Lens barrel and camera equipped therewith, rotational position detection device

Abstract

To provide a lens barrel which can improve the resolution of rotation detection without complicating a structure.SOLUTION: A lens barrel 100 comprises: a fifth-group unit 25; a focus ring 31; an internal gear 31b; a pinion gear 41; a magnet 43 for detection; and a GMR sensor 44. The internal gear 31b rotates integrally with the focus ring 31 and has a plurality of gear parts 31c. The pinion gear 41 is provided on the inner peripheral surface of the focus ring 31 and has a gear part 41a which is fit to the gear part 31c of the internal gear 31b and a guide shaft 42 which is inserted to the center of the gear part 41a. The magnet 43 for detection receives insertion of the guide shaft 42, rotates integrally with the gear part 41a and has a magnetization surface 43b on which different magnetic poles are alternately magnetized. The GMR sensor 44 is fixed to a different member from the magnet 43 for detection, is provided at a position adjacent to the magnet 43 for detection and detects rotation of the magnet 43 for detection that rotates together with the pinion gear 41.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a lens barrel including a manually operated ring such as a focus ring, a camera including the same, and a rotational position detection device.

Background Art

[0002] Generally, a lens barrel provided with a manually operated ring such as a focus ring or a zoom ring is used in a state where it is attached to a camera body. In a lens barrel provided with such a manually operated ring, position detection of the manually operated ring is performed using detection means such as a photointerrupter or a photoreflector, for example.

[0003] For example, Patent Document 1 discloses a displacement detection device that includes a magnetic scale having a magnetized surface with different magnetic poles alternately magnetized, and an MR sensor disposed opposite the magnetic scale at a predetermined interval, wherein either one of the magnetic scale and the MR sensor is configured to interlock with a moving body, the displacement detection device detects an output signal resulting from the relative movement between the MR sensor and the magnetic scale accompanying movement of the moving body, and detects the position of the moving body, and the displacement detection device is configured such that the magnetic scale and the MR sensor, which is disposed opposite the magnetic scale at the predetermined interval, are formed into a single unit via one member.

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] However, the conventional displacement detection device described above has the following problems. In other words, while the displacement detection device disclosed in the above publication can improve the detection resolution compared to a conventional displacement detection mechanism using a photointerrupter, it requires a dedicated component (casing component) to unitize the magnetic scale and the MR sensor. The object of this disclosure is to provide a lens barrel and a camera equipped therewith that can improve the resolution of rotation detection without complicating the structure. [Means for solving the problem]

[0006] The lens barrel according to this disclosure comprises a movable lens frame, a manual operation ring, a first gear unit, a second gear unit, a detection magnet, and a rotation detection sensor. The movable lens frame holds a lens and is movable back and forth in the optical axis direction. The manual operation ring is a substantially annular member that moves the movable lens frame in the optical axis direction when rotated. The first gear unit is provided on the inner circumferential surface side of the manual operation ring, rotates integrally with the manual operation ring, and has a plurality of first gear parts that protrude radially inward from the manual operation ring. The second gear unit is provided on the inner circumferential surface side of the manual operation ring, and has a second gear part that fits with the first gear part of the first gear unit, and a rotating shaft inserted through the center of the second gear part. The detection magnet has a rotating shaft inserted through it, rotates integrally with the second gear part, and has a magnetized surface with alternating different magnetic poles. The rotation detection sensor is fixed to a separate component from the detection magnet and is positioned adjacent to the detection magnet. It detects the rotation of the detection magnet, which rotates together with the second gear section. [Effects of the Invention]

[0007] The lens barrel according to this disclosure makes it possible to improve the resolution of rotation detection without complicating the structure. [Brief explanation of the drawing]

[0008] [Figure 1]Figure 1 is an overall perspective view showing the configuration of a camera in which a lens barrel according to one embodiment of the present disclosure is attached to the camera body. [Figure 2] Cross-sectional view of the lens barrel in Figure 1. [Figure 3A] Figure 2 is a cross-sectional view showing the lens barrel in the wide position. [Figure 3B] Figure 2 is a cross-sectional view showing the lens barrel in the telephoto position. [Figure 4] Figure 2 is a front view of the lens barrel as seen from the subject side in the optical axis direction. [Figure 5] Figure 4 is a cross-sectional view along line DD, and is an enlarged view of section A in Figure 2. [Figure 6] A perspective view showing the main component configuration included in part A of Figure 5. [Figure 7] Figure 6 shows an exploded perspective view of the parts. [Figure 8] A perspective view showing the configuration of the guide shaft included in the part in Figure 7. [Figure 9] A schematic diagram showing the arrangement of the detection magnet and MGR sensor included in the component shown in Figure 7. [Figure 10] Figure 2 shows the control block diagram for the lens barrel. [Modes for carrying out the invention]

[0009] The embodiments will be described in detail below, with reference to the drawings as appropriate. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters and redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding for those skilled in the art. The applicant provides the accompanying drawings and the following description so that a person skilled in the art can fully understand the disclosure, and not intends to limit the subject matter described in the claims.

[0010] (Embodiment 1) A lens barrel 100 and a camera 1 equipped therewith, according to one embodiment of this disclosure, will be described below with reference to Figures 1 to 10. (1) Configuration of lens barrel 100 Hereinafter, the configuration of a lens barrel 100 according to an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a perspective view showing a camera 1 configured by attaching the lens barrel 100 according to the present embodiment to a camera body 101.

[0011] As shown in FIG. 1, the lens barrel 100 is a retractable lens barrel that is detachably attached to the camera body 101. As shown in FIG. 2, the lens barrel 100 mainly includes a rectilinear barrel (fixed barrel) 11, a cam barrel 12, a first group unit 21, a second group unit 22, a third group unit 23, a fourth group unit 24, a fifth group unit (movable lens frame) 25, a sixth group unit 26, a seventh group unit 27, a focus ring (manual operation ring) 31, a zoom ring 32, and a base frame 34.

[0012] The rectilinear barrel (fixed barrel) 11 is a substantially cylindrical member, and holds the second to sixth group units 22 to 26 on its inner peripheral surface side in a state movable in the optical axis OP direction. The cam barrel 12 is disposed on the outer peripheral surface side of the aforementioned substantially cylindrical rectilinear barrel 11, and a plurality of cam grooves are formed in the substantially cylindrical main body. When the cam barrel 12 is rotated relative to the rectilinear barrel 11, a cam follower provided on the rectilinear barrel 11 side moves along the cam grooves formed in the cam barrel 12, whereby the cam barrel 12 moves back and forth in the optical axis OP direction.

[0013] The first group unit 21 is a substantially cylindrical member disposed on the outer peripheral surface side of the rectilinear barrel 11, and as shown in FIG. 2, holds a first group lens L1 at an end portion on the object side in the optical axis OP direction. The first group unit 21 is disposed closest to the object side in the optical axis OP direction of the lens barrel 100. As shown in FIG. 2, the first group unit 21 has a substantially cylindrical main body portion 21a and a cam follower 21b provided on an inner peripheral surface of the substantially cylindrical main body portion 21a.

[0014] The cam follower 21b of the first lens group unit 21 is provided so as to protrude radially inward from the outer peripheral surface near the end portion on the subject side on the inner peripheral surface of the substantially cylindrical main body portion 21a. The cam follower 21b engages with a rectilinear groove formed in the rectilinear barrel 11 and a cam groove formed in the cam barrel 12, and moves the first lens group unit 21 back and forth in the optical axis OP direction as the cam barrel 12 rotates.

[0015] The second lens group unit 22 is a substantially annular member contained on the inner peripheral surface side of the rectilinear barrel 11, and holds the second group lens L2 as shown in Figure 2. The second lens group unit 22 is disposed between the first lens group unit 21 and the third lens group unit 23 in the optical axis OP direction of the lens barrel 100. The second lens group unit 22 is fixed to the end surface on the subject side of the rectilinear barrel 11 using an unillustrated screw.

[0016] The third lens group unit 23 is a substantially annular member contained on the inner peripheral surface side of the rectilinear barrel 11, and holds the third group lens L3 as shown in Figure 2. The third lens group unit 23 is disposed between the second lens group unit 22 and the fourth lens group unit 24 in the optical axis OP direction of the lens barrel 100. The third lens group unit 23 has a cam follower provided so as to protrude radially outward from the outer peripheral surface.

[0017] The fourth lens group unit 24 is a substantially cylindrical member contained on the inner peripheral surface side of the rectilinear barrel 11, and holds the fourth group lens L4 as shown in Figure 2. The fourth lens group unit 24 is disposed between the third lens group unit 23 and the fifth lens group unit 25 in the optical axis OP direction of the lens barrel 100. The fourth lens group unit 24 has a cam follower provided so as to protrude radially outward from the outer peripheral surface.

[0018] The 5-group unit (movable lens frame) 25 is a substantially annular member enclosed on the inner circumferential side of the straight barrel 11, and as shown in Figure 2, it holds the 5-group lens (focusing lens) L5. The 5-group unit 25 is positioned between the 4-group unit 24 and the 6-group unit 26 in the optical axis OP direction of the lens barrel 100. The 5-group unit 25 is mounted suspended from the 4-group unit 24 by a guide shaft (not shown) with one end attached to the 4-group unit 24.

[0019] The 6-group unit 26 is a substantially annular member enclosed on the inner circumferential side of the straight barrel 11, and as shown in Figure 2, it holds the 6-group lens L6. The 6-group unit 26 is positioned between the 5-group unit 25 and the 7-group unit 27 in the optical axis OP direction of the lens barrel 100. Like the 5-group unit 25, the 6-group unit 26 is suspended from the 4-group unit 24 by a guide shaft (not shown).

[0020] The 7-group unit 27 is a substantially annular member enclosed on the inner circumferential side of the straight barrel 11, and as shown in Figure 2, it holds the 7-group lens L7. The 7-group unit 27 is positioned on the image plane side furthest away from the subject side in the optical axis OP direction of the lens barrel 100. The 7-group unit 27 has a cam follower that is provided to protrude radially outward from its outer surface.

[0021] Here, the lenses L1 to L7 of groups 1 to 7, held in the 1 to 7 group units 21 to 27, are arranged in this order from the subject side, with the optical axis OP as the central axis. The lens barrel 100 then moves the 1 to 7 group units 21 to 27 back and forth along the direction of the optical axis OP, between the Wide position shown in Figure 3A and the Tele position shown in Figure 3B, by rotating the zoom ring 32, which will be described later.

[0022] In other words, the lens barrel 100 is configured such that when the zoom ring 32, which is rotatably mounted on the outer surface of the base frame 34, is rotated, the cam cylinder 12 rotates in conjunction with the rotation of the zoom ring 32. When the cam cylinder 12 rotates, the 1st to 7th group units 21 to 27 are driven back and forth in the optical axis direction OP. In this context, lens barrels equipped with lenses that have a shallow depth of field, such as macro lenses, require a resolution even finer than the current detection resolution.

[0023] Furthermore, depth of field refers to the range in a photograph where, strictly speaking, only a single point is in focus when the lens is focused on a subject. However, to the human eye, the area in front of and behind that point also appears to be in focus. The lens barrel 100 of this embodiment comprises a 5-group unit 25, a focus ring 31, an internal gear 31b, a pinion gear 41, a detection magnet 43, and a GMR (Giant Magneto Resistive effect) sensor 44. The 5-group unit 25 holds the 5-group lens L5 and moves back and forth in the optical axis direction. The focus ring 31 is a substantially annular member and moves the 5-group unit 25 in the optical axis direction when rotated. The internal gear 31b is provided on the inner circumferential surface side of the focus ring 31, rotates integrally with the focus ring 31, and has a plurality of gear portions 31c that protrude radially inward from the focus ring 31. The pinion gear 41 is provided on the inner circumferential surface side of the focus ring 31 and has a gear portion 41a that engages with the gear portion 31c of the internal gear 31b, and a guide shaft 42 that is inserted through the center of the gear portion 41a. The detection magnet 43 has a guide shaft 42 inserted through it and rotates together with the gear portion 41a, and has magnetized surfaces 43b with alternating different magnetic poles. The GMR sensor 44 is fixed to a separate component from the detection magnet 43 and is located adjacent to the detection magnet 43, and detects the rotation of the detection magnet 43 which rotates together with the pinion gear 41.

[0024] More specifically, in the lens barrel 100, as shown in Figure 5, which is an enlarged view of part A in Figure 2 and a cross-sectional view of line DD shown in Figure 4, a rubber cover 31a is attached to the outer surface of the focus ring 31 to prevent slippage when rotating the focus ring 31. The focus ring 31 is a substantially annular member that, when rotated, moves the 5-group unit 25 back and forth in the direction of the optical axis OP.

[0025] Furthermore, as shown in Figures 5 and 6, an internal gear (first gear unit) 31b is provided on the inner circumferential surface side of the focus ring 31, which rotates in conjunction with the rotation of the focus ring 31. The internal gear 31b is provided on the inner circumferential surface side of the focus ring 31 and rotates integrally with the focus ring 31. As shown in Figure 6, it has a plurality of gear portions (first gear portions) 31c that protrude radially inward from the focus ring 31. The internal gear 31b is formed as a substantially arc-shaped member fixed to the inner circumferential surface of the focus ring 31 with a length corresponding to the operating range of the focus ring 31.

[0026] As shown in Figures 5 and 6, the multiple gear portions 31c are provided so as to protrude radially inward from the inner circumferential surface of the internal gear 31b. Each of the multiple gear portions 31c is arranged to mesh with the gear portion 41a of the pinion gear 41, which will be described later. As shown in Figure 7, the pinion gear (second gear unit) 41 is a substantially cylindrical gear member and is provided on the inner circumferential surface side of the internal gear 31b, as shown in Figures 5 and 6. The pinion gear 41 has a plurality of gear portions (second gear portions) 41a that engage with the gear portion 31c of the internal gear 31b, and a guide shaft 42 inserted through the center of the gear portions 41a. When the focus ring 31 is rotated, the pinion gear 41 rotates around the guide shaft (rotation axis) 42 inserted into the through hole 41b, in accordance with the rotation of the internal gear 31b, which rotates together with the focus ring 31.

[0027] Multiple gear portions 41a protrude radially outward from the outer circumferential surface of the substantially cylindrical pinion gear 41 and are formed with the same pitch as the gear portion 31c of the internal gear 31b. As shown in Figure 5, the end of the guide shaft 42 on the subject side (second end 42c), which will be described later, is inserted into the through hole 41b. The pinion gear 41 rotates in an integrated state with the guide shaft 42, with the second end 42c of the guide shaft 42 inserted into the through hole 41b.

[0028] As shown in Figure 7, the guide shaft 42 is inserted into through holes 41b and 43a provided in the center of the pinion gear 41 and the detection magnet 43 (described later), and is provided as the rotation axis of the pinion gear 41 and the detection magnet 43. As shown in Figure 8, the guide shaft 42 has a large diameter portion 42a, a first end 42b, and a second end 42c. As shown in Figure 8, the enlarged diameter portion 42a is located in the middle of the guide shaft 42 and has a larger outer diameter than the outer diameters of the first end 42b and the second end 42c. As shown in Figure 5, the enlarged diameter portion 42a is arranged such that the pinion gear 41 abuts against the end face on the subject side and the detection magnet 43 abuts against the end face on the image plane side.

[0029] This allows the enlarged diameter portion 42a to position the pinion gear 41 and the detection magnet 43 relative to the guide shaft 42. As shown in Figures 5 and 8, the first end 42b is positioned closer to the image plane than the larger diameter portion 42a and has a smaller outer diameter than the second end 42c. As shown in Figure 5, the first end 42b is pivotally supported by the first bearing portion 45, which is positioned closer to the image plane, allowing it to rotate.

[0030] As shown in Figures 5 and 8, the second end 42c is positioned closer to the subject than the larger diameter portion 42a and has a larger outer diameter than the first end 42b. As shown in Figure 5, the second end 42c is pivotally supported by a second bearing portion 46 located on the subject side, allowing it to rotate. Furthermore, when the focus ring 31 is rotated, the guide shaft 42 rotates together with the pinion gear 41 and the detection magnet 43, which rotate in conjunction with the rotation of the internal gear 31b that integrates the focus ring 31. At this time, the guide shaft 42 rotates with its first end 42b supported by the first bearing portion 45 and its second end 42c supported by the second bearing portion 46.

[0031] As shown in Figure 7, the detection magnet 43 has a guide shaft 42 inserted through it and rotates in conjunction with the pinion gear 41. The detection magnet 43 has a through hole 43a into which the guide shaft 42 is inserted, and a magnetized surface 43b in which different magnetic poles (N pole and S pole) are alternately magnetized. As shown in Figure 7, the through-hole 43a is formed in the central part of the substantially cylindrical detection magnet 43, into which the second end 42c of the thinner side of the guide shaft 42 is inserted.

[0032] As shown in Figure 9, on the magnetization surface 43b, north poles and south poles are alternately arranged in the circumferential direction of the substantially cylindrical detection magnet 43. Then, in the state shown in Figure 9, when the detection magnet 43 rotates, the GMR sensor 44, positioned close to the magnetized surface 43b, detects the rotation of the detection magnet 43, that is, the rotation of the internal gear 31b via the rotation of the pinion gear 41 integrated via the guide shaft 42, and as a result, the rotational position of the focus ring 31 integrated with the internal gear 31b can be detected.

[0033] As shown in Figures 5 and 6, the GMR sensor (rotation detection sensor) 44 is positioned adjacent to the magnetized surface 43b of the detection magnet 43 and detects the rotation of the detection magnet 43 as it rotates together with the pinion gear 41. Based on the detection result from the GMR sensor 44, the position detection unit 52 (see Figure 10), described later, can detect the rotational position of the rotated focus ring 31.

[0034] Furthermore, as shown in Figures 5 and 7, the GMR sensor 44 is fixed to a separate component (second bearing portion 46) from the detection magnet 43. As a result, the detection magnet 43 and the GMR sensor 44 are attached to separate components, which improves the resolution of rotation detection without complicating the structure.

[0035] Furthermore, the GMR sensor 44 is positioned outside the detection magnet 43 in the radial direction centered on the optical axis OP of the 5-group lens L5 held in the 5-group unit 25. This makes it easier to route the wiring for transmitting the detection results from the GMR sensor 44 compared to a configuration where the GMR sensor 44 is located radially inward in the lens barrel 100.

[0036] As shown in Figure 5, the first bearing portion 45 pivotally supports the first end 42b of the guide shaft 42 in a rotatable state. As shown in Figure 7, the first bearing portion 45 has a main body portion 45a, a pivot portion 45b into which the first end 42b of the guide shaft 42 into which the detection magnet 43 is loaded, and a projection portion 45c for alignment with the second bearing portion 46. As shown in Figure 7, the main body portion 45a is a substantially U-shaped member, and a pivot portion 45b and a projection portion 45c are provided on the surface facing the subject.

[0037] The shaft support portion 45b supports one end of the guide shaft 42 with the first end 42b, into which the detection magnet 43 of the guide shaft 42 is loaded, inserted. The projections 45c are two members used for alignment with the second bearing portion 46, and are inserted into the two insertion holes 46d on the second bearing portion 46 side, thereby positioning the first bearing portion 45 relative to the second bearing portion 46.

[0038] As shown in Figure 5, the second bearing portion 46 rotatably supports the second end 42c of the guide shaft 42. As shown in Figure 7, the second bearing portion 46 has a main body portion 46a, a support portion 46b, a filling space 46c, and an insertion hole 46d. As shown in Figure 7, the main body 46a has a pinion gear 41 positioned on the image plane side, and the GMR sensor 44 is held in a recess 46e formed on its upper surface. This allows the GMR sensor 44 to be positioned directly above the detection magnet 43.

[0039] Furthermore, as shown in Figure 7, a filling space 46c is provided on the end face of the main body 46a on the subject side, where the grease g1 is held. The shaft support portion 46b supports one end of the guide shaft 42 with the second end 42c, into which the pinion gear 41 of the guide shaft 42 is mounted, inserted. As shown in Figure 7, the filling space 46c is formed around the guide shaft 42 in the second bearing portion 46, on a plane perpendicular to the guide shaft 42, and is filled with grease (high viscosity substance) g1. The filling space 46c has a substantially cylindrical shape that is substantially concentric with the guide shaft 42 at its center. The filling space 46c is provided on the end face of the second bearing portion 46 opposite to the pinion gear 41.

[0040] In the filled space 46c, as shown in Figure 5, the second end 42c of the guide shaft 42 protrudes and is covered with grease g1. Furthermore, the second end 42c, which is provided to protrude into the filling space 46c, has an uneven surface. As a result, the contact area between the second end 42c of the guide shaft 42 and the grease g1 filled in the filling space 46c increases, making the second end 42c, covered with grease g1, less likely to move. Therefore, the looseness of the guide shaft 42 can be more effectively suppressed by the grease g1 in the filling space 46c.

[0041] The insertion holes 46d are through holes formed at both ends of the main body portion 46a along the optical axis OP direction, and as shown in Figure 7, the projections 45c of the first bearing portion 45 described above are inserted into them to position the first bearing portion 45 relative to the second bearing portion 46. As shown in Figure 7, the wiring 47 is electrically connected to the upper surface of the GMR sensor 44, which is held in the recess 46e of the second bearing portion 46, and transmits the detection result from the GMR sensor 44 to the lens control unit 50, which will be described later.

[0042] In this embodiment, the lens barrel 100, as shown in the control block of Figure 10, mainly includes a GMR sensor 44, a lens control unit 50, a drive unit 51, a position detection unit 52, and a storage unit 53, for detecting the rotational position of the focus ring 31. The detection result from the GMR sensor 44 is transmitted to the position detection unit 52 via the aforementioned wiring 47.

[0043] The position detection unit 52 detects the rotational position of the focus ring 31 based on the detection result received from the GMR sensor 44 and transmits it to the lens control unit 50. The lens control unit 50 adjusts the position of the lens by controlling a drive unit 51, such as a motor, located inside the lens barrel 100, according to the rotational position of the focus ring 31 detected by the position detection unit 52.

[0044] In the lens barrel 100 of this embodiment, as described above, a GMR sensor 44 is used as the detection system for the manually operated focus ring 31, and the transmission of the driving force associated with the rotational operation of the focus ring 31 is configured by a combination of gears (internal gear 31b and pinion gear 41). This allows the detection resolution of the manual focus to be increased by multiplying the number of detection pulses of the detection magnet 43 by the gear ratio of the pinion gear 41.

[0045] On the other hand, increasing the detection resolution may lead to false signal detection in situations unintended by the user due to play between the first end 42b and the second end 42c of the guide shaft 42 and the first and second bearing parts 45 and 46, as well as backlash between the gear parts 31c and 41a. Therefore, in the lens barrel 100 of this embodiment, as a countermeasure, a filling space 46c (grease reservoir) for storing highly viscous grease g1 is provided in the second bearing portion 46.

[0046] This prevents false detections caused by play between the first end 42b and the second end 42c of the guide shaft 42 and the first and second bearing parts 45 and 46, as well as backlash between the gear parts 31c and 41a. <Main Features> The lens barrel 100 of this embodiment comprises a 5-group unit 25, a focus ring 31, an internal gear 31b, a pinion gear 41, a detection magnet 43, and a GMR sensor 44, as described above. The 5-group unit 25 holds the 5-group lens L5 and moves back and forth in the optical axis direction. The focus ring 31 is a substantially annular member and moves the 5-group unit 25 in the optical axis direction when rotated. The internal gear 31b is provided on the inner circumferential surface side of the focus ring 31, rotates integrally with the focus ring 31, and has a plurality of gear portions 31c that protrude radially inward from the focus ring 31. The pinion gear 41 is provided on the inner circumferential surface side of the focus ring 31 and has a gear portion 41a that engages with the gear portion 31c of the internal gear 31b, and a guide shaft 42 that is inserted through the center of the gear portion 41a. The detection magnet 43 has a guide shaft 42 inserted through it and rotates together with the gear portion 41a, and has magnetized surfaces 43b with alternating different magnetic poles. The GMR sensor 44 is fixed to a separate component from the detection magnet 43 and is located adjacent to the detection magnet 43, and detects the rotation of the detection magnet 43 which rotates together with the pinion gear 41.

[0047] This allows for high-precision detection of the rotation position of the focus ring 31, which rotates in conjunction with the internal gear 31b that meshes with the gear portion 41a of the pinion gear 41 and rotates together with the pinion gear 41, by using the detection results from the GMR sensor 44 to detect the rotation of the detection magnet 43. Furthermore, since the GMR sensor 44 is attached to a separate component from the detection magnet 43, the resolution of rotation detection can be improved with a simple configuration without the need for dedicated parts.

[0048] Furthermore, the rotation position detection device 10 of this embodiment is attached to the lens barrel 100 described above and detects the rotation position of the focus ring 31. The lens barrel 100 includes a 5-group unit 25 that holds the lens and is movable back and forth in the optical axis direction OP, and a focus ring 31 which is a substantially annular member that moves the 5-group unit 25 in the optical axis direction OP when rotated. The rotation position detection device 10, as shown in Figure 6, includes an internal gear 31b, a pinion gear 41, a detection magnet 43, and a GMR sensor 44. The internal gear 31b is provided on the inner circumferential surface side of the focus ring 31 and rotates integrally with the focus ring 31 and has a plurality of gear portions 31c that protrude radially inward from the focus ring 31. The pinion gear 41 is provided on the inner circumferential surface side of the focus ring 31 and has a gear portion 41a that fits with the gear portion 31c of the internal gear 31b, and a guide shaft 42 that is inserted through the center of the gear portion 41a. The detection magnet 43 has a guide shaft 42 inserted through it and rotates together with the gear portion 41a, and has magnetized surfaces 43b with alternating different magnetic poles. The GMR sensor 44 is fixed to a separate component from the detection magnet 43 and is located adjacent to the detection magnet 43, and detects the rotation of the detection magnet 43 which rotates together with the pinion gear 41.

[0049] This allows for high-precision detection of the rotation position of the focus ring 31, which rotates in conjunction with the internal gear 31b that meshes with the gear portion 41a of the pinion gear 41 and rotates together with the pinion gear 41, by using the detection results from the GMR sensor 44 to detect the rotation of the detection magnet 43. Furthermore, since the GMR sensor 44 is attached to a separate component from the detection magnet 43, the resolution of rotation detection can be improved with a simple configuration without the need for dedicated parts.

[0050] Furthermore, the lens barrel 100 of this embodiment includes a 5-group unit 25, a focus ring 31, an internal gear 31b, and a pinion gear 41, as described above. The 5-group unit 25 holds the 5-group lens L5 and moves back and forth in the optical axis direction. The focus ring 31 is a substantially annular member and moves the 5-group unit 25 in the optical axis direction when rotated. The internal gear 31b is provided on the inner circumferential surface side of the focus ring 31, rotates integrally with the focus ring 31, and has a plurality of gear portions 31c that protrude radially inward from the focus ring 31. The pinion gear 41 is provided on the inner circumferential surface side of the focus ring 31 and has a gear portion 41a that engages with the gear portion 31c of the internal gear 31b, and a guide shaft 42 that is inserted through the center of the gear portion 41a. The guide shaft 42 has a first end 42b and a second end 42c opposite to the first end 42b. The pinion gear 41 further includes a first bearing portion 45 that supports the first end 42b of the guide shaft 42, a second bearing portion 46 that supports the second end 42c, and a filling space 46c formed in the second bearing portion 46 on a plane perpendicular to the guide shaft 42 and filled with grease g1.

[0051] As a result, even if play occurs in the guide shaft 42, the viscosity of the grease g1 filled in the filling space 46c so as to cover the tip of the second end 42c of the guide shaft 42 can effectively suppress the play of the guide shaft 42. Therefore, in a lens barrel 100 equipped with a GMR sensor 44 that has high detection resolution, as in this embodiment, the occurrence of false detections caused by looseness in the guide shaft 42 can be effectively suppressed.

[0052] [Other embodiments] Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the gist of the disclosure. (A) In the above embodiment, an example was given in which the disclosure is applied to the focus ring 31 as a manual operation ring. However, the disclosure is not limited thereto.

[0053] For example, the same effect as described above can be obtained when this disclosure is applied to a zoom ring, similar to the focus ring. (B) In the above embodiment, an example was described in which a pinion gear 41 is arranged on the subject side in the optical axis OP direction and a detection magnet 43 is arranged on the image plane side via the enlarged diameter portion 42a of the guide shaft 42. However, this disclosure is not limited to this.

[0054] For example, the pinion gear (second gear unit) and the detection magnet may be arranged in opposite directions in the optical axis direction. (C) In the above embodiment, an example was described in which the pinion gear 41 and the detection magnet 43 are positioned in the optical axis OP direction by a large-diameter portion 42a provided in the middle of the guide shaft 42. However, this disclosure is not limited to this.

[0055] For example, the guide shaft that serves as the rotation center for the pinion gear (second gear unit) and the detection magnet may have a configuration that does not include a large diameter section. (D) In the above embodiment, an example was given in which the filling space 46c, into which the grease g1 as a highly viscous substance is filled, is substantially cylindrical in shape and concentric with the guide shaft 42. However, the present disclosure is not limited thereto.

[0056] For example, the shape of the filling space into which a highly viscous substance such as grease is filled may be a shape other than a roughly cylindrical shape concentric with the guide shaft (rotation axis). (E) In the above embodiment, an example was given in which grease g1 was used as the high-viscosity substance filled in the filling space 46c to suppress play in the guide shaft 42. However, this disclosure is not limited to this.

[0057] For example, instead of grease, the filling space may be filled with another highly viscous substance, such as a highly viscous oil. (F) In the above embodiment, an example was described in which the surface of the second end 42c of the guide shaft 42, which is placed in the grease g1 of the filling space 46c, is given a textured finish to suppress play in the guide shaft 42. However, this disclosure is not limited thereto.

[0058] For example, instead of creating a textured surface, another surface treatment may be used to increase the contact area with the highly viscous substance. Alternatively, the second end of the guide shaft (rotating shaft) may not have any surface treatment such as uneven processing. Even in this case, the highly viscous substance covering the second end can effectively suppress the looseness of the guide shaft (rotating shaft).

[0059] (G) In the above embodiment, an example was given in which the first end 42b and the second end 42c of the guide shaft 42 are formed to have different thicknesses (outer diameters). However, this disclosure is not limited thereto. For example, the guide shaft (rotation axis) may have approximately the same diameter (outer diameter) at both the first and second ends.

[0060] Alternatively, the guide shaft (rotation axis) may have a diameter at the first end that is greater than that at the second end. (H) In the above embodiment, an example was given in which the present disclosure is applied to a lens barrel 100 that is detachably attached to the camera body 101 in an interchangeable manner. However, the present disclosure is not limited thereto.

[0061] For example, the present disclosure may be applied to a lens barrel that is fixed to the camera body in an inchangeable manner. [Industrial applicability]

[0062] The lens barrel of this disclosure has the effect of improving the resolution of rotation detection without complicating the structure, and is therefore widely applicable to various lens barrels equipped with a sensor for detecting rotational position. [Explanation of Symbols]

[0063] 1 Camera 10 Rotational position detection device 11. Straight-line cylinder (fixed cylinder) 12 Cam cylinder 21 Group 1 Unit 21a Main body 21b Cam Follower 22 Group 2 Units 23 Group 3 Unit 24 4-group unit 25 5-group unit (movable lens frame) 26 6-group unit 27 7-group unit 31. Focus ring (manual control ring) 31a Cover 31b Internal gear (first gear unit) 31c Gear section (1st gear section) 32 Zoom Ring 32a Main body 32b Pin insertion hole 32c Straight-line restriction groove 32d Zoom Ring Rubber 33 Zoom drive pins 34 Base frame 41. Pinion gear (second gear unit) 41a Gear section (second gear section) 41b Through hole 42 Guide axis (rotation axis) 42a Large diameter part 42b 1st end 42c 2nd end 43. Detection magnet 43a Through hole 43b Magnetized surface 44 GMR sensor (rotation detection sensor) 45 First bearing section 45a Main body 45b Axial support 45c protrusion 46. ​​Second bearing section 46a Main body 46b Axial support 46c filling space 46d Insertion hole 46e recess 47 Wiring 50 Lens control unit 51 Drive unit 52 Position detection unit 53 Memory section 100 Lens barrel 101 Camera body g1 Grease (high viscosity substance) L1-L7: Lens groups 1-7 OP optical axis

Claims

1. A movable lens frame that holds the lens and can move back and forth in the optical axis direction, A substantially annular member comprising a manual operation ring that moves the movable lens frame in the optical axis direction when rotated, A first gear unit is provided on the inner circumferential surface side of the manual operation ring, rotates integrally with the manual operation ring, and has a plurality of first gear portions that protrude radially inward from the manual operation ring, A second gear unit having a second gear portion provided on the inner circumferential surface side of the manual operation ring and fitting with the first gear portion of the first gear unit, and a rotating shaft inserted through the center of the second gear portion, A detection magnet through which the rotating shaft is inserted and which rotates integrally with the second gear portion, and which has a magnetized surface in which different magnetic poles are alternately magnetized, A rotation detection sensor is fixed to a separate component from the detection magnet, positioned adjacent to the detection magnet, and detects the rotation of the detection magnet which rotates together with the second gear section. A lens barrel equipped with this feature.

2. The rotating shaft has a first end on the side where the rotation detection sensor is located, and a second end on the opposite side from the first end. The second gear unit further comprises a first bearing portion that supports the first end of the rotating shaft, a second bearing portion that supports the second end, and a filling space formed around the rotating shaft in the second bearing portion and filled with a highly viscous substance. The lens barrel according to claim 1.

3. The aforementioned filling space is provided on the end face of the second bearing portion opposite to the second gear portion. The lens barrel according to claim 2.

4. In the aforementioned filling space, the second end of the rotating shaft protrudes and is covered with the highly viscous substance. The lens barrel according to claim 2 or 3.

5. The second end, which is provided to protrude into the filling space, has a larger diameter than the first end. The lens barrel according to claim 4.

6. The second end, which is provided to protrude into the aforementioned filling space, has an uneven surface formed on it. The lens barrel according to claim 4.

7. The filling space has a substantially cylindrical shape that is substantially concentric with respect to the axis of rotation. The lens barrel according to claim 2 or 3.

8. The system further includes a position detection unit that detects the rotational position of the manual operation ring based on the detection pulse detected by the rotation detection sensor and the gear ratio of the first gear unit and the second gear unit. The lens barrel according to claim 1 or 2.

9. The rotating shaft has a smaller diameter portion that is inserted through the second gear portion and the detection magnet, respectively, and a larger diameter portion that has a larger outer diameter than the smaller diameter portion. The second gear section and the detection magnet are attached to the rotating shaft so as to sandwich the larger diameter section. The lens barrel according to claim 1 or 2.

10. The rotation detection sensor is positioned outside the detection magnet in the radial direction centered on the optical axis of the lens held in the movable lens frame. The lens barrel according to claim 1 or 2.

11. A movable lens frame that holds the lens and can move back and forth in the optical axis direction, A substantially annular member comprising a manual operation ring that moves the movable lens frame in the optical axis direction when rotated, A rotational position detection device that is attached to a lens barrel equipped with the following, for detecting the rotational position of the manual operation ring, A first gear unit is provided on the inner circumferential surface side of the manual operation ring, rotates integrally with the manual operation ring, and has a plurality of first gear portions that protrude radially inward from the manual operation ring, A second gear unit having a second gear portion provided on the inner circumferential surface side of the manual operation ring and fitting with the first gear portion of the first gear unit, and a rotating shaft inserted through the center of the second gear portion, A detection magnet through which the rotating shaft is inserted and which rotates integrally with the second gear portion, and which has a magnetized surface in which different magnetic poles are alternately magnetized, A rotation detection sensor (GMR sensor) is fixed to a separate component from the detection magnet, positioned adjacent to the detection magnet, and detects the rotation of the detection magnet which rotates together with the second gear section. A rotational position detection device equipped with the following features.

12. The lens barrel according to claim 1, The camera body to which the aforementioned lens barrel is attached, A camera equipped with this.

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