JPH04208907A - Zoom lens barrel - Google Patents

Abstract

PURPOSE:To drastically improve assembling workability by engaging a first moving frame with a guiding bar, rotating a cam ring a little from a state where the cam pin of the first moving frame is abutted on the base rib of the cam ring so as to hold the guiding part of a cam rib between the cam pin and a rib presser foot. CONSTITUTION:A second moving frame pressing spring 10 and a guiding cover 8 are attached to a master frame receiver 13 holding a lens L4, then, a second moving frame 9 is engaged with the guiding bar 8 to be attached, and then, the cam ring 6 is incorporated so that the cam rib 6b is abutted on the cam pin 9a of the second moving frame 9 by the spring 10. Then, the first moving frame 5 is engaged with the guiding bar 8 to be incorporated, and simultaneously, the cam pin 5a of the first moving frame 5 is abutted on the base rib 6c of the cam ring 6. The cam ring 6 is rotated from a wide-direction to a tele- direction, so that the guiding part of the cam rib 6a is sandwiched by the cam pin 5a of the first moving frame 5 and the rib presser foot 5b.

Description

[Detailed description of the invention]

[00011

[Industrial Field of Application] The present invention relates to a zoom lens barrel suitable for use in video cameras, still cameras, and the like. [0002] [0002] In this type of zoom lens device, the zoom operation of changing the focal length while maintaining focus is as follows:
Usually, this is done by controlling the position of the first moving frame holding the variable magnification lens and the second moving frame holding the correction lens in the optical axis direction, but the structure is described in Japanese Utility Model Publication No. 57-8004. As shown in the figure, the lens frame is held so as to be movable in the optical axis direction by engaging the lens frame with a guide bar parallel to the optical axis fixed to the fixed frame, while the cam slot of the cam ring A metal cam pin is engaged with the lens frame, and this cam pin is fixed to the lens frame with a screw or the like, and by rotating the cam ring, the lens frame is moved in the optical axis direction along the cam groove. [0003]

[Problems to be Solved by the Invention] In the prior art having the structure as described above, in order to incorporate the cam pin,
A hole for assembling a cam pin must be provided in the fixed frame, and the cam pin of each lens frame cannot be assembled unless this hole is precisely aligned with the cam groove of the cam ring and the cam pin of each lens frame, making assembly complicated. Since the cam pin itself was small, it was difficult to handle, and overall assembly workability was poor. Furthermore, since the cam ring is a machined product of metal such as aluminum, it requires highly accurate dimensional control and is expensive. Therefore, the technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art, and its purpose is to improve the assembly workability of the zoom part and to provide an inexpensive zoom lens. It's about doing. [0004]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a plastic molded cam ring having two rib-like cams (cam ribs) on the inner circumference instead of the conventional cam grooves. The first moving frame is configured to sandwich one cam rib of the cam ring with a cam pin and a spring-like rib retainer integrated with the first moving frame, and the second moving frame is wound around the guide bar. The cam pin, which is integral with the second moving frame, is always pressed against the other cam rib from the rear by the coil spring. Furthermore, each of the two cam ribs is provided with a guide part for assembly in a part extending from the range used as a cam, and when assembling the first moving frame,
A pedestal rib is provided near the guide portion of the cam rib for the first moving frame on the inner periphery of the cam ring so that the cam pin and the rib presser are in a position where the cam rib can be smoothly sandwiched. With this, by engaging the first moving frame with the guide bar and rotating the cam ring a little from the state where the cam pin is in contact with the pedestal rib of the cam ring, the cam pin and the rib retainer will sandwich the guide part of the cam rib. , greatly improves assembly workability. [0005]

[Function] The cam ring, which used to be a metal machined product, is now a plastic molded product, reducing material and parts processing costs. By integrating the lens frame (first and second moving frames) and cam pin. In addition, the cam rib of the cam ring is extended from the area where it is used as a cam to provide a guide section for assembling the first and second moving frames, and the first moving frame is Combined with the fact that the cam ring is provided with a pedestal rib for positioning the cam pin for frame assembly, the assembly workability is significantly improved, making it possible to realize a zoom lens that is generally inexpensive. [0006]

[Example] The following shows a zoom lens barrel according to the present invention as shown in FIG.
- An example shown in FIG. 4 will be explained. [00071 FIG. 1 is a sectional view of a zoom lens barrel. In the figure, 1 is a distance ring that holds the focus lens L1, 2 is an index ring, 3 is a zoom ring, 4 is copper for macro switching, and 5 is a first moving frame made of a plastic molded product that holds a variable magnification lens L2. , 9 is a second movable frame made of a plastic molded product holding a correction lens L3; 6 is a cam rib 6a that controls the position of the first movable frame 5 in the optical axis direction; and 9 is the position of the second movable frame 9 in the optical axis direction. A cam ring made of a plastic molded product having controlling cam ribs 6b, etc., 7 a fixed frame that holds the zoom section, and 8 a guide bar that holds the first moving frame 5 and the second moving frame 9 movably in the optical axis direction. , 10 is a spring (coil spring) for pressing the cam pin 9a of the second moving frame 9 against the cam rib 6b of the cam ring 6, 11 is an iris, 1
2 is a master lens frame with a built-in master lens L5,
Reference numeral 13 denotes a master frame holder that holds the master lens frame 12 so as to be adjustable in the optical axis direction and also holds the lens L4. Here, the guide bar 8 is held parallel to the optical axis by the master frame holder 13 and the fixed frame 7, and the cam surface of the cam rib 6a is the right side surface in FIG. 5, a cam rib 6a is sandwiched between a cam pin 5a that abuts against this cam surface and a rib presser 5b having elastic force. [0008] In the above configuration, by rotating the cam ring 6, the first moving frame 5 and the second moving frame 9 move in the optical axis direction according to the two cam ribs 6a and 6b of the cam ring 6, thereby performing a known zoom operation. will be held. [00091 FIG. 2 is an exploded perspective view of the zoom section. The assembly order of the zoom section will be explained below with reference to the same figure. first,
A spring 10 for holding down the second moving frame and a guide bar 8 are attached to the master frame holder 13 holding the lens L4, and then a second moving frame 9 is attached by engaging with the guide bar 8.
Subsequently, the cam ring 6 is assembled so that the cam rib 6b of the cam ring 6 comes into contact with the cam pin 9a of the second moving frame 9 by the spring 10. At this time, the rotational direction position of the cam ring 6 is set such that the cam pin 9a contacts the guide portion of the cam rib 6b, which is a portion of the cam rib 6b outside the range used as a cam. [00101] Next, the first movable frame 5 is engaged with and assembled into the guide bar 8, and the cam pin 5a of the first movable frame 5 is abutted against the pedestal rib 6c of the cam ring 6. This pedestal rib 6c
is a position near the cam rib 6a for the first movable frame 5 formed on the inner circumferential surface of the cam ring 6, more specifically, a position slightly smaller than the guide portion of the cam rib 6a, which is a portion of the cam lip 6a outside the range used as a cam. are located at separate locations. Continuing from this state, by rotating the cam ring 6 from the wide direction to the telephoto direction, the guide portion of the cam rib 6a is sandwiched between the cam bin 5a of the first moving frame 5 and the rib presser 5b. In this embodiment, the rib presser 5b has an elastic plate spring-like structure that is integrally formed with the first moving frame 5, but the rib presser is a separate piece of spring material. It's okay. [00113 Next, the connecting pin (not shown) of the zoom ring 3 and the cam ring 6 is assembled in alignment with the connecting groove (not shown) of the cam ring 6, and finally the fixed frame 7 is assembled, and the master frame is assembled. The zoom section is assembled by fixing the receiver 13 and the fixed frame 7 with screws (not shown). [0012] FIGS. 3 and 4 are developed views of the cam ring 6 showing the positional relationship between the cam ribs 6a, 6b and the cam bins 5a, 9a when the first moving frame 5 is assembled, and in each figure, the upper direction is This is the front direction of the lens (toward the subject side). The ranges of the cam rib 6a for the first moving frame and the cam rib 6b for the second moving frame are θ1 and 02, respectively, and θ
3 and 04 are extended portions as guide portions for incorporating both the moving frames 5 and 9, respectively. The thickness of the cam rib 6a is changed so that the amount of elastic deformation of the leaf spring portion of the rib presser 5b of the first moving frame 5 does not change. [0013] FIG. 3 shows a state in which the first moving frame 5 is engaged with the guide bar 8 and assembled, and the cam bin 5a is abutted against the pedestal rib 6c. At this time, the second moving frame 9 has already been assembled as described above, and the cam pin 9a of the second moving frame 9 is in contact with the cam rib 6b in the range 04 (guide portion) by the spring 10. FIG. 4 shows a state in which the cam ring 6 is slightly rotated from this state in the direction from wide to tele (from left to right in FIG. 3). At the time shown in FIG. 4, the rib presser 5b is hooked on the guide portion of the cam rib 6a, and after this, when the cam ring 6 is further rotated in the same direction, the cam pin 5a enters the range of 01, and as a result, Rib presser 5b and cam bin 5
a and completely sandwich the cam rib 6a, completing the assembly. [0014]

As described above, according to the present invention, by simply rotating the cam ring when the cam bin of the first moving frame holding the variable magnification lens abuts against the pedestal rib of the cam ring, the first moving frame Since the cam ring and the cam ring can be easily combined, assembly work efficiency is improved. Furthermore, Kambin comes first. Since the cam ring, which is integrally formed with the second moving frame and has a cam rib, is made of plastic molding, the total parts cost can be reduced, and together with the effect of improving assembly workability, an inexpensive zoom lens can be realized. This type of zoom lens has great value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a zoom lens barrel according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of essential parts of a zoom lens barrel according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a method of assembling a zoom section according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a method of assembling a zoom section according to an embodiment of the present invention.

[Explanation of symbols]

5 First moving frame 5a Cam pin 5b Rib holder 6 Cam ring 6a Kamrib 6b Kamrib 6c Pedestal rib 7 Fixed frame 8 Guide bar 9 Second moving frame 9a Kambin 10 Spring 13 Master frame receiver

Claims (2)

[Claims] Claim 1: A first movable frame having a guide bar held in a fixed lens barrel parallel to the optical axis, a variable magnification lens engaged with the guide bar and held movably in the optical axis direction, and a correction The second movable frame has a lens, and a cam ring made of a plastic molded product integrally formed with two cam ribs for controlling the positions of the first movable frame and the second movable frame in the optical axis direction. The first moving frame always holds one cam rib of the cam ring between a cam pin integrally formed with the first moving frame and a rib retainer with elastic force provided on the first moving frame. The second moving frame rotates the cam ring by a coil spring wound around the guide bar so that a cam pin integrally formed on the second moving frame is always in contact with the other cam rib of the cam ring. The zoom lens barrel is capable of performing a zoom operation by moving the first moving frame and the second moving frame in the optical axis direction according to the two cam ribs of the cam ring, wherein the two cam ribs of the cam ring Each of the cam ribs is formed with a guide portion at a portion extending from the range where the cam rib is used as a cam, and the cam ring is provided with a guide portion for assembling and positioning the first moving frame at a position close to the one cam rib. by providing a pedestal rib for the first moving frame, engaging the first moving frame with the guide bar, and slightly rotating the cam ring with the cam pin of the first moving frame abutting against the pedestal rib,
A zoom lens barrel characterized in that the cam pin and the rib retainer of the first moving frame sandwich one guide portion of the cam rib of the cam ring, so that the first moving frame can be assembled. 2. According to claim 1, the elastic rib presser of the first movable frame has a leaf spring structure integrally formed with the first movable frame made of a plastic molded product. A zoom lens barrel featuring