Optical devices

Abstract

Optical devices with high impact resistance are desired. [Solution] The device includes a cam cylinder 300 having cam grooves 310 and 320, a first moving member 400 that holds an optical element and is movable in the optical axis direction and has a first cam follower 410, a guide member 200 that guides the first cam follower in the optical axis direction, and a second moving member 500 that is movable in the optical axis direction together with the first moving member and is connected to the first moving member so as to allow displacement of the first moving member in the optical axis direction and has a second cam follower 510. The cam groove has a first cam surface 311 that moves the biased first cam follower in the optical axis direction as the cam cylinder rotates, a stopper surface 312 that the first cam follower, which is away from the first cam surface, contacts, and a second cam surface 321 that is provided at a different position in the radial direction of the cam cylinder from the stopper surface and moves the biased second cam follower in the optical axis direction as the cam cylinder rotates.

Description

Technical Field

[0001] The present invention relates to an optical device that movably supports an optical element such as a lens.

Background Art

[0002] In an optical device as described above, a cam follower provided on a lens holding cylinder is engaged with a cam groove formed in a cam cylinder, and the cam cylinder is rotated to move the lens holding cylinder in the optical axis direction. In this configuration, the gap (play) between the cam follower and the cam groove may cause a decrease in the position accuracy of the lens or a decrease in optical performance due to the tilting of the lens. Patent Document 1 discloses a configuration in which two cam followers urged in a direction away from each other are respectively brought into contact with a first surface and a second surface of a single cam groove in order to prevent the above play.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An optical device having higher impact resistance than conventional ones is desired.

Means for Solving the Problems

[0005] An optical device as one aspect of the present invention includes a cam cylinder having a cam groove, a first moving member that holds an optical element and is movable in the optical axis direction and has a first cam follower, a guide member that guides the first cam follower in the optical axis direction, a second moving member that is movable in the optical axis direction together with the first moving member and is connected to the first moving member so as to allow displacement of the first moving member in the optical axis direction and has a second cam follower, and a biasing means that generates a biasing force that separates the first moving member and the second moving member from each other in the optical axis direction. The cam groove is characterized by having a first cam surface that receives a biasing force and contacts the first cam follower, which moves in the optical axis direction as the cam cylinder rotates, a stopper surface that the first cam follower, which is away from the first cam surface, contacts, and a second cam surface that is provided at a different position in the radial direction of the cam cylinder from the stopper surface, which receives a biasing force and contacts the second cam follower, which moves in the optical axis direction as the cam cylinder rotates. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide an optical device with high impact resistance. [Brief explanation of the drawing]

[0007] [Figure 1] Perspective view of the imaging system including the interchangeable lens unit of the embodiment. [Figure 2] Block diagram showing the configuration of the above imaging system. [Figure 3] Cross-sectional view of the interchangeable lens unit (wide-angle end) of the embodiment. [Figure 4] Cross-sectional view of the interchangeable lens unit (telephoto end) of the embodiment. [Figure 5] Cross-sectional view of the interchangeable lens unit (stored state) of the embodiment. [Figure 6] Decomposed perspective view of the first zoom group in the example. [Figure 7] Oblique view of the assembled state of the first zoom group in the embodiment. [Figure 8] Diagram showing the connecting portion in the embodiment. [Figure 9] Perspective view of the cam cylinder in the embodiment [Figure 10]Diagram showing the arrangement of the cam groove in the example and comparative example. [Figure 11] Diagram showing the cam cylinder and cam follower in the embodiment. [Figure 12] Cross-sectional view AA in Figure 11 [Figure 13] Diagram showing the cam cylinder and cam follower when subjected to external force in the embodiment. [Figure 14] BB cross-section view in Figure 13 [Modes for carrying out the invention]

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0009] Figures 1(a) and 1(b) show the external appearance of an imaging system comprising an interchangeable lens unit 101 as an optical device, which is an embodiment of the present invention, and a digital camera (hereinafter referred to as the camera body) 1 to which the interchangeable lens unit 101 is detachably attached. Figures 1(a) and 1(b) show the imaging system viewed from the oblique front side (object side) and the oblique rear side (image plane side), respectively. In this embodiment, an optical device that is detachable from the camera body is described, but the optical device may be integrally provided with the camera body.

[0010] As shown in Figure 1(a), the direction in which the optical axis of the imaging optical system housing the interchangeable lens unit 101 extends is defined as the X-axis direction (optical axis direction), and the directions perpendicular to this are defined as the Z-axis direction (horizontal direction) and the Y-axis direction (vertical direction). In the following explanation, the Z-axis direction and Y-axis direction will be collectively referred to as the Z / Y-axis direction. The direction of rotation around the Z-axis will be defined as the pitch direction, and the direction of rotation around the Y-axis will be defined as the yaw direction. The pitch direction and yaw direction (hereinafter collectively referred to as pitch / yaw direction) are directions of rotation around two mutually orthogonal axes, the Z-axis and the Y-axis.

[0011] On the left side (right side when viewed from the back) of the camera body 1 when viewed from the front, a grip portion 2 for the user to hold the camera body 1 by hand is provided. On the upper surface portion of the camera body 1, a power operation unit 3 is arranged. When the user performs an on-operation on the power operation unit 3 when the camera body 1 is in the power-off state, the camera body 1 becomes in the power-on state, and a computer program such as the origin detection process of the focus group is executed to enter the imaging standby state. When the user performs an off-operation on the power operation unit 3 when the camera body 1 is in the power-on state, the camera body 1 becomes in the power-off state.

[0012] On the upper surface portion of the camera body 1, a mode dial 4, a release button 5, and an accessory shoe 6 are provided. By rotating the mode dial 4 by the user, the imaging mode can be switched. The imaging modes include a manual still image imaging mode in which the user can arbitrarily set imaging conditions such as the shutter speed and aperture value, an auto still image imaging mode in which an appropriate exposure amount can be obtained automatically, and a video imaging mode for performing video imaging. Also, by the user pressing the release button 5 halfway, imaging preparation operations such as autofocus and automatic exposure control can be instructed, and by pressing the release button 5 fully, the imaging operation can be instructed. An accessory such as an external flash can be detachably attached to the accessory shoe 6.

[0013] The interchangeable lens unit 101 includes a lens mount 102 that can be mechanically and electrically connected to a camera mount 7 provided on the camera body 1. The lens mount 102 and the camera mount 7 are formed of a conductive metal material and can be mechanically coupled by bayonet coupling.

[0014] The interchangeable lens unit 101 houses an imaging optical system that forms an image of light from a subject as an object to form a subject image. On the outer periphery of the interchangeable lens unit 101, a zoom operation ring 103 is provided as an operation member that can be rotated about the optical axis by a user operation. When the zoom operation ring 103 is rotated by the user, the zoom group that constitutes the imaging optical system moves within the zoom range from the wide-angle end to the telephoto end. As a result, a zoom state (angle of view) corresponding to the rotation angle of the zoom operation ring 103 is set.

[0015] Further, in the interchangeable lens unit 101 of this embodiment, when the zoom operation ring 103 is rotated beyond the wide-angle end to the side opposite to the telephoto end side, the imaging optical system enters a storage state as a non-use state. In the storage state, the length of the interchangeable lens unit 101 in the optical axis direction becomes the shortest.

[0016] As shown in FIG. 1(b), a rear operation unit 8 and a display unit 9 are provided on the back surface of the camera body 1. The rear operation unit 8 includes a plurality of buttons and dials to which various functions are assigned. When the camera body 1 is in the power-on state and the still image or video shooting mode is set, a live view image showing the subject image captured by the imaging device described later is displayed on the display unit 9. Further, imaging conditions (imaging parameters) such as shutter speed and aperture value are displayed on the display unit 9. The user can change the set value of the imaging parameters by operating the rear operation unit 8 while viewing the display of the imaging parameters. The rear operation unit 8 includes a playback button for instructing playback of the recorded imaging image, and by operating the playback button by the user, the imaging image can be reproduced and displayed on the display unit 9. The display unit 9 may be provided with a touch sensor and have the same functions as the rear operation unit 8.

[0017] Figure 2 shows the electrical and optical configuration of the imaging system. The camera body 1 includes a power supply unit 10 that supplies power to the camera body 1 and the interchangeable lens unit 101, and an operation unit 11 that includes the aforementioned power operation unit 3, mode dial 4, release button 5, rear operation unit 8, and touch panel functions of the display unit 9. In this embodiment, the overall system control of the camera body 1 and the interchangeable lens unit 101 is performed by the cooperation of the camera control unit 12 provided in the camera body 1 and the lens control unit 104 provided in the interchangeable lens unit 101. The camera control unit 12 and the lens control unit 104 each have a built-in computer for controlling the camera body 1 and the interchangeable lens unit 101, respectively, and the overall system of the camera body 1 and the interchangeable lens unit 101 is controlled by coordinating their operation.

[0018] The camera control unit 12 reads and executes the computer program stored in the memory unit 13. At that time, the camera control unit 12 communicates with the lens control unit 104 via the communication terminal of the electrical contact 105 provided on the lens mount 102, sending various control signals and data. The electrical contact 105 includes a power terminal that supplies power from the aforementioned power supply unit 10 to the interchangeable lens unit 101.

[0019] The imaging optical system of the interchangeable lens unit 101 is connected to the zoom operation ring 103 and includes a zoom group 110 that moves the zoom lens in the optical axis direction to change the angle of view, and an aperture group 120 that adjusts the amount of light. The imaging optical system also includes an image stabilization group 113 that reduces image shake by moving (shifting) a shift lens, which acts as an image stabilization element, in the Z / Y axis direction perpendicular to the optical axis. Furthermore, the imaging optical system includes a focus group 116 that adjusts the focus by moving the focus lens in the optical axis direction. The interchangeable lens unit 101 includes an aperture drive unit 121 that drives the aperture group 120, an image stabilization drive unit 130 that drives the image stabilization group 113, and a focus drive unit 140 that drives the focus group 116.

[0020] The camera body 1 includes a shutter unit 14, a shutter drive unit 15, an image sensor 16, an image processing unit 17, and the aforementioned camera control unit 12. The shutter unit 14 controls the exposure amount of the image sensor 16. The image sensor 16 converts the subject image formed by the imaging optical system into an image (imaging) and outputs an imaging signal. The image processing unit 17 generates an image signal by performing various image processing on the imaging signal. The display unit 9 displays the image signal (live view image) output from the image processing unit 17, displays imaging parameters as described above, and plays back and displays the image recorded in the storage unit 13 or a recording medium (not shown).

[0021] The camera control unit 12 controls the focus drive unit 140 in response to the image preparation operation (half-press operation of the release button 5) on the operation unit 11. For example, if autofocus operation is instructed, the focus detection unit 18 generates a focus signal indicating the focus state of the subject image using the image signal generated by the image processing unit 17 and transmits it to the camera control unit 12. The focus drive unit 140 transmits information regarding the current position of the focus group 116 to the camera control unit 12. The camera control unit 12 calculates the focus drive amount using the focus state and the current position of the focus group 116 and transmits the focus drive amount to the lens control unit 104. The lens control unit 104 moves the focus group 116 to the target position in the optical axis direction via the focus drive unit 140 to achieve focus.

[0022] The focus drive unit 140 includes a focus motor as an actuator and a photointerrupter that detects when the focus group 116 is in the origin position. A stepping motor, DC motor, vibration motor, servo motor, etc., can be used as the focus motor. The photointerrupter has a configuration in which light emitted from a light-emitting unit is received by a light-receiving unit, and detects that the focus group 116 has reached the origin position when the light is blocked by the focus group 116 that has moved to the origin position. Instead of the photointerrupter, a photoreflector that receives reflected light from a reflective surface, or a potentiometer that contacts a conductive pattern and outputs an electrical signal corresponding to the position may be used.

[0023] The camera control unit 12 controls the driving of the aperture group 120 and the shutter unit 14 via the aperture drive unit 121 and the shutter drive unit 15, according to the aperture value and shutter speed settings received from the operation unit 11. For example, if automatic exposure control is instructed, the camera control unit 12 performs photometering calculations using the luminance signal generated by the image processing unit 17. Then, when an imaging instruction operation (such as fully pressing the release button 5) is performed on the operation unit 11, the camera control unit 121 is controlled based on the result of the photometering calculation. Furthermore, the camera control unit 12 controls the driving of the shutter unit 14 via the shutter drive unit 15 to control the exposure amount of the image sensor 16.

[0024] The camera body 1 has a pitch shake detection unit 19 and a yaw shake detection unit 20 that detect camera shake caused by hand shake, etc. The pitch shake detection unit 19 and the yaw shake detection unit 20 each use an angular velocity sensor (vibration gyro) and an angular acceleration sensor to detect camera shake in the pitch direction (around the Z axis) and the yaw direction (around the Y axis), and output shake signals.

[0025] The camera control unit 12 calculates the shift position of the vibration isolation group 113 in the Y-axis direction using the vibration signal from the pitch vibration detection unit 19, and calculates the shift position of the vibration isolation group 113 in the Z-axis direction using the vibration signal from the yaw vibration detection unit 20. The camera control unit 12 moves the vibration isolation group 113 to the target position in the Z / Y axis direction via the vibration isolation drive unit 130 according to the calculated pitch / yaw direction shift position, thereby reducing image shake during exposure and live view image display.

[0026] The interchangeable lens unit 101 includes a zoom operation ring 103 that the user rotates to change the angle of view of the imaging optical system, and a zoom detection unit 106 that detects the angle of the zoom operation ring 103. The zoom detection unit 106 detects the angle of the zoom operation ring 103 as an absolute value and is configured, for example, using a potentiometer. The zoom position information indicating the angle of view, which is the angle of view of the zoom operation ring 103 detected by the zoom detection unit 106, is transmitted to the lens control unit 104 and reflected in the various controls performed by the camera control unit 12 as described above. In addition, various information such as the zoom position information is recorded together with the captured image in the storage unit 13 or a recording medium (not shown).

[0027] The main components of the interchangeable lens unit 101 will be explained using Figures 3, 4, and 5. Figures 3, 4, and 5 show XY cross-sections of the interchangeable lens unit 101, including the optical axis at the wide-angle end, telephoto end, and retracted state, respectively. The state from the wide-angle end to the telephoto end, where imaging is possible through the imaging optical system, is defined as the imaging state. Rotating the zoom operation ring 103 in one direction from the telephoto end shown in Figure 4 leads to the wide-angle end shown in Figure 3 and then to the retracted state shown in Figure 5. In each figure, the optical axis of the imaging optical system is shown by a dashed line.

[0028] As shown in Figures 3 and 4, this embodiment employs a seven-group optical system as the imaging optical system. The zoom group 110 is composed of the first zoom group 111, the second zoom group 112, the vibration-damping group 113 as the third zoom group, the fourth zoom group 114, the fifth zoom group 115, the focus group 116 as the sixth zoom group, and the seventh zoom group 117, arranged in order from the object side. Note that the imaging optical system may have a configuration other than that described above. Also, the vibration-damping group 113 and the focus group 116 do not have to move as a zoom group, and the imaging optical system may include fixed groups that do not move for zooming.

[0029] The guide tube 200, acting as a guide member, is a fixed component that is fixed to the lens mount 102 via a fixed tube (not shown). The outer circumferential surface of the guide tube 200 is provided with bayonet claws (not shown) at equal intervals in the circumferential direction (around the optical axis). The inner circumferential surface of the cam tube 300 is provided with a circumferential groove (not shown). The cam tube 300 is also connected to the zoom operating ring 103. Therefore, when the user rotates the zoom operating ring 103, the cam tube 300 rotates around the optical axis while its movement in the optical axis direction is restricted by the engagement of the bayonet claws and the circumferential groove.

[0030] As will be explained in more detail later, the guide tube 200 has multiple linear guide grooves that restrict rotation around the optical axis of the first to seventh zoom groups 111 to 117 while guiding them in a straight line in the optical axis direction. The cam tube 300 also has multiple cam grooves that correspond to each of the first to seventh zoom groups 111 to 117, each having a different cam shape (rate of change of cam lift with respect to rotation). Meanwhile, cam followers for the first to seventh zoom groups 111 to 117 are provided, and each cam follower engages with the corresponding linear guide groove and cam groove. Therefore, when the user rotates the zoom operating ring 103 and the cam tube 300 rotates, the engagement of the linear guide groove and cam groove of the cam follower restricts the rotation around the optical axis of the first to seventh zoom groups 111 to 117 while they move in the optical axis direction.

[0031] In this embodiment, the interchangeable lens unit 101 allows the zoom group 110 to be moved closer to the image plane than its position at the wide-angle end when stored. This shortens the overall length of the interchangeable lens unit 101 when not in use, improving the portability of both the interchangeable lens unit 101 and the camera body 1.

[0032] At the wide-angle end shown in Figure 3, the distance between the second zoom group 112 and the image stabilization group (third zoom group) 113 is wide. Similarly, at the telephoto end shown in Figure 4, the distance between the first zoom group 111 and the second zoom group 112 is wide. In the retracted state shown in Figure 5, the first to third zoom groups 111 to 113 (and furthermore, the fourth to seventh zoom groups 114 to 117) are moved closer to each other to narrow these distances and shorten the overall length of the imaging optical system. When the user rotates the zoom operation ring 103 from the retracted state to the wide-angle end angle, each zoom group moves toward the object, enabling imaging at the wide-angle end as shown in Figure 3.

[0033] Figure 6 shows the first zoom group 111, cam cylinder 300, and guide cylinder 200 disassembled and viewed from the oblique object side. Figure 7 shows the first zoom group 111 in its assembled state and viewed from the oblique image plane side.

[0034] The first zoom group 111 includes a moving cylinder 400 as a first moving member, a support ring 500 as a second moving member, a first cam follower 410, a second cam follower 510, and a biasing member 600 as a biasing means. The moving cylinder 400 and the support ring 500 are arranged on the outer circumference of the cam cylinder 300, which is positioned on the outer circumference of the guide cylinder 200. The moving cylinder 400 holds optical elements such as lenses directly or via a holding member. Three first cam followers 410 are provided on the inner circumference of the moving cylinder 400 at equal intervals in the circumferential direction.

[0035] The support ring 500 is positioned such that a protrusion (a second connecting portion, described later) on the support ring 500, which is provided to protrude toward the object, fits into a recess (a first connecting portion, described later) provided at the image plane end of the moving cylinder 400. Second cam followers 510 are provided on the inner circumference of the support ring 500 at equal intervals in the circumferential direction. The first cam follower 410 and the second cam follower 510 are positioned at different positions (phases) relative to each other in the circumferential direction (around the optical axis) of the cam cylinder 300. Three biasing members 600 are positioned between the moving cylinder 400 and the support ring 500 so as to be sandwiched between them. In this embodiment, the biasing members 600 are coil springs that generate a biasing force that acts to separate the moving cylinder 400 and the support ring 500 from each other in the direction of the optical axis.

[0036] Figure 8 shows the first connecting portion 420 on the moving cylinder 400 and the second connecting portion 520 on the support ring 500, viewed from the radial direction perpendicular to the optical axis OA. The first connecting portion 420 is formed as a recess at the end of the moving cylinder 400 on the image plane side. The second connecting portion 520 is formed as a convex portion toward the object side on the support ring 500. The first connecting portion 420 and the second connecting portion 520 are each provided with a slanted surface (connecting surface) having an inclination angle θ with respect to the optical axis OA.

[0037] The biasing force of the biasing member 600 biases the movable cylinder 400 and the support member 500 toward the object side and the image plane side, respectively, so that they are separated from each other in the optical axis direction, causing the inclined surface of the first connecting part 420 and the inclined surface of the second connecting part 520 to come into contact with each other. As a result, the movable cylinder 400 and the support ring 500 are connected in such a way that they can move together (as a single unit) in the optical axis direction, and that the movable cylinder 400 can be displaced in the optical axis direction relative to the support ring 500.

[0038] Furthermore, the movable cylinder 400 is provided with a first locking portion 430, and the support ring 500 is provided with a second locking portion 530. By engaging these with each other, the support ring 500 is prevented from coming off the movable cylinder 400 due to the biasing force of the biasing member 600, and the assembly of the movable cylinder 400, to which the support ring 500 is attached, to the outer circumference of the cam cylinder 300 is made easier. After assembly to the cam cylinder 300, a gap in the optical axis direction is provided between the movable cylinder 400 and the support ring 500, excluding the first connecting portion 420 and the second connecting portion 520 that come into contact with each other.

[0039] Figure 9 shows the cam cylinder 300. Three sets of first cam grooves 310 and second cam grooves 320 are provided on the circumferential wall of the cam cylinder 300 at equal intervals in the circumferential direction. The second cam grooves 320 are formed to overlap with the first cam grooves 310 in the circumferential and optical axis directions, except for a portion on the object side. In other words, the second cam grooves 320 are formed to have an inner surface on only one side in the groove width direction, except for a portion on the object side.

[0040] The first cam groove 310 is formed to penetrate the peripheral wall of the cam cylinder 300. The second cam groove 320 is formed on the outer circumference side of the peripheral wall of the cam cylinder 300 so as not to penetrate it (so as to have a bottom surface). The first cam groove 310 has a first cam surface 311 as one of its inner surfaces in the groove width direction, and a stopper surface 312 as the inner surface opposite to the first cam surface 311. The second cam groove 320 has a second cam surface 321 on the opposite side of the first cam surface 311, with the stopper surface 312 in between, in the circumferential and optical axis directions. The stopper surface 312 is provided on the inner circumference side of the peripheral wall of the cam cylinder 300, and the second cam surface 321 is provided on the outer circumference side of the peripheral wall.

[0041] Thus, the first cam groove 310 and the second cam groove 320 are formed as a single continuous (undivided) groove in the groove width direction, and the stopper surface 312 and the second cam surface 321 are provided at different positions in the radial direction of the cam cylinder 300.

[0042] Furthermore, the second cam groove 320 has a third cam surface 322 as a wall surface on the opposite side of the second cam surface 321 in the groove width direction of a portion of the object side.

[0043] Figure 10(a) shows the first cam groove 310 and the second cam groove 320 and the first cam follower 410 and the second cam follower 510 in this embodiment. Figures 10(b) and 10(c) show the first cam groove 310 and the second cam groove 320 provided on the cam cylinder 300 when the support ring 500 is guided by the guide cylinder 200 instead of the moving cylinder 400.

[0044] In Figure 10(a), a circumferential gap d is provided between the first cam follower 410 and the second cam follower 510. On the other hand, in Figures 10(b) and 10(c), a gap d' larger than gap d is provided. This is because it is necessary to secure the circumferential wall width between two guide grooves (not shown) provided on the circumferential wall of the guide cylinder 200 in order to guide the first cam follower 410 and the second cam follower 510, respectively. For this reason, in Figure 10(b), the first cam follower 410 and the second cam follower 510 cannot be brought close enough to have a gap smaller than gap d'. As a result, the area in which the first cam groove 310 and the second cam groove 320 overlap in the optical axis direction (from the object side to the image side), similar to that in Figure 10(a), is reduced. As a result, the area occupied by the first cam groove 310 and the second cam groove 320 in the circumferential direction becomes larger, which may restrict the design of other cam grooves and potentially increase the length of the cam cylinder 300 in the optical axis direction.

[0045] Furthermore, as shown in Figure 10(c), in order to increase the overlapping area between the first cam groove 310 and the second cam groove 320, it is necessary to offset the first cam groove 310 and the second cam groove 320 relative to each other in the optical axis direction. As a result, the length of the cam cylinder 300 increases.

[0046] In this embodiment, the movable cylinder 400 and the support ring 500 are connected by the first connecting portion 420 and the second connecting portion 520, thereby adopting a configuration in which the guide cylinder 200 does not have a guide groove for guiding the support ring 500 in the optical axis direction. This maintains the strength of the guide cylinder 200 itself and preserves impact resistance, while suppressing the increase in the arrangement space for the first cam groove portion 310 and the second cam groove portion 320, thereby shortening the length of the cam cylinder 300 and improving design flexibility.

[0047] Figure 11 shows a magnified view of the assembled first zoom group 111 (first and second cam followers 410, 510), cam cylinder 300 (first cam surface 311, stopper surface 312, second cam surface 321), and guide cylinder 200 (guide groove portion 210). The movable cylinder 400 and support ring 500 are not shown in the figure. Figure 12 shows the AA cross-section of Figure 11.

[0048] The first cam follower 410 is biased by the biasing member 600 shown in Figures 6 to 8 such that its first follower surface 411 abuts against the first cam surface 311 and is separated from the stopper surface 312. The second follower surface 412 of the first cam follower 410 is engaged with the guide groove 210. As a result, as the cam cylinder 300 rotates, the moving cylinder 400 moves to a position in the optical axis direction determined by the first cam surface 311 and the guide groove 210.

[0049] The second cam follower 510 is biased by the biasing member 600 so that its first follower surface 511 contacts the second cam surface 321. As mentioned above, the support ring 500 is restricted from rotating around the optical axis relative to the moving cylinder 400 by the second connecting portion 520 contacting the first connecting portion 420 of the moving cylinder 400. Therefore, as the moving cylinder 400 moves in the direction of the optical axis, the support ring 500 moves to a position in the direction of the optical axis determined by the second cam surface 321 with which the second cam follower 510 contacts and the first connecting portion 420 with which the second connecting portion 520 contacts.

[0050] In this way, the movable cylinder 400 moves in the optical axis direction due to the lift of the first cam surface 311, and the support ring 500 moves in the optical axis direction due to the lift of the second cam surface 321.

[0051] Figure 13 shows the change in the configuration shown in Figure 11 when the interchangeable lens unit 101 is subjected to impact or other external force from the object side. Figure 14 shows the BB cross section of Figure 13.

[0052] In this case, the first zoom group 111 (moving cylinder 400), which is closest to the object in the interchangeable lens unit 101, is subjected to an external force as shown by the arrow in Figure 14. If the external force is greater than the biasing force of the biasing member 600, the first cam follower 410 is displaced toward the image side relative to the support ring 500 together with the moving cylinder 400, to a position where the first follower surface 411 moves away from the first cam surface 311 and contacts the stopper surface 312. At this time, the inclined surface of the second connecting part slides against the inclined surface of the first connecting part, causing the support ring 500 to rotate circumferentially relative to the moving cylinder 400 and be displaced toward the image side.

[0053] As shown in Figure 12, when no external force is applied, a gap α in the optical axis direction is provided between the parts of the movable cylinder 400 and the support ring 500 other than the first and second connecting parts 420 and 520 that are in contact with each other. This gap α is set to be larger than the amount of displacement in the optical axis direction from the position where the first cam follower 410 contacts the first cam surface 311 to the position where it contacts the stopper surface 312, throughout the entire area of ​​the parts other than the first and second connecting parts 420 and 520. Therefore, the first cam follower 410 contacts the stopper surface 312 before the movable cylinder 400 contacts the support ring 500. In other words, because the stopper surface 312 receives the external force, the second cam surface 321, which determines the position of the support ring 500 in the optical axis direction when no external force is applied, does not receive the external force.

[0054] On the other hand, when the interchangeable lens unit 101 is subjected to impact or other external forces from the image plane side, the external force is first primarily received by the lens mount 102. At this time, an inertial force acts on the first zoom group 111 (moving cylinder 400) toward the lens mount 102 side. If the inertial force is greater than the biasing force of the biasing member 600, the first cam follower 410 is displaced toward the image side relative to the support ring 500 together with the moving cylinder 400 to a position where it moves away from the first cam surface 311 and contacts the stopper surface 312. In other words, just as when an external force is received from the object side, the inertial force of the first zoom group 111 is received by the stopper surface 312, and the inertial force is not transmitted to the second cam surface 321.

[0055] As explained above, in this embodiment, regardless of whether the interchangeable lens unit 101 receives an external force from the object side or the image plane side, the external force is absorbed by the stopper surface 312, thus eliminating the risk of deformation of the second cam surface 321.

[0056] Furthermore, when the interchangeable lens unit 101 is subjected to an external force from the image plane side, an inertial force acting on the support ring 500 toward the lens mount 102 side acts on it, similar to the movement cylinder 400. As a result, the second cam surface 321 is subjected to an external force from the second cam follower 510. However, as mentioned above, the inclined surfaces of the first connecting portion 420 and the second connecting portion 520 have an inclination angle θ with respect to the optical axis OA, so the external force is received not only by the second cam surface 321 but also by the first connecting portion 420 and the second connecting portion 520.

[0057] The larger the inclination angle θ, the greater the external force acting on the first connecting portion 420 and the second connecting portion 520, thus reducing the external force acting on the second cam surface 321. However, if the cam shapes of the first cam surface 311 and the second cam surface 321 are different, and the inclination angle θ is made too large, the second cam follower 510 will no longer follow the second cam surface 321 due to friction between the inclined surfaces of the first and second connecting portions 420 and 520. Therefore, when the coefficient of static friction between the inclined surfaces (connecting surfaces) of the first connecting portion 420 and the second connecting portion 520 is μ, it is preferable to satisfy the conditions of the following equation (1).

[0058] μ < 1 / tanθ (1) Furthermore, if the inclination angle θ coincides with the angle that the tangential direction of the second cam surface 321 makes with the optical axis OA, the position of the support ring 500 becomes uncertain. For this reason, it is preferable that the inclination angle θ is different from the angle that the tangential direction of the second cam surface 321 makes with the optical axis OA across its entire surface.

[0059] By tilting the inclined surface of the first connecting portion 420 with respect to the optical axis OA while satisfying these conditions, the external force can be dispersed, and the external force acting on the second cam surface 321 can be further reduced.

[0060] This configuration is particularly effective when the support member 500 is heavy, but if the support member 500 is sufficiently lightweight, a configuration that restricts the rotation of the support member 500 by providing a groove in the optical axis direction may also be used.

[0061] As described above, in this embodiment, a stopper surface 312 is provided between the first cam surface 311, to which the first cam follower 410 is biased and makes contact, and the second cam surface 321, to which the second cam follower 510 is biased and makes contact, to receive the external force received by the first zoom group 111. Furthermore, by providing the first cam surface 311 and the second cam surface 321 at different positions in the radial direction of the cam cylinder 300, the first cam groove 310 and the second cam groove 320 are formed to have overlapping portions. This makes it possible to realize an interchangeable lens unit 101 with improved impact resistance while suppressing an increase in the length of the cam cylinder 300 in the optical axis direction.

[0062] In this embodiment, the movable cylinder 400 is positioned on the outer circumference of the cam cylinder 300, but the movable cylinder may also be positioned on the inner circumference of the cam cylinder and guide cylinder. In this case, the first connecting portion may be provided on the guide cylinder instead of the movable cylinder.

[0063] In this embodiment, the integrally formed support ring 500 holds the three second cam followers 510, but for miniaturization purposes, the support ring may be divided into multiple parts, and each divided part may hold a second cam follower.

[0064] Furthermore, in this embodiment, the biasing member 600 is provided as a separate component from the movable cylinder 400 and the support ring 500, but it may also be provided as an integral elastic part (elastic section) of the movable cylinder or the support ring.

[0065] The above embodiments include the following configurations.

[0066] (Composition 1) A cam cylinder having a cam groove, A first moving member that holds an optical element and is movable in the optical axis direction, and has a first cam follower, A guide member that guides the first cam follower in the optical axis direction, A second moving member having a second cam follower is connected to the first moving member so as to be movable in the optical axis direction together with the first moving member and to allow displacement of the first moving member in the optical axis direction, The device includes a biasing means that generates a biasing force to separate the first moving member and the second moving member from each other in the direction of the optical axis, The aforementioned cam groove portion is A first cam surface that moves the first cam follower, which is in contact with the biasing force, in the optical axis direction as the cam cylinder rotates, A stopper surface to which the first cam follower, which is separated from the first cam surface, contacts, The optical device is characterized in that the stopper surface is provided at different positions in the radial direction of the cam cylinder and has a second cam surface that moves the second cam follower, which is in contact with the biasing force, in the optical axis direction as the cam cylinder rotates. (Configuration 2) The optical device according to configuration 1, characterized in that the cam groove portion is formed as a single continuous groove portion in the groove width direction of the cam groove portion. (Composition 3) The optical device according to configuration 1 or 2, characterized in that the cam groove portion is formed by a first cam groove portion having a first cam surface and a stopper surface, and a second cam groove portion having a second cam surface, which is formed as a groove portion continuous with the groove width direction of the first cam groove portion. (Composition 4) The first and second cam grooves form the peripheral wall portion of the cam cylinder, The first cam groove is formed to penetrate the peripheral wall in the radial direction, The optical device according to configuration 3, characterized in that the second cam groove portion is formed so as not to penetrate the peripheral wall portion in the radial direction. (Composition 5) The optical apparatus according to configuration 3 or 4, characterized in that the first cam groove and the second cam groove have portions that overlap with each other in the optical axis direction. (Composition 6) The optical device according to any one of configurations 1 to 5, characterized in that the second cam surface has a different cam shape from the first cam surface. (Composition 7) The optical apparatus according to any one of configurations 1 to 6, characterized in that the guide member does not guide the second cam follower in the optical axis direction. (Composition 8) The first moving member and the second moving member each have a connecting surface that is inclined with respect to the optical axis direction, The optical apparatus according to any one of configurations 1 to 7, characterized in that the connecting surfaces of the first and second moving members are biased by the biasing force and come into contact with each other, so that the first moving member and the second moving member are connected so that they can move together in the optical axis direction and the displacement of the first moving member of the second moving member in the optical axis direction is permitted. (Composition 9) The angle θ that the connecting surfaces of the first and second moving members make with respect to the optical axis is such that, when the coefficient of static friction between the connecting surfaces of the first and second moving members is μ, μ < 1 / tanθ The optical device according to configuration 8, characterized by satisfying the following conditions. (Composition 10) The optical apparatus according to configuration 9, characterized in that the angle θ is different from the angle that the tangential direction of the second cam surface makes with respect to the optical axis direction. (Composition 11) The optical apparatus according to any one of configurations 1 to 10, characterized in that the first cam follower and the second cam follower are arranged in different phases relative to each other in the direction of the optical axis. (Composition 12) The optical device according to any one of configurations 1 to 11, characterized in that the first moving member holds the optical element closest to the object in the optical device as the optical element. (Composition 13) The first moving member is displaced in the optical axis direction relative to the second moving member when the optical device receives external forces from the object side and the image side. The optical apparatus according to any one of configurations 1 to 12, characterized in that the first cam follower comes into contact with the stopper surface due to the displacement.

[0067] The embodiments described above are merely representative examples, and various modifications and changes can be made to each embodiment when implementing the present invention. [Explanation of symbols]

[0068] 1. Camera body 101 Interchangeable Lens Unit 111 Zoom Group 1 200 Guide tubes 300 Cam Cylinder 310 First cam groove 311 First cam surface 312 Stopper surface 320 Second cam groove 321 Second cam surface 400 Portable Cylinder 410 First Cam Follower 420 1st connection part 500 support rings 510 Second Cam Follower 520 2nd connection part 600 Biasing member

Claims

1. A cam cylinder having a cam groove, A first moving member that holds an optical element and is movable in the optical axis direction, and has a first cam follower, A guide member that guides the first cam follower in the direction of the optical axis, A second moving member having a second cam follower is connected to the first moving member so as to be movable in the optical axis direction together with the first moving member and to allow displacement of the first moving member in the optical axis direction, The device includes a biasing means that generates a biasing force to separate the first moving member and the second moving member from each other in the direction of the optical axis, The aforementioned cam groove portion is A first cam surface that moves the first cam follower, which is in contact with the biasing force, in the optical axis direction as the cam cylinder rotates, A stopper surface to which the first cam follower, which is separated from the first cam surface, contacts, The optical device is characterized in that the stopper surface is provided at different positions in the radial direction of the cam cylinder and has a second cam surface that moves the second cam follower, which is in contact with the biasing force, in the optical axis direction as the cam cylinder rotates.

2. The optical device according to claim 1, characterized in that the cam groove portion is formed as a single continuous groove portion in the groove width direction of the cam groove portion.

3. The optical device according to claim 1, characterized in that the cam groove portion is formed by a first cam groove portion having a first cam surface and a stopper surface, and a second cam groove portion having a second cam surface, which is formed as a groove portion continuous with the first cam groove portion in the groove width direction.

4. The first and second cam grooves form the peripheral wall portion of the cam cylinder, The first cam groove is formed to penetrate the peripheral wall in the radial direction, The optical device according to claim 3, characterized in that the second cam groove is formed so as not to penetrate the peripheral wall in the radial direction.

5. The optical apparatus according to claim 3, characterized in that the first cam groove and the second cam groove have portions that overlap with each other in the optical axis direction.

6. The optical device according to claim 1, characterized in that the second cam surface has a different cam shape from the first cam surface.

7. The optical apparatus according to claim 1, characterized in that the guide member does not guide the second cam follower in the optical axis direction.

8. The first moving member and the second moving member each have a connecting surface that is inclined with respect to the optical axis direction, The optical apparatus according to claim 1, characterized in that the connecting surfaces of the first and second moving members are biased by the biasing force and come into contact with each other, so that the first moving member and the second moving member are connected so that they can move together in the optical axis direction and the displacement of the first moving member of the second moving member in the optical axis direction is permitted.

9. The angle θ that the connecting surfaces of the first and second moving members make with respect to the optical axis is such that, when the coefficient of static friction between the connecting surfaces of the first and second moving members is μ, μ < 1 / tanθ The optical apparatus according to claim 8, characterized in that it satisfies the following conditions.

10. The optical apparatus according to claim 9, characterized in that the angle θ is different from the angle that the tangential direction of the second cam surface makes with respect to the optical axis direction.

11. The optical apparatus according to claim 1, characterized in that the first cam follower and the second cam follower are arranged in different phases relative to each other in the direction of the optical axis.

12. The optical device according to claim 1, characterized in that the first moving member holds the optical element closest to the object in the optical device as the optical element.

13. The first moving member is displaced in the optical axis direction relative to the second moving member when the optical device receives external forces from the object side and the image side. The optical apparatus according to any one of claims 1 to 12, characterized in that the first cam follower comes into contact with the stopper surface due to the displacement.

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