Lens device and imaging system

Abstract

To provide a lens device having high optical performance while stably holding an optical element.SOLUTION: Provided is a lens device (101) detachably attached to an imaging device (1), the lens device having a lens mount (102) for detachably attaching to the imaging device. The lens mount has: a second bayonet claw part (121) that engages with a first bayonet claw part (71) of the imaging device; a second terminal part (105) that comes into contact with a first terminal part (21) of the imaging device when the lens device is attached to the imaging device; and a bayonet groove part (703) that detachably attached to an optical element unit (701). The bayonet groove part and the second terminal part are disposed on a predetermined circumference around an optical axis of the lens device.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a lens apparatus and an imaging system. [Background technology]

[0002] In a large-diameter lens device, it is effective to enlarge the aperture of the lens mount so as not to degrade optical performance. Also, a lens device is known in which a mechanism for holding an optical filter (optical element) is provided in the lens mount, allowing the user to attach any optical filter.

[0003] Patent Document 1 discloses a configuration having a locking mechanism that detachably holds a filter in a lens mount, and Patent Document 2 discloses a configuration in which a filter is attached to a lens device via a holding frame. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-67575 [Patent Document 2] Japanese Patent Application Publication No. 2019-105704 Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration disclosed in Patent Document 1, the filter is positioned closer to the object than the bayonet section, which requires a long back focus to prevent interference between the filter and the lens closest to the image plane, resulting in constraints on optical design and optical performance. Furthermore, because the filter retention mechanism is located on the inner diameter side of the lens mount, the lens mount opening becomes narrow, making it difficult to realize a large-aperture, bright lens device. Furthermore, because the retention mechanism cannot be retracted even when the filter is not in use, incident light may be reflected or diffused by the retention mechanism, potentially allowing unwanted light to enter the imaging plane.

[0006] In the configuration disclosed in Patent Document 2, the magnetic attraction force allows the user to easily attach and detach the filter, but the filter holding frame may fall off due to vibration or impact, and enter the camera mount, potentially damaging the shutter or image sensor.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a lens device that stably holds optical elements and has high optical performance. [Means for solving the problem]

[0008] A lens device according to one aspect of the present invention is a lens device that is detachable from an imaging device, and has a lens mount for detachably mounting the lens mount on the imaging device, the lens mount having a second bayonet claw portion that can engage with a first bayonet claw portion of the imaging device, a second terminal portion that contacts a first terminal portion of the imaging device when the lens device is mounted on the imaging device, and a bayonet groove portion for detachably mounting an optical element unit, the bayonet groove portion and the second terminal portion being arranged on a predetermined circumference centered on the optical axis of the lens device.

[0009] Other objects and features of the present invention are illustrated in the following examples. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a lens device that has high optical performance while stably holding an optical element. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a perspective view of an imaging system in each embodiment. [Figure 2] FIG. 2 is a block diagram of an imaging system in each embodiment. [Figure 3] FIG. 2 is a cross-sectional view of an interchangeable lens in each example. [Figure 4] FIG. 2 is a front view of the camera body in each embodiment. [Figure 5]FIG. 2 is a perspective view of an interchangeable lens in each embodiment. [Figure 6] 3A and 3B are a rear view and a cross-sectional view of the lens mount in the first embodiment. [Figure 7] 3A and 3B are a rear view and a rear perspective view of the lens mount in the first embodiment. [Figure 8] 2A and 2B are a rear perspective view and an exploded perspective view of the optical element unit in Example 1. [Figure 9] 10A and 10B are a rear view and a cross-sectional view of a lens mount in a second embodiment. [Figure 10] 10A and 10B are a rear view and a rear perspective view of a lens mount in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same reference numerals indicate the same or corresponding parts throughout the drawings. In this embodiment, an interchangeable lens will be described as an example of a lens device, but various other modifications and variations of the present invention are possible within the scope of the present invention.

[0013] First, the external configuration of an imaging system 100 in each embodiment will be described with reference to Figs. 1(a) and 1(b). Figs. 1(a) and 1(b) are external views of the imaging system 100. Fig. 1(a) shows a perspective view of the imaging system 100 seen from the front side, and Fig. 1(b) shows a perspective view of the imaging system 100 seen from the rear side. The imaging system 100 is configured to include a camera body (an imaging device such as a digital camera) 1 and an interchangeable lens (lens device) 101 that is detachable from the camera body 1.

[0014] As shown in FIG. 1(a), the direction in which the optical axis OA of the imaging optical system of the interchangeable lens 101 extends (optical axis direction) is referred to as the X-axis direction, and the directions perpendicular to the optical axis direction are referred to as the Z-axis direction (horizontal direction) and the Y-axis direction (vertical direction). Hereinafter, the Z-axis direction and the Y-axis direction will be collectively referred to as the Z / Y-axis direction. Furthermore, the rotation direction around the Z axis will be referred to as the pitch direction, and the rotation direction around the Y axis will be referred to as the yaw direction. The pitch direction and yaw direction (hereinafter collectively referred to as the pitch / yaw direction) are the rotation directions around two axes, the Z axis and the Y axis, which are perpendicular to each other.

[0015] A grip section 2 is provided on the left side of the camera body 1 when viewed from the front (the subject side) (the right side when viewed from the back) to allow the user to hold the camera body 1 with their hand. A power operation section 3 is also located on the top surface of the camera body 1. When the user turns on the power operation section 3 while the camera body 1 is in the power-off state, the camera body 1 is turned on and becomes capable of capturing images. When the user turns off the power operation section 3 while the camera body 1 is in the power-on state, the camera body 1 is turned off.

[0016] The top surface of the camera body 1 is provided with a mode dial 4, a release button 5, and an accessory shoe 6. The user can switch between imaging modes by rotating the mode dial 4. The imaging modes include a manual still image capture mode, in which the user can freely set imaging conditions such as shutter speed and aperture value; an auto still image capture mode, in which the appropriate exposure is automatically obtained; and a video capture mode for capturing videos. The user can also half-press the release button 5 to initiate imaging preparation operations such as autofocus and autoexposure control, or fully press the button to initiate imaging. Accessories such as an external flash can be detachably attached to the accessory shoe 6. The camera body 1 also has an image sensor that photoelectrically converts (captures) a subject image (optical image) formed by the imaging optical system within the interchangeable lens 101.

[0017] The interchangeable lens 101 has a lens mount 102 for being detachably attached to the camera body 1. The interchangeable lens 101 is mechanically and electrically connected to a camera mount 7 provided on the camera body 1 via the lens mount 102. As described above, the interchangeable lens 101 has an imaging optical system that forms an image of a subject by focusing light from the subject.

[0018] As shown in FIG. 1(b), the rear surface of the camera body 1 is provided with a rear operation unit 8 and a display unit 9. The rear operation unit 8 includes a plurality of buttons and dials to which various functions are assigned. When the power of the camera body 1 is on and the still image or video shooting mode is set, the display unit 9 displays a through image of the subject image captured by the image sensor. The display unit 9 also displays imaging parameters indicating imaging conditions such as shutter speed and aperture value (F-number). The user can change the settings of the imaging parameters by operating the rear operation unit 8 while viewing the display. The rear operation unit 8 includes a playback button for instructing playback of a recorded captured image, and when the user operates the playback button, the captured image is played back and displayed on the display unit 9.

[0019] Next, the internal configuration of the imaging system 100 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the electrical and optical configuration of the imaging system 100. The camera body 1 has a power supply unit 10 that supplies power to the camera body 1 and the interchangeable lens 101, and an operation unit 11 that includes a power operation unit 3, a mode dial 4, a release button 5, a rear operation unit 8, and a touch panel function of the display unit 9. The camera body 1 and the interchangeable lens 101 as an entire system are controlled by a camera control unit 12 provided in the camera body 1 and a lens control unit 104 provided in the interchangeable lens 101 in cooperation with each other.

[0020] The camera control unit 12 reads and executes a computer program stored in the storage unit 13. In doing so, the camera control unit 12 communicates various control signals, data, and the like with the lens control unit 104 via electrical contacts between a camera terminal 21 provided on the camera mount 7 and a lens terminal unit 105 provided on the lens mount 102. The camera terminal 21 and the lens terminal unit 105 include power terminals that supply power from the power supply unit 10 described above to the interchangeable lens 101.

[0021] The imaging optical system of the interchangeable lens 101 has a focus group 200 (first focus group 201, second focus group 202) including a focus lens that moves in the optical axis direction to perform focus adjustment, and an aperture group (aperture diaphragm unit) 401 that performs a light amount adjustment operation. The interchangeable lens 101 also has a focus driver 301 that drives the focus group 200, and an aperture driver 402 that drives the aperture group 401.

[0022] The camera body 1 has a shutter unit 14, a shutter drive unit 15, an image sensor 16, an image processing unit 17, and the aforementioned camera control unit 12. The shutter unit 14 controls the amount of light collected by the imaging optical system in the interchangeable lens 101 and exposed to the image sensor 16. The image sensor 16 photoelectrically converts the subject image formed by the imaging optical system and outputs an image signal. The image processing unit 17 performs various image processes on the image signal and then generates an image signal. The display unit 9 displays the image signal (through image) and imaging parameters output from the image processing unit 17, and also plays back and displays captured images recorded in the memory unit 13 or a recording medium (not shown).

[0023] The camera control unit 12 controls the driving of the focus group 200 in response to an image capture preparation operation (half-pressing the release button 5) on the operation unit 11. For example, when an autofocus operation is instructed, the focus detection unit 18 determines the focus state of the subject image formed on the image sensor 16 based on the image signal generated by the image processing unit 17, generates a focus signal, and sends it to the camera control unit 12. At the same time, the focus drive unit 301 detects the current position of the focus group 200 and sends the detection signal to the camera control unit 12 via the lens control unit 104. The camera control unit 12 compares the focus state of the subject image with the current position of the focus group 200, calculates a focus drive amount based on the deviation amount obtained as a result of the comparison, and sends it to the lens control unit 104. The lens control unit 104 then controls the driving of the focus group 200 to a target position via the focus drive unit 301, thereby correcting the defocus of the subject image.

[0024] The focus driver 301 includes a focus motor that functions as an actuator and a position detector that detects the position of the focus group 200. Generally, a stepping motor, an ultrasonic motor, or a voice coil motor, which are types of actuators, is often used as the focus motor. However, a DC motor, a servo motor, an ultrasonic motor, or a similar motor equipped with an encoder may also be used.

[0025] Camera control unit 12 controls the driving of aperture group 401 and shutter unit 14 via aperture drive unit 402 and shutter drive unit 15 in accordance with the aperture value or shutter speed setting value received from operation unit 11. For example, when an automatic exposure control operation is instructed, camera control unit 12 receives a luminance signal generated by image processing unit 17 and performs a photometric calculation. Based on the photometric calculation result, camera control unit 12 controls the driving of aperture group 401 in accordance with an image capture instruction operation on operation unit 11 (full depression of release button 5). At the same time, camera control unit 12 controls the driving of shutter unit 14 via shutter drive unit 15 and performs exposure processing by image sensor 16.

[0026] Next, the positional relationship between the interchangeable lens 101 and the components in the camera body 1 will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view of the imaging system 100 on the XY plane including the optical axis. The center line shown in Fig. 3 substantially coincides with the optical axis OA determined by the imaging optical system, and therefore will be hereinafter referred to as the optical axis.

[0027] In each embodiment, the imaging optical system is a five-group optical system consisting of a first fixed group 601, a first focusing group 201, a second fixed group 602, a second focusing group 202, and a third fixed group 603, arranged in this order from the subject side to the image side. The first fixed group 601 includes a first fixed lens 611, a second fixed lens 612, and a third fixed lens 613. The first focusing group 201 includes a first focusing lens 211. The second fixed group 602 includes a fourth fixed lens 621. The second focusing group 202 includes a second focusing lens 221. The third fixed group 603 includes a fifth fixed lens 631.

[0028] The fixed barrel 106 holds a first fixed group 601, a second fixed group 602, and a third fixed group 603 on its inner periphery, and also has a focus driver 301 (see FIG. 2) and a linear guide unit (not shown) in the optical axis direction. The first focus group 201 and the second focus group 202 move to predetermined optical positions in response to defocus of the subject image. As a result, light from the subject is imaged on the imaging surface of the image sensor 16 via the first fixed group 601, the first focus group 201, the second fixed group 602, the second focus group 202, and the third fixed group 603.

[0029] The aperture group 401 is housed in the second fixed group 602 together with the fourth fixed lens 621. The lens mount 102 is fixed to the fixed barrel 106 and connected to the camera mount 7.

[0030] The optical element unit 701 is detachably held by the lens mount 102 between the third fixed group 603 and the image sensor 16. The optical element unit 701 can obtain desired optical characteristics by transmitting a portion of light from a subject. The optical element unit 701 has optical filters such as a soft filter that softens the captured image or an ND filter that weakens the intensity of light. However, the embodiments are not limited to these, and other types of optical filters may also be used. Various optical filters can expand the range of photographic expression methods.

[0031] Furthermore, in order to maintain the optical performance of the imaging optical system as a whole, the imaging optical system of each embodiment has an adjustment mechanism that intentionally shifts the position of the second focus lens 221. This allows workers in the assembly process to reduce the effects of manufacturing errors or assembly variations that occur in each component while checking the overall optical performance state.

[0032] Next, the mount portion in each embodiment will be described in detail with reference to Figures 4 and 5. Figure 4 is a front view of the camera body 1, showing the camera mount 7. Figure 5 is a perspective view of the interchangeable lens 101 as seen from the rear side, showing the lens mount 102.

[0033] The camera mount 7 has a plurality of camera bayonet claws (first bayonet claw portions) 71 for mechanical connection with the lens mount 102, and a plurality of camera terminals (first terminal portions) 21 for electrical connection with the lens mount 102. The lens mount 102 has a plurality of lens bayonet claws (second bayonet claw portions) 121 for mechanical connection with the camera mount 7, and a plurality of lens terminals (second terminal portions) 105 for electrical connection with the camera mount 7.

[0034] The multiple lens bayonet claws 121 are engageable with the multiple camera bayonet claws 71. When attaching the interchangeable lens 101 to the camera body 1, the interchangeable lens 101 is inserted at an angle that allows the lens bayonet claws 121 to fit into the spaces between the multiple camera bayonet claws 71 in the circumferential direction centered on the optical axis OA (X-axis). Then, the camera mount 7 and the lens mount 102 are rotated to a desired angle while abutting against each other in the optical axis (X-axis) direction. This engages the camera bayonet claws 71 and the lens bayonet claws 121 and mechanically connects them. Furthermore, the multiple camera terminals 21 and the multiple lens terminal units 105 come into contact with each other and are electrically connected. That is, the multiple lens terminal units 105 come into contact with the multiple camera terminals 21 when the interchangeable lens 101 is attached to the camera body 1. Furthermore, an optical element unit 701 is disposed inside the lens mount 102 and is detachably held by the lens mount 102.

[0035] Each example will be described in detail below.

[0036] Example 1 First, with reference to FIGS. 6(a) and 6(b), a structure for holding the optical element unit 701 on the lens mount 102 in the first embodiment will be described. FIG. 6(a) is a rear view of the lens mount 102. FIG. 6(b) is a cross-sectional view taken along line AA including the optical axis OA in FIG. 6(a). FIGS. 6(a) and 6(b) each show an engagement state between the lens mount 102 and the optical element unit 701. The optical element unit 701 has an opening 708 (optical element 711) that transmits light in the center, and two optical element bayonet claws (third bayonet claw portions) 702 on the periphery for holding the optical element unit 701 on the lens mount 102. The two optical element bayonet claws 702 are provided at positions facing each other across the optical axis OA (positions rotated 180° with respect to the optical axis OA).

[0037] The two bayonet grooves 703 provided in the lens mount 102 are provided for detachably mounting the optical element unit 701. That is, the optical element unit 701 is detachably mounted to the interchangeable lens 101 by the two bayonet grooves 703 engaging with the two optical element bayonet claws 702.

[0038] The position of the optical element unit 701 in the optical axis direction is determined by the two optical element bayonet claws 702 being sandwiched (held) by the two bayonet grooves 703. For this reason, the two bayonet grooves 703, like the two optical element bayonet claws 702, are provided at positions facing each other across the optical axis OA (positions rotated 180° with respect to the optical axis OA). In other words, at least two of the multiple bayonet grooves 703 are arranged at positions facing each other with respect to the optical axis OA. As a result, the optical element unit 701 is stably held by the lens mount 102 at positions facing each other across the optical axis OA.

[0039] Furthermore, by fitting the tip of the first protrusion 704 provided on the optical element unit 701 into the inner peripheral surface of the lens mount 102, it is possible to determine the position with high precision with respect to the optical axis OA of the interchangeable lens 101. Furthermore, by abutting the side surface of the first protrusion 704 against the side surface of the second protrusion 122 provided on the lens mount 102, rotation of the optical element unit 701 around the optical axis relative to the lens mount 102 is restricted. This makes it possible to reduce the possibility of the optical element unit 701 falling off accidentally due to external forces such as impact or vibration.

[0040] Next, we will explain the positional relationship between the lens terminal portion 105 and the optical element bayonet claw 702. When viewed from the rear side, the lens terminal portion 105 is arranged in an arc shape so as to follow the inner diameter side of the lens bayonet claw 121. This allows the opening of the lens mount 102 to be large.

[0041] On the other hand, in order to enlarge the opening of the optical element unit 701, it is necessary to arrange the optical element bayonet claws 702 in a position as far away from the optical axis OA as possible. For this reason, the optical element bayonet claws 702 are arranged on a predetermined circumference (on the same circumference) centered on the lens terminal unit 105 and the optical axis OA, in a phase that does not overlap with the lens terminal unit 105 (a circumferential position different from that of the lens terminal unit 105). This makes it possible to enlarge the opening of the optical element unit 701.

[0042] In this embodiment, the bayonet groove 703 and the lens terminal portion 105 are arranged on a predetermined circumference centered on the optical axis OA of the interchangeable lens 101. Preferably, when viewed from a direction perpendicular to the optical axis OA, at least a portion of the bayonet groove 703 and at least a portion of the lens terminal portion 105 are arranged to overlap each other on the predetermined circumference. Also preferably, when viewed from the optical axis direction, the bayonet groove 703 and the lens terminal portion 105 are arranged at different positions on the predetermined circumference.

[0043] 6(b), when viewed from the cross-sectional (XY plane) direction, the lens terminal portion 105 is disposed at the rear end (-X direction) of the lens mount 102 to connect to the camera terminal 21. On the other hand, the optical element unit 701 is disposed at the rear end (-X direction) so as to overlap (stay on top of) the lens mount 102 in the X direction. This allows the fifth fixed lens 631 to be brought closer to the image plane, thereby shortening the back focus.

[0044] Next, the configuration of the attachment / detachment mechanism of the optical element unit 701 will be described with reference to Figures 7(a) and (b). Figure 7(a) is a rear view of the lens mount 102. Figure 7(b) is a perspective view (rear perspective view) of the lens mount 102. Figures 7(a) and (b) each show a state in which the optical element unit 701 is disengaged.

[0045] The optical element unit 701 includes an outer peripheral grip 705 for gripping during attachment and detachment. The outer peripheral grip 705 is located in the same radial direction as the first protrusion 704. The outer peripheral grip 705 is knurled to prevent slipping when gripped with the user's fingers. When removing the optical element unit 701 from the lens mount 102, the outer peripheral grip 705 is gripped with the fingers and the optical element unit 701 is slightly bent in the direction of arrow B in FIG. 7( a) to separate the contact portions between the side surfaces of the first protrusion 704 and the second protrusion 122. In this state, the optical element unit 701 can be rotated in the direction of arrow C in FIG. 7( a) to release the engagement between the optical element bayonet claw 702 and the bayonet groove 703.

[0046] Here, area D in FIG. 7(a) will be described. As mentioned above, when removing the interchangeable lens 101 from the camera body 1, it can be attached and detached by rotating the interchangeable lens 101. Area D is the area where the interchangeable lens 101 rotates and the camera terminal 21 enters the lens mount 102 (the first area where the camera terminal 21 moves when the interchangeable lens 101 is removed from the camera body 1). Area D is where the lens mount 102 is shifted in the +X direction to a height where it does not come into contact with the tip of the camera terminal 21. For this reason, it is not possible to place the bayonet groove 703 in area D.

[0047] Therefore, in this embodiment, by arranging the bayonet groove portion 703 adjacent to region D in the circumferential direction, the region (second region) where the optical element bayonet claw 702 retracts overlaps with region D (first region) when attaching or detaching the optical element unit 701. In other words, at least a part of the first region (region D) and at least a part of the second region where the optical element bayonet claw 702 moves when the optical element unit 701 is detached from the interchangeable lens 101 are common to each other.

[0048] This allows the optical element unit 701 to be easily attached and detached, and can be reliably fixed when attached. Furthermore, since the attachment and detachment mechanism can be efficiently arranged, the opening of the lens mount 102 can be made larger. Furthermore, when the optical element unit 701 is detached, it is possible to suppress unnecessary light on the imaging surface that is generated by reflection and diffusion of incident light.

[0049] Next, the configuration of the optical element unit 701 will be described with reference to FIGS. 8(a) and 8(b). FIG. 8(a) is a rear perspective view of the optical element unit 701. FIG. 8(b) is an exploded perspective view of the optical element unit 701. FIGS. 8(a) and 8(b) each show a holding configuration for an optical element 711. The optical element unit 701 includes an optical element 711 that transmits light and a holding frame (optical element holding frame) 712 that holds the optical element 711 and has optical element bayonet claws 702 on its outer periphery. The optical element 711 is a sheet-like optical filter that can be cut into a desired shape by the user. The holding frame 712 includes an optical element holding portion 713, an optical element locking wall 714, and an optical element locking protrusion 715 on the side of the opening for holding the optical element 711. The holding frame 712 holds the optical element 711 outside the effective range through which light from the optical element 711 passes.

[0050] The optical element holding portion 713 has a slit shape that holds the end of the optical element 711, and allows the optical element 711 to be inserted from the Z direction. Note that in this embodiment, the shape and configuration of the optical element holding portion 713 are not limited to this as long as it can hold the optical element 711, and a claw member, a cover member, or the like may also be used.

[0051] The optical element locking wall 714 and the optical element locking protrusion 715 prevent the optical element 711 inserted from the Z direction from jumping out of the lens mount 102. The optical element locking protrusion 715 is also arranged side by side in the Z direction on the side where the optical element 711 is inserted relative to the optical element holding portion 713. Therefore, when inserting the optical element 711, it can be mounted without damaging the effective range through which light passes.

[0052] This allows the user to easily replace the optical filter with any desired one. Furthermore, since the optical element 711 is held by the optical element holding portion 713, the optical element locking wall 714, and the optical element locking protrusion 715, the optical element 711 can be prevented from jumping out of the lens mount 102 and being damaged.

[0053] <Example 2> Next, with reference to Figures 9(a) and (b), a description will be given of a structure for holding the optical element unit 1701 in the lens mount 1102 in Example 2. Figure 9(a) is a rear view of the lens mount 1102. Figure 9(b) is a cross-sectional view taken along line EE including the optical axis OA in Figure 9(a). Figures 9(a) and (b) each show an engagement state between the lens mount 1102 and the optical element unit 1701.

[0054] The optical element unit 1701 is a sheet-like optical filter that transmits light, and is provided on its outer periphery with two optical element bayonet claws (third bayonet claw portions) 1702 for holding it in the lens mount 1102. The two optical element bayonet claws 1702 are arranged in opposing positions across the optical axis OA (positions rotated 180° about the optical axis OA). The position of the optical element unit 1701 in the optical axis direction is determined by the optical element bayonet claws 1702 being held in bayonet groove portions 1703 provided in the lens mount 1102. As a result, the optical element unit 1701 is stably held in the lens mount 1102 in opposing positions across the optical axis OA.

[0055] Furthermore, by fitting the tip of the first protrusion 1704 provided on the optical element unit 1701 into the inner peripheral surface of the lens mount 1102, it is possible to determine the position with high precision with respect to the optical axis OA of the interchangeable lens 1101. Furthermore, by abutting the side surface of the first protrusion 1704 against the side surface of the second protrusion 1122 provided on the lens mount 1102, the optical element unit 1701 is prevented from rotating about the optical axis OA. This makes it possible to reduce the possibility of the optical element unit 1701 falling off accidentally due to external forces such as impact or vibration.

[0056] Next, we will explain the positional relationship between the lens terminal portion (second terminal portion) 1105 and the optical element bayonet claw 1702. When viewed from the back, the lens terminal portion 1105 is arranged in an arc shape along the inner diameter side of the lens bayonet claw 1121, which allows the opening of the lens mount 1102 to be large.

[0057] On the other hand, in order to enlarge the opening of the optical element unit 1701, it is necessary to arrange the optical element bayonet claw 1702 in a position as far away from the optical axis OA as possible. For this reason, the optical element bayonet claw 1702 is arranged on the same circumference as the lens terminal portion 1105, in a phase that does not overlap with the lens terminal portion 1105 (a different position in the circumferential direction). This makes it possible to enlarge the opening of the optical element unit 1701.

[0058] 9(a), when viewed from the cross section (XY plane), the lens terminal portion 1105 is disposed at the rear end (-X direction) of the lens mount 1102 to connect to the camera terminal 21. On the other hand, the optical element unit 1701 is disposed at the rear end (-X direction) so as to overlap with the lens mount 1102 in the X direction. This allows the fifth fixed lens 631 to be positioned closer to the image plane, thereby shortening the back focus.

[0059] Next, the configuration of the attachment / detachment mechanism of the optical element unit 1701 will be described with reference to Figures 10(a) and (b). Figure 10(a) is a rear view of the lens mount 1102. Figure 10(b) is a perspective view (rear perspective view) of the lens mount 1102. Figures 10(a) and (b) each show a state in which the optical element unit 1701 is disengaged.

[0060] When attaching or detaching the optical element unit 1701 to or from the lens mount 1102, a tool such as tweezers is used to separate the contact portions between the side surface of the first protrusion 1704 and the side surface of the second protrusion 1122. In this state, by rotating in the direction of arrow F in Figure 10(a), the engagement between the optical element bayonet claw 1702 and the bayonet groove 1703 can be released.

[0061] Here, we will explain area G in Figure 10(a). As mentioned above, when removing the interchangeable lens 101 from the camera body 1, it can be attached and detached by rotating the interchangeable lens 101. Area G is the area where the interchangeable lens 101 rotates and the camera terminal 21 enters the lens mount 1102, and the lens mount 1102 is shifted in the +X direction to a height where it does not come into contact with the tip of the camera terminal 21. For this reason, it is not possible to place the bayonet groove 1703 in area G.

[0062] Therefore, in this embodiment, by arranging the bayonet groove 1703 adjacent to region G in the circumferential direction, the region where the optical element bayonet claw 1702 is retracted when attaching or detaching the optical element unit 1701 overlaps with region G. This allows the optical element unit 1701 to be easily attached or detached, and also ensures that it is securely fixed when attached. Furthermore, since the attachment / detachment mechanism can be efficiently positioned, the opening of the lens mount 1102 can be made larger. Furthermore, when the optical element unit 1701 is detached, unnecessary light on the imaging surface, which is generated by reflection or diffusion of incident light, can be suppressed.

[0063] According to each embodiment, by providing a space-saving holding mechanism in the lens mount that allows for the attachment and detachment of an optical filter, it is possible to shorten the back focus and expand the effective range of the optical filter. This allows for improved optical performance. Furthermore, by making it possible to enlarge the opening of the lens mount when the optical filter is not in use, it is possible to reduce unnecessary light that reaches the imaging surface due to the reflection or diffusion of incident light by the holding mechanism. Furthermore, the optical filter can be easily attached and detached by the user while being firmly held. Therefore, according to each embodiment, it is possible to provide a lens device and an imaging system that stably holds an optical element and has high optical performance.

[0064] The disclosure of each embodiment includes the following configuration. (Configuration 1) A lens device that is detachable from an imaging device, a lens mount for detachably mounting on the imaging device; The lens mount is a second bayonet claw portion engageable with the first bayonet claw portion of the imaging device; a second terminal portion that comes into contact with a first terminal portion of the imaging device when the lens device is attached to the imaging device; a bayonet groove for detachably mounting the optical element unit; The lens device, wherein the bayonet groove and the second terminal are arranged on a predetermined circumference centered on the optical axis of the lens device. (Configuration 2) The lens device described in configuration 1, characterized in that when viewed from a direction perpendicular to the optical axis, at least a portion of the bayonet groove portion and at least a portion of the second terminal portion are arranged so as to overlap each other on the specified circumference. (Configuration 3) The lens device described in configuration 1 or 2, characterized in that when viewed from the optical axis direction, the bayonet groove portion and the second terminal portion are arranged at different positions on the specified circumference. (Configuration 4) The lens device described in any one of configurations 1 to 3, characterized in that the optical element unit is detachably attached to the lens device by engaging the bayonet groove portion of the lens device with the third bayonet claw portion of the optical element unit. (Configuration 5) 5. The lens device according to configuration 4, wherein the optical element unit includes an optical element and a holding frame having the third bayonet claw portion. (Configuration 6) 6. The lens device according to configuration 5, wherein the holding frame holds the optical element outside an effective range through which light rays of the optical element pass. (Configuration 7) The lens device described in any one of configurations 4 to 6, characterized in that at least a portion of a first region to which the first terminal portion moves when the lens device is detached from the imaging device and at least a portion of a second region to which the third bayonet claw portion moves when the optical element unit is detached from the lens device are common to each other. (Configuration 8) The bayonet groove portion has a plurality of bayonet grooves, 8. The lens device according to any one of configurations 1 to 7, wherein at least two of the plurality of bayonet grooves are arranged at positions opposite each other with respect to the optical axis. (Configuration 9) the lens mount has a second protrusion that abuts against the first protrusion of the optical element unit, The lens device described in any one of configurations 1 to 8, characterized in that the first protrusion and the second protrusion abut against each other, thereby restricting rotation of the optical element unit around the optical axis relative to the lens mount. (Configuration 10) An imaging system comprising the lens apparatus according to any one of configurations 1 to 9 and an imaging device.

[0065] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments and various modifications and changes are possible within the scope of the invention. [Explanation of symbols]

[0066] 1. Camera body (imaging device) 21 Camera terminal (first terminal) 71 Camera bayonet claw (first bayonet claw) 101 Interchangeable lenses (lens devices) 102, 1102 lens mount 105, 1105 Lens terminal (second terminal) 121 Lens bayonet claw (second bayonet claw) 703, 1703 Bayonet groove

Claims

1. A lens device that is detachable from an imaging device, a lens mount for detachably mounting on the imaging device; The lens mount is a second bayonet claw portion engageable with the first bayonet claw portion of the imaging device; a second terminal portion that comes into contact with a first terminal portion of the imaging device when the lens device is attached to the imaging device; a bayonet groove for detachably mounting the optical element unit; The lens device, wherein the bayonet groove and the second terminal are arranged on a predetermined circumference centered on the optical axis of the lens device.

2. 2. The lens device according to claim 1, wherein, when viewed from a direction perpendicular to the optical axis, at least a portion of the bayonet groove portion and at least a portion of the second terminal portion are arranged to overlap each other on the predetermined circumference.

3. 3. The lens device according to claim 1, wherein the bayonet groove and the second terminal are disposed at different positions on the predetermined circumference when viewed from the optical axis direction.

4. The lens device according to claim 1 or 2, wherein the optical element unit is removably attached to the lens device by engaging the bayonet groove portion of the lens device with a third bayonet claw portion of the optical element unit.

5. 5. The lens device according to claim 4, wherein the optical element unit includes an optical element and a holding frame having the third bayonet claw portion.

6. 6. The lens device according to claim 5, wherein the holding frame holds the optical element outside an effective range through which light rays of the optical element pass.

7. The lens device described in claim 4, characterized in that at least a portion of the first area through which the first terminal portion moves when the lens device is detached from the imaging device and at least a portion of the second area through which the third bayonet claw portion moves when the optical element unit is detached from the lens device are common to each other.

8. The bayonet groove portion has a plurality of bayonet grooves, 3. The lens device according to claim 1, wherein at least two of the plurality of bayonet grooves are arranged at positions opposite to each other with respect to the optical axis.

9. the lens mount has a second protrusion that comes into contact with the first protrusion of the optical element unit, 3. The lens device according to claim 1, wherein the first protrusion and the second protrusion come into contact with each other, thereby restricting rotation of the optical element unit about the optical axis relative to the lens mount.

10. 3. An imaging system comprising: a lens apparatus according to claim 1; and an imaging device.

Images