Lens barrel

Abstract

To provide a quick and delicate focusing operation without making a structure of a lens barrel largely different from a conventional lens barrel.SOLUTION: A lens barrel comprises: a focusing lens holding frame 1 that holds a focusing lens; an intermediate helicoid member 2 that causes the focusing lens holding frame 1 to move along an optical axis, in which a reed is different; a first focusing operation ring 3 that is integral with the intermediate helicoid member 2, and provided rotatably in a peripheral surface of the focusing lens holding frame 1; a second focusing operation ring 4 that provides a male screw part engaging with a female screw part provided in an outer peripheral surface of the intermediate helicoid member 2 in an inner peripheral surface, and is provided rotatably in the peripheral surface of the focusing lens holding frame 1; a first locking screw 8 that locks rotation of the first focusing operation ring 3; and a second locking screw 9 that locks rotation of the second focusing operation ring 4. The lens barrel is mountable to a camera main body. A rectilinear advancement key 6 is locked by a stationary barrel 5, and a focusing lens group does not rotate even when rotating the second focusing operation ring 4, so that a change in a resolution performance of a periphery of an imaging screen can be suppressed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a lens barrel detachable from a camera body. In particular, it relates to a lens barrel having a double helicoid structure.

Background Art

[0002] Lens barrels attached to a camera body are desired to have products with different focal lengths and shooting distances depending on the application. In a lens with a short focal length, when shooting at a short distance, the amount of movement of the focusing lens group with respect to the displacement of the shooting distance tends to be small. Therefore, even if the focus operation ring is rotated slightly, the shooting distance is greatly displaced and fine adjustment of focus becomes difficult. A lens barrel having a double helicoid structure as a focusing mechanism is disclosed as in Patent Document 1. In a lens barrel having a double helicoid structure, the movement of the focusing lens group in the optical axis direction is performed by the lead due to the synthesis of the helicoid that engages with the fixed barrel and the helicoid that holds the focusing lens group.

[0003] FIG. 4 is a longitudinal sectional view of a lens barrel having a double helicoid structure as a conventional focusing mechanism. In a lens barrel having a double helicoid structure, the rotation of the focus operation ring 3 causes the movement of the focusing lens group in the X direction of the optical axis by the combined lead of the helicoid 2a that engages with the focusing lens holding frame 1 and the helicoid 2b that engages with the fixed barrel 5. However, in the movement of the focusing lens by the combined lead, there is a problem that it becomes difficult to adjust the focus operation ring when the shooting distance is minute.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention aims to provide rapid and precise focusing without significantly altering the structure of the lens barrel compared to conventional lens barrels. [Means for solving the problem]

[0006] The problem of the present invention can be solved by the following embodiments (1) or (2). Specifically,

[0007] (Aspect 1) A fixed cylinder having a male screw portion that can be screwed into the camera body; a focusing lens holding frame that holds the focusing lens; an intermediate helicoid member for moving the focusing lens holding frame along the optical axis, wherein the female screw portion on the inner circumferential surface and the female screw portion on the outer circumferential surface have different leads; a first focusing operation ring integrally with the intermediate helicoid member and rotatably provided on the circumferential surface of the focusing lens holding frame; and a male screw portion that screws into the female screw portion on the outer circumferential surface of the intermediate helicoid member. This lens barrel, which is detachable from a camera body, comprises: a second focusing operation ring rotatably mounted on the circumferential surface of the focusing lens holding frame with a threaded portion on its inner surface; a first locking screw for locking the rotation of the first focusing operation ring; a second locking screw for locking the rotation of the second focusing operation ring; a guide groove formed in the focusing lens holding frame parallel to the optical axis; a straight key that engages with the guide groove to restrict the rotation of the focusing lens holding frame; and a straight key locking screw for locking the straight key to a fixed cylinder.

[0008] This is because by using both a coarse focusing operation by rotating the first focusing ring (coarse adjustment function), which operates independently for focus adjustment, and a fine focusing operation by rotating the second focusing ring (fine adjustment function), it is possible to provide quick and precise focusing. Furthermore, by locking the straight-line key to the fixed cylinder with a straight-line key control screw, when fine-tuning the focus operation by rotating the second focusing operation ring (fine-tuning function), the focusing lens group can be moved parallel to the optical axis without the focusing lens holding frame rotating. As a result, even when the second focusing operation ring (fine-tuning function) is rotated, the focusing lens group does not rotate, thus suppressing changes in resolution performance at the edges of the image.

[0009] (Aspect 2) The lens barrel according to aspect 1, characterized in that it is provided with a rotation control screw that limits the rotation range of the second focusing operation ring. By providing a rotation control screw, the range of motion of the second focusing operation ring (fine adjustment function) is limited, preventing the second focusing operation ring (fine adjustment function) from coming off the fixed cylinder 5, and limiting the range of motion of the second focusing operation ring (fine adjustment function) to the range in which it performs the fine adjustment function. [Effects of the Invention]

[0010] According to the present invention, by dividing the focusing operation into a coarse focusing ring and a fine focusing ring, it is possible to provide quick and precise focusing without significantly changing the structure of the lens barrel from that of conventional lens barrels. [Brief explanation of the drawing]

[0011] [Figure 1] This is a longitudinal cross-sectional view showing an example of the configuration of the lens barrel of the present invention. [Figure 2] This is an external side view showing an example of the configuration of the lens barrel of the present invention. [Figure 3] This is an enlarged longitudinal cross-sectional view of the intermediate helicoid member of the lens barrel of the present invention. [Figure 4] This is a longitudinal cross-sectional view showing an example of a conventional lens barrel configuration. [Figure 5] This is a longitudinal cross-sectional view showing the cross-sectional position of an embodiment in which a second focusing operation ring is fitted into the fixed cylinder of the lens barrel of the present invention. [Figure 6] This is a cross-sectional view showing an embodiment in which a second focusing operation ring is fitted onto the fixed cylinder of the lens barrel of the present invention. [Modes for carrying out the invention]

[0012] The embodiments for carrying out the present invention will be described based on the drawings. However, the drawings are just one example of an embodiment, and the present invention is not limited thereto.

[0013] 1. Basic structure of the lens barrel The lens barrel 100 of the present invention is configured to be detachable from a camera body (not shown). Further, it is a lens barrel having a double helicoid structure as a focusing mechanism. FIG. 1 is a longitudinal sectional view showing an example of the configuration of the lens barrel 100 of the present invention, and FIG. 2 is an external side view showing an example of the configuration of the lens barrel of the present invention. Further, FIG. 3 is a longitudinal sectional view showing an enlarged example of an intermediate helicoid member 2 of the lens barrel 100 of the present invention. The lens barrel 100 of the present invention includes a fixed barrel 5 having a male screw portion 5a that can be screwed into a camera body (not shown), a focusing lens holding frame 1 that holds a focusing lens group (L1, L2, L3, L4), and an intermediate helicoid member 2 having different leads provided on an inner peripheral surface for moving the focusing lens holding frame 1 along the optical axis X and on an outer peripheral surface, a first focusing operation ring 3 provided integrally with the intermediate helicoid member 2 and rotatably provided on the peripheral surface of the focusing lens holding frame 1, a second focusing operation ring 4 provided integrally with the fixed barrel 8 and rotatably provided on the peripheral surface of the focusing lens holding frame 1, and a straight key 6 that is locked to the fixed barrel 5 and restricts the rotation of the focusing lens holding frame 1.

[0014] 2. Focus adjustment The focusing operation of the lens barrel 100 of the present invention will be described. The focusing of the lens barrel 100 of the present invention is characterized by using both a coarse focusing operation by the rotation of the first focusing operation ring 3 (coarse adjustment function) and a fine focusing operation by the rotation of the second focusing operation ring 4 (fine adjustment function). The lens barrel 100 of the present invention employs an intermediate helicoid member 2 with different leads, and by appropriately selecting the lead by the rotation of the first focusing operation ring 3 and the magnitude of the lead by the rotation of the second focusing operation ring 4, the coarse focusing operation (coarse adjustment function) and the fine focusing operation (fine adjustment function) can be appropriately adjusted.

[0015] 3. Coarse focusing adjustment The second focusing operation ring 4 (fine adjustment function) rotatably provided on the peripheral surface of the focusing lens holding frame 1 is locked to the fixed barrel 5 by a second locking screw 9 to restrict rotation. Next, when the photographer manually rotates the first focusing operation ring 3 (coarse adjustment function), the focusing lens holding frame 1 whose rotation is restricted by the straight key 6 engaged with the fixed cylinder 5 moves in the optical axis direction according to the pitch synthesized by the engagement of the male screw portion 1a provided on the outer peripheral surface and the female screw portion 2a provided on the inner peripheral surface of the intermediate helicoid member 2. The pitch synthesized by the engagement of the male screw portion 1a provided on the outer peripheral surface and the female screw portion 2a provided on the inner peripheral surface of the intermediate helicoid member 2 is large, so coarse focus adjustment can be performed.

[0016] 4. Fine Focus Adjustment Loosen the second locking screw 9 to make the second focusing operation ring 4 (fine adjustment function) locked to the fixed cylinder 5 rotatable. Next, when the photographer manually rotates the second focusing operation ring 4 (fine adjustment function), the focusing lens holding frame 1 whose rotation is restricted by the straight key 6 engaged with the fixed cylinder 5 moves in the optical axis direction according to the pitch synthesized by the engagement of the female screw portion 2b provided on the outer peripheral surface of the intermediate helicoid member 2 and the male screw portion 4a provided on the inner peripheral surface of the second focusing operation ring 4. The pitch synthesized by the engagement of the female screw portion 2b provided on the outer peripheral surface of the intermediate helicoid member 2 and the male screw portion 4a provided on the inner peripheral surface of the second focusing operation ring 4 is small, so fine focus adjustment can be performed.

[0017] 5. Rotation Control Screw FIG. 5 is a longitudinal sectional view showing the cross-sectional position of a mode in which the second focusing operation ring is fitted to the fixed cylinder of the lens barrel of the present invention. FIG. 6 is a cross-sectional view showing a mode in which the second focusing operation ring 4 (fine adjustment function) is fitted to the fixed cylinder 5. Respectively, (a) the fitting mode, (b) the mode in which the second focusing operation ring 4 (fine adjustment function) is rotated counterclockwise and the rotation control screw 10 is locked to the fixed cylinder 5, and (c) the mode in which the second focusing operation ring 4 (fine adjustment function) is further rotated counterclockwise. The viewpoint is on the side of the second focusing operation ring 4 (fine adjustment function), and the pattern of the overlapping portion of the second focusing operation ring 4 (fine adjustment function) is overlapped on the fixed cylinder 5. The rotation control screw 10 restricts the movable range of the second focusing operation ring 4 (fine adjustment function) to prevent the second focusing operation ring 4 (fine adjustment function) from coming off the fixed cylinder 5, and also functions to limit the movable range of the second focusing operation ring 4 (fine adjustment function) to the range where the fine adjustment function is achieved.

[0018] 6. Straight-line key control screw The linear key control screw 11 of the present invention serves to fix the linear key 6 to the fixed cylinder 5. By fixing the linear key 6 to the fixed cylinder 5 with the linear key control screw 11, when fine-tuning the focusing operation by rotating the second focusing operation ring 4 (fine-tuning function), the focusing lens holding frame 1 does not rotate, and the focusing lens group (L1, L2, L3, L4) can be moved parallel to the optical axis without any problems. As a result, even when the second focusing operation ring (fine-tuning function) is rotated, the focusing lens group does not rotate, thus suppressing changes in the resolution performance at the edges of the image sensor. [Industrial applicability]

[0019] The present invention provides a lens barrel that enables rapid and precise focusing. [Explanation of symbols]

[0020] 100 Lens barrel 200 Lens barrel (conventional product) L1, L2, L3, L4 focusing lens group X optical axis 1. Focusing lens holding frame 1a Male screw part (focusing lens holding frame) 2. Intermediate helicoid member 2a, 2b Female threaded section (intermediate helicoid member) 3 1st focusing operation ring 4 Second focusing ring 5 Fixed tube 6. Straight key 8. First locking screw 9. Second locking screw 10 Rotation-controlled screws 11 Straight-line key control screws

Claims

1. A fixing cylinder having a male screw portion that can be screwed onto the camera body, A focusing lens retaining frame that holds the focusing lens, An intermediate helicoid member for moving the focusing lens holding frame along the optical axis, wherein the lead of the female screw portion provided on the inner circumferential surface and the female screw portion provided on the outer circumferential surface are different, A first focusing operation ring is provided integrally with the intermediate helicoid member and rotatably mounted on the circumferential surface of the focusing lens holding frame, A male screw portion is provided on the inner circumferential surface of the intermediate helicoid member, which engages with a female screw portion provided on the outer circumferential surface of the intermediate helicoid member, and a second focusing operation ring is rotatably provided on the circumferential surface of the focusing lens holding frame, A first locking screw that locks the rotation of the first focusing operation ring, A second locking screw that locks the rotation of the second focusing operation ring, The focusing lens holding frame has a guide groove formed parallel to the optical axis, A straight key engages with the guide groove and restricts the rotation of the focusing lens holding frame, A straight key locking screw for locking the aforementioned straight key to the fixing cylinder, A lens barrel that can be attached to the camera body.

2. The lens barrel according to claim 1, characterized in that it is provided with a rotation control screw that limits the rotation range of the second focusing operation ring.

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