Optical instrument and imaging apparatus

Abstract

To provide an optical instrument that allows insertion of a conversion lens group without losing operability, while preventing deterioration of optical performance.SOLUTION: An optical instrument has: a first lens group; a second lens group that rotates about a first rotation shaft, and is retreated from an optical axis of the first lens group to change a focal distance range of an optical system from a second focal distance range to a first focal distance range; and a first urging member that rotates about the first rotation shaft and urges the second lens group. The amount of deformation of the first urging member when the focal distance range is the second focal distance range is larger than the amount of deformation of the first urging member while the focal distance range shifts from the first focal distance range to the second focal distance range.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an optical device and an imaging device that are capable of changing the focal length range of a master lens by inserting or retracting a built-in conversion lens. [Background technology]

[0002] In optical devices such as digital cameras, video cameras, and interchangeable lenses, a configuration is known in which a conversion lens is inserted into the optical path to change the focal length range of the imaging optical system to the telephoto side or the wide-angle side. Patent Document 1 discloses a configuration in which a conversion lens built into a camera body is moved between an inserted position where it is inserted into the optical path and a retracted position where it is retracted outside the optical path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-311828 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the configuration of Patent Document 1 does not have a biasing structure for when the conversion lens is in the inserted position, which makes it difficult to stabilize the optical performance when the conversion lens is in the inserted position.

[0005] Another possible configuration is to use a toggle spring as a means for biasing the conversion lens to the inserted position and the retracted position. However, when using a toggle spring, the operating force required when switching between the inserted position and the retracted position increases, which can impair operability.

[0006] An object of the present invention is to provide an optical device in which a conversion lens group can be inserted and removed without impairing operability while suppressing deterioration of optical performance. [Means for solving the problem]

[0007] An optical device according to one aspect of the present invention includes a first lens group, a second lens group that rotates about a first rotation axis and moves away from the optical axis of the first lens group to change the focal length range of the optical system from a second focal length range to the first focal length range, and a first biasing member that rotates about the first rotation axis and biases the second lens group, wherein the amount of deformation of the first biasing member when the focal length range is the second focal length range is greater than the amount of deformation of the first biasing member when the focal length range transitions from the first focal length range to the second focal length range. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an optical device in which the conversion lens group can be inserted and removed without impairing operability, while suppressing deterioration of optical performance. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a front perspective view of a camera system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a rear perspective view of the camera system. [Figure 3] 10 is a cross-sectional view of a camera system when the focal length range of the imaging optical system is set to a second focal length range. FIG. [Figure 4] 1 is a cross-sectional view of a camera system when the focal length range of an imaging optical system is set to a first focal length range. [Figure 5] 10 is an external view of each lens group of the interchangeable lens when the focal length range of the imaging optical system is set to a second focal length range, as viewed from the Z axis direction. FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line AA in FIG. 5. [Figure 7] 6A and 6B are external views of the lens groups of the interchangeable lens when the focal length range of the imaging optical system is set to a second focal length range, as viewed from the Y-axis direction, and cross-sectional views taken along line BB in FIG. 5. [Figure 8] 6A and 6B are external views of each lens group of the interchangeable lens during transition and a cross-sectional view taken along line BB in FIG. 5. [Figure 9] 6A and 6B are external views of each lens group of the interchangeable lens during transition and a cross-sectional view taken along line BB in FIG. 5. [Figure 10] 6A and 6B are external views of each lens group of the interchangeable lens during transition and a cross-sectional view taken along line BB in FIG. 5. [Figure 11] 6A and 6B are external views of each lens group of the interchangeable lens during transition and a cross-sectional view taken along line BB in FIG. 5. [Figure 12] 6A and 6B are external views of each lens group of the interchangeable lens during transition and a cross-sectional view taken along line BB in FIG. 5. [Figure 13] 6A and 6B are external views of the lens groups of the interchangeable lens when the focal length range of the imaging optical system is set to a first focal length range, as viewed from the Y-axis direction, and cross-sectional views taken along line BB in FIG. 5. [Figure 14] 10 is a graph showing the amount of deformation of a biasing member of an interchangeable lens during transition. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same components, and redundant explanations will be omitted.

[0011] 1 and 2 are respectively a front perspective view and a rear perspective view of a camera system (imaging device) according to an embodiment of the present invention. The camera system has an interchangeable lens 100 and a digital camera (hereinafter referred to as a camera body) 1 to which the interchangeable lens 100 is detachably attached. In FIGS. 1 and 2, the focal length range of the imaging optical system housed in the interchangeable lens 100 is set to a second focal length range. Also, FIG. 2 shows the interchangeable lens 100 detached from the camera body 1. Note that, although an interchangeable lens, which is an example of an optical device, will be described in this embodiment, the present invention is also applicable to integrated lens cameras and the like.

[0012] In this embodiment, as shown in Fig. 1, the optical axis direction, which is the direction in which the optical axis of the imaging optical system extends (the direction along the optical axis), is defined as the X-axis direction, and the directions perpendicular to the X-axis direction are defined 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 also be collectively referred to as the Z / Y-axis direction. Furthermore, the rotation direction around the Z axis will be defined as the pitch direction, and the rotation direction around the Y axis will be defined as the yaw direction. The pitch direction and yaw direction (hereinafter collectively referred to as the pitch / yaw direction) are rotation directions around two axes, the Z axis and the Y axis, which are perpendicular to each other.

[0013] A grip section 2 is provided on the left side of the camera body 1 as viewed from the front (the right side as viewed from the rear) for the user to hold the camera body 1 with their hand. A power operation section 3 is also provided 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, power is supplied and the camera body 1 enters the power-on state, and a computer program such as an origin detection process for the focus group (focus lens) is executed, and the camera body 1 enters an image capture standby state. On the other hand, 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 enters the power-off state.

[0014] 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 instruct imaging preparation operations such as autofocus and auto exposure control, and can fully press the button to instruct imaging. An accessory (camera accessory) such as an external flash or other lighting or light-emitting device can be detachably attached to the accessory shoe 6.

[0015] The interchangeable lens 100 is equipped with a lens mount (second mount) 102 that can be mechanically connected to a camera mount (first mount) 7 provided on the camera body 1. The interchangeable lens 100 also has an electrical connection member 101, and is electrically connected to the camera body 1. As shown in FIG. 2, in this embodiment, the electrical connection member 101 is arranged at a lower phase in the circumferential direction of the lens mount 102, but the present invention is not limited to this, and the electrical connection member 101 may also be arranged at an upper phase.

[0016] The interchangeable lens 100 houses an imaging optical system that forms a subject image on an image plane using light from the subject. A focus operation ring (operation member) 103 that can be rotated around the optical axis by user operation is provided on the outer periphery of the interchangeable lens 100. For example, in manual focus mode, when the user rotates the focus operation ring 103, all or some of the lens groups (focus groups) that make up the imaging optical system move to predetermined usage positions that correspond to the angle of the focus operation ring 103. In this way, the user can perform the desired focus adjustment.

[0017] As shown in FIG. 2 , 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 camera body 1 is powered on and the still image capture mode or video capture mode is set, the display unit 9 displays a through image of a subject captured by an image sensor (described later). The display unit 9 also displays imaging parameters indicating imaging conditions such as shutter speed and aperture value. 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. When the user operates the playback button, the captured image is played back and displayed on the display unit 9. The display unit 9 may be a touch panel type having the same functions as the rear operation unit 8.

[0018] The positional relationship of the members (components) that make up the interchangeable lens 100 of this embodiment will be described below with reference to FIGS. 3 and 4. FIGS. 3 and 4 are cross-sectional views on the XZ plane including the first optical axis 10 of the camera system when the focal length range of the imaging optical system is set to the second focal length range and the first focal length range, respectively. The center line shown here substantially coincides with the first optical axis 10 determined by the first lens group (first lens group) 110, and will therefore be synonymous with the aforementioned X-axis hereinafter. The image plane of the imaging element 16 is perpendicular to the first optical axis 10 and is synonymous with the aforementioned YZ plane.

[0019] Fig. 3 shows a case where the second lens group (third lens group) 210 and the third lens group (second lens group) 310 are arranged on the image plane side of the first lens group 110, and the focal length range of the imaging optical system is set to the second focal length range. Fig. 4 shows a case where the second lens group 210 and the third lens group 310 are retracted from the first optical axis 10, and the first lens group 110 moves into the vacant space, and the focal length range of the imaging optical system is set to the first focal length range. Fig. 3 shows a state where the overall length of the interchangeable lens 100 is longer, and Fig. 4 shows a state where the overall length of the interchangeable lens 100 is shorter. In both Figs. 3 and 4, imaging is possible.

[0020] The imaging optical system of the interchangeable lens 100 is composed of a first lens group 110 as a master lens, and second and third lens groups 210 and 310 as extender lenses, which are a type of conversion lens. When only the first lens group 110 is arranged on the first optical axis 10 and the second and third lens groups 210 and 310 are not on the first optical axis 10, the focal length range of the imaging optical system is set to a first focal length range. On the other hand, when the second and third lens groups 210 and 310 are inserted onto the first optical axis 10 on the image plane side of the first lens group 110, the focal length range of the imaging optical system is changed from the first focal length range to a second focal length range. In this case, the first focal length range is the wide-angle side with a short focal length, and the second focal length range is the telephoto side with a long focal length. In the following description, the expression "from the first focal length range to the second focal length range" is an abbreviation for "the focal length range of the imaging optical system changes from the first focal length range to the second focal length range."

[0021] Furthermore, the interchangeable lens 100 has a first holding frame 111 that holds a first lens group 110, which is a master lens, and a first cam barrel 108 and a second cam barrel 109 that move the first holding frame 111 along the first optical axis 10. This allows the first lens group 110 to move along the first optical axis 10 within each focal length range, enabling desired focus adjustment.

[0022] As will be described in detail later, the interchangeable lens 100 can switch between a first focal length range and a second focal length range without using a dedicated actuator. FIGS. 1 to 3 show, as an example, a case where the interchangeable lens 100 is set to the second focal length range on the telephoto side. When the user rotates the focus ring 103 toward the infinite direction from the second focal length range, the first lens group 110 moves toward the image plane in conjunction with the rotation. At this time, the second lens group 210 held by the second holding frame 211 and the third lens group 310 held by the third holding frame 311 retract from the first optical axis 10 to their respective retracted positions. By moving the first lens group 110 into the space thus created and further retracting it toward the image plane, the interchangeable lens 100 reaches the state shown in FIG. 4, thereby shortening the overall lens length.

[0023] In this embodiment, the master lens has a single-group configuration and the extender lens has a two-group configuration, but the present invention does not limit the configuration of the imaging optical system. For example, the master lens may have a multi-group configuration, or may include a separate, independent focus group or lens vibration isolation group, or the extender lens may have a single-group configuration. Furthermore, the conversion lens of the present invention may be a wide-angle conversion lens, a macro lens, or a reducer lens, rather than the extender lens of this embodiment.

[0024] The first lens group 110 includes an aperture group 120 that adjusts the amount of light, and is held by a first holding frame 111. The aperture group 120 includes an aperture drive unit (not shown), a plurality of aperture blades 121, and a drive ring 122, and the aperture drive unit adjusts the amount of light by changing the opening shape of the aperture blades 121 via the drive ring 122.

[0025] The shutter unit 14 disposed in the camera body 1 is a focal plane shutter equipped with a leading blade and a trailing blade, each of which is composed of a plurality of light-shielding blades. During imaging, the leading blade moves from a light-shielding position where it closes the exposure opening to an exposure position where it opens the exposure opening, thereby allowing light from the subject to pass toward the image plane. After that, when the set exposure time has elapsed, the trailing blade moves from the exposure position to the light-shielding position. At this time, the direction in which the leading blade and the trailing blade move is substantially the same as the direction of the short side of the image sensor 16 in the camera body 1, i.e., the Y-axis direction.

[0026] Note that light rays entering the interchangeable lens 100 from the subject side pass through the aperture shape formed by the aperture blades 121 while being subjected to the light refraction action of the first lens group 110. In the state of FIG. 3, the light rays are further subjected to the light refraction action of the second lens group 210 and the third lens group 310, and then pass through the opening of the shutter unit 14 to reach the image plane. On the other hand, in the state of FIG. 4, the light rays pass through the opening of the shutter unit 14 to reach the image plane without being subjected to the light refraction action of the second lens group 210 or the third lens group 310. In other words, the path (optical path) taken by the light rays differs depending on whether the imaging optical system is set to the first focal length range or the second focal length range.

[0027] The fixed barrel 106 is a fixed member fixed to the lens mount 102. The fixed barrel 106 has linear guide grooves (not shown) formed in three equal parts in the circumferential direction. The linear guide grooves engage with linear keys (not shown) provided on the linear guide barrel 107 to guide the linear guide barrel 107 along the first optical axis 10 while restricting movement of the linear guide barrel 107 in the rotational direction. A first cam barrel 108 is held on the outer periphery of the fixed barrel 106 by a bayonet (not shown) so as to be rotatable about the first optical axis 10, and the first cam barrel 108 is connected to the focus operation ring 103 via a connecting key (not shown). Similar to the fixed barrel 106, the linear guide barrel 107 has linear guide grooves (not shown) formed in three equal parts in the circumferential direction. The linear guide grooves engage with linear keys (not shown) provided on the first holding frame 111. By fitting the linear key into the linear guide groove, the first holding frame 111 is guided along the first optical axis 10 while restricting movement in the rotational direction. A second cam cylinder 109 is held on the outer periphery of the linear guide cylinder 107 by a bayonet (not shown) so as to be rotatable about the first optical axis 10.

[0028] First and second cam grooves (not shown) that fit with cam followers (not shown) provided on the linear guide barrel 107 and the first holding frame 111 are formed on the inner peripheral sides of the first cam barrel 108 and the second cam barrel 109, respectively, and are equally spaced apart in the circumferential direction. The second cam barrel 109 is configured to move integrally with the linear guide barrel 107 along the first optical axis 10. Meanwhile, the first cam barrel 108 and the second cam barrel 109 are restricted in rotation by a connecting key (not shown), and while moving relatively along the first optical axis 10, they rotate coupled together in the circumferential direction. Therefore, when the focus operation ring 103 is rotated by the user, the first holding frame 111 moves along the first optical axis 10 via the linear guide barrel 107 and the second cam barrel 109, with its movement in the rotational direction restricted.

[0029] In this embodiment, by adopting a lens barrel configuration with this so-called two-stage extension system, it is possible to move the first lens group 110 into the space created when the second lens group 210 and the third lens group 310 are retracted. In particular, as shown in Figure 4, when the first focal length range on the wide-angle side is set, the first lens group 110 can be retracted toward the image plane side, thereby shortening the overall length of the interchangeable lens 100 and achieving high portability.

[0030] Conventionally, there are known configurations that shorten the overall lens length in the optical axis direction by retracting a retractable lens group from the optical axis of an imaging optical system, narrowing the spacing between each lens group, and moving them to a retracted position where they are closer to each other. However, these configurations employ a retractable mechanism that transitions from an imaging state to a non-imaging state, and imaging is not possible in the retracted state where the overall lens length is shortened. Therefore, although highly portable, it takes time to transition from a retracted state in which imaging is restricted to a state in which imaging is possible.

[0031] On the other hand, the imaging optical system of this embodiment is set to the first focal length range by retracting the second lens group 210 and the third lens group 310, and imaging is possible even with the overall lens length shortened as shown in Fig. 4. In other words, compared to optical devices that employ a general retractable mechanism, it is possible to shorten the time required before imaging can begin, and it is possible to reduce loss of imaging opportunities while achieving high portability.

[0032] The base member 410 is a cylindrical fixed member fixed to the inner periphery of the fixed barrel 106. An interlocking member 400 that is movable along the first optical axis 10 is disposed in the space between the fixed barrel 106 and the base member 410. As will be described in detail later, the interlocking member 400 is a cylindrical moving member that rotates and retracts the second lens group 210 and the third lens group 310. On the inner periphery of the first cam barrel 108, third cam grooves (not shown) are formed in the circumferential direction, and each of the plurality of cam followers 420 provided on the interlocking member 400 is fitted thereto. The fixed barrel 106 is formed with rectilinear guide grooves (not shown) in the circumferential direction, and each of the plurality of cam followers 420 provided on the interlocking member 400 is fitted thereto. By fitting the cam followers 420 into the rectilinear guide grooves, the interlocking member 400 is guided along the first optical axis 10 while restricting movement in the rotational direction.

[0033] When the focus operation ring 103 is rotated by the user, the interlocking member 400 moves along the first optical axis 10 between the position shown in FIG. 3 and the position shown in FIG. 4 while its movement in the rotational direction is restricted via the first cam barrel 108. At this time, the direction of movement of the interlocking member 400 is opposite to the direction of movement of the first lens group 110. For example, as shown in FIG. 3, when the first lens group 110 moves toward the subject, the interlocking member 400 moves toward the image plane on the opposite side. Also, as shown in FIG. 4, when the first lens group 110 moves toward the image plane, the interlocking member 400 moves toward the subject on the opposite side.

[0034] The movement of each lens group in the interchangeable lens 100 of this embodiment will be described below with reference to FIGS. 5 to 13. FIG. 5 is an external view of the first lens group 110, the second lens group 210, and the third lens group 310 as viewed from the Z axis direction when the focal length range of the imaging optical system is set to the second focal length range. FIG. 6 is a cross-sectional view taken along line AA in FIG. 5. FIGS. 7(a) and 7(b) are external views of the first lens group 110, the second lens group 210, and the third lens group 310 when the focal length range of the imaging optical system is set to the second focal length range, and a cross-sectional view taken along line BB in FIG. 5, respectively. FIGS. 8(a) to 12(a) are external views of the first lens group 110, the second lens group 210, and the third lens group 310 during transition. FIGS. 8(b) to 13(b) are cross-sectional views taken along line BB in FIG. 5 during transition. 13(a) and 13(b) are respectively an external view and a cross-sectional view along line BB in Fig. 5 of the first lens group 110, the second lens group 210, and the third lens group 310 when the focal length range of the imaging optical system is set to the first focal length range. The external view and the cross-sectional view show the XZ plane from above in the Y-axis direction.

[0035] 5, the second lens group 210 is provided with a second rotation shaft 225, and the third lens group 310 is provided with a first rotation shaft 325. One end of each of the second rotation shaft 225 and the first rotation shaft 325 is fixed to a base member 410, and the second lens group 210 and the third lens group 310 are held rotatably relative to the base member 410. The direction in which the center of the second rotation shaft 225 extends and the direction in which the center of the first rotation shaft 325 extends are substantially parallel to each other and substantially perpendicular to the first optical axis 10. Furthermore, it is preferable that the second rotation shaft 225 and the first rotation shaft 325 have a double-supported structure in which they are divided into two parts and arranged symmetrically to each other when viewed from the direction of the first optical axis 10. In this embodiment, a double-supported structure is adopted, which is more advantageous than a cantilevered structure in terms of rigidity and durability, and as shown in Figure 13, the second rotation axis 225 and the first rotation axis 325 are positioned so that they overlap with the first lens group 110 in the direction of the first optical axis 10.

[0036] 6, the second connecting portion (third connecting portion) 440 is a gear, and is rotatably attached to the second rotating shaft 225 and the second holding frame 211. The second connecting portion 440 is provided with a first pressing portion 441 and a third pressing portion 442. The first biasing member 460 is a leaf spring, and is held in the gap between the first pressing portion 441 and the third pressing portion 442, and rotates about the second rotating shaft 225 in conjunction with the second connecting portion 440.

[0037] The third connecting portion (second connecting portion) 450 is a gear, and is rotatably attached to the first rotating shaft 325 and the second holding frame 311. The third connecting portion 450 is provided with a second pressing portion 451 and a fourth pressing portion 452. The second biasing member 470 is a leaf spring, and is held in the gap between the second pressing portion 451 and the fourth pressing portion 452, and rotates around the first rotating shaft 325 in conjunction with the third connecting portion 450.

[0038] 7(a), the first lens group 110, the second lens group 210, and the third lens group 310 are arranged in any position on the first optical axis 10, in that order from the subject side. When the imaging optical system is set to the second focal length range, the desired focus adjustment can be performed by moving the first lens group 110 along the first optical axis 10. At this time, the second lens group 210 and the third lens group 310 remain positioned within the aforementioned optical path and do not move.

[0039] As shown in FIGS. 3 and 4 , the first lens group 110 and the second lens group 210 are always disposed closer to the subject than the connection surface (mount surface) between the camera mount 7 and the lens mount 102 in the direction of the first optical axis 10. On the other hand, when the third lens group 310 is set to the second focal length range, at least a portion of the third lens group 310 overlaps with the mount surface. In this case, if a lens with a relatively large diameter such as the third lens group 310 were to be retracted around a rotation axis parallel to the first optical axis 10, a large space would be required in the outer diameter direction of the interchangeable lens 100. If a component that is difficult to avoid, such as the lens mount 102, were disposed in the space in the outer diameter direction when the third lens group 310 were to be retracted, the third lens group 310 would not be able to be completely retracted from the first optical axis 10.

[0040] In this embodiment, by making the first rotation axis 325 approximately perpendicular to the first optical axis 10, when the first focal length range is set, the third lens group 310 is retracted to a position on the subject side that does not overlap with the lens mount 102 in the direction of the first optical axis 10. In this way, even lenses with relatively large diameters can be completely retracted from the first optical axis 10 without being restricted by parts that are difficult to avoid, such as the lens mount 102.

[0041] Interlocking member 400 is provided with a first connecting portion (first connecting portion) 430 at a position on the inner circumferential side of base member 410. First connecting portion 430 is a rack, and moves along first optical axis 10 together with interlocking member 400. It is preferable that first connecting portions 430 are arranged in pairs so that they are symmetrical to each other when viewed from the direction of first optical axis 10.

[0042] The second lens group 210 is provided with a second connecting portion 440 and a second biasing member 470 that rotate about the second rotation axis 225. The third lens group 310 is provided with a third connecting portion 450 and a first biasing member 460 that rotate about the first rotation axis 325. Similar to the first connecting portion 430, the second connecting portion 440 and the second biasing member 470, and the third connecting portion 450 and the first biasing member 460 are preferably arranged in pairs so as to be symmetrical to each other when viewed from the direction of the first optical axis 10. The first connecting portion 430 and the third connecting portion 450 are connected by meshing of a rack and a gear, and the third connecting portion 450 and the second connecting portion 440 are connected by meshing of gears. In this embodiment, first biasing member 460 and second biasing member 470 are leaf springs formed from elastic sheet metal, but the present invention is not limited to this and may be a torsion spring, a tension coil spring, a compression coil spring, etc. Furthermore, elastic materials such as rubber and elastomer may also be used.

[0043] When the imaging optical system is set to the second focal length range, the rotational movement of the second holding frame 211 and the third holding frame 311 is restricted by a restricting portion (not shown). In this case, the first biasing member 460 presses the first biasing portion 351 provided on the third holding frame 311, thereby suppressing rattle of the third lens group 310 when the imaging optical system is at the second focal length. Similarly, the second biasing member 470 presses the second biasing portion 251 provided on the second holding frame 211, thereby suppressing rattle of the second lens group 210 when the imaging optical system is at the second focal length. As a result, the third optical axis 30 corresponding to the third lens group 310 and the second optical axis 20 corresponding to the second lens group 210 are stably held in a state where they are aligned with the first optical axis 10.

[0044] Dotted lines 460b and 470b indicate the unloaded shapes of the first biasing member 460 and the second biasing member 470. DT and DT2 are the deformation amounts of the first biasing member 460 and the second biasing member 470, respectively.

[0045] FIG. 8(a) shows the arrangement of the first lens group 110, the second lens group 210, and the third lens group 310 when the imaging optical system begins to transition from the second focal length range to the first focal length range. When the imaging optical system transitions from the second focal length range to the first focal length range, the first lens group 110 first begins to move in a first direction 115 that is substantially parallel to the first optical axis 10. Immediately after the transition begins, the first connecting portion 430 of the interlocking member 400 has not moved, and the second lens group 210 and the third lens group 310 remain inserted in the optical path and do not move. Therefore, as shown in FIG. 8(b), the deformation amount DT of the first biasing member 460 and the deformation amount DT2 of the second biasing member 470 do not change from the state shown in FIG. 7(b).

[0046] 9(a) and 9(b) show a state in which the first lens group 110 has moved beyond the desired focus adjustment range and further toward the image plane along the first direction 115. At this time, the first connecting portion 430 provided on the interlocking member 400 starts to move toward the subject side 116. The third connecting portion 450 and the first biasing member 460 rotate counterclockwise around the first rotation axis 325 as the first connecting portion 430, which is connected by the aforementioned meshing, moves toward the subject side. Similarly, the second connecting portion 440 and the second biasing member 470 rotate clockwise around the second rotation axis 225 as the third connecting portion 450, which is connected by the aforementioned meshing, rotates. However, immediately after the rotation starts, the first biasing member 460 presses the first biasing portion 351, and the second biasing member 470 presses the second biasing portion 251, so the third holding frame 311 and the second holding frame 211 do not move.

[0047] 10(a) and 10(b) show a state in which the first connector 430 has further advanced in the subject-side direction 116. As the movement of the first connector 430 advances and the third connector 450 and the second connector 440 rotate by a certain angle or more, the first biasing member 460 and the second biasing member 470 begin to press the third biasing portion 352 and the fourth biasing portion 252, respectively. This changes the biasing direction of the third holding frame 311 and the second holding frame 211, and they begin to move toward their retracted positions. As the first connector 430 thus moves in the subject-side direction 116, the third lens group 310 and the second lens group 210 begin to retract in the third direction 315 and the second lens group 210 begin to retract in the second direction 215. DM and DM2 are the deformation amounts of the first biasing member 460 and the second biasing member 470 during the movement of the third holding frame 311 and the second holding frame 211, respectively.

[0048] 11(a) and 11(b) show the state immediately after the third holding frame 311 and the second holding frame 211 have rotated to positions where they can move. The third holding frame 311 and the second holding frame 211 are restricted from rotational movement in the retraction direction by a restricting portion (not shown).

[0049] 12(a) and 12(b) show a state in which the transition from the second focal length to the first focal length is complete. From the state in which the rotational movement of the third holding frame 311 and the second holding frame 211 was restricted (FIG. 11), the first connecting portion 430 has further advanced toward the subject side 116. Accordingly, the third connecting portion 450 and the first biasing member 460, and the second connecting portion 440 and the second biasing member 470 have also further rotated. Thus, the rotation ranges of the third connecting portion 450, the second connecting portion 440, the first biasing member 460, and the second biasing member 470 are wider than the rotation ranges of the retracted third holding frame 311 and the second holding frame 211. DW and DW2 are the deformation amounts of the first biasing member 460 and the second biasing member 470, respectively.

[0050] 13(a) and 13(b) show the state when the first lens group 110 is retracted to the furthest image plane side by focus adjustment in the first focal length range. At this time, the first connecting portion 430 does not move from the state shown in FIG. 12, and the deformation amounts of the first biasing member 460 and the second biasing member 470 are the same as those in FIG. 12.

[0051] 10 to 13, when the second lens group 210 and the third lens group 310 are retracted in the second direction 215 and the third direction 315, respectively, and reach retracted positions outside the optical path, the first lens group 110 moves into the space created by the retraction. At this time, the maximum rotation angle of the second lens group 210 and the third lens group 310 is 90 degrees or less. The second lens group 210 and the third lens group 310 are retracted into the space created by the movement of the interlocking member 400. When the second focal length range is set, the third lens group 310 is positioned closer to the image plane than the second lens group 210, but when the first focal length range is set, the third lens group 310 is positioned closer to the subject than the second lens group 210.

[0052] In this embodiment, the third lens group 310 is heavier than the second lens group 210, and has a longer retraction distance. In this configuration, by arranging the first rotation shaft 325 in the opposite phase to the third direction 315 when viewed from the direction of the first optical axis 10, retraction in the third direction 315, which has a longer retraction distance than the second direction 215, is possible. Here, focusing on the retraction directions of the second lens group 210 and the third lens group 310, the second direction 215 and the third direction 315 are opposite directions across the first optical axis 10. By arranging them in opposite directions, it is possible to cancel out and reduce vibrations and fluctuations in the center of gravity position that occur when the second lens group 210 moves in the second direction 215 and the third lens group 310 moves in the third direction 315.

[0053] 7 to 13 are external views and cross-sectional views of the XZ plane as viewed from above in the Y-axis direction. As shown in Fig. 2, the electrical connection member 101 is disposed on the lower side on the Y-axis, so the second lens group 210 and the third lens group 310 are retracted to a different phase from the electrical connection member 101. This allows for efficient use of the space around the lens mount 102, making it possible to prevent the interchangeable lens 100 from becoming larger.

[0054] In the state shown in FIG. 7 , the direction in which the centers of the second rotation shaft 225 and the first rotation shaft 325 extend is substantially parallel to the Y-axis. The direction in which the centers of the second rotation shaft 225 and the first rotation shaft 325 extend is substantially aligned with the short side direction of the image sensor 16 in the camera body 1, i.e., the direction in which the light-shielding blades of the shutter unit 14 travel. During image capture, the leading blade travels from the light-shielding position to the exposure position and is stopped by colliding with a stopper (not shown). In particular, vibrations caused by the collision of the leading blade occur during exposure, and if the vibrations caused by the collision are transmitted to the interchangeable lens 100, they may degrade the image quality of the captured image. Therefore, in this embodiment, the retraction direction of the second lens group 210 and the third lens group 310 is substantially perpendicular to the travel direction of the leading blades.

[0055] Furthermore, the Y-axis direction, which is the direction in which the centers of the second rotation axis 225 and the first rotation axis 325 extend, is generally parallel to the direction in which a user places the camera body 1 with the interchangeable lens 100 attached. In other words, when a user places the camera body 1, the interchangeable lens 100 receives an impact in the Y-axis direction, which is different from the direction in which the second lens group 210 and the third lens group 310 retract. In this way, this embodiment is configured to be sufficiently rigid and less susceptible to image quality degradation even against impacts generated by user handling.

[0056] Even after the second lens group 210 and the third lens group 310 have completed retraction, the first lens group 110 can still move in the first direction 115. Furthermore, when the first lens group 110 moves in the first direction 115 and completes its movement to an arbitrary position, the transition from the second focal length range to the first focal length range is completed ( FIG. 13 ). In the state of FIG. 13 , the first lens group 110 is positioned closest to the image plane compared to the states shown in FIGS. 7 to 12 . In other words, by transitioning from the second focal length range to the first focal length range, it is possible to shorten the overall length of the interchangeable lens 100.

[0057] Furthermore, as described above, imaging is possible even when the second lens group 210 and the third lens group 310 are retracted and the first lens group 110 has moved toward the image plane side, as shown in Fig. 13, resulting in the shortest overall lens length. When the imaging optical system is set to the first focal length range, the desired focus adjustment (focus adjustment) is performed by moving the first lens group 110 along the first optical axis 10, just as when the imaging optical system is set to the second focal length range. When the first lens group 110 moves, the second lens group 210 and the third lens group 310 remain in the optical path and do not move.

[0058] Up to this point, we have described the case of transitioning from the second focal length range to the first focal length range. However, conversely, when transitioning from the first focal length range to the second focal length range, the procedure is reversed from that shown in Figures 7 to 13. For example, when the first lens group 110 is moved from the image plane side to the subject side by a user's operation, the second lens group 210 and the third lens group 310 rotate and move from a retracted position outside the optical path to a position within the optical path where they are positioned on the first optical axis 10. After the third holding frame 311 and the second holding frame 211 reach their limiting ends (not shown), further movement of the first interlocking member causes the deformation amounts of the first biasing member 460 and the second biasing member 470 to become DT and DT2, respectively, and a desired biasing force is applied (Figure 7).

[0059] When transitioning from the second focal length range to the first focal length range again, the second lens group 210 and the third lens group 310 are moved to retracted positions outside the optical path by the same user operation. In this way, in this embodiment, the interchangeable lens 100 is configured to be able to switch between the first focal length range and the second focal length range without using a dedicated actuator.

[0060] Fig. 14 is a graph showing the amount of deformation of the first biasing member 460 when the imaging optical system transitions from the first focal length range to the second focal length range. In Fig. 14, the horizontal axis represents the number of steps, and the vertical axis schematically represents the amount of deformation of the first biasing member 460. Here, the number of steps represents the number of steps into which the transition from the second focal length range to the first focal length range is divided.

[0061] As described above, in response to the transition from the first focal length range to the second focal length range, after the third holding frame 311 reaches the limiting end, the third connecting portion 450 and the first biasing member 460 further rotate, and the deformation amount of the first biasing member 460 becomes DT, thereby generating the desired biasing force.

[0062] The relationship between the deformation amount DT of the first biasing member 460 when the focal length range is the second focal length range and the deformation amount DM of the first biasing member 460 during the transition from the first focal length range to the second focal length range is DT>DM. Also, the relationship between the deformation amount DW of the first biasing member 460 when the focal length range is the first focal length range and the deformation amount DM during the transition is DW>DM.

[0063] In other words, the force (torque) required to drive the interlocking member 400 during switching is smaller than the force (torque) required when the third holding frame 311 is positioned on the first optical axis 10 or in the retracted position. Therefore, compared to when the force reaches its maximum during switching of the biasing direction in a toggle mechanism or the like, this embodiment achieves a structure to eliminate backlash in the third holding frame 311 with minimal biasing force, thereby reducing power consumption when switching using an actuator. Furthermore, in a toggle mechanism, a force is generated in the opposite direction after the operating force reaches its maximum, resulting in a sudden change in operating force when switching manually. However, this embodiment eliminates such a sudden change in operating force, thereby reducing concerns about impaired operability. Furthermore, in a toggle mechanism, when changing the biasing direction of the biased member and rotating it, a separate rotation axis for the biasing member is required. In this embodiment, the same rotation axis as the first rotation axis 325, which is the rotation center of the third holding frame 311, is used, allowing for a compact biasing structure.

[0064] The holding accuracy of the third holding frame 311 at the retracted position (first focal length) is not directly related to optical performance, and does not require as much biasing force as at the inserted position (second focal length), so the relationship between the deformation amounts of the first biasing member 460 is DT>DW>DM. This makes it possible to minimize the force and rotation amount required for the switching operation.

[0065] The amount of deformation of the first biasing member 460 has been described, but the same applies to the amount of deformation of the second biasing member 470, and the relationship is DT2>DW2>DM2.

[0066] Focusing on the second focal length range and the first focal length range, the imageable range extends from the closest point to the infinity point, and the movement of the second lens group 210 and the third lens group 310 must be limited. However, due to various manufacturing errors and assembly variations in the interchangeable lens 100 and the camera body 1, there is a risk that the timing at which the movement of the first lens group 110 and the interlocking member 400 begins and ends may differ. Therefore, when transitioning from the second focal length range to the first focal length range, the deformation amount of the first biasing member 460 changes from DT to DM with a delay after the first lens group 110 begins moving toward the image plane. Furthermore, the deformation amount of the first biasing member 460 reaches DW before the movement of the first lens group 110 completes. In this manner, in this embodiment, by differentiating the trajectory along which the first lens group 110 is moved from the trajectory along which the interlocking member 400 is moved, a configuration is achieved which is less susceptible to the effects of manufacturing errors and assembly variations.

[0067] In this embodiment, the weight of the third lens group 310 and the third holding frame 311 is heavier than the weight of the second lens group 210 and the second holding frame 211. Furthermore, the distance from the first rotation axis 325 to the center of gravity of the third lens group 310 and the third holding frame 311 is longer than the distance from the second rotation axis 225 to the center of gravity of the second lens group 210 and the second holding frame 211. Therefore, it is preferable that the biasing force of the first biasing member 460 is greater than the biasing force of the second biasing member 470. Because backlash exists between each connecting portion, when the same connecting member is used, the amount of rotation decreases toward the later stage. The third connecting portion 450 is first interlocked with the first connecting portion 430, and the relationship between the deformation amount DT of the first biasing member 460 and the deformation amount DT2 of the second biasing member 470 is set to be DT>DT2, thereby making the biasing force of the first biasing member 460 larger. In this manner, in this embodiment, the difference in biasing force is achieved by devising the order of connection, but other configurations may also be used, such as changing the spring constant of the biasing member, changing the diameter of the connecting portion (gear), or changing the rotatable angle of each holding frame.

[0068] As described above, the first lens group 110 of this embodiment moves toward the image plane by moving in the first direction 115 that is substantially parallel to the first optical axis 10. The second lens group 210 moves in the second direction 215, thereby moving toward the subject in the direction of the first optical axis 10 and moving away from the first optical axis 10 in the radial direction. Furthermore, the third lens group 310 moves in the third direction 315, thereby moving toward the subject in the direction of the first optical axis 10 and moving away from the second lens group 210 in the radial direction. With this configuration, the transition from the second focal length range to the first focal length range is completed.

[0069] In this embodiment, the built-in conversion lens is configured by combining the second lens group 210 and the third lens group 310, but the present invention is not limited to this. For example, a configuration may be adopted in which switching between the first focal length range and the second focal length range is achieved by at least the second lens group 210 alone. In this case, the third lens group 310 may be a neutral density filter, a protective filter, or a polarizing filter.

[0070] The disclosure of this embodiment includes the following configuration. (Configuration 1) a first lens group; and a second lens group that rotates about a first rotation axis and moves away from the optical axis of the first lens group to change the focal length range of the optical system from the second focal length range to the first focal length range; a first biasing member that rotates about the first rotation axis and biases the second lens group, an amount of deformation of the first biasing member when the focal length range is the second focal length range is greater than an amount of deformation of the first biasing member when the focal length range transitions from the first focal length range to the second focal length range. (Configuration 2) an interlocking member having a first connecting portion; a second connecting portion that rotates about the first rotation axis, The optical device described in configuration 1, characterized in that when the focal length range transitions from the first focal length range to the second focal length range, the first connecting portion connects to the second connecting portion to rotate the first biasing member, and the first biasing member deforms to bias the second lens group. (Configuration 3) 3. The optical device according to configuration 1 or 2, wherein the first lens group includes a focus lens that adjusts the focus of the optical system by moving along the optical axis. (Configuration 4) further comprising an operating member rotatable around the optical axis, the first lens group includes a focus lens that adjusts the focus of the optical system by moving along the optical axis, 4. The optical device according to configuration 2 or 3, wherein the focus lens and the interlocking member move in conjunction with the rotation of the operating member. (Configuration 5) 5. The optical device according to any one of configurations 1 to 4, wherein a deformation amount of the first biasing member when the focal length range is the first focal length range is greater than a deformation amount of the first biasing member when the focal length range transitions from the first focal length range to the second focal length range. (Configuration 6) The optical device described in configuration 5, wherein the deformation amount of the first biasing member when the focal length range is the second focal length range is greater than the deformation amount of the first biasing member when the focal length range is the first focal length range. (Configuration 7) 7. The optical apparatus according to any one of configurations 1 to 6, wherein the first rotation axis is perpendicular to the optical axis. (Configuration 8) a third lens group that rotates about a second rotation axis and moves away from the optical axis to change the focal length range from the second focal length range to the first focal length range; a second biasing member that rotates about the second rotation axis and biases the third lens group, 8. The optical device according to any one of configurations 1 to 7, wherein a deformation amount of the second biasing member when the focal length range is the second focal length range is greater than a deformation amount of the second biasing member when the focal length range transitions from the first focal length range to the second focal length range. (Configuration 9) a second connecting portion that rotates around the first rotation axis; a third connection portion that rotates about the second rotation axis, 9. The optical device of configuration 8, wherein when the focal length range transitions from the first focal length range to the second focal length range, the second connecting portion connects to the third connecting portion to rotate the second biasing member, and the second biasing member deforms to bias the third lens group. (Configuration 10) 10. The optical device of claim 8, wherein a deformation amount of the second biasing member when the focal length range is the first focal length range is greater than a deformation amount of the second biasing member when the focal length range transitions from the first focal length range to the second focal length range. (Configuration 11) 11. The optical device of claim 10, wherein the amount of deformation of the second biasing member when the focal length range is the second focal length range is greater than the amount of deformation of the second biasing member when the focal length range is the first focal length range. (Configuration 12) 12. The optical apparatus according to any one of configurations 8 to 11, wherein the second axis of rotation is perpendicular to the optical axis. (Configuration 13) 13. The optical device according to any one of configurations 8 to 12, wherein a deformation amount of the first biasing member when the focal length range is the second focal length range is greater than a deformation amount of the second biasing member when the focal length range is the second focal length range. (Configuration 14) The optical device according to any one of configurations 8 to 13, wherein when the focal length range is the second focal length range, the third lens group is located closer to the image plane than the first lens group, and the second lens group is located closer to the image plane than the first lens group and the third lens group. (Configuration 15) a body having a first mount; a second mount connectable to the first mount; a first lens group; and a second lens group that rotates about a first rotation axis and moves away from the optical axis of the first lens group to change the focal length range of the optical system from the second focal length range to the first focal length range; a first biasing member that rotates about the first rotation axis and biases the second lens group, an amount of deformation of the first biasing member when the focal length range is the second focal length range is greater than an amount of deformation of the first biasing member when the focal length range transitions from the first focal length range to the second focal length range.

[0071] 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 gist of the present invention. [Explanation of symbols]

[0072] 100 Interchangeable lenses (optical equipment) 110 First lens group (first lens group) 310 Third lens group (Second lens group) 325 First Rotation Axis 460 first biasing member

Claims

1. a first lens group; and a second lens group that rotates about a first rotation axis and moves away from the optical axis of the first lens group to change the focal length range of the optical system from a second focal length range to the first focal length range; a first biasing member that rotates about the first rotation axis and biases the second lens group, an amount of deformation of the first biasing member when the focal length range is the second focal length range is greater than an amount of deformation of the first biasing member when the focal length range transitions from the first focal length range to the second focal length range.

2. an interlocking member including a first connecting portion; a second coupling portion that rotates about the first rotation axis, 2. The optical device according to claim 1, wherein, when the focal length range transitions from the first focal length range to the second focal length range, the first connecting portion connects to the second connecting portion to rotate the first biasing member, and the first biasing member deforms to bias the second lens group.

3. 3. The optical device according to claim 1, wherein the first lens group includes a focus lens that adjusts the focus of the optical system by moving along the optical axis.

4. further comprising an operating member rotatable around the optical axis, the first lens group includes a focus lens that adjusts the focus of the optical system by moving along the optical axis, 3. The optical device according to claim 2, wherein the focus lens and the interlocking member move in conjunction with the rotation of the operating member.

5. 3. The optical device according to claim 1, wherein a deformation amount of the first biasing member when the focal length range is the first focal length range is larger than a deformation amount of the first biasing member when the focal length range transitions from the first focal length range to the second focal length range.

6. 6. The optical device according to claim 5, wherein a deformation amount of the first biasing member when the focal length range is the second focal length range is larger than a deformation amount of the first biasing member when the focal length range is the first focal length range.

7. 3. The optical device according to claim 1, wherein the first rotation axis is perpendicular to the optical axis.

8. a third lens group that rotates about a second rotation axis and moves away from the optical axis to change the focal length range from the second focal length range to the first focal length range; a second biasing member that rotates about the second rotation axis and biases the third lens group, 3. The optical device according to claim 1, wherein a deformation amount of the second biasing member when the focal length range is the second focal length range is larger than a deformation amount of the second biasing member when the focal length range transitions from the first focal length range to the second focal length range.

9. a second connecting portion that rotates about the first rotation axis; a third connection portion that rotates about the second rotation axis, 9. The optical device according to claim 8, wherein, when the focal length range transitions from the first focal length range to the second focal length range, the second connecting portion connects to the third connecting portion to rotate the second biasing member, and the second biasing member deforms to bias the third lens group.

10. 9. The optical device according to claim 8, wherein a deformation amount of the second biasing member when the focal length range is the first focal length range is larger than a deformation amount of the second biasing member when the focal length range transitions from the first focal length range to the second focal length range.

11. 11. The optical device according to claim 10, wherein a deformation amount of the second biasing member when the focal length range is the second focal length range is greater than a deformation amount of the second biasing member when the focal length range is the first focal length range.

12. 9. The optical apparatus of claim 8, wherein the second axis of rotation is perpendicular to the optical axis.

13. 9. The optical device according to claim 8, wherein a deformation amount of the first biasing member when the focal length range is the second focal length range is larger than a deformation amount of the second biasing member when the focal length range is the second focal length range.

14. 9. The optical device according to claim 8, wherein, when the focal length range is the second focal length range, the third lens group is located closer to the image plane than the first lens group, and the second lens group is located closer to the image plane than the first lens group and the third lens group.

15. a body having a first mount; a second mount connectable to the first mount; a first lens group; and a second lens group that rotates about a first rotation axis and moves away from the optical axis of the first lens group to change the focal length range of the optical system from a second focal length range to the first focal length range; a first biasing member that rotates about the first rotation axis and biases the second lens group, an amount of deformation of the first biasing member when the focal length range is the second focal length range is greater than an amount of deformation of the first biasing member when the focal length range transitions from the first focal length range to the second focal length range.

Images