Lens device and imaging apparatus

Abstract

To provide an optical device capable of stably driving a moving lens barrel.SOLUTION: A lens device 100 includes moving frames 22 and 23, a moving base 30, and a cam barrel 24. A cam follower 42 is provided in the moving frame 22. A cam follower 43 is provided in the moving frame 23. An energizing cam follower 44 is provided in the moving base 30. A cam 46 with which the cam follower 42 and the energizing cam follower 44 are engaged and a cam 47 with which the cam follower 43 is engaged are provided in the cam barrel 24. The cam 46 includes cam surfaces 46a and 46b. The cam 47 includes a cam surface 47a. The direction of energizing force Fs1 of a compression coil spring 31 includes a component in the direction where the cam follower 42 is abutted on the cam surface 46a and a component in the direction where the energizing cam follower 44 is abutted on the cam surface 46b. The direction of energizing force Fs2 of a tension coil spring 37 includes a component in the direction where the cam follower 43 is abutted on the cam surface 47a and a component in the direction where the energizing cam follower 44 is abutted on the cam surface 46b.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a lens device and an imaging device.

Background Art

[0002] In a lens that linearly moves a moving lens barrel in the optical axis direction according to the locus of a cam applied to a rotatable cam member, there is a configuration in which a cam follower is biased against the cam by the biasing force of an elastic member to avoid an engagement gap between the cam and the cam follower.

[0003] Patent Document 1 discloses a configuration in which a cam pin provided on a lens support frame of a variable magnification lens group engages with one side of a cam groove, a cam pin provided on a lens support frame of an aberration correction lens group engages with the other side of the cam groove, and the cam pins are biased in a direction away from each other by a coil spring.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in Patent Document 1, since the angles formed by the tangents of the cam surfaces at the contact portions of the two cam pins with the cam surfaces and the optical axis are different, the circumferential component forces generated at the contact portions of the respective cam pins due to the biasing force of the coil spring become unbalanced, and there is a risk that a rotational force is generated in the zoom cam barrel.

[0006] Therefore, an object of the present invention is to provide a lens device capable of stably driving a moving lens barrel.

Means for Solving the Problems

[0007] The optical device of the present invention includes a first moving member and a second moving member that each hold an optical member and are movable in the optical axis direction, a third moving member that is movably connected to the first moving member via a first elastic member in the optical axis direction, a cam member that rotates to move the first moving member and the second moving member, and a fixing member that holds the first moving member, the second moving member, and the cam member. A first cam follower is provided on the first moving member, a second cam follower is provided on the second moving member, and a third cam follower is provided on the third moving member. The first moving member and the second moving member are connected to each other via a second elastic member. The cam member is provided with a first cam groove that engages with the first cam follower and the third cam follower, and a second cam groove that engages with the second cam follower. The first cam groove includes a first cam surface that the first cam follower contacts and a third cam surface that the third cam follower contacts. The second cam groove includes a second cam surface that the second cam follower contacts. The direction of the biasing force of the first elastic member includes a component in the direction in which the first cam follower contacts the first cam surface and a component in the direction in which the third cam follower contacts the third cam surface. The direction of the biasing force of the second elastic member includes a component in the direction in which the second cam follower contacts the second cam surface and a component in the direction in which the third cam follower contacts the third cam surface.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a lens device that can stably drive a moving lens barrel.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0010] (Example) Hereinafter, with reference to the attached FIGS. 1 to 4, the lens device 100 (optical device) of an embodiment of the present invention will be described. Throughout all the figures for explaining the embodiment, in principle (unless otherwise noted), the same members and the like are denoted by the same reference numerals, and repeated explanations thereof are omitted.

[0011] FIG. 1 is a diagram showing a configuration example of the lens device 100. The lens device 100 includes a lens body 100a, a rectangular lens cover 100b that covers the lens body 100a from the outer periphery, and a mount portion 100c for connecting to a camera.

[0012] The lens body 100a includes, but is not limited to, a focus portion 1 in which at least a part of a lens group (optical member) moves for focusing, and a zoom portion 2 including a plurality of lens groups that move for zooming. It also includes an aperture stop 3 for adjusting the amount of light, an extender portion 4 for switching the focal length range, and a relay portion 5 including an imaging optical system.

[0013] The zoom portion 2 has a fixed barrel 20 (fixed member), a moving frame 21 that holds a lens group so as to be movable in the optical axis direction, a moving frame 22 (first lens unit, first moving member), a moving frame 23 (second lens unit, second moving member), and a cam barrel 24 (cam member). The cam barrel 24 is rotatably supported by the fixed barrel 20 on a cam axis CA parallel to the optical axis OA, and a plurality of cam grooves are provided in the cam barrel 24.

[0014] The cam axis CA, which is the rotation axis of the cam barrel 24, is parallel to the optical axis OA and along the optical axis OA, but is a different axis from the optical axis OA and is outside the moving frame 21, the moving frame 22, and the moving frame 23. The moving frame 21, the moving frame 22, and the moving frame 23 each include a cam follower 41, a cam follower 42 (first cam follower), and a cam follower 43 (second cam follower) (which may be, for example, each columnar).

[0015] Further, the cam followers 41, 42, 43 are respectively engaged with cams 45, 46, 47 (which may be, for example, grooves) formed in the cam cylinder 24. The moving frames 21, 22, and 23 each include guide followers 48, 49, 50 (48 and 50 are not shown). The guide followers 48, 49, 50 are respectively engaged with linear guides 20a, 20b, 20c (which may be, for example, grooves) (20a and 20c are not shown) formed in the fixed lens barrel 20 along the optical axis OA.

[0016] One end of the cam cylinder 24 is provided with a cam gear 27 and a support shaft 25, and the other end of the cam cylinder 24 is provided with a support shaft 26. The cam cylinder 24 is rotatably supported by the lens device 100 by the support shaft 25 and the support shaft 26. When the cam gear 27 is rotationally driven by a driving unit or the like, the cam cylinder 24 is rotationally driven around the cam axis CA. As a result, the moving frames 21, 22, and 23 are respectively driven along the optical axis OA, and the focal length of the lens device 100 changes.

[0017] Here, with reference to FIGS. 2 and 3, the structures of the moving frame 22 and the moving frame 23 will be described. FIG. 2 is a diagram showing the biasing structure according to the embodiment, and FIG. 3 is a cross-sectional view of the movable unit according to the embodiment (cross-sectional view taken along line III-III in FIG. 2). The moving frame 22 is provided with a linear guide 51 composed of a rail 52 and a block 53 extending in the direction of the optical axis OA. A moving table 30 (third moving member) is disposed on the block 53. A compression coil spring 31 (first elastic member) is disposed between the moving table 30 and the wall 22a of the moving frame 22. A positioning shaft 32 fixed to the moving table 30 is inserted through the center of the compression coil spring 31 and a shaft insertion hole 22b formed in the wall 22a of the moving frame 22. Further, an urging cam follower 44 (third cam follower) and a spring hanging shaft 35 are provided on the moving table 30. That is, the urging cam follower 44 is movably held in the direction of the optical axis with respect to the moving frame 22 via the compression coil spring 31. A tension coil spring 37 (second elastic member) is hung on a spring hanging shaft 36 provided on the moving frame 23 and a spring hanging shaft 35 provided on the moving frame 22, and the moving frame 22 and the moving frame 23 are connected by the tension coil spring 37. With such a configuration, the moving table 30 is movable in the direction of the optical axis with respect to the moving frame 22 and is biased in the direction of the moving frame 23.

[0018] Next, with reference to FIG. 4, the arrangement relationship among the cams 46 and 47, the cam followers 42 and 43, and the urging cam follower 44 will be described. FIG. 4 is a diagram showing the arrangement relationship between each cam follower and each cam surface. The cam 46 (first cam groove) engages the cam follower 42 and the urging cam follower 44. Due to the urging force of the compression coil spring 31, the cam follower 42 abuts against one cam surface 46a (first cam surface), and the urging cam follower 44 abuts against the other cam surface 46b (third cam surface). The cam surface 46a and the cam surface 46b are formed in the same cam 46 (cam groove). The cam follower 43 engages the cam 47 (second cam groove) and is urged toward the moving frame 22 by the urging force of the tension coil spring 37 and abuts against the cam surface 47a (second cam surface). Here, the cam surface 46a and the cam surface 47a each have a lift shape along the optical trajectories of the moving frame 22 and the moving frame 23.

[0019] Next, the shape of the cam surface 46b will be described. Here, the angle formed by the tangent line at an arbitrary position on each cam surface and the plane perpendicular to the optical axis OA is referred to as the rising angle. The rising angles α, β, and γ formed by the tangent lines of the cam surfaces 46a, 47a, and 46b and the plane perpendicular to the optical axis OA are parameters indicating the respective movement trajectories of the moving frame 22, the moving frame 23, and the biasing cam follower 44. Note that the rising angle of the cam surface 47b facing the cam surface 47a may be an arbitrary value.

[0020] The rotational forces Fr1, Fr2, and Fr3 of the cam cylinder 24 generated at the contact portions of the cam followers 42, 43, and the biasing cam follower 44 with the respective cam surfaces due to the biasing force Fs1 of the compression coil spring 31 and the biasing force Fs2 of the tension coil spring 37 are expressed by the following equations. Fr1 = Fs1·tanα Fr2 = Fs2·tanβ Fr3 = -(Fs1 + Fs2)·tanγ

[0021] In order to prevent the cam cylinder 24 from rotating due to the biasing force Fs1 of the compression coil spring 31 and the biasing force Fs2 of the tension coil spring 37, it is necessary to make the sum of the rotational forces Fr1, Fr2, and Fr3 of the cam cylinder 24 smaller than the rotational force Frc required to rotationally drive the cam cylinder 24. Note that Frc includes the frictional forces and inertial forces of each part. Expressed by an equation, it is as follows. |Fr1 + Fr2 + Fr3| < |Frc|

[0022] From the above equations, the angle γ (rising angle) of the cam surface 47a can be expressed by the following equation, and the cam trajectory of the cam surface 47a is formed so that this equation holds. tanγ > (Fs1·tanα + Fs2·tanβ - Frc) / (Fs1 + Fs2)

[0023] Further, the cam followers 42 and 43 are in contact with the cam surfaces 46a and 47a throughout the zoom range and maintain the contact state even when the posture of the lens device 100 changes. That is, when the guaranteed use angle (the angle formed by the horizontal plane and the optical axis OA) of the lens device 100 is θmax, the minimum values Fs1min and Fs2min of the biasing forces Fs1 and Fs2 satisfy the following relationship with the mass M1 of the moving frame 22 and the mass M2 of the moving frame 23. Here, g is the gravitational acceleration. Fs1min > M1·g·sinθmax Fs2min > M2·g·sinθmax

[0024] Assuming that the elastic coefficients of the compression coil spring 31 and the tension coil spring 37 are k1 and k2, and the displacement amounts from the natural lengths are Δx1 and Δx2, the biasing forces Fs1 and Fs2 by the compression coil spring 31 and the tension coil spring 37 are expressed by the following formulas. Further, the direction of the biasing force Fs1 of the compression coil spring 31 is the direction in which the cam follower 42 contacts the cam surface 46a and the direction in which the biasing cam follower 44 contacts the cam surface 46b. The direction of the biasing force Fs2 of the tension coil spring 37 is the direction in which the cam follower 43 contacts the cam surface 47a and the direction in which the biasing cam follower 44 contacts the cam surface 46b. That is, the direction of the biasing force Fs1 of the compression coil spring 31 includes the component in the direction in which the cam follower 42 contacts the cam surface 46a and the component in the direction in which the biasing cam follower 44 contacts the cam surface 46b. Also, the direction of the biasing force Fs2 of the tension coil spring 37 includes the component in the direction in which the cam follower 43 contacts the cam surface 47a and the component in the direction in which the biasing cam follower 44 contacts the cam surface 46b. Fs1 = k1·Δx1 Fs2 = k2·Δx2

[0025] Assuming that the minimum values of Δx1 and Δx2 throughout the zoom range are Δx1min and Δx2min, the minimum values Fs1min and Fs2min of the biasing forces Fs1 and Fs2 are expressed by the following formulas. Fs1min = k1·Δx1min Fs2min = k2·Δx2min

[0026] From the above equations, the elastic coefficients k1 and k2 of the compression coil spring 31 and the tension coil spring 37 satisfy the following relationship. k1 > M1·g·sinθmax / Δx1min k2 > M2·g·sinθmax / Δx2min

[0027] As described above, according to the present invention, it is possible to provide a lens device 100 that reduces the automatic rotational force of the cam member due to the secondary action of the biasing force applied to the cam follower while applying a biasing force to the cam followers of the two moving lens barrels. As a result, the automatic rotation of the cam member is reduced, the moving lens barrel can be stably driven with high positional accuracy, and a lens device 100 with reduced power consumption can be provided.

[0028] In this embodiment, the linear guide 51 is used as the means for moving the biasing cam follower 44 in the optical axis direction. However, the present invention is not limited to this as long as the structure is such that the position of the moving base 30, which is movable in the optical axis direction and to which the biasing cam follower 44 is fixed, is stable. Also, although the compression coil spring 31 and the tension coil spring 37 are used as the means for applying a biasing force to each cam follower, a leaf spring, a torsion spring, a soft rubber, etc. may also be used. Further, although the driving cam followers and the biasing cam follower 44 are arranged in the optical axis direction, some of the cam followers may be displaced in the circumferential direction of the cam member.

[0029] Also, in this embodiment, an example is shown in which one cam follower 42 and the biasing cam follower 44 are inserted into one cam 46 in order to reduce the size of the lens device 100. However, they may be inserted into separate cams. Further, although a lens device 100 having a cylindrical cam as the cam member is shown as an example, the same effect can be obtained by arranging the biasing cam follower 44 in the circumferential direction of the moving frame with respect to an annular cam as shown in Patent Document 1.

[0030] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist thereof.

[0031] (Application Example) FIG. 5 is a schematic diagram showing a configuration example of a camera device 200 (imaging device) using a lens device 100 to which the present invention is applied. The imaging device includes a lens device 100 and a camera device 200 including a camera body 200a having an imaging element 200b that captures an image of an object formed by the lens device 100. Further, the imaging device may be configured such that the lens device 100 is detachably attached to the camera body 200a of the camera device 200.

[0032] The disclosure of this embodiment includes the following configurations. (Configuration 1) A first moving member and a second moving member that each hold an optical member and are movable in the optical axis direction, A third moving member movably connected in the optical axis direction to the first moving member via a first elastic member, A cam member that rotates to move the first moving member and the second moving member, A fixing member that holds the first moving member, the second moving member, and the cam member, A first cam follower is provided on the first moving member, a second cam follower is provided on the second moving member, and a third cam follower is provided on the third moving member, The first moving member and the second moving member are connected to each other via a second elastic member, The cam member is provided with a first cam groove that engages with the first cam follower and the third cam follower, and a second cam groove that engages with the second cam follower, The first cam groove includes a first cam surface with which the first cam follower abuts and a third cam surface with which the third cam follower abuts, and the second cam groove includes a second cam surface with which the second cam follower abuts, The direction of the biasing force of the first elastic member includes a component in the direction in which the first cam follower abuts on the first cam surface and a component in the direction in which the third cam follower abuts on the third cam surface, An optical device, wherein the direction of the biasing force of the second elastic member includes a component in the direction in which the second cam follower abuts on the second cam surface and a component in the direction in which the third cam follower abuts on the third cam surface. (Configuration 2) The angle formed by the tangent of the third cam surface and the optical axis at the contact portion between the third cam follower and the third cam surface is formed such that the sum of the rotational forces of the cam member due to the biasing forces of the first and second elastic members generated at each of the contact portions between the first cam follower and the first cam surface, the second cam follower and the second cam surface, and the third cam follower and the third cam surface is smaller than the rotational force required for the rotational drive of the cam member. The optical device according to Configuration 1, characterized in that (Configuration 3) The optical device according to Configuration 1 or 2, characterized in that the first cam surface and the third cam surface are formed in the same cam groove. (Configuration 4) The optical device according to any one of Configurations 1 to 3, characterized in that the rotation axis of the cam member is parallel to the optical axis and is a different axis from the optical axis. (Configuration 5) Let the angles formed by the tangents of the first cam surface, the second cam surface, and the third cam surface and the plane perpendicular to the optical axis be α, β, and γ, respectively. Let the rotational forces of the cam member generated at the contact portions where the first cam follower and the second cam follower contact the first cam surface and the second cam surface due to the biasing forces of the first elastic member and the second elastic member be Fr1 and Fr2, respectively. When the rotational force required to rotate the cam member is Frc, The angle γ formed by the tangent of the third cam surface and the plane perpendicular to the optical axis is represented by the following formula tanγ > (Fs1·tanα + Fs2·tanβ - Frc) / (Fs1 + Fs2). The optical device according to any one of Configurations 1 to 4, characterized in that (Configuration 6) An imaging device, characterized by comprising the optical device according to any one of Configurations 1 to 5 and an imaging element that captures an image formed by the optical device.

Explanation of Reference Numerals

[0033] 20 ···· Fixed lens barrel (fixed member) 22 ···· Moving frame (first lens unit, first moving member) 23 ···· Moving frame (second lens unit, second moving member) 24 ···· Cam cylinder (cam member) 30 ···· Moving base (third moving member) 31 ···· Compression coil spring (first elastic member) 37 ···· Tension coil spring (second elastic member) 42 ···· Cam follower (first cam follower) 43 ···· Cam follower (second cam follower) 44 ···· Biasing cam follower (third cam follower) 46 ···· Cam (first cam groove, cam groove) 46a···· Cam surface (first cam surface) 46b···· Cam surface (third cam surface) 47 ···· Cam (second cam groove) 47a···· Cam surface (second cam surface) 100 ··· Lens device (optical device) 200 ··· Camera device (imaging device) 200b ·· Image sensor CA ···· Cam shaft (rotating shaft) Fs1 ··· Biasing force Fs2 ··· Biasing force Fr1 ··· Rotating force Fr2 ··· Rotating force OA ···· Optical axis α ····· Upright angle (angle) β ····· Upright angle (angle) γ ····· Upright angle (angle)

Claims

1. A first moving member and a second moving member that each hold an optical member and are movable in the optical axis direction, A third moving member movably connected to the first moving member in the optical axis direction via a first elastic member, A cam member that rotates to move the first moving member and the second moving member, A fixing member that holds the first moving member, the second moving member, and the cam member, A first cam follower is provided on the first moving member, a second cam follower is provided on the second moving member, and a third cam follower is provided on the third moving member, The first moving member and the second moving member are connected to each other via a second elastic member, The cam member is provided with a first cam groove with which the first cam follower and the third cam follower engage, and a second cam groove with which the second cam follower engages, The first cam groove includes a first cam surface with which the first cam follower abuts and a third cam surface with which the third cam follower abuts, and the second cam groove includes a second cam surface with which the second cam follower abuts, The direction of the biasing force of the first elastic member includes a component in the direction in which the first cam follower abuts against the first cam surface and a component in the direction in which the third cam follower abuts against the third cam surface, An optical device, wherein the direction of the biasing force of the second elastic member includes a component in the direction in which the second cam follower abuts against the second cam surface and a component in the direction in which the third cam follower abuts against the third cam surface.

2. The sum of the rotational forces of the cam member due to the biasing forces of the first and second elastic members generated at each of the contact portions between the first cam follower and the first cam surface, the second cam follower and the second cam surface, and the third cam follower and the third cam surface is smaller than the rotational force required for driving the rotation of the cam member. An angle formed by the tangent of the third cam surface at the contact portion between the third cam follower and the third cam surface and the optical axis is formed. The optical device according to claim 1.

3. The optical device according to claim 1, wherein the first cam surface and the third cam surface are formed in the same cam groove.

4. The optical device according to claim 1, wherein the rotation axis of the cam member is parallel to the optical axis and is a different axis from the optical axis.

5. The angles formed between the tangents to the first cam surface, the second cam surface, and the third cam surface, respectively, and a plane perpendicular to the optical axis are α, β, and γ, respectively. The rotational forces of the cam member generated at the contact portions where the first cam follower and the second cam follower contact the first cam surface and the second cam surface, respectively, due to the biasing forces of the first elastic member and the second elastic member are Fr1 and Fr2, respectively. When the rotational force required to rotate the cam member is Frc, The angle γ formed between the tangent to the third cam surface and a plane perpendicular to the optical axis satisfies the following equation The optical device according to claim 1, characterized in that tan γ > (Fs1 · tan α + Fs2 · tan β - Frc) / (Fs1 + Fs2). **Claim 6** An imaging device comprising the optical device according to any one of claims 1 to 5, and an imaging element that captures an image formed by the optical device.

Images