Optical device and imaging unit provided with optical device

Abstract

The present disclosure provides an optical device capable of sufficiently removing foreign matter adhering to the surface of a light-transmitting body, and an imaging unit provided with the optical device. An optical device (10) is provided with an outermost layer lens (1) (translucent body), a housing (2), a vibrating body (3), and a piezoelectric element (5). The outermost layer lens (1) allows light of a predetermined wavelength to pass therethrough. The housing (2) holds the outermost layer lens (1). The vibrating body (3) is a cylindrical body, one end of the vibrating body (3) is in contact with the outermost layer lens (1), and the other end (32) of the vibrating body (3) is provided with a piezoelectric element (5). As a heat generation mode among a plurality of vibration modes for vibrating the outermost layer lens (1), the vibrating body (3) vibrates the outermost layer lens (1) at a natural vibration frequency of the outermost layer lens (1) and at a vibration acceleration in a range of 3.0 * 106 m / s2 or more and 3.0 * 108 m / s2 or less.

Description

Technical Field

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

[0002] The following configuration is performed: a camera unit is installed at the front or rear of the vehicle, and the images obtained by the camera unit are used to control the safety device or perform driving assistance control. Such camera units are mostly installed outside the vehicle, so there are cases where foreign objects such as raindrops (water drops), mud, and dust adhere to the light-transmitting body (protective cover, lens) covering the outside. In addition, in cold weather, the camera unit installed outside the vehicle may not be able to obtain a clear image due to ice or frost on the surface of the light-transmitting body.

[0003] Therefore, in the optical unit described in Patent Document 1, the light-transmitting body can be vibrated at a first frequency (cleaning mode) to remove foreign matter attached to the surface of the light-transmitting body, and the light-transmitting body can be vibrated at a second frequency (heating mode) to heat the light-transmitting body. Specifically, in the optical unit described in Patent Document 1, the controller circuit switches whether the light-transmitting body is vibrated in the cleaning mode or in the heating mode.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent Application Publication No. 2018 / 0246323 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] However, although Patent Document 1 describes an imaging unit that causes a light-transmitting body to vibrate in a heating mode at a second frequency different from the first frequency, it does not describe an imaging unit that causes a light-transmitting body to vibrate in a heating mode under conditions where there are constraints such as allowable power consumption and allowable waiting time. Therefore, in the imaging unit described in Patent Document 1, foreign matter such as ice and frost attached to the surface of the light-transmitting body may not be sufficiently removed under conditions where there are constraints.

[0009] Therefore, an object of the present disclosure is to provide an optical device and an imaging unit including the optical device that can sufficiently remove foreign matter attached to the surface of a light-transmitting body under a restricted situation.

[0010] Solutions for solving problems

[0011] An optical device according to one embodiment of the present disclosure includes: a light-transmitting body that transmits light of a predetermined wavelength; a housing that holds the light-transmitting body; a vibrating body that contacts the light-transmitting body held by the housing; and a piezoelectric element that is disposed on the vibrating body and causes the vibrating body to vibrate. The vibrating body is a cylindrical body that contacts the light-transmitting body at a first end and is provided at a second end on the opposite side of the first end. As a heat generation mode among a plurality of vibration modes for vibrating the light-transmitting body, the vibrating body causes the light-transmitting body to vibrate at a natural vibration frequency of the light-transmitting body and at a frequency of 3.0×10 6 m / s 2 Above ~3.0×10 8 m / s 2 Vibrate within the following range of vibration acceleration.

[0012] An imaging unit according to one aspect of the present disclosure includes: the optical device described above; and an imaging element disposed so that a light-transmitting body is located in a field of view direction.

[0013] Effects of the Invention

[0014] According to the present disclosure, as a heating mode, the vibrator causes the light-transmitting body to vibrate at a natural vibration frequency of the light-transmitting body and at a frequency of 3.0×10 6 m / s 2 Above ~3.0×10 8 m / s 2 The light-transmitting body is vibrated at a vibration acceleration within the following range, and therefore, foreign matter adhering to the surface of the light-transmitting body can be sufficiently removed under restricted conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a half cross-sectional view of the imaging unit according to the embodiment.

[0016] Figure 2 This is a schematic diagram for explaining displacement occurring in the optical device according to the embodiment.

[0017] Figure 3 This is a graph for explaining the vibration acceleration and the temperature rise rate when vibrating in the heat generation mode.

[0018] Figure 4 This is a graph showing the relationship between the frequency and the resonance resistance when the outermost lens according to the embodiment is vibrated in the heating mode.

[0019] Figure 5 This is a graph showing the relationship between the frequency and the electromechanical coupling coefficient when the outermost lens according to the embodiment is vibrated in the heating mode.

[0020] Figure 6 This is a schematic diagram for explaining the displacement that occurs in the optical device when the set conditions are deviated.

[0021] Figure 7 This is a schematic diagram for explaining the displacement of the outermost lens 1 when the vibrator according to the embodiment is driven in the foreign matter removal mode.

[0022] Figure 8 This is a schematic diagram for explaining the displacement of the outermost lens 1 when the vibrator according to the embodiment is driven in another foreign matter removal mode. DETAILED DESCRIPTION

[0023] Hereinafter, with reference to the accompanying drawings, an optical device of an embodiment and a camera unit equipped with the optical device are described in detail. In addition, the same reference numerals in the figures represent the same or corresponding parts. The optical device described below is applied to, for example, a camera unit for vehicle use, and can vibrate the light-transmitting body in order to remove foreign matter attached to the surface of the light-transmitting body (for example, the outermost lens). The optical device is not limited to the use of a camera unit for vehicle use. For example, the optical device can also be applied to security-oriented surveillance cameras, camera units for drones, etc.

[0024] (Implementation Method)

[0025] Figure 1 1 is a half cross-sectional view of the image pickup unit 100 according to the embodiment. In addition, the X direction and the Z direction in the figure respectively represent the lateral direction and the height direction of the image pickup unit 100. Figure 1 The dashed line shown is a portion passing through the central axis of the imaging unit 100. The imaging unit 100 includes an optical device 10 and an imaging element 20 arranged in such a manner that the outermost lens 1 and the inner lens 4 are in the field of view. The imaging element 20 is, for example, 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).

[0026] The optical device 10 has an outermost lens 1, a housing 2, a vibrator 3, an inner lens 4, a piezoelectric element 5, and an excitation circuit 6. In the present disclosure, the optical device 10 only needs to include at least the outermost lens 1, the housing 2, the vibrator 3, and the piezoelectric element 5, and may also be a structure in which the inner lens 4 or the excitation circuit 6, or the inner lens 4 and the excitation circuit 6 are included in the imaging unit 100. After the alignment adjustment of the outermost lens 1 and the inner lens 4 is performed, the housing including the imaging element 20 is mounted on the optical device 10, thereby forming the imaging unit 100.

[0027] The outermost lens 1 is a light-transmitting body for transmitting light of a predetermined wavelength (e.g., a wavelength of visible light, a wavelength that can be photographed by an imaging element, etc.), and is, for example, a convex meniscus lens. In addition, the optical device 10 may use a transparent member such as a protective cover instead of the outermost lens 1. The protective cover is made of resin such as glass or transparent plastic.

[0028] The end of the outermost lens 1 is held by the end of the leaf spring 2a extending from the housing 2. In addition, an adhesive is filled between the outermost lens 1 and the holding portion 2b which is the end of the leaf spring 2a. In addition, in the optical device 10, in order to vibrate the outermost lens 1 held by the housing 2, a vibrator 3 is provided at a position in contact with the outermost lens 1.

[0029] The vibrating body 3 is a cylindrical body, and is in contact with the outermost lens 1 at one end 31 (first end), and a piezoelectric element 5 is provided at the other end 32 (second end) on the opposite side of the one end. The vibrating body 3 is a structure in which the one end 31 and the other end 32 are connected by a support portion 33. In addition, the cross-sectional shape of the support portion 33 is the letter S shape. Figure 1 As shown, an inner lens 4 is arranged inside the cylinder of the vibrating body 3 .

[0030] One end portion 31 is a shape extending in the radial direction (X, Y direction) of the cylindrical body, and can be stably connected to the peripheral portion of the outermost lens 1. The other end portion 32 is a portion that vibrates together with the vibration of the piezoelectric element 5, and has a thicker plate thickness than other portions. As a result, it is easy to transmit the vibration of the piezoelectric element 5 to the outermost lens 1 more efficiently. The support portion 33 is a portion that supports the one end portion 31 and transmits the vibration of the other end portion 32 to the one end portion 31. In addition, the one end portion 31, the other end portion 32 and the support portion 33 can be formed integrally or separately. In addition, as Figure 1 As shown, the maximum outer dimension of the support portion 33 is larger than the maximum outer dimension of the one end portion 31, and the maximum outer dimension of the other end portion 32 is larger than the maximum outer dimension of the support portion 33. Thus, the vibration of the other end portion 32 (i.e., the vibration of the piezoelectric element 5) can be efficiently transmitted to the outermost lens 1 (translucent body).

[0031] The piezoelectric element 5 is provided at the other end 32. The piezoelectric element 5 is hollow and circular, and vibrates by polarization in the thickness direction, for example. The piezoelectric element 5 is composed of a lead zirconate titanate piezoelectric ceramic. However, other piezoelectric ceramics such as (K, Na) NbO3 may also be used. Piezoelectric single crystals such as LiTaO3 may also be used. The piezoelectric element 5 is connected to an excitation circuit 6, and the outermost lens 1 is vibrated based on a signal from the circuit.

[0032] In order to remove foreign matter such as raindrops, mud, and dust attached to the outermost lens 1, the excitation circuit 6 can drive the piezoelectric element 5 in a foreign matter removal mode, in which the outermost lens 1 is vibrated at the resonance frequency of the vibrator 3. In addition, in order to remove foreign matter such as ice and frost attached to the outermost lens 1, the excitation circuit 6 can drive the piezoelectric element 5 in a heating mode, in which the outermost lens 1 is vibrated at the natural vibration frequency of the outermost lens 1. The excitation circuit 6 can drive the piezoelectric element 5 by switching between multiple vibration modes including the foreign matter removal mode and the heating mode. The excitation circuit 6 is also a switching unit that switches the mode of vibrating the outermost lens 1 from the multiple vibration modes.

[0033] In the heating mode, the outermost lens 1 is heated by utilizing the mechanical loss of vibration generated by vibrating the outermost lens 1. In order to efficiently generate heat for the outermost lens 1, it is necessary to vibrate the outermost lens 1 at the natural vibration frequency of the outermost lens 1. However, even if the outermost lens 1 is vibrated at the natural vibration frequency, the camera unit 100 cannot capture a desired image while foreign matter such as ice or frost is attached to the outermost lens 1. Therefore, in a system (such as an in-vehicle system) incorporating the camera unit 100, the time (allowable waiting time) until the foreign matter such as ice or frost is removed and the desired image can be captured in the heating mode is limited.

[0034] In the optical device 10, in order to increase the heat generated by the outermost lens 1, it is necessary to increase the vibration acceleration of the outermost lens 1. For example, through repeated simulations, it was found that when the allowable waiting time is limited to about 200 seconds to 400 seconds, the vibration acceleration of the outermost lens 1 required to remove foreign matter such as ice and frost attached to the outermost lens 1 within the allowable waiting time is about 3.0×10 6 m / s 2 above.

[0035] In the optical device 10, by setting the vibration acceleration of the outermost lens 1 to about 3.0×10 6 m / s 2 By vibrating the outermost lens 1 in the above manner, foreign matter such as ice or frost attached to the outermost lens 1 can be removed within the allowable waiting time. In the optical device 10, by further increasing the vibration acceleration of the outermost lens 1, the time until foreign matter such as ice or frost attached to the outermost lens 1 is removed can be shortened. However, as the vibration acceleration of the outermost lens 1 is increased, the power consumed by the piezoelectric element 5 increases.

[0036] In a system (e.g., a vehicle-mounted system) in which the camera unit 100 is assembled, the power consumption (allowable power consumption) allocated to the camera unit 100 is often limited. Therefore, in the optical device 10, it is necessary to vibrate the outermost lens 1 within the allowable power consumption range to remove foreign matter such as ice and frost attached to the outermost lens 1. For example, through repeated simulations and experiments, it was found that when the allowable power consumption is limited to about 3W to 7W, the vibration acceleration of the outermost lens 1 that can be vibrated within the allowable power consumption range is about 3.0×10 8 m / s 2 the following.

[0037] Therefore, in the optical device 10, when the outermost lens 1 is vibrated in the heat generation mode under the condition of restrictions such as the allowable power consumption and the allowable waiting time, it is preferable to vibrate the outermost lens 1 at the natural vibration frequency of the outermost lens 1 and at a frequency of about 3.0×10 6 m / s 2 Above ~ about 3.0×10 8 m / s 2 More preferably, the outermost lens 1 is vibrated at a natural vibration frequency of the outermost lens 1 and at a vibration acceleration within the range below 3.0×10 6 m / s 2 Above ~ about 4.9×10 7 m / s 2 The optical device 10 vibrates the outermost lens 1 in such a heating mode, so that foreign matter such as ice and frost adhering to the surface of the outermost lens 1 can be sufficiently removed even under restricted conditions.

[0038] In the optical device 10, foreign matter such as ice and frost adhering to the surface of the outermost lens 1 can be removed by vibrating the outermost lens 1 in a heating mode, but foreign matter can be removed more efficiently by further causing the outermost lens 1 to have a maximum displacement due to vibration. Figure 2 Schematic diagram for explaining displacement generated in the optical device 10 according to the embodiment. Figure 2 , the result of a simulation in which the optical device 10 is vibrated is shown, and displacement caused by the vibration in the optical device 10 is shown. Figure 2 The dashed line shown is a portion passing through the central axis of the optical device 10. Figure 2 In FIG. 1 , the density of hatching indicates the magnitude of displacement due to vibration, and a portion with denser hatching indicates a portion with larger displacement due to vibration.

[0039] according to Figure 2It can be seen that the central portion M of the outermost lens 1 is deformed to a large extent. On the other hand, the deformation of other portions is smaller than the deformation of the outermost lens 1. That is, in the optical device 10, when the outermost lens 1 is vibrated in the heating mode, the outermost lens 1 can be vibrated in a manner that generates the maximum displacement based on the vibration in the outermost lens 1. In this way, by vibrating the outermost lens 1 in the heating mode by the optical device 10, the energy input from the piezoelectric element 5 can be efficiently consumed in the heating of the outermost lens 1.

[0040] Figure 3 This is a graph for explaining the vibration acceleration and the temperature rise rate when vibrating in the heat generation mode. Figure 3 This is experimental data that compares the vibration acceleration and temperature rise rate for the vibration mode and heating mode of the comparison object. Figure 3 , the vibration acceleration and temperature rise rate when the outermost lens 1 is vibrated in the heating mode are shown when the vibration acceleration and temperature rise rate when the outermost lens 1 is vibrated in the vibration mode of the comparison object are set to "1" respectively. In addition, the two vibration modes are driven with the same power consumption, which is within the range of allowable power consumption of 3W to 7W. In addition, the vibration acceleration of the vibration mode of the comparison object is lower than the lower limit of the specified range of 3.0×10 6 m / s 2 .according to Figure 3 It can be seen that the vibration acceleration in the heating mode is about 6.7 times that of the comparison object, and the temperature rise rate in the heating mode is about 5.0 times. Therefore, by vibrating the outermost lens 1 in the heating mode, a faster temperature rise rate can be achieved compared to the case where the outermost lens 1 is vibrated in the vibration mode of the comparison object, and the input energy (power consumption) can be efficiently consumed in temperature rise (thawing). In other words, compared to the case where the maximum displacement due to vibration is not generated in the outermost lens 1, the optical device 10 can remove foreign matter such as ice and frost more efficiently.

[0041] In the optical device 10, by vibrating the outermost lens 1 at the natural vibration frequency of the outermost lens 1, the proportion of energy allocated to the outermost lens 1 in the energy input from the piezoelectric element 5 can be increased, thereby speeding up the vibration acceleration of the outermost lens 1 and causing the outermost lens 1 to produce a maximum displacement based on the vibration.

[0042] Furthermore, in order to efficiently convert the energy distributed to the outermost lens 1 into heat energy in the optical device 10 , it is necessary to optimize the electromechanical coupling coefficient between the outermost lens 1 and the piezoelectric element 5 .

[0043] Figure 4 : is a graph showing the relationship between the frequency and the resonance resistance when the outermost lens 1 of the embodiment is vibrated in the heating mode. Figure 3 In FIG. 1 , the horizontal axis is the frequency (kHz) of the piezoelectric element 5 , and the vertical axis is the resonance resistance (Ω) of the vibrating body 3 including the outermost lens 1 . Figure 5 : is a graph showing the relationship between the frequency and the electromechanical coupling coefficient when the outermost lens 1 of the embodiment is vibrated in the heating mode. Figure 5 In FIG. 5 , the horizontal axis is set to the frequency (kHz) of the piezoelectric element 5, and the vertical axis is set to the electromechanical coupling coefficient (%) between the outermost lens 1 and the piezoelectric element 5. Figure 4 and Figure 5 The data depicted in is a simulation result of vibrations capable of converting the energy distributed to the outermost lens 1 into heat energy at an efficiency of a predetermined value or more.

[0044] In the optical device 10, when the outermost lens 1 is vibrated so as to efficiently convert the energy distributed to the outermost lens 1 into heat energy, according to Figure 4 It is known that the resonant resistance is preferably set to 60Ω or more. In the optical device 10, when the outermost lens 1 is vibrated in such a manner that the energy distributed to the outermost lens 1 is efficiently converted into heat energy, according to Figure 5 It can be seen that the electromechanical coupling coefficient between the outermost lens 1 and the piezoelectric element 5 is preferably set in the range of 0% to 6%.

[0045] The optical device 10 satisfies the setting conditions that the electromechanical coupling coefficient between the outermost lens 1 and the piezoelectric element 5 is in the range of 0% to 6% or less, or the resonance resistance is 60Ω or more, so that when the outermost lens 1 is vibrated in the heating mode, it becomes a vibration mode that does not overlap with the high-order resonance mode of the piezoelectric element 5. Therefore, in the optical device 10, the energy allocated to the outermost lens 1 can be efficiently converted into heat energy, so that the outermost lens 1 can generate heat efficiently.

[0046] When the electromechanical coupling coefficient between the outermost lens 1 and the piezoelectric element 5 of the optical device 10 exceeds 6% or the resonance resistance is less than 60Ω and deviates from the set conditions, the displacement due to vibration increases in the portion other than the outermost lens 1, and the heat generated in this portion increases. Figure 6 It is a schematic diagram for explaining the displacement generated in the optical device 10 when the set conditions are deviated.

[0047] Figure 6 This is the result of vibration simulation of the optical device 10 in which the electromechanical coupling coefficient between the outermost lens 1 and the piezoelectric element 5 is greater than 6% or the resonance resistance is less than 60Ω. Figure 6 The dashed line shown is a portion passing through the central axis of the optical device 10. Figure 6 In FIG. 1 , the density of hatching indicates the magnitude of displacement due to vibration, and a portion with denser hatching indicates a portion with larger displacement due to vibration.

[0048] When the optical device 10 is vibrated in a state deviating from the set conditions, a vibration mode overlapping with a high-order resonance mode of the piezoelectric element 5 is formed, such as Figure 6 As shown in FIG. 1 , the displacement of the piezoelectric element 5 is larger than that of the outermost lens 1. Since the part with larger displacement becomes a heat source, Figure 6 In the case shown, the energy consumed in heat generation in the piezoelectric element 5 is greater than the energy consumed in heat generation in the outermost lens 1. In addition, when the displacement of the outermost lens 1 decreases, the energy distributed to the outermost lens 1 cannot be efficiently converted into heat energy.

[0049] In addition to being able to drive the piezoelectric element 5 in a heating mode, the optical device 10 can also drive the piezoelectric element 5 in a foreign matter removal mode in order to remove foreign matter such as raindrops, mud, dust, etc. attached to the outermost lens 1. In this foreign matter removal mode, the outermost lens 1 is vibrated at the resonance frequency of the vibrator 3. Figure 7 This is a schematic diagram for explaining the displacement of the outermost lens 1 when the vibrator 3 according to the embodiment is driven in the foreign matter removal mode.

[0050] exist Figure 7 In (a), the maximum displacement position of the outermost lens 1 when the vibrator 3 is driven in the foreign matter removal mode is shown. Figure 7 (b) shows the vibration amplitude when the outermost lens 1 is assumed to be a flat plate and is vibrated in the foreign matter removal mode.

[0051] The optical device 10 can vibrate the outermost lens 1 in the foreign matter removal mode when the piezoelectric element 5 is driven at the resonance frequency of the vibrator 3. When the outermost lens 1 is vibrated in the foreign matter removal mode, the outermost lens 1 will Figure 7 As shown in (a) of FIG. 1 , the maximum vibration displacement occurs at the center portion 1a. Figure 7 As shown in (b), when the outermost lens 1 is assumed to be a flat plate, the portion with greater displacement is the central portion 1a of the outermost lens 1 (the antinode 1b of vibration), and the portion with smaller displacement is the peripheral portion of the outermost lens 1 (the node 1c of vibration).

[0052] As a foreign matter removal mode among the multiple vibration modes, the vibrator 3 can vibrate the outermost lens 1 at a resonant frequency such that the central portion 1a of the outermost lens 1 becomes a vibration antinode 1b and the peripheral portion of the outermost lens 1 held by the housing 2 becomes a vibration node 1c. Thus, the optical device 10 can remove foreign matter such as raindrops, mud, and dust attached to the outermost lens 1 by vibrating the outermost lens 1.

[0053] Foreign matter removal mode is not limited to Figure 7 Vibration shown. Figure 8 1 is a schematic diagram for explaining the displacement of the outermost lens 1 when the vibrator of the embodiment is driven in another foreign matter removal mode. Figure 8 It can be seen that the vibrator 3 elastically deforms like a spring to displace the entire outermost lens 1 in the Z direction (viewing direction). The leaf spring 2a of the housing 2 that holds the outermost lens 1 is also elastically deformed by the vibration of the vibrator 3. Figure 8 It can be seen that the vibrating body 3 has a vibration node N in the center of the portion whose cross-sectional shape is in the shape of the letter S. Here, the vibration node N refers to a portion whose amplitude is less than approximately 1 / 50 of the maximum amplitude of the vibrating body 3. Therefore, the displacement of the outermost lens 1 is maximized by the vibration of the vibrating body 3, while the displacement of the vibration node N is small. Figure 8 In the figure, the size of the displacement is represented by the density of the hatching. The denser the hatching, the larger the displacement. The displacement is larger at the outermost lens 1.

[0054] The optical device 10 can switch between the foreign matter removal mode and the heating mode by using the excitation circuit 6. The optical device 10 can also switch between the foreign matter removal mode and the heating mode according to the image captured by the imaging element 20, for example. Specifically, the optical device 10 can also pre-store an image of a case where foreign matter such as raindrops, mud, dust, etc. is attached to the outermost lens 1 and an image of a case where foreign matter such as ice and frost is attached to the outermost lens 1, and switch between the foreign matter removal mode and the heating mode according to whether it is consistent with any of the images.

[0055] (Variation Example)

[0056] In the optical device 10 of the embodiment, it is described that the cross-sectional shape of the support portion 33 is set to the letter S shape. However, as long as the shape is such that stress concentration is avoided in the vibrating body, the cross-sectional shape of the support portion is not limited to the letter S shape. For example, the cross-sectional shape of the support portion 33 may be a shape in which a plurality of letters S are connected. In addition, as long as the cross-sectional shape of the portion in the support portion 33 that reduces stress concentration is sufficient, the cross-sectional shape may also be a curved shape that is half of the letter S shape.

[0057] The imaging unit 100 of the above-mentioned embodiment may include a camera, LiDAR (laser radar), Radar (radar), etc. In addition, a plurality of imaging units 100 may be arranged in parallel.

[0058] The imaging unit 100 of the above-described embodiment is not limited to an imaging unit provided in a vehicle, but can be similarly applied to any imaging unit including an optical device and an imaging element arranged so that a light-transmitting body is in a field of view and requiring removal of foreign matter from a light-transmitting body.

[0059] (plan)

[0060] (1) The optical device disclosed in the present invention comprises: a light-transmitting body that transmits light of a predetermined wavelength; a housing that holds the light-transmitting body; a vibrating body that contacts the light-transmitting body held by the housing; and a piezoelectric element that is disposed on the vibrating body and causes the vibrating body to vibrate. The vibrating body is a cylindrical body that contacts the light-transmitting body at a first end and has a piezoelectric element disposed at a second end opposite to the first end. The vibrating body causes the light-transmitting body to vibrate at a natural vibration frequency of the light-transmitting body and at a frequency of 3.0×10 6 m / s 2 Above ~3.0×10 8 m / s 2 Vibrate within the following range of vibration acceleration.

[0061] (2) The optical device according to (1), wherein when the vibrator vibrates the light-transmitting body in a heat generation mode, the vibrator vibrates the light-transmitting body so as to generate a maximum displacement due to the vibration in the light-transmitting body.

[0062] (3) An optical device according to (1) or (2), wherein when the light-transmitting body is vibrated in a heating mode, an electromechanical coupling coefficient between the light-transmitting body and the piezoelectric element is in a range of 0% to 6%, or a resonance resistance is 60Ω or more.

[0063] (4) An optical device according to any one of (1) to (3), wherein, as a foreign matter removal mode among multiple vibration modes, the vibrating body causes the light-transmitting body to vibrate at a resonant frequency such that the central portion of the light-transmitting body becomes a vibration antinode and the peripheral portion of the light-transmitting body held in the shell becomes a vibration node, or causes the light-transmitting body held in the shell to vibrate as a whole in the field of view direction.

[0064] (5) The optical device according to (4), further comprising a switching unit that switches a mode for vibrating the light-transmitting body from a plurality of vibration modes, the switching unit switching between the foreign matter removal mode and the heating mode based on an image obtained by the imaging element.

[0065] (6) An imaging unit of the present disclosure includes: the optical device according to any one of (1) to (5); and an imaging element disposed so that the light-transmitting body is in a field of view direction.

[0066] The embodiments disclosed this time should be considered as illustrative in all aspects and not restrictive. The scope of the present disclosure is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0067] Description of Reference Numerals

[0068] 1. Outermost lens; 2. Shell; 2a. Leaf spring; 2b. Holding part; 3. Vibrating body; 4. Inner lens; 5. Piezoelectric element; 6. Excitation circuit; 10. Optical device; 20. Image pickup element; 100. Image pickup unit.

Claims

1. An optical device, wherein: The optical device has: A light-transmitting body for transmitting light of a predetermined wavelength; A housing that holds the light-transmitting body; a vibrating body in contact with the light-transmitting body held by the housing; and a piezoelectric element provided on the vibrating body to vibrate the vibrating body, The vibrating body is a cylindrical body, the first end of which is in contact with the light-transmitting body, and the piezoelectric element is provided at the second end on the opposite side of the first end. As a heat generation mode among a plurality of vibration modes for vibrating the light-transmitting body, the vibrating body causes the light-transmitting body to vibrate at a natural vibration frequency of the light-transmitting body and at a frequency of 3.0×10 6 m / s 2 Above ~3.0×10 8 m / s 2 Vibrate within the following range of vibration acceleration.

2. The optical device according to claim 1, wherein: When the vibrator vibrates the light-transmitting body in the heat generation mode, the vibrator vibrates the light-transmitting body so that a maximum displacement due to vibration occurs in the light-transmitting body.

3. The optical device according to claim 1 or 2, wherein: When the light-transmitting body is vibrated in the heat generation mode, an electromechanical coupling coefficient between the light-transmitting body and the piezoelectric element is in a range of 0% to 6%, or a resonance resistance is 60Ω or more.

4. The optical device according to any one of claims 1 to 3, wherein: As a foreign matter removal mode among the multiple vibration modes, the vibrating body causes the translucent body to vibrate at a resonant frequency such that the central portion of the translucent body becomes a vibration antinode and the peripheral portion of the translucent body held in the shell becomes a vibration node, or causes the translucent body held in the shell to vibrate as a whole in the field of view direction.

5. The optical device according to claim 4, wherein: The optical device further includes a switching unit that switches a mode for vibrating the light-transmitting body from among the plurality of vibration modes. The switching unit switches between the foreign matter removal mode and the heating mode based on an image obtained by an imaging element.

6. A camera unit, wherein: The camera unit has: The optical device according to any one of claims 1 to 5; and The imaging element is arranged so that the light-transmitting body is in a field of view direction.

Images