Optical device and imaging apparatus

Abstract

This optical device comprises: an ND filter that is provided closer to an object side as compared with a light-receiving surface of an image sensor; and at least one translucent member that is provided between the light-receiving surface and the ND filter and is used for dust reduction.

Description

Optical device and imaging apparatus

[0001] The present disclosure relates to optical devices and imaging apparatuses.

[0002] 4 of WO 2017 / 061169 discloses a mechanism in which the liquid crystal light control element 11 is held by a holder 11a and the clear glass 82 is held by a holder 82a. This mechanism moves the liquid crystal light control element 11 and the clear glass 82 together and switches the liquid crystal light control element 11 and the clear glass 82 to the incident light path.

[0003] One embodiment of the present disclosure provides an optical device and an imaging apparatus that can prevent dust from appearing in an image obtained by capturing an image with an image sensor.

[0004] A first aspect of the present disclosure is an optical device comprising an ND filter disposed on the subject side of the light receiving surface of an image sensor, and at least one light-transmitting member disposed between the light receiving surface and the ND filter and used for dust reduction.

[0005] A second aspect of the present disclosure is the optical device according to the first aspect, in which the ND filter is an electronic ND filter.

[0006] A third aspect of the present disclosure is the optical device according to the first or second aspect, wherein the dust reduction is achieved by vibrating at least one light-transmitting member.

[0007] A fourth aspect of the present disclosure is an optical device according to any one of the first to third aspects, wherein dust reduction is achieved by applying an antistatic coating to at least one of the light-transmitting members.

[0008] A fifth aspect of the present disclosure is an optical device according to any one of the first to fourth aspects, in which dust reduction is achieved by discharging electricity from at least one translucent member.

[0009] A sixth aspect of the present disclosure is an optical device according to any one of the first to fifth aspects, in which a plurality of light-transmitting members are positioned between the light-receiving surface and the ND filter, and the plurality of light-transmitting members include a first light-transmitting member and a second light-transmitting member positioned closer to the light-receiving surface than the first light-transmitting member.

[0010] A seventh aspect according to the present disclosure is the optical device according to the sixth aspect, in which dust reduction is achieved by vibrating the second light-transmitting member.

[0011] An eighth aspect according to the present disclosure is the optical device according to the sixth or seventh aspect, in which the ND filter and the first light-transmitting member are alternately inserted into and removed from the optical path.

[0012] A ninth aspect of the present disclosure is the optical device according to the sixth aspect, in which dust reduction is achieved by applying an antistatic coating to the first light-transmitting member.

[0013] A tenth aspect of the present disclosure is an optical device according to any one of the sixth to ninth aspects, in which dust reduction is achieved by discharging electricity from the first translucent member.

[0014] An eleventh aspect of the present disclosure is the optical device according to the tenth aspect, wherein the first light-transmitting member has a coating film that prevents static buildup and includes a metal frame that holds the first light-transmitting member, the coating film being in contact with the metal frame, and when the first light-transmitting member, while held by the metal frame, moves from one of a first position where the first light-transmitting member is inserted into the optical path and a second position where the first light-transmitting member is removed from the optical path to the other, static elimination is performed by the metal frame coming into contact with a grounded conductor.

[0015] A twelfth aspect of the present disclosure is the optical device according to any one of the sixth to eleventh aspects, including a holding frame that holds the ND filter and the first light-transmitting member.

[0016] A thirteenth aspect of the present disclosure is an optical device according to the twelfth aspect, in which the ND filter and the first light-transmitting member are provided with a power receiving mechanism that receives power to alternately insert and remove the ND filter and the first light-transmitting member into and from the optical path, the holding frame has an opening that exposes the power receiving mechanism from the holding frame, a power applying mechanism is attached to the holding frame that applies power to the power receiving mechanism through the opening, and an adhesive is applied to at least the surface of the inner surface of the holding frame that faces the power receiving mechanism.

[0017] A fourteenth aspect of the present disclosure is an optical device according to the thirteenth aspect, in which a housing that houses a power-giving mechanism is attached to the holding frame, and the housing has a blocking wall that blocks the opening when the housing is attached to the holding frame.

[0018] A fifteenth aspect of the present disclosure is an optical device according to the twelfth aspect, in which the ND filter and the first light-transmitting member are provided with a power receiving mechanism that receives power to alternately insert and remove the ND filter and the first light-transmitting member into and from the optical path, the holding frame has an opening that exposes the power receiving mechanism from the holding frame, a housing that houses a power applying mechanism that applies power to the power receiving mechanism from the opening is attached to the holding frame, and the housing has a blocking wall that closes the opening when the housing is attached to the holding frame.

[0019] A sixteenth aspect of the present disclosure is an optical device according to any one of the thirteenth to fifteenth aspects, in which the power receiving mechanism includes a first rack provided on the ND filter and a second rack provided on the first translucent member, and the power applying mechanism includes a first gear that meshes with the first rack and a second gear that meshes with the second rack.

[0020] A seventeenth aspect of the present disclosure is an optical device according to any one of the sixth to sixteenth aspects, comprising a first protective frame that protects the ND filter and the first light-transmitting member from the ND filter side, and a second protective frame that protects the ND filter and the first light-transmitting member from the first light-transmitting member side, wherein the first protective frame and the second protective frame are fitted together via a fitting structure.

[0021] An eighteenth aspect of the present disclosure is an optical device according to the seventeenth aspect, in which an adhesive is applied to the position where the first protective frame and the second protective frame are fitted together via a fitting structure and / or around the position.

[0022] A 19th aspect of the present disclosure is an imaging apparatus comprising an optical device according to any one of the first to eighteenth aspects and an image sensor, in which subject light that has passed through the optical device is captured by the image sensor.

[0023] 1 is a schematic diagram showing an example of the overall configuration of an imaging device. FIG. 1 is a schematic diagram showing an example of the hardware configuration of an optical system and an electrical system of an imaging device. FIG. 2 is an exploded perspective view showing an example of the configuration of an optical filter. FIG. 3 is a perspective view and a cross-sectional view showing an example of the configuration of an electronic ND filter and a holder that holds the electronic ND filter. FIG. 4 is a front view showing an example of the configuration of an electronic ND filter and a holding frame that holds the electronic ND filter. FIG. 5 is a perspective view showing an example of the appearance of an optical filter and an image sensor as viewed from the back. FIG. 6 is a perspective view showing an example of an aspect in which an electronic ND filter is inserted into an optical path and the clear glass of a second clear glass component is removed from the optical path, and a cross-sectional view showing an example of a partial configuration of the second clear glass component. FIG. 7 is a perspective view showing an example of an aspect of the second clear glass component within the rear protective frame when the clear glass of the second clear glass component has moved from a position inserted into the optical path to a position removed from the optical path. FIG. 8 is a perspective view showing an example of the appearance of an optical filter and an image sensor as viewed from the back. FIG. 9 is a perspective view showing an example of a longitudinal section of an optical filter and an image sensor. FIG. 10 is a cross-sectional view showing an example of the configuration of an electronic ND filter and a holding frame that holds the electronic ND filter. Fig. 1 is a conceptual diagram showing an example of a state of a vibrating first clear glass component. Fig. 2 is a front view showing an example of a state of a second clear glass component within a rear protective frame when the clear glass of the second clear glass component moves from a first position where it is inserted into the optical path to a second position where it is removed from the optical path. Fig. 3 is a cross-sectional view showing a modified example of the configuration of an electronic ND filter and a holder that holds the electronic ND filter. Fig. 4 is a perspective view showing a modified example of the configuration of an electronic ND filter and a holder that holds the electronic ND filter. Fig. 5 is a cross-sectional view showing an example of a cross-sectional configuration of an optical device.

[0024] Hereinafter, an example of an embodiment of an optical device and an imaging apparatus according to the present disclosure will be described with reference to the accompanying drawings.

[0025] First, the terms used in the following description will be explained.

[0026] CPU is an abbreviation for "Central Processing Unit". GPU is an abbreviation for "Graphics Processing Unit". GPGPU is an abbreviation for "General-purpose computing on graphics processing units". APU is an abbreviation for "Accelerated Processing Unit". TPU is an abbreviation for "Tensor processing unit". NVM is an abbreviation for "Non-volatile memory". RAM is an abbreviation for "Random Access Memory". ASIC is an abbreviation for "Application Specific Integrated Circuit". PLD is an abbreviation for "Programmable Logic Device". FPGA is an abbreviation for "Field-Programmable Gate Array". SoC is an abbreviation for "System-on-a-chip". CMOS is an abbreviation for "Complementary Metal Oxide Semiconductor". CCD is an abbreviation for "Charge Coupled Device". ND is an abbreviation for "Neutral Density." EL is an abbreviation for "Electro Luminescence."

[0027] In the following description, "same" refers to not only complete sameness but also sameness in the sense of including an error that is generally acceptable in the technical field to which the present disclosure belongs and that does not contradict the spirit of the present disclosure. Also, in the following description, "constant" refers to not only complete sameness but also sameness in the sense of including an error that is generally acceptable in the technical field to which the present disclosure belongs and that does not contradict the spirit of the present disclosure.

[0028] In the following description, a processor (hereinafter simply referred to as a "processor") may be a single physical or virtual computing device, or a combination of multiple physical or virtual computing devices. Furthermore, a processor may be a single type of computing device, or a combination of multiple types of computing devices. Examples of computing devices include a CPU, a GPU, a GPGPU, an APU, and a TPU.

[0029] In the following description, a memory is a memory such as a RAM that temporarily stores information and is used as a work memory by a processor.

[0030] In the following description, storage refers to one or more nonvolatile storage devices that store various programs, various parameters, etc. Examples of nonvolatile storage devices include flash memory, magnetic disks, and magnetic tapes. Another example of storage is cloud storage.

[0031] In the following embodiments, "A and / or B" is synonymous with "at least one of A and B." In other words, "A and / or B" means that it may be only A, only B, or a combination of A and B. Furthermore, in this specification, the same concept as "A and / or B" is also applied when three or more things are expressed by connecting them with "and / or."

[0032] Fig. 1 shows an example of the appearance of an imaging device 10. As shown in Fig. 1, the imaging device 10 is a device that captures an image of a subject, and includes an imaging device body 16 and an interchangeable lens 18. The interchangeable lens 18 is replaceably attached to the imaging device body 16. The imaging device 10 is an example of an "imaging device" according to the present disclosure.

[0033] 1 illustrates an interchangeable-lens digital camera as an example of the imaging device 10, but this is merely an example and a fixed-lens digital camera may also be used. The present disclosure is also applicable to smart devices, wearable devices, infrared cameras, multispectral cameras, hyper-multispectral cameras, cinema cameras, television broadcast video cameras, surveillance cameras, cell observation devices, endoscopes, ophthalmic observation devices, surgical microscopes, and the like. Smart devices, wearable devices, infrared cameras, multispectral cameras, hyper-multispectral cameras, cinema cameras, television broadcast video cameras, surveillance cameras, cell observation devices, endoscopes, ophthalmic observation devices, surgical microscopes, and the like are examples of "imaging devices" according to the present disclosure.

[0034] The imaging device main body 16 is provided with an image sensor 20 and an optical filter 22. The image sensor 20 is an example of an "image sensor" according to the present disclosure, and the optical filter 22 is an example of an "optical device" according to the present disclosure.

[0035] The image sensor 20 is a CMOS image sensor.

[0036] In the present embodiment, a CMOS image sensor is used as the image sensor 20, but the present disclosure is not limited thereto, and the present disclosure can be applied even if the image sensor 20 is another type of image sensor, such as a CCD image sensor.

[0037] The optical filter 22 is provided closer to the subject than the image sensor 20. When the interchangeable lens 18 is attached to the imaging device body 16, subject light, which is light representing the subject, passes through the optical filter 22 via the interchangeable lens 18 and is focused on the image sensor 20. The image sensor 20 photoelectrically converts the received subject light to generate image data representing an image of the subject.

[0038] In this embodiment, as shown in FIG. 1 , the imaging device 10 has an X-axis, a Y-axis, and a Z-axis, and the orientation of the imaging device 10 is determined by the X-axis, the Y-axis, and the Z-axis. The Y-axis is an axis along the optical axis OA of the interchangeable lens 18 when the imaging device 10 is placed horizontally on a horizontal surface 24 (e.g., the state shown in FIG. 1 ). The X-axis is an axis perpendicular to the Y-axis within the horizontal surface 24. The Z-axis is an axis perpendicular to both the X-axis and the Y-axis (i.e., an axis along the vertical direction when the imaging device 10 is placed horizontally on the horizontal surface 24). In this embodiment, the direction along the X-axis is referred to as the X-direction, the direction along the Y-axis is referred to as the Y-direction, and the direction along the Z-axis is referred to as the Z-direction. In this embodiment, the direction toward the subject on the Y-axis is referred to as the +Y-direction, and the direction opposite to the +Y-direction is referred to as the −Y-direction. In this embodiment, the direction to the right of the imaging device 10 as viewed from the front when the imaging device 10 is placed horizontally on the horizontal surface 24 is referred to as the +X direction, and the direction to the left of the imaging device 10 as viewed from the front when the imaging device 10 is placed horizontally on the horizontal surface 24 is referred to as the -X direction. In this embodiment, the direction vertically above the imaging device 10 as viewed from the front when the imaging device 10 is placed horizontally on a horizontal surface is referred to as the +Z direction, and the direction vertically below the imaging device 10 as viewed from the front when the imaging device 10 is placed horizontally on the horizontal surface 24 is referred to as the -Z direction. The relative positional relationship between the X-axis, Y-axis, and Z-axis remains unchanged regardless of the orientation of the imaging device 10.

[0039] Fig. 2 shows an example of the hardware configuration of the imaging device 10. As shown in Fig. 2, the image sensor 20 has a light receiving surface 20A. The image sensor 20 is disposed within the imaging device body 16 so that the center of the light receiving surface 20A coincides with the optical axis OA.

[0040] The interchangeable lens 18 includes an imaging lens 40. The imaging lens 40 has an objective lens 40A, a variable magnification lens 40B, and a movable diaphragm 40C.

[0041] The objective lens 40A, variable magnification lens 40B, and aperture 40C are arranged along the optical axis OA from the subject side (object side) to the imaging device body 16 side (image side) in this order. The variable magnification lens 40B moves along the optical axis OA in accordance with instructions from the imaging device body 16. The aperture 40C has an aperture 40C1, the size of which is variable, and exposure is adjusted by changing the size of the aperture 40C1 in accordance with instructions from the imaging device body 16.

[0042] The imaging device main body 16 includes a system controller 28. For example, the system controller 28 includes a computer equipped with a processor, storage, and memory. The system controller 28 controls the entire imaging device 10. The system controller 28 may include an ASIC, a PLD, an FPGA, and / or an SoC.

[0043] The imaging device main body 16 includes an acceptance device 30, a display device 32, an image processing circuit 34, an image sensor driver 36, an ND filter driver 38, a motor driver 41, and a vibration source driver 42. The acceptance device 30, the display device 32, the image processing circuit 34, the image sensor driver 36, the ND filter driver 38, the motor driver 41, and the vibration source driver 42 are connected to the system controller 28.

[0044] The reception device 30 includes instruction keys and / or dials, etc., and receives instructions from a user of the imaging device 10. The system controller 28 acquires, from the reception device 30, an instruction signal indicating the instruction received by the reception device 30, and operates in accordance with the instruction signal.

[0045] The display device 32 includes a liquid crystal display and / or an EL display. Under the control of the system controller 28, the display device 32 displays various information including an image obtained by capturing an image of a subject using the imaging device 10.

[0046] An image sensor driver 36 is connected to the image sensor 20. The image sensor driver 36 supplies an imaging timing signal, which defines the timing of imaging performed by the image sensor 20, to the image sensor 20 in accordance with instructions from the system controller 28. The image sensor 20 performs resetting, exposure, image generation and output, etc. in accordance with the imaging timing signal supplied from the system controller 28. Examples of imaging timing signals include a vertical synchronization signal and a horizontal synchronization signal.

[0047] The image processing circuit 34 is connected to the image sensor 20, and under the control of the system controller 28, acquires an image generated by the image sensor 20 and performs various types of image processing on the acquired image. The system controller 28 acquires an image that has been subjected to various types of image processing by the image processing circuit 34. The image acquired by the system controller 28 is stored in a storage medium such as a memory card (not shown), displayed on the display device 32, or transmitted to an external device (e.g., a smart device, a personal computer, and / or a server) via a communication interface (not shown).

[0048] The optical filter 22 is provided on the subject side of the light receiving surface 20A within the image capturing device body 16. It includes a first clear glass component 46, an electronic ND filter 48, and a second clear glass component 50. The first clear glass component 46, the electronic ND filter 48, and the second clear glass component 50 are arranged in this order from the subject side to the light receiving surface 20A side (in other words, from the +Y direction side to the −Y direction side).

[0049] Although the present disclosure provides an example in which the first clear glass component 46, the electronic ND filter 48, and the second clear glass component 50 are mounted on the image capture device body 16, the present disclosure is not limited to this. For example, the first clear glass component 46, the electronic ND filter 48, and the second clear glass component 50 may be mounted on the interchangeable lens 18. Alternatively, the electronic ND filter 48 and the second clear glass component 50 may be mounted on the interchangeable lens 18, and the first clear glass component 46 may be mounted on the image capture device body 16. Alternatively, the electronic ND filter 48 may be mounted on the interchangeable lens 18, and the first clear glass component 46 and the second clear glass component 50 may be mounted on the image capture device body 16. In either case, the first clear glass component 46 and the second clear glass component 50 are provided between the light receiving surface 20A and the electronic ND filter 48, and the first clear glass component 46 is provided closer to the light receiving surface 20A than the second clear glass component 50.

[0050] The electronic ND filter 48 is an electronic variable neutral density filter that uses a material containing liquid crystal that changes orientation when a voltage is applied. The electronic ND filter 48 adjusts the amount of light that passes through the electronic ND filter 48 uniformly by changing its transmittance depending on the voltage applied. The transmittance of the electronic ND filter 48 can be changed seamlessly. Therefore, for example, when the aperture value is maintained, the depth of field is maintained by changing the transmittance of the electronic ND filter 48.

[0051] The target exposure (for example, an appropriate exposure for the brightness of the subject of the image capture device 10) is achieved while the aperture value is maintained. Furthermore, if the aperture value is changing, the transmittance of the electronic ND filter 48 is changed so as to compensate for the increase or decrease in exposure that accompanies the change in aperture value, making it possible to maintain a constant exposure even while the aperture value is changing.

[0052] The electronic ND filter 48 is connected to the ND filter driver 38. The ND filter driver 38 controls the transmittance of the electronic ND filter 48 by applying a voltage to the electronic ND filter 48 in accordance with instructions from the system controller 28.

[0053] The first clear glass component 46 and the second clear glass component 50 are optical components that transmit subject light. The optical path length of the second clear glass component 50 is the same as the optical path length of the electronic ND filter 48.

[0054] The imaging device 10 includes a shift mechanism 52. The shift mechanism 52 is mounted on the imaging device body 16. The shift mechanism 52 has a motor 54. An example of the motor 54 is a stepping motor. The shift mechanism 52 transmits power generated by the motor 54 to the electronic ND filter 48 and the second clear glass component 50, thereby shifting the electronic ND filter 48 and the second clear glass component 50 in the Z direction.

[0055] A motor driver 41 is connected to the motor 54. The motor driver 41 generates a motor control signal in accordance with instructions from the system controller 28 and supplies the signal to the motor 54 to control the motor 54. In other words, the motor 54 operates under the control of the motor driver 41 in accordance with instructions from the system controller 28.

[0056] The motor 54 is mechanically connected to the electronic ND filter 48 and the second clear glass component 50 via a plurality of gears and the like. Under the control of the motor driver 41 in accordance with instructions from the system controller 28, the motor 54 applies power to the electronic ND filter 48 and the second clear glass component 50, thereby selectively inserting the electronic ND filter 48 and the second clear glass component 50 into or removing them from the optical path. Here, the optical path refers to, for example, the optical path of subject light.

[0057] A plurality of gears mechanically connecting the motor 54 to the electronic ND filter 48 and the second clear glass component 50 imparts power in the rotational direction of the motor 54 to the electronic ND filter 48, and imparts power in the opposite direction to the rotational direction of the motor 54 to the second clear glass component 50.

[0058] For example, when forward rotation power is generated by the motor 54, forward rotation power is applied to the electronic ND filter 48, and reverse rotation power is applied to the second clear glass component 50. Furthermore, when reverse rotation power is generated by the motor 54, forward rotation power is applied to the second clear glass component 50, and reverse rotation power is applied to the electronic ND filter 48. In this manner, by applying power from the motor 54 to the electronic ND filter 48 and the second clear glass component 50, one of the electronic ND filter 48 and the second clear glass component 50 is inserted into the optical path, and the other is removed from the optical path. Even if the electronic ND filter 48 is removed from the optical path, the second clear glass component 50 is inserted into the optical path. When the second clear glass component 50 is inserted into the optical path of the optical filter 22, the optical path length of the electronic ND filter 48 and the optical path length of the second clear glass component 50 are the same, so the same optical path length is maintained as when the electronic ND filter 48 is inserted into the optical path.

[0059] A vibration source 56 is mechanically connected to the first clear glass component 46. The vibration source 56 includes at least one piezoelectric element. A vibration source driver 42 is connected to the vibration source 56. The vibration source driver 42 controls the vibration source 56 by generating a vibration source control signal in accordance with instructions from the system controller 28 and supplying the signal to the vibration source 56. In other words, the vibration source 56 operates under the control of the vibration source driver 42 in accordance with instructions from the system controller 28.

[0060] The vibration source 56 vibrates or stops vibrating in accordance with the supplied vibration source control signal. The vibrations generated by the vibration source 56 are transmitted to the first clear glass component 46. In this manner, when the vibrations generated by the vibration source 56 are transmitted to the first clear glass component 46, the first clear glass component 46 vibrates.

[0061] 3 shows an example of the configuration of the optical filter 22. The optical filter 22 has a mask 58. The mask 58 is located closer to the subject than the electronic ND filter 48 (i.e., on the +Y direction side).

[0062] The electronic ND filter 48 is held by a holder 60 from the outer periphery of the electronic ND filter 48 .

[0063] A mask 58 is attached to the holder 60. The mask 58 is a frame having a rectangular opening 58A when viewed from the front. The mask 58 is attached to the front surface of the holder 60, i.e., the surface facing the subject (in other words, the surface on the +Y direction side), so that the electronic ND filter 48 is exposed from the opening 58A.

[0064] The second clear glass component 50 has a flat clear glass 62 that is the main body of the second clear glass component 50. In this embodiment, the optical path length of the clear glass 62 is the same as the optical path length of the electronic ND filter 48. The clear glass 62 is held by a metal frame 64 from the outer periphery of the clear glass 62. Although a metal frame 64 is exemplified here, the present disclosure is not limited to this, and any frame having electrical conductivity may be used.

[0065] The shift mechanism 52 includes a first power receiving mechanism 52A and a second power receiving mechanism 52B. The first power receiving mechanism 52A and the second power receiving mechanism 52B are examples of a "power receiving mechanism" according to the present disclosure. The first power receiving mechanism 52A is provided in the electronic ND filter 48, and the second power receiving mechanism 52B is provided in the second clear glass component 50. The first power receiving mechanism 52A and the second power receiving mechanism 52B receive power from a motor 54 (see FIG. 2 ) to alternately insert and remove the electronic ND filter 48 and the clear glass 62 into and from the optical path.

[0066] The first power receiving mechanism 52A includes a base 66, a rack 68, and a pair of guide rods 70. The base 66 is a frame having an opening (not shown). The back surface of the holder 60 holding the electronic ND filter 48 is attached to the base 66 so that the back surface of the electronic ND filter 48 is exposed on the −Y direction side of the opening of the base 66.

[0067] A rack 68 is provided along the Z direction at the end of the base 66 in the +X direction. The rack 68 receives power in the Z direction from the motor 54 (see FIG. 2).

[0068] A pair of guide rods 70 are inserted in the Z direction into both ends of the base 66 in the X direction. The rack 68 receives power in the Z direction from the motor 54 (see FIG. 2 ), causing the base 66 to slide on the pair of guide rods 70. This causes the electronic ND filter 48 attached to the base 66 via the holder 60 to move in the Z direction.

[0069] The second power receiving mechanism 52B includes a base 72, a rack 74, and a pair of guide rods 76. The base 72 is a frame having an opening (not shown). The second clear glass component 50 is attached to the base 72. That is, the back surface of the metal frame 64 holding the clear glass 62 is attached to the base 72 so that the back surface of the clear glass 62 is exposed on the −Y direction side from the opening of the base 72.

[0070] A rack 74 is provided along the Z direction at the end of the base 72 in the +X direction. The rack 74 receives power in the Z direction from the motor 54 (see FIG. 2).

[0071] A pair of guide rods 76 are inserted in the Z direction into both ends of the base 72 in the X direction. The rack 74 receives power in the Z direction from the motor 54 (see FIG. 2 ), causing the base 72 to slide on the pair of guide rods 76. This causes the clear glass 62 attached to the base 72 via the metal frame 64 to move in the Z direction.

[0072] In this embodiment, the electronic ND filter is an example of an "electronic ND filter" and an "ND filter" according to the present disclosure. In addition, in this embodiment, the clear glass 62 is an example of a "translucent member" and a "first translucent member" according to the present disclosure. In addition, in this embodiment, the rack 68 is an example of a "first rack" according to the present disclosure. In addition, in this embodiment, the rack 74 is an example of a "second rack" according to the present disclosure.

[0073] The first clear glass component 46 has a flat clear glass 78 that is the main body of the first clear glass component 46, a frame 80, and a base 82. The clear glass 78 is held by the frame 80 from the outer periphery of the clear glass 78. The base 82 is a frame having an opening (not shown). The clear glass 78 is attached to the base 82. That is, the back surface of the frame 80 that holds the clear glass 62 is attached to the base 82 so that the back surface of the clear glass 62 is exposed on the −Y direction side from the opening of the base 82.

[0074] In this embodiment, the clear glass 78 is an example of a "translucent member" and a "second translucent member" according to the present disclosure. Also, in this embodiment, the clear glasses 62 and 78 are an example of a "plurality of translucent members" according to the present disclosure.

[0075] Fig. 4 shows an example of the configuration of the electronic ND filter 48 and the holder 60. As shown in Fig. 4, the holder 60 includes a mask 84, a buffer frame 86, and a holding frame 88. The mask 84 and the buffer frame 86 are provided on the holding frame 88.

[0076] The mask 84 is placed over the front of the electronic ND filter 48 from the +Y direction side (in other words, the light receiving surface 20A side), and the holding frame 88 holds the electronic ND filter 48 from the -Y direction side (in other words, the subject side) via the buffer frame 86.

[0077] The mask 84 has a frame 84A that is rectangular in front view. The frame 84A has an opening 84A1. The frame 84A covers the front surface of the electronic ND filter 48. As a result, the front surface of the electronic ND filter 48 is exposed on the +Y direction side from the opening 84A1.

[0078] The frame 84A has a plurality of protrusions 84A2 (four protrusions 84A2 in the example shown in FIG. 4) on its outer periphery. The protrusions 84A2 protrude in the -Y direction from the outer periphery of the frame 84A. Two protrusions 84A2 are provided at both ends of the right edge of the frame 84A when viewed from the front (i.e., the side edge of the frame 84A facing the +X direction). One protrusion 84A2 is provided at the end of the upper edge of the frame 84A facing the -X direction. One protrusion 84A2 is provided at the end of the lower edge of the frame 84A facing the -X direction. Each protrusion 84A2 has an opening 84A2a.

[0079] L-shaped buffer materials 84B are attached to each of the four corners of the front surface of the frame 84A (i.e., the surface on the +Y direction side). The rear surface of the mask 58 (see FIG. 3) is attached to the front surface of the frame 84A via a plurality of buffer materials 84B (four buffer materials 84B in the example shown in FIG. 3). Examples of materials for the buffer materials 84B include rubber-based adhesive or elastic materials such as sponge.

[0080] The holding frame 88 is a square frame recessed in the -Y direction when viewed from the front. The holding frame 88 has a square opening 88A1 when viewed from the front. The electronic ND filter 48 is disposed on a front surface 88A2 of the holding frame 88 (i.e., the surface on the +Y direction side) via a buffer frame 86.

[0081] The holding frame 88 is provided with a plurality of protrusions 88A3 (three protrusions 88A3 in the example shown in FIG. 4 ). Two protrusions 88A3 are provided at a distance in the Z direction on the right edge of the holding frame 88 as viewed from the front (i.e., the side edge of the holding frame 88 in the +X direction). The two protrusions 88A3 provided on the right edge of the holding frame 88 as viewed from the front protrude in the +X direction from the right edge of the holding frame 88 as viewed from the front. One protrusion 88A3 is provided at the center of the left edge of the holding frame 88 as viewed from the front (i.e., the side edge of the holding frame 88 in the −X direction). One protrusion 88A3 provided at the center of the left edge of the holding frame 88 as viewed from the front protrudes in the −X direction from the center of the left edge of the holding frame 88 as viewed from the front. Each protrusion 88A3 has a circular opening 88A3a in front view into which a screw (not shown) for fixing the holding frame 88 inside the imaging device body 16 (for example, inside the rear protective frame 106 shown in FIG. 6) can be inserted.

[0082] The holding frame 88 is provided on its outer periphery with a plurality of protrusions 88A4 (four protrusions 88A4 in the example shown in FIG. 4 ) at positions corresponding to the positions of the plurality of protrusions 84A2 of the mask 84. Each protrusion 88A4 is fitted into an opening 84A2a of each protrusion 84A2 at a position corresponding to the position of each protrusion 88A4. This connects the mask 84 and the holding frame 88.

[0083] A step portion 88A5 is provided at each of the four corners of the front surface 88A2 of the holding frame 88. The step portion 88A5 protrudes from the front surface 88A2 in the +Y direction. The step portion 88A5 has a rising surface 88A5a that rises from the front surface 88A2. The rising surface 88A5a rises perpendicularly to the front surface 88A2 in the +Y direction.

[0084] The mask 84 and the holding frame 88 are connected with the electronic ND filter 48 placed on the front surface 88A2 of the holding frame 88 via the buffer frame 86, so that the electronic ND filter 48 is supported from the +Y direction side by the mask 84 and from the -Y direction side by the front surface 88A2 of the holding frame 88 via the buffer frame 86.

[0085] The electronic ND filter 48 has a light-transmitting region 48A. The light-transmitting region 48A is a light-transmitting region (i.e., a region that transmits subject light) and includes glass plates 90 and 92 and a liquid crystal 96. Each of the glass plates 90 and 92 is a flat, light-transmitting, clear glass plate formed in a rectangular shape when viewed from the front. The glass plate 90 has a front surface 90A and a back surface 90B. Subject light enters the glass plate 90 from the front surface 90A and exits from the back surface 90B. The glass plate 92 also has a front surface 92A and a back surface 92B. Subject light enters the glass plate 92 from the front surface 92A and exits from the back surface 92B. Each of the glass plates 90 and 92 has an electrode incorporated therein. A voltage is applied to the electrodes incorporated in each of the glass plates 90 and 92 by the ND filter driver 38 (see FIG. 2 ). Here, glass plates 90 and 92 are shown as examples, but this is merely an example, and the glass plates 90 and / or 92 may also be translucent resin members (e.g., flat plate-shaped members).

[0086] The electronic ND filter 48 has a bonding member 94. The bonding member 94 is a member that bonds the edges of the glass plates 90 and 92 together when the glass plates 90 and 92 face each other with a gap between them. The bonding member 94 is made of an adhesive (e.g., a rubber-based adhesive). The outer periphery of the back surface 90B of the glass plate 90 and the outer periphery of the front surface 92A of the glass plate 92 are bonded together by the bonding member 94. In other words, the bonding member 94 is interposed between the outer periphery of the back surface 90B of the glass plate 90 and the outer periphery of the front surface 92A of the glass plate 92, and bonds the outer periphery of the back surface 90B of the glass plate 90 (i.e., the outer periphery of the surface on the -Y direction side) to the outer periphery of the front surface 92A of the glass plate 92 (i.e., the outer periphery of the surface on the +Y direction side). Because the glass plates 90 and 92 are translucent plate-like members, the bonding member 94 is visible through the glass plate 90 and also through the glass plate 92. As shown in FIG. 4 , the electronic ND filter 48 has a hollow region 48B. Here, the hollow region 48B refers to the region surrounded by the glass plates 90, 92, and bonding member 94, where the outer periphery of the back surface 90B of the glass plate 90 is bonded to the outer periphery of the front surface 92A of the glass plate 92 with the bonding member 94, when the glass plates 90 and 92 face each other with a gap between them. A liquid crystal 96 (e.g., a guest-host liquid crystal) is sealed in the hollow region 48B. Here, adhesive is exemplified as a material for the joining member 94, but this is merely one example, and any joining member that can form the hollow region 48B and can seal the liquid crystal 96 in the hollow region 48B so that the liquid crystal 96 does not leak out of the electronic ND filter 48 can be used.

[0087] The holding frame 88 holds the electronic ND filter 48 from the glass plate 92 side (in other words, the side in the -Y direction) via the buffer frame 86. The buffer frame 86 is a frame that follows the edge of the glass plate 92 and is formed from a rubber-based adhesive. The buffer frame 86 is provided between the glass plate 92 and a front surface 88A2 of the holding frame 88, and has elasticity at least in the Y direction (in other words, the direction along the optical axis OA shown in FIGS. 1 to 3).

[0088] The shape and size of the buffer frame 86 correspond to the shape and size of the joining member 94. The buffer frame 86 is provided around an opening 88A1 on a front surface 88A2 of the holding frame 88. The buffer frame 86 is pressed against a portion 92B1 on a back surface 92B of the glass plate 92, which corresponds to the position of the joining member 94, from the side from which subject light is emitted from the electronic ND filter 48, i.e., the glass plate 92 side (in other words, the side in the -Y direction). The buffer frame 86 is sandwiched between the portion 92B1 and the front surface 88A2 of the holding frame 88.

[0089] The frame 84A of the mask 84 is placed against a portion 90A1 on the front surface 90A of the glass plate 90, which corresponds to the position of the joining member 94, from the side where subject light is incident on the electronic ND filter 48, i.e., the glass plate 90 side (in other words, the +Y direction side).

[0090] The mask 84 and the holding frame 88 are connected in a state in which the buffer frame 86 provided around the opening 88A1 on the front surface 88A2 of the holding frame 88 is pressed against the portion 92B1, and the frame 84A of the mask 84 is pressed against the portion 90A1. As a result, the portion 90A1 is supported from the glass plate 90 side by the frame 84A of the mask 84, and the portion 92B1 is supported from the glass plate 92 side by the buffer frame 86 provided around the opening 88A1 on the front surface 88A2 of the holding frame 88.

[0091] 5 shows an example of how the holding frame 88 holds the electronic ND filter 48. As shown in FIG. 5, a plurality of buffer materials 98 are interposed between the outer periphery of the electronic ND filter 48 and the inner periphery of the holding frame 88. The buffer materials 98 are adhesive. An example of the adhesive used as the buffer materials 98 is a rubber-based adhesive. The buffer materials 98 may be a material such as a sponge, and are preferably a material having elasticity.

[0092] A rubber-based adhesive is injected into a portion of the inner periphery of the holding frame 88 as a cushioning material 98, which bonds the outer periphery of the electronic ND filter 48 to the inner periphery of the holding frame 88. The portions into which the rubber-based adhesive is injected as the cushioning material 98 are the raised surfaces 88A5a of the multiple step portions 88A5 of the holding frame 88. By injecting the rubber-based adhesive as the cushioning material 98 between the raised surfaces 88A5a of the multiple step portions 88A5 and the outer periphery of the electronic ND filter 48, the outer periphery of the electronic ND filter 48 is bonded to the raised surfaces 88A5a of the multiple step portions 88A5. The cushioning material 98 absorbs external forces acting from one side of the outer periphery of the electronic ND filter 48 and the inner periphery of the holding frame 88 to the other side. This prevents direct contact (i.e., collision) between the outer periphery of the electronic ND filter 48 and the inner periphery of the holding frame 88.

[0093] A gap 100 is provided between the outer periphery of the electronic ND filter 48 and a portion of the inner periphery of the holding frame 88 other than where the buffer material 98 has been injected. When the outer periphery of the electronic ND filter 48 approaches the inner periphery of the holding frame 88 via the buffer material 98, the outer periphery of the electronic ND filter 48 enters the gap 100 against the repulsive force of the buffer material 98. This prevents contact between the outer periphery of the electronic ND filter 48 and the inner periphery of the holding frame 88, even in areas where the buffer material 98 is not interposed between the outer periphery of the electronic ND filter 48 and the inner periphery of the holding frame 88.

[0094] 5 shows an example in which the buffer material 98 is interposed between a part of the inner periphery of the holding frame 88 and a part of the outer periphery of the electronic ND filter 48, but this is merely one example. For example, the buffer material 98 may be interposed between the entire inner periphery of the holding frame 88 and the entire outer periphery of the electronic ND filter 48.

[0095] Fig. 6 shows an example of the rear view of the optical filter 22. As shown in Fig. 6, the optical filter 22 includes a housing 102. The housing 102 houses the first clear glass component 46, the electronic ND filter 48, the second clear glass component 50, and the shift mechanism 52.

[0096] Housing 102 has a front protective frame 104 and a rear protective frame 106. Front protective frame 104 and rear protective frame 106 are connected by a plurality of screws with first clear glass component 46, electronic ND filter 48, second clear glass component 50, and shift mechanism 52 housed inside.

[0097] The front protective frame 104 is a frame that protects the first clear glass component 46, the electronic ND filter 48, and the second clear glass component 50 from the front side (in other words, the side in the +Y direction). The rear protective frame 106 is a frame that protects the first clear glass component 46, the electronic ND filter 48, and the second clear glass component 50 from the rear side (in other words, the side in the −Y direction).

[0098] The rear protective frame 106 accommodates and holds the first clear glass component 46 , the electronic ND filter 48 , and the second clear glass component 50 inside the rear protective frame 106 .

[0099] The image sensor 20 is attached to the rear surface of the rear protective frame 106. An opening 106A corresponding to the light receiving surface 20A of the image sensor 20 is formed in the rear surface of the rear protective frame 106. When the image sensor 20 is attached to the rear surface of the rear protective frame 106 with the position of the opening 106A of the rear protective frame 106 aligned with the position of the light receiving surface 20A of the image sensor 20, the light receiving surface 20A is exposed on the +Y direction side of the opening 106A of the rear protective frame 106 (in other words, inside the housing 102).

[0100] The clear glass 78 (see FIG. 3) of the first clear glass component 46 held by the rear protective frame 106 faces the light-receiving surface 20A through the opening 106A. When the light-transmitting region 48A (see FIG. 4) of the electronic ND filter 48 held by the rear protective frame 106 is inserted into the optical path, the light-transmitting region 48A (see FIG. 4) of the electronic ND filter 48 faces the light-receiving surface 20A through the opening 106A. When the clear glass 62 of the second clear glass component 50 held by the rear protective frame 106 is inserted into the optical path, the clear glass 62 of the second clear glass component 50 faces the light-receiving surface 20A through the opening 106A.

[0101] The front protective frame 104 is formed with an opening 104A having a shape and size corresponding to the shape and size of the opening 58A of the mask 58. The mask 58 is attached to the front of the front protective frame 104 with the position of the opening 104A and the position of the opening 58A of the mask 58 aligned.

[0102] An opening 106B is formed in the center of the left side surface (i.e., the side surface facing the +X direction) in rear view of the rear protective frame 106. The opening 106B exposes the rack 68 of the first power receiving mechanism 52A (see FIG. 3) and the rack 74 of the second power receiving mechanism 52B (see FIG. 3) from the rear protective frame 106.

[0103] A power applying mechanism 108 is attached to the rear protective frame 106. The power applying mechanism 108 applies power to the rack 68 of the first power receiving mechanism (see FIG. 3) and the rack 74 of the second power receiving mechanism 52B (see FIG. 3) through an opening 106B.

[0104] The power applying mechanism 108 includes a motor 54, a gear 112, and a gear 114. The gear 112 and the gear 114 are meshed with each other. The power of the motor 54 is transmitted to the gear 112. The gear 112 rotates when the power of the motor 54 is transmitted to the gear 112. The gear 114 is driven by the gear 112. That is, the gear 114 receives the rotational force of the gear 112 and rotates in the opposite direction to the gear 112. Note that, although an example in which the power of the motor 54 is transmitted to the gear 112 is given here, this is merely an example. The power of the motor 54 may also be transmitted to the gear 114. In this case, the gear 112 may be driven by the gear 114. Furthermore, the gears 112 and 114 may be rotated in opposite directions by separate motors.

[0105] The power applying mechanism 108 is housed in a housing 116. The housing 116 is provided with a blocking wall 116A that blocks the opening 106B. The housing 116 is attached to the rear protective frame 106 so that the opening 106B is blocked by the blocking wall 116A. When the housing 116 is attached to the rear protective frame 106 in this manner, the gear 112 meshes with the rack 68, and the gear 114 meshes with the rack 74.

[0106] When power is applied from motor 54 to rack 68 via gear 112, electronic ND filter 48 moves in one of the +Z and −Z directions, and when power is applied from motor 54 to rack 74 via gear 114 from gear 112, second clear glass component 50 moves in the other of the +Z and −Z directions, thereby alternately inserting and removing electronic ND filter 48 and second clear glass component 50 into and from the optical path.

[0107] In this embodiment, the front protective frame 104 is an example of a "first protective frame" according to the present disclosure. In addition, in this embodiment, the rear protective frame 106 is an example of a "holding frame" and a "second protective frame" according to the present disclosure. In addition, in this embodiment, the opening 106B is an example of a "holding frame" and a "second protective frame" according to the present disclosure.

[0108] In the present embodiment, the power applying mechanism 108 is an example of a "power applying mechanism" according to the present disclosure. In the present embodiment, the blocking wall 116A is an example of a "blocking wall" according to the present disclosure. In the present embodiment, the gear 112 is an example of a "first gear" according to the present disclosure. In the present embodiment, the gear 114 is an example of a "second gear" according to the present disclosure.

[0109] FIG. 7 shows an example of an embodiment in which the electronic ND filter 48 is inserted into the optical path and the clear glass 62 of the second clear glass component 50 is removed from the optical path. As shown in FIG. 7 , the clear glass 62 has a coating film 118. The coating film 118 is a film that prevents static buildup. The coating film 118 is formed on the surface of the clear glass 62 by applying a coating agent that prevents static buildup to the surface of the clear glass 62. In the example shown in FIG. 7 , the coating film 118 is formed on the front surface of the clear glass 62 (i.e., the surface facing the subject) by applying a coating agent that prevents static buildup. Note that the coating film 118 may be formed on the back surface of the clear glass 62 (i.e., the surface facing the light receiving surface 20A) or on both the front and back surfaces of the clear glass 62.

[0110] To increase the electrical capacitance, the coating film 118 is in contact with the metal frame 64. A conductive leaf spring 120 (e.g., a metal leaf spring) is attached to the lower edge (i.e., the edge on the side facing the −Z direction) of the metal frame 64 of the second clear glass component 50, and the coating film 118 and the leaf spring 120 are electrically connected.

[0111] 8 shows an example of the state of the second clear glass component 50 within the rear protective frame 106 when the clear glass 62 of the second clear glass component 50 moves from a position inserted into the optical path to a position removed from the optical path. As shown in Fig. 8, when the clear glass 62 of the second clear glass component 50 moves from a position inserted into the optical path to a position removed from the optical path, the second clear glass component 50 rattles in the Z direction due to backlash between the rack 74 and the gear 114 (see Fig. 7).

[0112] Therefore, in this embodiment, a conductive leaf spring 120 is attached to the lower edge of the metal frame 64 to prevent the lower edge of the second clear glass component 50 from colliding with the lower edge of the inner periphery of the rear protective frame 106 due to rattle of the second clear glass component 50 in the Z direction. Therefore, when the clear glass 62 of the second clear glass component 50 moves from a position inserted into the optical path to a position removed from the optical path, the leaf spring 120 absorbs rattle in the Z direction caused by backlash.

[0113] Furthermore, a grounded conductor 122 is provided on the lower inside of the rear protective frame 106. When the clear glass 62 of the second clear glass component 50 moves from a position inserted into the optical path to a position removed from the optical path, the leaf spring 120 comes into contact with the conductor 122, thereby grounding the coating film 118. That is, when the leaf spring 120, which is electrically connected to the coating film 118 via the metal frame 64, comes into contact with the grounded conductor 122, static is removed from the clear glass 62. In other words, when the leaf spring 120 comes into contact with the conductor 122, the charge on the coating film 118 is absorbed by the grounded conductor 122 through the metal frame 64 and the leaf spring 120.

[0114] Although the embodiment has been described above with reference to an example in which the plate spring 120 used for backlash prevention and static elimination is used to eliminate static electricity from the clear glass 62 of the second clear glass component 50 when it moves from a position inserted into the optical path to a position removed from the optical path, the present disclosure is not limited to this. For example, when the clear glass 62 of the second clear glass component 50 moves from a position removed from the optical path to a position inserted into the optical path, static electricity may be eliminated from the clear glass 62 in a similar manner.

[0115] In this case, a metal leaf spring is attached to the upper edge of the metal frame 64, and a grounded conductor is provided on the upper inside surface of the rear protective frame 106. When the clear glass 62 of the second clear glass component 50 moves from a position where it is inserted into the optical path to a position where it is removed from the optical path, the leaf spring attached to the upper edge of the metal frame 64 comes into contact with the conductor provided on the upper inside surface of the rear protective frame 106. This grounds the coating film 118.

[0116] In this embodiment, the coating film 118 is an example of a "coating film" according to the present disclosure. Also, in this embodiment, the metal frame 64 is an example of a "metal frame" according to the present disclosure. Also, in this embodiment, the conductor 122 is an example of a "conductor" according to the present disclosure.

[0117] Fig. 9 shows an example of the inner surface 106C on the opening 106B side of the rear protective frame 106. As shown in Fig. 9, an adhesive 123 is applied to a first inner surface 106C1, a second inner surface 106C2, and a third inner surface 106C3 of the inner surfaces 106C on the opening 106B side of the rear protective frame 106. Examples of the adhesive 123 include dust traps and bird glue.

[0118] The first inner surface 106C1, the second inner surface 106C2, and the third inner surface 106C3 are parts of the inner surface 106C and are surfaces that face the first power receiving mechanism 52A and the second power receiving mechanism 52B housed in the rear protective frame 106. The first inner surface 106C1 faces the movement path of the rack 68 of the first power receiving mechanism 52A. That is, the first inner surface 106C1 faces the rack 68 during its movement. The second inner surface 106C2 faces the movement path of the rack 74 of the second power receiving mechanism 52B. That is, the second inner surface 106C2 faces the rack 74 during its movement. The third inner surface 106C3 is a surface that is perpendicular to the first inner surface 106C1 and the second inner surface 106C2 and connects the first inner surface 106C1 and the second inner surface 106C2.

[0119] Fig. 10 shows an example in which the front protective frame 104 and the rear protective frame 106 are fitted together in the Y direction. As shown in Fig. 10 , the housing 102 has a fitting structure 124. The front protective frame 104 and the rear protective frame 106 are fitted together via the fitting structure 124. In the example shown in Fig. 10 , the fitting structure 124 has a step 104B formed along the outer periphery of the rear surface of the front protective frame 104 and a step 106D formed along the outer periphery of the front surface of the rear protective frame 106. By fitting the step 106D into the step 104B, the outer periphery of the rear surface of the front protective frame 104 and the outer periphery of the front surface of the rear protective frame 106 are in close contact with each other. The front protective frame 104 and the rear protective frame 106 are connected by screws or the like with the outer periphery of the rear surface of the front protective frame 104 and the outer periphery of the front surface of the rear protective frame 106 in close contact with each other.

[0120] An adhesive 125 is applied to the position where the front protective frame 104 and the rear protective frame 106 are fitted together via the fitting structure 124 and / or the periphery of the position where the front protective frame 104 and the rear protective frame 106 are fitted together via the fitting structure 124. Examples of the adhesive 125 include dust traps and bird glue.

[0121] Next, the operation and effects of the imaging device 10 will be described.

[0122] As shown in FIG. 11 , the electronic ND filter 48 included in the optical filter 22 applied to the imaging device 10 is held by a holder 60. A portion 90A1 of the electronic ND filter 48 is supported from the glass plate 90 side by the frame 84A of the mask 84, and a portion 92B1 of the electronic ND filter 48 is supported from the glass plate 92 side by the buffer frame 86. In other words, the electronic ND filter 48 is supported at its entirety by the mask 84 and the buffer frame 86, except for the light-transmitting region 48A. As a result, even if an external force is applied in the +Y direction to the rear surface of the holding frame 88 or an external force in the −Y direction to the front surface of the frame 84A of the mask 84, the frame 84A of the mask 84 is in contact with the portion 90A1 of the electronic ND filter 48 and the buffer frame 86 is in contact with the portion 92B1 of the electronic ND filter 48, so that the external force is less likely to be applied to the light-transmitting region 48A. This makes it difficult for the glass plates 90 and 92 in the light-transmitting region 48A to deform, allowing the holder 60 to hold the electronic ND filter 48 while maintaining a good distribution of the liquid crystals 96 sealed in the electronic ND filter 48. By maintaining a good distribution of the liquid crystals 96 in this way, brightness unevenness is less likely to occur. In other words, brightness unevenness caused by uneven distribution of the liquid crystals 96 is less likely to occur in the image obtained by capturing an image.

[0123] Furthermore, since the portion 90A1 of the electronic ND filter 48 is supported by the frame 84A of the mask 84 from the glass plate 90 side, and the portion 92B1 of the electronic ND filter 48 is supported by the buffer frame 86 from the glass plate 92 side, the holding force of the holder 60 on the electronic ND filter 48 can be increased.

[0124] Furthermore, because the buffer frame 86 is provided between the glass plate 92 and the front surface 88A2 of the holding frame 88 and has elasticity in the optical axis direction (i.e., the Y direction), the buffer frame 86 can absorb the impact force when an impact is applied to the holder 60 without affecting the light transmittance of the electronic ND filter 48. In particular, when an impact is applied to the holder 60 in the Y direction, the buffer frame 86 can efficiently absorb the impact force in the Y direction. As a result, the impact force when an impact is applied to the holder 60 is less likely to be transmitted to the electronic ND filter 48, thereby maintaining a good distribution of the liquid crystal 96 sealed in the electronic ND filter 48. Damage to the electronic ND filter 48 can also be suppressed.

[0125] Furthermore, a plurality of buffer materials 98 are interposed between the outer periphery of the electronic ND filter 48 and the inner periphery of the holding frame 88 (see FIG. 5 ), which makes it possible to suppress damage to the holding frame 88 and / or the electronic ND filter 48 due to collision and / or friction between the inner periphery of the holding frame 88 and the outer periphery of the electronic ND filter 48.

[0126] Furthermore, a rubber-based adhesive that bonds the outer periphery of the electronic ND filter 48 to the inner periphery of the holding frame 88 is injected into a portion of the inner periphery of the holding frame 88 as a cushioning material 98 (see FIG. 5 ). This bonds the electronic ND filter 48 to the holding frame 88, thereby preventing the electronic ND filter 48 from falling off the holding frame 88. Even if an impact is applied to the holding frame 88, the impact force is absorbed by the cushioning material 98, so rattle of the electronic ND filter 48 within the holding frame 88 (for example, rattle in the X, Y, and Z directions) can be prevented.

[0127] Furthermore, even if an impact is applied to the holding frame 88 and the outer peripheral surface of the electronic ND filter 48 approaches the inner peripheral surface of the holding frame 88 via the buffer material 98, the outer periphery of the electronic ND filter 48 will enter the gap 100 against the repulsive force of the buffer material 98 (see FIG. 5). This makes it possible to prevent the outer peripheral surface of the electronic ND filter 48 from colliding with the inner peripheral surface of the holding frame 88. As a result, damage to the electronic ND filter 48 and the holding frame 88 can be prevented.

[0128] 11, the light-transmitting region 48A includes glass plates 90 and 92. The glass plates 90 and 92 are flat, transparent clear glass plates, which facilitate achieving the desired light control by the electronic ND filter 48.

[0129] The first clear glass component 46 and the second clear glass component 50 included in the optical filter 22 mounted on the imaging device 10 according to this embodiment are used for dust reduction, which refers to the removal of particles and dirt (hereinafter referred to as "dust").

[0130] Dust reduction is achieved by vibrating the first clear glass component 46, applying an antistatic coating to the surface of the clear glass 62 of the second clear glass component 50, or discharging static electricity from the clear glass 62 of the second clear glass component 50.

[0131] As shown in FIG. 12 , vibrations are transmitted from the vibration source 56 to the first clear glass component 46 when a dust reduction start condition is satisfied. Examples of dust reduction start conditions include a condition in which a dust reduction instruction is received by the reception device 30, a condition in which dust is recognized in an image obtained by capturing an image through image recognition processing, or a condition in which a certain amount of time has elapsed since the imaging device 10 entered imaging mode. When vibrations are transmitted from the vibration source 56 to the first clear glass component 46, the first clear glass component 46 vibrates. The vibration of the first clear glass component 46 shakes off dust adhering to the clear glass 78. As a result, dust can be prevented from appearing in an image obtained by capturing an image with the image sensor 20 (e.g., an image displayed on the display device 32).

[0132] Additionally, a coating film is formed on the surface of the clear glass 62 of the second clear glass component 50. The coating film 118 is a film that prevents the surface of the clear glass 62 from becoming electrically charged. This makes it possible to prevent dust from adhering to the clear glass 62 due to static electricity. As a result, it is possible to prevent dust from appearing in the image obtained by capturing an image with the image sensor 20.

[0133] 13 , the clear glass 62 of the second clear glass component 50 is neutralized. For example, as shown in FIG. 13 , when the clear glass 62 of the second clear glass component 50 moves from a first position P1, where the clear glass 62 is inserted into the optical path, to a second position P2, where the clear glass 62 is removed from the optical path, the metal frame 64 in contact with the coating film 118 contacts the grounded conductor 122 via the leaf spring 120. This allows static electricity on the clear glass 62 to escape to the grounded conductor 122, thereby preventing dust from adhering to the clear glass 62 due to static electricity. As a result, dust can be prevented from appearing in the image captured by the image sensor 20.

[0134] Furthermore, the leaf spring 120 absorbs the impact caused by backlash when the second clear glass component 50 moves from the first position P1 to the second position P2, thereby preventing damage to the second clear glass component 50 and / or the rear protective frame 106 due to a collision between the second clear glass component 50 and the rear protective frame 106.

[0135] Furthermore, the first clear glass component 46 and the second clear glass component 50 are disposed between the light receiving surface 20A and the electronic ND filter 48 (see FIG. 3). The clear glass 78 of the first clear glass component 46 is located closer to the light receiving surface 20A than the clear glass 62 of the second clear glass component 50 (see FIG. 3). Therefore, dust adhesion to the light receiving surface 20A can be reduced compared to when only the second clear glass component 50 is disposed between the light receiving surface 20A and the electronic ND filter 48. As a result, dust can be prevented from appearing in the image captured by the image sensor 20.

[0136] Furthermore, the first clear glass component 46, the electronic ND filter 48, and the second clear glass component 50 are housed in the rear protective frame 106 and are held inside by the rear protective frame 106 (see FIG. 10 ). This allows the positions of the first clear glass component 46, the electronic ND filter 48, and the second clear glass component 50 relative to the light receiving surface 20A to be stabilized.

[0137] Furthermore, the electronic ND filter 48 and the clear glass 62, which has the same optical path length as the electronic ND filter 48, are alternately inserted into and removed from the optical path by a shift mechanism 52 that operates under the control of the system controller 28 (see FIG. 2). Therefore, it is possible to suppress the difference between the optical path length when the electronic ND filter 48 is inserted into the optical path and the optical path length when the electronic ND filter 48 is not inserted into the optical path.

[0138] Furthermore, adhesive 123 is applied to the first inner surface 106C1, the second inner surface 106C2, and the third inner surface 106C3 of the inner surfaces 106C on the opening 106B side of the rear protective frame 106 (see FIG. 9 ). The first inner surface 106C1, the second inner surface 106C2, and the third inner surface 106C3 face the first power receiving mechanism 52A and the second power receiving mechanism 52B housed in the rear protective frame 106 (see FIG. 9 ). Therefore, dust that is stirred up by the movement of the first power receiving mechanism 52A and the second power receiving mechanism 52B (e.g., rack 68, rack 74, gear 112, and gear 114) or that is attracted to the first power receiving mechanism 52A and the second power receiving mechanism 52B can be adhered to the adhesive 123, thereby preventing dust from adhering to the light receiving surface 20A. This reduces the amount of dust that appears in the image obtained by capturing an image.

[0139] Furthermore, opening 106B of rear protective frame 106 is closed by closing wall 116A of housing 116 (see FIG. 6 ), which makes it possible to prevent dust from entering the inside of housing 102 from the outside through opening 106B.

[0140] Furthermore, the front protective frame 104 and the rear protective frame 106 are fitted together via a fitting structure 124 (see FIG. 10 ). This makes it possible to prevent dust from entering through the gap between the front protective frame 104 and the rear protective frame 106.

[0141] Furthermore, adhesive 125 is applied to the position where the front protective frame 104 and the rear protective frame 106 are fitted together via the fitting structure 124 and / or the periphery of the position where the front protective frame 104 and the rear protective frame 106 are fitted together via the fitting structure 124. Therefore, dust is captured at the position where the front protective frame 104 and the rear protective frame 106 are fitted together via the fitting structure 124 and / or the periphery of the position where the front protective frame 104 and the rear protective frame 106 are fitted together via the fitting structure 124. This makes it possible to suppress adhesion of dust to the light receiving surface 20A. As a result, it is possible to suppress dust from appearing in images obtained by capturing images.

[0142] In the above embodiment, an example was given in which the buffer frame 86 is interposed between the front surface 88A2 of the holding frame 88 and the point 92B1 (i.e., the outer peripheral edge of the back surface 92B), and the buffer frame 86 is pressed against the point 92B1, thereby absorbing the impact applied from the back surface side of the holding frame 88 by the buffer frame 86, but the present disclosure is not limited to this.

[0143] 14 , a buffer frame 126 having a similar configuration to the buffer frame 86 may be interposed between the back surface of the frame 84A of the mask 84 and the portion 90A1 (i.e., the outer peripheral edge of the front surface 90A), and the buffer frame 126 may be pressed against the portion 90A1. In this case, the buffer frame 126 can absorb impacts applied from the front surface of the frame 84A of the mask 84 without affecting the light transmittance of the electronic ND filter 48. Furthermore, because the frame 84A of the mask 84 and the portion 90A1 do not come into direct contact with each other, damage to the frame 84A and the portion 90A1 due to collision or friction between the frame 84A of the mask 84 and the portion 90A1 can be suppressed.

[0144] In the above embodiment, a continuous buffer frame 86 is illustrated along the portion 92B1 (i.e., the outer peripheral edge of the rear surface 92B). However, this is merely an example. For example, as shown in FIG. 15 , a plurality of buffer materials 128 may be used that are intermittently provided along the portion 92B1 (i.e., the outer peripheral edge of the rear surface 92B). For example, the buffer materials 128 may be made of a rubber adhesive or a material with elasticity, such as sponge. In this case, the same effect as when the buffer frame 86 is used can be expected. Furthermore, instead of the buffer frame 126 shown in FIG. 14 , a plurality of buffer materials may be used that are intermittently provided along the portion 90A1 (i.e., the outer peripheral edge of the front surface 90A), similar to the buffer material 128. In this case, the same effect as when the buffer material 128 is used can be expected.

[0145] In the above embodiment, a single electronic ND filter 48 is illustrated, but the present disclosure is not limited to this. For example, as shown in FIG. 16 , instead of the single electronic ND filter 48, an optical device 129 having a plurality of electronic ND filters 48 may be used.

[0146] The optical device 129 is held by a holder 60. The optical device 129 transmits subject light, and the subject light that has passed through the optical device 129 is captured by the image sensor 20 (see FIGS. 1 to 3).

[0147] The optical device 129 includes a plurality of electronic ND filters 48 and a retardation layer 130 disposed between the plurality of electronic ND filters 48. The retardation layer 130 is a layer for changing the phase of subject light transmitted through the electronic ND filter 48 from the subject side (i.e., the +Y direction). The retardation layer 130 may contain a liquid crystal compound (e.g., a liquid crystal compound oriented by polymerization). The retardation layer 130 may also include a plurality of optically anisotropic layers and a fixation layer that fixes the plurality of optically anisotropic layers. The retardation layer 130 may also be composed of a film (e.g., a half-wave plate).

[0148] The buffer frame 86 is interposed between an outer peripheral edge 129A of the rear surface of the optical device 129 (i.e., the surface on the side facing the −Y direction) and a front surface 88A2 of the holding frame 88, and the buffer frame 86 is sandwiched between the outer peripheral edge 129A of the rear surface of the optical device 129 and the front surface 88A2 of the holding frame 88. The buffer frame 126 is also interposed between the rear surface of the frame 84A of the mask 84 and an outer peripheral edge 129B of the rear surface of the optical device 129 (i.e., the surface on the side facing the +Y direction), and the buffer frame 126 is sandwiched between the rear surface of the frame 84A of the mask 84 and the outer peripheral edge 129B of the rear surface of the optical device 129.

[0149] In the example shown in Figure 16, the retardation layer 130 is placed between two electronic ND filters 48, but this is merely one example, and the retardation layer 130 may be placed between each of three or more electronic ND filters 48.

[0150] By providing the phase difference layer 130 between the plurality of electronic ND filters 48 in this manner, polarized light in a direction that the electronic ND filters 48 cannot absorb can be absorbed by the phase difference layer 130, so the light attenuation rate can be increased compared to when light is attenuated by the electronic ND filters 48 alone.

[0151] In the above embodiment, an electronic ND filter 48 is exemplified, but the present disclosure is not limited to this, and instead of the electronic ND filter 48, an ND filter having a single transmittance or multiple ND filters having different transmittances (e.g., turret filters) may be applied.

[0152] In the above embodiment, dust reduction is achieved by vibrating the first clear glass component 46, applying an antistatic coating to the surface of the clear glass 62 of the second clear glass component 50, or performing static elimination on the clear glass 62 of the second clear glass component 50. However, this is merely an example. For example, dust reduction may be achieved by vibrating the second clear glass component 50, applying an antistatic coating to the surface of the clear glass 78 of the first clear glass component 46, or performing static elimination on the clear glass 78 of the first clear glass component 46. One example of a method for eliminating static electricity from the surface of the clear glass 78 of the first clear glass component 46 is to form a film similar to the coating film 118 on the surface of the clear glass 78, use a metal frame 80, contact the film on the surface of the clear glass 78 with the frame 80, and then contact the frame 80 with a conductor configured similar to the grounded conductor 122.

[0153] In the above embodiment, a configuration example was given in which the racks 68 and 74 receive power from the power imparting mechanism 108, but this is merely one example, and for example, a lifting mechanism such as a ball screw may also receive power from the power imparting mechanism 108 (for example, power generated by the motor 54).

[0154] In the above embodiment, a vibration source including a piezoelectric element is exemplified as an example of the vibration source 56, but this is merely an example, and a vibrator using a motor may also be used as the vibration source 56. The frequency and intensity of the vibration of the vibrator may be such that a certain amount or more of dust adhering to the clear glass 78 can be shaken off.

[0155] In the above embodiment, the electronic ND filter 48 is directly exposed to the outside from the imaging device body 16, but this is merely one example, and a cut filter for a specific wavelength range, such as an infrared light cut filter and / or an ultraviolet light cut filter, may be arranged on the front side of the electronic ND filter 48 (i.e., on the glass plate 90 side).

[0156] The above-described description and illustrations are a detailed explanation of the parts related to the present disclosure and are merely an example of the present disclosure. For example, the above description of the configuration, functions, actions, and effects is an explanation of an example of the configuration, functions, actions, and effects of the parts related to the present disclosure. Therefore, it goes without saying that unnecessary parts may be deleted, new elements may be added, or elements may be replaced with other parts from the above-described description and illustrations, as long as they do not deviate from the gist of the present disclosure. Furthermore, in order to avoid confusion and facilitate understanding of the parts related to the present disclosure, the above-described description and illustrations omit explanations of common general technical knowledge that do not require particular explanation to enable the implementation of the present disclosure.

[0157] All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

[0158] The following additional notes are provided regarding the above-described embodiments.

[0159] an optical device including: an ND filter provided on the subject side of a light receiving surface of an image sensor; and a first light-transmitting member and a second light-transmitting member provided between the light receiving surface and the ND filter and used for dust reduction, wherein the second light-transmitting member is located closer to the light receiving surface than the first light-transmitting member, and the dust reduction is achieved by removing static electricity from the first light-transmitting member, the first light-transmitting member having a coating film that prevents static electricity, and a metal frame that holds the first light-transmitting member, the coating film being in contact with the metal frame, and a conductive leaf spring being provided on the metal frame, and when the first light-transmitting member moves from one of a first position where the first light-transmitting member is inserted into the optical path and a second position where the first light-transmitting member is removed from the optical path to the other while the first light-transmitting member is held by the metal frame, the leaf spring comes into contact with a grounded conductor, thereby removing static electricity.

[0160] (Supplementary Note 2) The optical device according to Supplementary Note 1, wherein the leaf spring absorbs an impact force generated when the first light-transmitting member moves from one of the first position and the second position to the other.

[0161] (Supplementary Note 3) The optical device according to Supplementary Note 2, wherein the leaf spring simultaneously absorbs impact force and neutralizes electricity when the first light-transmitting member moves from one of the first position and the second position to the other.

Claims

1. An optical device comprising: an ND filter disposed on the subject side of the light receiving surface of an image sensor; and at least one light-transmitting member disposed between the light receiving surface and the ND filter and used for dust reduction.

2. The optical device according to claim 1, wherein the ND filter is an electronic ND filter.

3. The optical device according to claim 1, wherein the dust reduction is achieved by vibrating the at least one light-transmitting member.

4. The optical device according to claim 1, wherein the dust reduction is achieved by applying an antistatic coating to the at least one light-transmitting member.

5. The optical device according to claim 1, wherein the dust reduction is achieved by removing static electricity from the at least one light-transmitting member.

6. The optical device according to claim 1, wherein a plurality of the light-transmitting members are located between the light-receiving surface and the ND filter, and the plurality of light-transmitting members include a first light-transmitting member and a second light-transmitting member located closer to the light-receiving surface than the first light-transmitting member.

7. The optical device according to claim 6, wherein the dust reduction is achieved by vibrating the second light-transmitting member.

8. The optical device according to claim 6, wherein the ND filter and the first light-transmitting member are alternately inserted into and removed from the optical path.

9. The optical device according to claim 6, wherein the dust reduction is achieved by applying an antistatic coating to the first light-transmitting member.

10. The optical device according to claim 6, wherein the dust reduction is achieved by removing static electricity from the first light-transmitting member.

11. The optical device according to claim 10, wherein the first light-transmitting member has a coating film that prevents static buildup, and the optical device further comprises a metal frame that holds the first light-transmitting member, the coating film being in contact with the metal frame, and when the first light-transmitting member, while held by the metal frame, moves from one of a first position where the first light-transmitting member is inserted into an optical path and a second position where the first light-transmitting member is removed from the optical path to the other, the metal frame comes into contact with a grounded conductor, thereby eliminating static electricity.

12. The optical device according to claim 6, further comprising a holding frame for holding the ND filter and the first light-transmitting member.

13. The optical device according to claim 12, wherein the ND filter and the first light-transmitting member are provided with a power receiving mechanism that receives power to alternately insert and remove the ND filter and the first light-transmitting member into and from the optical path, the holding frame has an opening that exposes the power receiving mechanism from the holding frame, a power applying mechanism is attached to the holding frame that applies the power to the power receiving mechanism through the opening, and an adhesive is applied to at least the surface of the inner surface of the holding frame that faces the power receiving mechanism.

14. An optical device according to claim 13, wherein a housing that houses the power applying mechanism is attached to the holding frame, and the housing has a blocking wall that blocks the opening when the housing is attached to the holding frame.

15. The optical device described in claim 12, wherein the ND filter and the first light-transmitting member are provided with a power receiving mechanism that receives power to alternately insert and remove the ND filter and the first light-transmitting member into and from the optical path, the holding frame has an opening that exposes the power receiving mechanism from the holding frame, a housing that houses a power applying mechanism that applies the power to the power receiving mechanism from the opening is attached to the holding frame, and the housing has a blocking wall that closes the opening when the housing is attached to the holding frame.

16. The optical device described in claim 13, wherein the power receiving mechanism includes a first rack provided on the ND filter and a second rack provided on the first light-transmitting member, and the power applying mechanism includes a first gear that meshes with the first rack and a second gear that meshes with the second rack.

17. The optical device according to claim 6, comprising: a first protective frame that protects the ND filter and the first light-transmitting member from the ND filter side; and a second protective frame that protects the ND filter and the first light-transmitting member from the first light-transmitting member side, wherein the first protective frame and the second protective frame are fitted together via a fitting structure.

18. The optical device according to claim 17, wherein an adhesive is applied to the position where the first protective frame and the second protective frame are fitted together via the fitting structure and / or around the position.

19. An imaging apparatus comprising: an optical device according to any one of claims 1 to 18; and an image sensor, wherein the image sensor captures an image of subject light that has passed through the optical device.

Images