Optical instruments and imaging devices

Abstract

To solve the problem that a large space is required for a conversion lens to be inserted or retracted in the inside of an optical apparatus and it is difficult to reduce the size of the optical apparatus.SOLUTION: The optical apparatus comprises a first lens group, a second lens group that changes the focal distance range of an optical system from a first focal distance range to a second focal distance range, a guide cylinder which has a rectilinear guide groove, a cam barrel that is rotatably held to the guide cylinder, and an interlock member that has a first connection part. The cam barrel includes a first cam groove that moves the first lens group, a second cam groove, different from the first cam barrel, that moves the interlock member. When the focal distance range of the optical system transitions from the second focal distance range to the first focal distance range, the first lens group is moved in the optical axis direction by the rectilinear guide groove and the first cam groove.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an optical instrument, and more particularly to an optical instrument with a variable focal length range. [Background technology]

[0002] 2. Description of the Related Art It is known that in optical devices such as digital cameras, video cameras, and interchangeable lenses, the focal length range can be changed by inserting a conversion lens into the optical path.

[0003] Patent Document 1 discloses a technology for moving a conversion lens built into a camera body between an inserted position where it is inserted into the optical path and a retracted position where it is retracted outside the optical path. The built-in conversion lens described therein is retracted into the space between the prism that guides the subject image to the viewfinder and the strobe stored above the lens barrel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-311828 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the built-in conversion lens described in Patent Document 1 is moved to the retracted position using a dedicated actuator, which requires space inside the lens to accommodate the actuator, making it difficult to prevent the lens from becoming too large.

[0006] Therefore, an object of the present invention is to provide an optical device that incorporates a conversion lens, thereby preventing the lens from becoming larger while ensuring space for inserting or retracting the built-in conversion lens. [Means for solving the problem]

[0007] In order to achieve the above object, an optical apparatus according to one aspect of the present invention includes a first lens group, a second lens group that changes the focal length range of an optical system from a first focal length range to a second focal length range, a guide barrel having a rectilinear guide groove, a cam barrel rotatably held on the guide barrel, and an interlocking member having a first connecting portion, wherein the cam barrel has a first cam groove that moves the first lens group, and a second cam groove that is different from the first cam groove and moves the interlocking member, and when the focal length range of the optical system shifts from the second focal length range to the first focal length range, the first lens group is moved by the rectilinear guide groove and the first cam groove. Parallel to the optical axis on the image plane side and the interlocking member is moved by the linear guide groove and the second cam groove. Parallel to the optical axis, on the subject side and the first connecting portion moves the second lens group out of the optical path of the first lens group. [Effects of the Invention]

[0008] According to the present invention, an optical device can be provided that can change the focal length range by retracting the built-in conversion lens, and can prevent the lens from becoming too large by improving the efficiency of the configuration for retracting the built-in conversion lens. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a front perspective view of an interchangeable lens and a camera body in the second focal length range according to an embodiment of the present invention. [Figure 2] FIG. 2 is a rear perspective view of an interchangeable lens and a camera body in the second focal length range according to an embodiment of the present invention. [Figure 3] 1 is a cross-sectional view of an interchangeable lens and a camera body according to an embodiment of the present invention. [Figure 4] FIG. 2 is a cross-sectional view of an interchangeable lens and a camera body in the case of a first focal length range according to an embodiment of the present invention. [Figure 5]FIG. 2 is an external view of each lens group in an interchangeable lens in the second focal length range according to an embodiment of the present invention. [Figure 6] 1A and 1B are external views of each lens group in an interchangeable lens at the start of transition according to an embodiment of the present invention. [Figure 7] 10A and 10B are external views of each lens group in the interchangeable lens when transition is complete according to an embodiment of the present invention. [Figure 8] 1A and 1B are external views of each lens group of an interchangeable lens in the case of a first focal length range according to an embodiment of the present invention. [Figure 9] FIG. 2 is a perspective view of each lens group in an interchangeable lens in the case of a second focal length range according to an embodiment of the present invention. [Figure 10] 1A and 1B are perspective views of each lens group of an interchangeable lens at the start of transition according to an embodiment of the present invention. [Figure 11] 10A and 10B are perspective views of the lens groups in the interchangeable lens when the transition is complete according to an embodiment of the present invention. [Figure 12] FIG. 2 is a perspective view of each lens group of an interchangeable lens in the case of a first focal length range according to an embodiment of the present invention. [Figure 13] 10 is a graph showing the relationship between the cam barrel rotation angle and the position in the optical axis direction of an interchangeable lens according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The same reference numerals indicate the same or corresponding parts throughout the drawings. Note that, in this embodiment, an interchangeable lens will be described as an example of an optical device, but various modifications and changes can be made to other optical devices, such as an integrated lens camera, within the scope of the present invention.

[0011] 1 and 2 show the appearance of an interchangeable lens 100, which is an optical device according to an embodiment of the present invention, and a digital camera (hereinafter referred to as a camera body) 1 to which the interchangeable lens 100 is detachably attached. FIG. 1 is a front perspective view of the interchangeable lens 100 (in a second focal length range) and the camera body 1 according to this embodiment. FIG. 2 is a rear perspective view of the interchangeable lens 100 (in a second focal length range) and the camera body 1 according to this embodiment (with the interchangeable lens 100 removed). 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 housed in the interchangeable lens 100 extends (the direction along the optical axis), is defined as the X-axis direction, and 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 are collectively referred to as the Z / Y-axis direction. Furthermore, the rotation direction around the Z-axis is defined as the pitch direction, and the rotation direction around the Y-axis is defined as the yaw direction. The pitch direction and yaw direction (hereinafter collectively referred to as the pitch / yaw direction) are directions of rotation around two axes, the Z axis and the Y axis, which are perpendicular to each other.

[0012] The camera body 1 shown in FIG. 1 has a grip section 2 on the left side when viewed from the front (right side when viewed from the back) that allows 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 camera body 1 is in a power-off state, if the user turns on the power operation section 3, power begins to flow, the camera body 1 enters a power-on state, and a computer program such as an origin detection process for the focus group (focus lens) is executed, and the camera enters an image capture standby state. Conversely, when the camera body 1 is in a power-on state, if the user turns off the power operation section 3, the camera body 1 enters a power-off state.

[0013] Furthermore, 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 autoexposure control, and 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.

[0014] The interchangeable lens 100 includes a lens mount 102 that can be mechanically connected to a camera mount 7 provided on the camera body 1. Furthermore, the interchangeable lens 100 has an electrical connection member 101, and is electrically connected to the camera body 1. As shown in FIG. 2 , the electrical connection member 101 in this embodiment 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.

[0015] The interchangeable lens 100 houses an imaging optical system that forms an image of a subject by focusing light from the subject on an image plane. A focus ring (operation member) 103 that can be rotated around the optical axis by a user's operation is provided on the outer periphery of the interchangeable lens 100. For example, in manual focus mode, when the user rotates the focus 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 ring 103. In this way, the user can perform the desired focus adjustment.

[0016] 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 assigned with various functions. When the camera body 1 is powered on and the still image 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.

[0017] Next, the positional relationship of the members (components) constituting the interchangeable lens 100 of this embodiment will be described 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. FIG. 3 is a cross-sectional view showing the XZ plane of the interchangeable lens 100 (second focal length range) and camera body 1 of this embodiment from below in the Y-axis direction. FIG. 4 is a cross-sectional view showing the XZ plane of the interchangeable lens 100 (first focal length range) and camera body 1 of this embodiment from below in the Y-axis direction. The center line shown here substantially coincides with the first optical axis 10 determined by the first lens group 110, and will hereinafter be referred to as the X-axis. Furthermore, the image plane 16, which is the image sensor, is perpendicular to the first optical axis 10 and is therefore synonymous with the YZ plane.

[0018] Fig. 3 shows a case where the focal length range of the imaging optical system is the second focal length range when the second lens group 210 and the third lens group 310 are arranged on the image plane side of the first lens group 110. Fig. 4 shows a case where the focal length range of the imaging optical system is the first focal length range when 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. Here, Fig. 3 shows a state where the overall length of the interchangeable lens 100 in this embodiment is longer, and Fig. 4 shows a state where the overall length is shorter, and in both cases imaging is possible.

[0019] 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 a first optical axis 10 and the remaining 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 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. The first focal length range is the wide-angle side, which provides a short focal length, and the second focal length range is the telephoto side, which provides a long focal length. 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 in the direction of the first optical axis 10. This allows the first lens group 110 to move in the direction of the first optical axis 10 within each focal length range, enabling desired focus adjustment (focus adjustment).

[0020] In the following description, expressions such as "from a first focal length range to a second focal length range" are abbreviations for "the focal length range of the imaging optical system is from the first focal length range to the second focal length range."

[0021] As will be described in detail later, the interchangeable lens 100 of the present invention can switch between a first focal length range and a second focal length range without using a dedicated actuator. FIGS. 1 to 3 show the second focal length range on the telephoto side. When the user rotates the focus ring 103 toward the infinite focal length range from the second focal length range shown in the figures, 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 a holding frame (not shown) 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.

[0022] 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 not be an extender lens as shown in this embodiment, but may instead be a wide-angle conversion lens, a macro lens, or a reducer lens.

[0023] The first lens group 110 has an aperture group 120 that adjusts the amount of light, and is held by a first holding frame 111. The aperture group 120 is made up of 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.

[0024] The shutter unit 14 disposed in the camera body 1 is a focal plane shutter having 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 16. 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 in the camera body 1, i.e., the Y-axis.

[0025] 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 shown in FIG. 3, the light is further subjected to the light refraction action of the second lens group 210 and the third lens group 310, passes through the opening of the shutter unit 14, and is imaged on the image plane 16. On the other hand, in the state shown in FIG. 4, the light passes through the opening of the shutter unit 14 and is imaged on the image plane 16 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 focal length range of the imaging optical system is the first focal length range or the second focal length range.

[0026] 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 restrict movement of the linear guide barrel 107 in the rotational direction and guide the linear guide barrel 107 toward the first optical axis 10. 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. The linear key is fitted into the linear guide groove, thereby restricting the movement of the first holding frame 111 in the rotational direction and guiding the first holding frame 111 in the direction of the first optical axis 10. 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.

[0027] 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, respectively, are formed on the inner peripheral sides of the first cam barrel 108 and the second cam barrel 109, 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 in the direction of 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 move relatively in the direction of the first optical axis 10 while rotating in a circumferential direction. Therefore, when the focus operation ring 103 is rotated by the user, the first holding frame 111 moves along the direction of 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.

[0028] In this embodiment, by adopting a lens barrel configuration of 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 focal length range of the imaging optical system is in the first focal length range on the wide-angle side, the first lens group 110 can be retracted toward the image plane, thereby shortening the overall length of the interchangeable lens 100 and achieving high portability. Note that the configuration of the lens barrel in this embodiment is a well-known technology that has been adopted in many optical devices, so a detailed description thereof will be omitted here.

[0029] In the past, there have been cameras 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 cameras employed a retractable mechanism that transitioned from an imaging state to a non-imaging state, and imaging was not possible in the retracted state with the overall lens length shortened. Therefore, although highly portable, it took extra time to transition from a retracted state in which imaging was limited to a state in which imaging was possible.

[0030] In contrast to the conventional technology, in this embodiment, the focal length range of the imaging optical system becomes 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 suppress loss of imaging opportunities while achieving high portability.

[0031] The retraction base 410 is a cylindrical fixed member fixed to the inner periphery of the fixed barrel 106. An interlocking member 400 that is movable in the direction of the first optical axis 10 is disposed in the space between the fixed barrel 106 and the retraction base 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) that fit in correspondence with each of the multiple cam followers 420 provided on the interlocking member 400 are formed in the circumferential direction. The fixed barrel 106 is formed in the circumferential direction with linear guide grooves (not shown) that fit in correspondence with each of the multiple cam followers 420 provided on the interlocking member 400. The cam follower 420 is fitted into the linear guide groove, thereby restricting the movement of the interlocking member 400 in the rotational direction and guiding the interlocking member 400 in the direction of the first optical axis 10.

[0032] When the focus operation ring 103 is rotated by the user, the interlocking member 400 moves along the first optical axis 10 between the positions shown in FIG. 3 and 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 has moved toward the subject, the interlocking member 400 has moved toward the image plane on the opposite side. Furthermore, as shown in FIG. 4, when the first lens group 110 has moved toward the image plane, the interlocking member 400 has moved toward the subject on the opposite side.

[0033] Next, the movement of each lens group of the interchangeable lens 100 in this embodiment will be described in detail using FIGS. 5 to 8. FIGS. 5 to 8 are diagrams for explaining the appearance of the first lens group 110, the second lens group 210, and the third lens group 310. The above-mentioned XZ plane is shown from below in the Y-axis direction, illustrating the transition from the second focal length range to the first focal length range. FIG. 5 is an appearance diagram of each lens group in the interchangeable lens 100 in this embodiment (second focal length range). FIG. 6 is an appearance diagram of each lens group in the interchangeable lens 100 in this embodiment (at the start of the transition). FIG. 7 is an appearance diagram of each lens group in the interchangeable lens 100 in this embodiment (at the completion of the transition). FIG. 8 is an appearance diagram of each lens group in the interchangeable lens 100 in this embodiment (first focal length range).

[0034] 5 shows a case where the focal length range of the imaging optical system is the second focal length range, and it can be seen that the first lens group 110, the second lens group 210, and the third lens group 310 are arranged at arbitrary positions on the first optical axis 10, in that order from the subject side. When the focal length range of the imaging optical system is 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 in the aforementioned optical path and do not move.

[0035] The second lens group 210 is provided with a first rotation shaft 225, and the third lens group 310 is provided with a second rotation shaft 325. One end of each of the first rotation shaft 225 and the second rotation shaft 325 is fixed to the retraction base 410, and the second lens group 210 and the third lens group 310 are rotatably held relative to the retraction base 410. The direction in which the center of the first rotation shaft 225 extends and the direction in which the center of the second rotation shaft 325 extends are substantially parallel to each other and substantially perpendicular to the first optical axis 10. Furthermore, it is more preferable that the first rotation shaft 225 and the second rotation shaft 325 have a double-supported structure in which they are divided into two halves 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 8, the first rotation axis 225 and the second 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] Interlocking member 400 is provided with a first connecting portion 430 (rack) at a position on the inner periphery of retracting base 410. First connecting portion 430 is configured to move along first optical axis 10 integrally with interlocking member 400. It is more preferable that first connecting portions 430 are arranged in pairs so as to be symmetrical to each other when viewed from the direction of first optical axis 10.

[0037] The second lens group 210 is provided with a second connecting portion 440 (gear) centered on the first rotation axis 225, and the third lens group 310 is provided with a third connecting portion 450 (gear) centered on the second rotation axis 325. Similar to the first connecting portion 430, the second connecting portion 440 and the third connecting portion 450 are more preferably arranged in pairs so that they are 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.

[0038] When the imaging optical system transitions from the second focal length range to the first focal length range, first lens group 110 first starts moving in first direction 115 that is substantially parallel to first optical axis 10 (FIG. 6). Immediately after the transition begins, first connecting portion 430 provided on interlocking member 400 has not yet moved, and second lens group 210 and third lens group 310 remain inserted in the optical path without moving.

[0039] When the first lens group 110 moves further toward the image plane in the first direction 115 beyond the desired focus adjustment range, the first coupling portion 430 provided on the interlocking member 400 starts to move toward the object on the opposite side. As the first coupling portion 430, which is connected by the aforementioned meshing, moves toward the object, the third coupling portion 450 rotates counterclockwise about the second rotation axis 325. Similarly, as the third coupling portion 440, which is connected by the aforementioned meshing, rotates, the second coupling portion 440 rotates clockwise about the first rotation axis 225. Thus, when the first coupling portion 430 moves toward the object, the second lens group 210 rotates in the second direction 215, and the third lens group 310 rotates in the third direction 315 (FIG. 7).

[0040] As shown in FIG. 7 , when the second lens group 210 further retracts in the second direction 215 and the third lens group 310 further retracts in the third direction 315 to retract positions outside the optical path, the first lens group 110 moves into the space created by the retraction. 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 retract into the space created by the movement of the interlocking member 400. When the focal range of the imaging optical system is the second focal length range, the third lens group 310 is positioned closer to the image plane than the second lens group 210. However, when the focal length range is the first focal length range, the third lens group 310 is positioned closer to the subject than the second lens group 210.

[0041] 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 second 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, when focusing on the retraction directions of the second lens group 210 and the third lens group 310, it can be seen that 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 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.

[0042] 5 to 8 are external views of the XZ plane as viewed from below in the Y-axis direction, as described above. As shown in Fig. 2, the electrical connection member 101 is disposed below on the Y-axis, and therefore 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.

[0043] In the state shown in FIG. 5 , the direction in which the centers of the first rotation shaft 225 and the second rotation shaft 325 extend is substantially parallel to the Y-axis. The direction in which the centers of the first rotation shaft 225 and the second rotation shaft 325 extend is substantially aligned with the short side direction of the image sensor 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.

[0044] Furthermore, the Y-axis direction, which is the direction in which the centers of the first rotation axis 225 and the second 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 the user places the camera body 1, the interchangeable lens 100 receives an impact in a different Y-axis direction from the direction in which the second lens group 210 and the third lens group 310 are retracted. In this way, this embodiment has a configuration that is sufficiently rigid and less susceptible to image quality degradation even against impacts generated by user handling.

[0045] Even after the second lens group 210 and the third lens group 310 have completed their retraction, the first lens group 110 can still move in the first direction 115. When the first lens group 110 moves further in the first direction 115 from the state shown in FIG. 7 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. 8). In the state shown in FIG. 8, the first lens group 110 is positioned closest to the image plane compared to the states shown in FIGS. 5 to 7. 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.

[0046] 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 is moved toward the image plane side, as shown in Fig. 8, resulting in the shortest overall lens length. When the imaging optical system is in 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, as in the case of the second focal length range. Here, when the position of the first lens group 110 moves, the positions of the second lens group 210 and the third lens group 310 do not move.

[0047] Up to this point, we have explained the case of transitioning from the second focal length range to the first focal length range, but the opposite case of transitioning from the first focal length range to the second focal length range involves the reverse procedure to that shown in Figures 5 to 8. For example, when the first lens group 110 moves from the image plane side to the subject side by a user operation, the second lens group 210 and the third lens group 310 rotate and move from a retracted position outside the optical path shown in Figure 8 to a position within the optical path where they are arranged on the first optical axis 10 shown in Figure 5.

[0048] To switch 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, the interchangeable lens 100 shown in this embodiment is configured to be switchable between the first focal length range and the second focal length range without using a dedicated actuator.

[0049] 9 is a perspective view showing the imaging optical system in the second focal length range, similar to FIG. 5. The first lens group 110, the second lens group 210, and the third lens group 310 are arranged in this order from the subject side at arbitrary positions on the first optical axis 10. The interlocking member 400 is provided with a cam follower 420 and a first connecting portion 430. The cam follower 420 is arranged in a phase adjacent to the first connecting portion 430 in the circumferential direction.

[0050] Fig. 10 is a perspective view showing the start of the transition from the second focal length range to the first focal length range, similar to Fig. 6. At the start of the transition, the first lens group 110 moves toward the image plane along the first optical axis 10, but the second lens group 210 and the third lens group 310 do not move.

[0051] FIG. 11, like FIG. 7, is a perspective view showing the completion of the transition from the second focal length range to the first focal length range. When the first lens group 110 further moves toward the image plane along the first direction 115, the interlocking member 400 moves in the opposite direction toward the subject. In this way, the first connecting portion 430 rotates the third connecting portion 450 connected by the aforementioned meshing, and the third lens group 310 retracts from the first optical axis 10 to a retracted position outside the optical path. In addition, the third connecting portion 450 rotates the second connecting portion 440 connected by the aforementioned meshing, and the second lens group 210 retracts from the first optical axis 10 to a retracted position outside the optical path.

[0052] Fig. 12 is a perspective view showing the imaging optical system in the first focal length range, similar to Fig. 8. In the state shown in Fig. 12, the transition from the second focal length range to the first focal length range is complete, and the second lens group 210 and the third lens group 310 remain in their retracted positions outside the optical path.

[0053] Fig. 13 is a graph showing the movement amount of the first lens group 110 and the interlocking member 400 relative to the rotation angle of the focus ring 103 when the imaging optical system transitions from the second focal length range to the first focal length range. In Fig. 13, the horizontal axis represents the rotation angle of the focus ring 103, and the vertical axis represents the distance from the image plane 16 to the first lens group 110 and the interlocking member 400 in the direction of the first optical axis 10. Note that the upper side of the vertical axis in Fig. 13 is the subject side, and the lower side is the image plane side.

[0054] The first lens group 110 moves linearly along the first optical axis 10 in accordance with the rotation angle of the focus operation ring 103, enabling desired focus adjustment. The distance from the image plane 16 to the first lens group 110 is longest at the close end of the second focal length range, and the overall length of the interchangeable lens 100 is longest when the distance between the image plane 16 and the first lens group 110 is longest. Furthermore, as the second focal length range transitions to the first focal length range, the distance from the image plane 16 to the first lens group 110 decreases relatively steeply, and the overall length of the interchangeable lens 100 is shortest at the infinity end of the first focal length range.

[0055] It can be seen that interlocking member 400 does not move and maintains its distance from image plane 16 between the close-up end and infinity end of the first focal length range, and between the close-up end and infinity end of the second focal length range. On the other hand, when transitioning from the second focal length range to the first focal length range, the distance of interlocking member 400 from image plane 16 increases. Therefore, it can be seen that with the transition from the second focal length range to the first focal length range, first lens group 110 moves toward the image plane, and interlocking member 400 moves toward the subject on the opposite side.

[0056] 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, various manufacturing errors and assembly variations exist in the interchangeable lens 100 and the camera body 1, which may result in a mismatch between the start and completion timing of the movement of the first lens group 110 and the interlocking member 400. Therefore, as described above, when transitioning from the second focal length range to the first focal length range, the interlocking member 400 begins moving toward the subject after the first lens group 110 begins moving toward the image plane. Furthermore, the interlocking member 400 has already completed its movement before the first lens group 110 has completed its movement. In this way, this embodiment achieves a configuration that is less susceptible to manufacturing errors and assembly variations by differentiating the trajectory of the movement of the first lens group 110 from the trajectory of the movement of the interlocking member 400.

[0057] 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.

[0058] (Other embodiments) While the present invention has been described in detail above based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included. Furthermore, each of the above-described embodiments merely represents one embodiment of the present invention, and each embodiment can be appropriately combined. [Explanation of symbols]

[0059] 1 camera body 7. Camera Mount 10 First optical axis 16 Image plane 100 interchangeable lenses 101 Electrical connection parts 102 lens mount 103 Focus control ring 106 Fixed tube 107 Straight guide tube 108 First cam barrel 109 Second cam barrel 110 First lens group 115 First Direction 210 Second lens group 215 Second Direction 225 First Rotation Axis 310 Third Lens Group 315 The Third Direction 325 Second Rotation Axis 400 Interlocking parts 410 Evacuation Base 420 Cam Follower 430 First connection part (rack) 440 Second connection part (gear) 450 Third linkage (gear)

Claims

1. a first lens group; and a second lens group that changes the focal length range of the optical system from the first focal length range to a second focal length range; a guide tube having a linear guide groove; a cam barrel rotatably held by the guide barrel; a linking member having a first connecting portion, the cam barrel has a first cam groove that moves the first lens group, and a second cam groove that is different from the first cam groove and moves the interlocking member, when the focal length range of the optical system transitions from the second focal length range to the first focal length range, the first lens group moves parallel to the optical axis toward the image plane by the rectilinear guide groove and the first cam groove, the interlocking member moves parallel to the optical axis toward the subject by the rectilinear guide groove and the second cam groove, and the first connecting portion retracts the second lens group out of the optical path of the first lens group.

2. 2. The optical device according to claim 1, wherein, when the focal length range of the optical system transitions from the second focal length range to the first focal length range, the interlocking member starts moving after the first lens group starts moving and completes moving before the first lens group completes moving.

3. 3. The optical device according to claim 1, wherein when the focal length range of the optical system is the second focal length range, the second lens group is located closer to the image plane than the first lens group.

4. 4. The optical device according to claim 1, further comprising a third lens group that changes the focal length range of the optical system from the first focal length range to the second focal length range.

5. 5. The optical device according to claim 4, wherein when the focal length range of the optical system 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.

6. when the focal length range of the optical system is the second focal length range, the third lens group is located closer to an image plane than the second lens group, 6. The optical device according to claim 4, wherein when the focal length range of the optical system is the first focal length range, the third lens group is located closer to the subject than the second lens group.

7. 7. The optical device according to claim 4, wherein at least one of the second lens group and the third lens group is retracted while rotating into a space created by the movement of the interlocking member.

8. the second lens group has a first rotation axis that is substantially perpendicular to the optical axis and a second connecting portion; 8. The optical device according to claim 4, wherein when the focal length range of the optical system transitions from the second focal length range to the first focal length range, the first connecting portion connects to the second connecting portion, and retracts the second lens group out of the optical path of the first lens group around the first rotation axis.

9. the third lens group has a second rotation axis perpendicular to the optical axis and a third connection portion, 9. The optical device according to claim 8, wherein, when the focal length range of the optical system transitions from the second focal length range to the first focal length range, the first connecting portion connects to the third connecting portion to retract the third lens group around the second rotation axis to outside the optical path of the first lens group, and the third connecting portion connects to the second connecting portion to retract the second lens group around the first rotation axis to outside the optical path of the first lens group.

10. 10. The optical device according to claim 9, wherein the first connecting portion is a rack, and the second connecting portion and the third connecting portion are gears that are connected by meshing with each other.

11. 11. The optical device according to claim 1, wherein the interlocking member has a cam follower.

12. 12. The optical device according to claim 1, wherein the first lens group includes a focus lens, and the focus lens adjusts focus by moving along a direction parallel to the optical axis.

13. 13. The optical device according to claim 12, further comprising an operating member that is rotatable about the optical axis, wherein the focus lens and the interlocking member move in conjunction with the rotation of the operating member.

14. 14. An imaging device comprising: a camera body having a camera mount; and the optical device according to claim 1, having a lens mount connectable to the camera mount.

Images