation 3) In an optical device 100C according to Modification 2, weight 32b of vibrating body 3C is provided on the surface of vibrating part 32a opposite to the side in contact with outermost lens 1. However, weight 32c may be provided on the surface of vibrating part 32a on the side in contact with outermost lens 1. FIG. 10 is a half cross-sectional view of optical device 100D according to Modification 3. In optical device 100D shown in FIG. 10, the same components as those in optical device 100 shown in FIG. 1 are designated by the same reference numerals, and their description will not be repeated. The X and Z directions in the figure indicate the horizontal and height directions of optical device 100D, respectively. The dashed dotted line shown in FIG. 10 indicates a portion passing through the central axis of optical device 100D.

[0044] 10, the optical device 100D has an outermost lens 1, a housing 2, a vibrating body 3D, an inner lens 4, and a piezoelectric element 5. The vibrating body 3D is a cylindrical body, and has a connecting portion 31 (first portion) that contacts the outermost lens 1, a vibrating portion 32a (second portion) that is provided with the piezoelectric element 5, and a connecting portion 31 and a vibrating portion 32b. aThe vibrating body 3D is made up of a support portion 33C (third portion) that connects the connecting portion 31 and the vibrating portion 32a, and a weight portion 32c. The thickness of the connecting portion 31, the vibrating portion 32a, and the support portion 33C is uniform so that the vibrating body 3D can be formed using inexpensive press work or the like. The connecting portion 31, the vibrating portion 32a, and the support portion 33C may be formed integrally or separately.

[0045] In the vibrating body 3D, weight portion 32c, which is processed separately from vibrating portion 32a to add a function as a weight to the vibrating portion, is provided on the surface of vibrating portion 32a that contacts the outermost lens 1. Note that vibrating portion 32a and weight portion 32c are joined together using an adhesive, screws, or the like. Furthermore, while piezoelectric element 5 is provided on the surface of vibrating portion 32a opposite the side that contacts outermost lens 1, this is not limiting. Weight portion 32c may be provided on the same surface that contacts vibrating portion 32a, or on the surface of weight portion 32c that contacts outermost lens 1 (a configuration in which weight portion 32c and piezoelectric element 5 are stacked on vibrating portion 32a). In this way, by devising the arrangement of piezoelectric element 5 and weight portion 32c relative to vibrating portion 32a, the height of vibrating body 3D can be reduced, thereby enabling a low-profile optical device 100D and increasing the degree of freedom in the design of optical device 100D. The radial lengths of weight portion 32c and piezoelectric element 5 may be approximately the same.

[0046] (Other variations) The imaging unit according to the above-described embodiment may include a camera, a LiDAR, a Radar, etc. Also, a plurality of imaging units may be arranged side by side.

[0047] The imaging unit according to the above-described embodiment is not limited to an imaging unit installed in a vehicle, but can be similarly applied to any imaging unit that includes an optical device and an imaging element arranged so that a light-transmitting body is in the field of view, and that requires removal of foreign matter from the light-transmitting body.

[0048] (Aspect) (1) The optical device according to the present disclosure comprises a translucent body that transmits light of a predetermined wavelength, a housing that holds the translucent body, a vibrating body that contacts the translucent body held in the housing, and a piezoelectric element that is provided on the vibrating body and vibrates the vibrating body, wherein the vibrating body is a cylindrical body, and the cross-sectional shape of a third part that connects a first part that contacts the translucent body and a second part that has the piezoelectric element provided thereon is curved.

[0049] As a result, in the optical device according to the present disclosure, the vibrating body is a cylindrical body, and the cross-sectional shape of the third part connecting the first part that contacts the translucent body and the second part where the piezoelectric element is provided is curved, so that stress is less likely to concentrate in the vibrating body, and the occurrence of cracks can be reduced.

[0050] (2) In the optical device described in (1), the vibrating body has a first portion whose shape is elongated in the axial direction of the cylindrical body, which makes it easier to cause the light-transmitting body to vibrate in a piston-like manner in the Z direction.

[0051] (3) In the optical device according to (1) or (2), the vibrating body has a second portion whose shape is elongated in the radial direction of the cylindrical body, and the end of the second portion is located outside the other portion of the cylindrical body, which makes it easier to cause piston vibration of the light-transmitting body in the Z direction.

[0052] (4) In the optical device described in any one of (1) to (3), the cross section of the vibrating body at the third portion is S-shaped, which makes it possible to prevent stress from concentrating on the vibrating body.

[0053] (5) In the optical device described in (4), the radius of curvature of the third portion on the side closer to the second portion is larger than the radius of curvature of the third portion on the side closer to the first portion, thereby making it more difficult for stress to concentrate on the vibrating body.

[0054] (6) In the optical device according to any one of (1) to (5), the vibrating body includes a first portion and a second portion. 3 Compared to the thickness of the plate in the 2 This makes it easier to transmit the vibration of the piezoelectric element to the transparent body more efficiently.

[0055] (7) In the optical device according to any one of (1) to (6), when the vibrating body is vibrated by a piezoelectric element, a vibration node is formed in the center of a third portion extending from the first portion to the second portion, thereby facilitating piston vibration of the transparent body in the Z direction.

[0056] (8) In the optical device according to any one of (1) to (7), the vibrating body has the first, second and third parts integrally formed, thereby increasing the rigidity of the vibrating body.

[0057] (9) In the optical device according to any one of (1) to (8), the vibrating body has a shape in which the connection point between the light-transmitting body and the first portion, the connection point between the first portion and the third portion, and the connection point between the third portion and the second portion are arranged on a straight line, which facilitates piston-like vibration of the light-transmitting body in the Z direction.

[0058] (10) An imaging unit according to the present disclosure includes the optical device according to any one of (1) to (9) and an imaging element arranged so that the light-transmitting body is in the field of view, thereby realizing a highly reliable imaging unit with reduced cracks occurring in the optical device.

[0059] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0060] 1 outermost lens, 2 housing, 3 vibrating body, 4 inner lens, 5 piezoelectric element, 6 imaging element, 31 connection portion, 32 vibrating portion, 33, 33A, 33B support portion, 100, 100A, 100B optical device.

Claims

1. a transparent body that transmits light of a predetermined wavelength; a housing for holding the light-transmitting body; a vibrator held by the housing and in contact with the light-transmitting body; a piezoelectric element provided on the vibrating body to vibrate the vibrating body, The vibrating body is a cylindrical body, and the cross-sectional shape of a third part connecting a first part that contacts the translucent body and a second part in which the piezoelectric element is provided is curved in a plane parallel to the axial direction of the cylindrical body.

2. The optical device according to claim 1 , wherein the vibrating body has the first portion whose shape is elongated in the axial direction of the cylindrical body.

3. 3. The optical device according to claim 1, wherein the vibrating body has the second portion whose shape is extended in the radial direction of the cylindrical body, and the end of the second portion is located outside the other portion of the cylindrical body.

4. 3. The optical device according to claim 1, wherein the vibrating body has an S-shaped cross section taken along a plane parallel to an axial direction of the cylindrical body of the third portion.

5. The optical device according to claim 4 , wherein the third portion has a larger radius of curvature on a side closer to the second portion than on a side closer to the first portion.

6. 3. The optical device according to claim 1, wherein the third portion of the vibrating body has a thickness greater than the thicknesses of the first and second portions.

7. 3. The optical device according to claim 1, wherein the vibrating body has a vibration node at a center of the third portion extending from the first portion to the second portion when vibrated by the piezoelectric element.

8. 3. The optical device according to claim 1, wherein the first portion, the second portion, and the third portion of the vibrating body are integrally formed.

9. 3. The optical device of claim 1, wherein the vibrating body has a shape in which the connection point between the transparent body and the first portion, the connection point between the first portion and the third portion, and the connection point between the third portion and the second portion are arranged on a straight line.

10. The optical device according to claim 1 or 2; an imaging element disposed so that the light-transmitting body is in the field of view;

Images