JP4045676B2 - Lens barrel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens barrel, and more particularly, to a lens barrel suitable for a thin camera equipped with a zoom mechanism.
[0002]
[Prior art]
As disclosed in Japanese Patent Application Laid-Open No. 9-329735, an elastic member such as a spring is provided between the flange portion of the lens barrel body and the end surface of the cam ring in order to eliminate the backlash of the conventional cam ring (rotating cylinder). An arrangement is known in which the cam ring is urged in the optical axis direction with respect to the lens barrel body (fixed cylinder). In the above publication, a coil spring is used as the biasing means. However, an annular wave plate spring such as a wave washer may be disposed on the end face of the cam ring.
[0003]
[Problems to be solved by the invention]
However, the conventional structure requires a space for arranging the elastic member on the front end or rear end face of the cam ring, which hinders shortening of the entire length of the lens barrel. In particular, with the recent thinning of cameras, the total length of the lens barrel has been required to be as short as possible (even 0.1 mm).
[0004]
The present invention has been made in view of such circumstances, and a lens mirror capable of arranging a cam ring backlash elastic member without extending the overall length of the lens barrel and realizing a reduction in the overall length of the lens barrel. The purpose is to provide a torso.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a lens barrel according to the present invention includes a barrel main body having a cylindrical shape, and one or more movements disposed inside the barrel main body and movable along an optical axis. A lens frame, a guide member that guides the moving lens frame in the optical axis direction, and a rotation member that is rotatable around a rotation axis in the same direction as the optical axis inside or outside the barrel body. And a cam ring having a cam groove for moving the movable lens frame in the optical axis direction according to the optical axis, and a front end portion or a rear end portion of the cam ring, the cam ring being disposed on the optical axis relative to the lens barrel body. A plurality of urging means having a deflection portion urging in one direction along the cam ring, and the cam groove orbit is disposed with respect to the end face of one cam ring end face on which the urging means is disposed. A storage portion for storing the biasing means is formed at a place avoiding the closest approach position, Substantially whole of the flexure of the biasing means to the serial receiving unit is characterized in that the biasing force is provided by the biasing means in a state of being housed.
[0006]
According to the present invention, on the basis of the track shape of the cam groove, the storage portion is provided in a portion having a sufficient wall thickness between the cam groove and the end face of the cam ring, and the urging means is stored therein. Therefore, the overall length of the lens barrel can be made smaller than before.
As the urging means, an elastic member separate from the cam ring may be used, or the urging means may be formed integrally with the cam ring. Further, the cam ring can be urged in a balanced manner by arranging the plurality of urging means at symmetrical positions along the circumference of the cam ring.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of a lens barrel according to the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of a lens barrel showing an embodiment of the present invention, and FIG. 2 is a perspective view of a cam ring used in the lens barrel. As shown in FIG. 1, this lens barrel 10 is a lens barrel of a zoom lens composed of a front group lens 12 and a rear group lens 14, and includes a lens barrel body 16, a cam ring 18, a front group moving frame 20, a rear group lens. It is composed of a group moving frame 22, an elastic member (corresponding to an urging means) 24, and the like.
[0008]
The lens barrel body 16 has a substantially cylindrical shape, and rectilinear grooves 26 and 28 for guiding the front group moving frame 20 and the rear group moving frame 22 in the optical axis direction are formed on the peripheral surface thereof. The rear end portion (right end portion in FIG. 1) of the lens barrel body 16 is fixed to a camera body (not shown), and subject light is incident from the left side of FIG.
The cam ring 18 is provided inside the lens barrel body 16 so as to be coaxial with the lens barrel body 16 and rotatable around the optical axis 30. Although the detailed structure of the cam ring 18 will be described later, the front ring cam groove 32 (see FIG. 2) for regulating the position of the front group moving frame 20 and the position of the rear group moving frame 22 are regulated on the cam ring 18. A rear group cam groove 34 is formed.
[0009]
The front group lens 12 is held by the front group moving frame 20, and a cam pin 20A that engages with the front group cam groove projects from the outer peripheral surface of the front group moving frame 20. The cam pins 20A are respectively provided at three positions that equally distribute the circumference of the cam ring 18 by 120 degrees. These cam pins 20 </ b> A pass through the front group cam groove 32 and are also engaged with the rectilinear groove 26 of the lens barrel body 16. Similarly, the rear group lens 14 is held by the rear group moving frame 22, and a cam pin 22A that engages the rear group cam groove 34 is arranged on the outer peripheral surface of the rear group moving frame 22 so that the circumference is equally distributed by 120 degrees. Projected at the place. The cam pins 22A pass through the rear group cam groove 34 and are also engaged with the rectilinear groove 28 of the lens barrel body 16. The moving frames (20, 22) may be configured integrally with the lenses (12, 14).
[0010]
A flange portion 16A is formed at the front end portion of the lens barrel body 16, and the cam ring 18 is urged rearward in the optical axis direction between the inner wall surface of the flange portion 16A and the front end surface of the cam ring 18. An elastic member 24 is provided. Although the arrangement structure of the elastic member 24 will be described later, the backlash of the cam ring 18 is removed by the urging force of the elastic member 24 so that the cam pins 20A and 22A are surely brought into contact with one side surface of the cam grooves 32 and 34. It has become. Since the elastic member 24 slides with respect to the flange portion 16A as the cam ring 18 rotates, the elastic member 24 has a configuration that reduces sliding friction (for example, an Ω-type leaf spring). Is preferably used.
[0011]
A gear portion 36 is formed on the outer peripheral surface of the rear end portion of the cam ring 18, and a motor 38 serving as a power source for rotating the cam ring 18 is disposed outside the lens barrel body 16. The motor 38 is mounted on a mounting portion 16B provided in the lens barrel body 16 via a support member (not shown). A gear 40 fixed to the rotating shaft of the motor 38 is engaged with a reduction gear 42 supported by the mounting portion 12B, and the reduction gear 42 passes through the opening 16C of the lens barrel body 16 and the cam ring 18 is rotated. The gear portion 36 is meshed.
[0012]
When the rotational driving force of the motor 38 is transmitted to the cam ring 18 via the gears 40, 42 and the gear portion 36, the cam ring 18 rotates around the optical axis 30, and this rotation causes the front group cam groove to rotate. The front group moving frame 20 and the rear group moving frame 22 move back and forth in the optical axis direction according to the curved shapes of the 32 and rear group cam grooves 34.
Next, the structure of the cam ring 18 and the arrangement structure of the elastic member 24 will be described.
[0013]
As shown in FIG. 2, the front group cam groove 32 and the rear group cam groove 34 formed in the cam ring 18 have a front group lens 12 and a rear group lens 14 in order to realize zooming performance as a zoom lens. Each of the lenses (12, 14) has a curved shape (hereinafter referred to as a trajectory) designed so as to be able to move back and forth along the optical axis while restricting the optical positional relationship.
[0014]
In addition, the front group cam groove 32 and the rear group cam groove 34 are each three along the circumferential surface of the cam ring 18 in accordance with the number and position of the cam pins 20A and 22A (in a position of 1/3 rotational symmetry). 3) provided.
On the front end face 18F of the cam ring 18, recesses 44 are formed in three places where there is a sufficient thickness between the end face 12F and the cam groove 32 in relation to the track of the front group cam groove 32. An elastic member (for example, a leaf spring having an Ω shape) 24 is disposed in the recess 44.
[0015]
That is, the wall thickness dimension from the cam groove 32 to the cam ring end face (12F) at the position where the track of the front group cam groove 32 is closest to the front end face 18F of the cam ring 18 (this is called the closest position). When a is the thickness dimension at the position where the track of the rear group cam groove 34 is closest to the rear end face 18R of the cam ring 18, the dimension a and Let b be as small as the so-called processing limit. The total length of the cam ring 18 realized in this way is Lmin.
[0016]
In the portion where the track of the front group cam groove 32 is lowered to the rear side of the cam ring 18 from the closest position, the thickness dimension from the cam ring end face 18F to the cam groove 32 is larger than the minimum thickness dimension, There is room for wall thickness. Three portions having a 1/3 rotational symmetry relationship are selected from the portions having such a sufficient wall thickness, and a recess 44 for accommodating the elastic member 24 is formed in each portion. And the elastic member 24 is arrange | positioned at each recessed part 44 as shown in FIG.
[0017]
According to the lens barrel configured as described above, the track position of the front group cam groove 32 formed in the cam ring 18 is secured at a position closest to the cam ring end face 18F, and the closest position thereof. Since the concave portion 44 is formed in a portion having a sufficient wall thickness (a portion that can be a wall thickness greater than the minimum wall thickness) and the elastic member 24 is immersed therein, the cam ring is conventionally used. Compared with a structure in which a coil spring or the like is provided on the end face, the total length of the lens barrel can be reduced by the thickness of the coil spring or the like.
[0018]
In addition, since a plurality of elastic members 24 are used and these are arranged at three 対 称 rotationally symmetrical positions along the circumference of the cam ring 18, the cam ring 18 can be urged with a good balance. Of course, the number of the elastic members 24 is not particularly limited, and any number of the elastic members 24 may be provided. The number of the elastic members 24 may be appropriately designed in consideration of the number of cam grooves, the balance of the track and the urging force, and the like.
[0019]
Although FIG. 2 shows an example in which the elastic member (plate spring) 24 is divided into three parts, these plate springs can be integrally connected to form one component. That is, as shown in FIG. 4, a single spring member 46 having a ring shape is provided with a plurality of (three in this case) flexible portions (elastic portions) 46A corresponding to the elastic member 24 of FIG. Can be used.
[0020]
FIG. 5 shows an example in which the flexure 46 shown in FIG. 4 is replaced with another form. The spring member 46 shown in FIG. 5 is formed with an appropriately shaped cut portion 46B along the circumferential direction, and the peripheral portion cut out by the cut portion 46B is bent in the optical axis 30 direction, so that the optical member 30 is moved in the optical axis 30 direction. A swingable flexible portion 46C is formed.
[0021]
When the spring member 46 shown in FIGS. 4 and 5 is used instead of the three elastic members 24 shown in FIG. 2, the flexible portions 46A and 46C are housed in the recess 44, so that the conventional coil spring is used. The total length of the lens barrel can be shortened compared to the conventional lens barrel. Further, by using such an integral spring member 46, there is an advantage that assembly work in the manufacturing process can be facilitated. In addition, it is also possible to use a C-shaped spring member in which a part of the connecting portion 46D that connects the flexible portions 46A and 46C is divided.
[0022]
Next, another embodiment of the present invention will be described.
In the above-described embodiment, the elastic member 24 that is separate from the cam ring 18 is used as the biasing means. However, as shown in FIG. 4, the elastic member may be formed integrally with the cam ring. 4 that are the same as those in FIG. 2 are assigned the same reference numerals, and descriptions thereof are omitted.
[0023]
The cam ring 48 shown in FIG. 4 is formed using a material having appropriate strength and elasticity, such as polycarbonate (with glass). In the front end portion of the cam ring 48, notches 50 (corresponding to storage portions) are provided at a plurality of locations (three locations in FIG. 4) with a sufficient margin in relation to the track of the front group cam groove 32, A spring portion 52 corresponding to an elastic member is formed integrally with the cam ring 48. The spring portion 52 can be elastically deformed in the optical axis direction with the base end portion 52A as a viewpoint, and the distal end 52B of the spring portion 52 is slid to realize smooth sliding with the flange portion 16A of the lens barrel body 16. It has an arc shape with little dynamic friction.
[0024]
The cam ring 48 having such a configuration can be incorporated in the lens barrel 10 in place of the cam ring 18 and the elastic member 24 shown in FIG. As a result, the spring portion 52 of the cam ring 48 is deformed rearward in the optical axis direction while being in contact with the inner wall surface of the flange portion 16A, and the cam ring 48 is urged rearward in the optical axis direction by its repulsive force (restoring force). Is done.
Even when the cam ring 48 having the above structure is used, the entire length of the lens barrel 10 can be reduced, and the cam ring 48 can be urged in a balanced manner.
[0025]
In each of the above embodiments, biasing means (elastic member 24, spring portion 52) is provided at the front end of the cam rings 18 and 48 to bias the cam rings 18 and 48 rearward in the optical axis direction. A biasing means may be provided at the rear end portion of the cam ring to bias the cam ring forward in the optical axis direction.
In each of the above embodiments, the cam rings 18 and 48 are arranged inside the lens barrel main body 16, but a structure in which the cam rings are arranged outside the lens barrel main body is also possible.
[0026]
In each of the above embodiments, the rectilinear grooves 26 and 28 are formed in the lens barrel body 16 and the lens barrel body 16 is also used as a guide member for the moving frame (20, 22). And a separate guide shaft or the like.
In the above description, the cam ring is structured to rotate around the optical axis of the lens (rotation axis). However, the rotation axis of the cam ring does not necessarily need to coincide with the optical axis of the lens. In other words, the cam ring only needs to have a structure that can be rotated around a rotation axis that is the same (parallel) as the optical axis direction of the lens, and the center axis of the cam ring or the lens barrel body is shifted from the optical axis of the lens. The present invention can also be applied to a lens barrel having a (decentered) structure.
[0027]
In the example described with reference to FIGS. 1 to 5, the cam ring 18 is provided with three front group cam grooves 32. If the position where the track of the cam groove 56 is closest to the end face of the cam ring 18 is one place, for example, as shown in FIG. It is also possible to connect the three recesses 44 shown in FIG.
[0028]
Further, in the above-described embodiment, the example in which the present invention is applied to the lens barrel of the two-group zoom lens has been described. However, the scope of the present invention is not limited to this, and at least a moving lens is used regardless of the application. It can be widely applied to a lens barrel having one lens.
[0029]
【The invention's effect】
As described above, according to the lens barrel of the present invention, the storage portion for storing the biasing means is provided at a position not close to the cam at the front end portion or the rear end portion of the cam ring, and is attached to the storage portion. Since the biasing means is arranged, the total length of the lens barrel can be minimized with respect to the total length of the cam ring. Accordingly, it is possible to achieve a small lens barrel having a shorter overall length than the conventional one.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a lens barrel according to an embodiment of the present invention. FIG. 2 is a perspective view of a cam ring incorporated in the lens barrel shown in FIG. FIG. 4 is a perspective view showing another embodiment of the elastic member. FIG. 5 is a perspective view showing still another embodiment of the elastic member. 7 is a perspective view of a cam ring showing another embodiment of the present invention. FIG. 7 is a perspective view of a cam ring showing still another embodiment of the present invention.
10 ... Lens barrel 16 ... Lens barrel body (also used as guide member)
18 ... Cam ring 20 ... Front group moving frame (moving lens frame)
22 ... Rear group moving frame 24 ... Elastic member (biasing means)
26, 28 ... Straight running groove 32 ... Front group cam groove 34 ... Rear group cam groove 44 ... Recess (housing)
46 ... Spring members 46A, 46C ... Deflection part (biasing means)
50 ... Incision (storage part)

Claims (5)

A lens barrel body having a cylindrical shape;
One or more movable lens frames disposed inside the lens barrel body and movable along the optical axis;
A guide member for guiding the moving lens frame in the optical axis direction;
A cam having a cam groove that is rotatably provided around a rotation axis in the same direction as the optical axis inside or outside the lens barrel body and moves the moving lens frame in the optical axis direction according to the rotation. Ring,
A plurality of urging means provided at a front end portion or a rear end portion of the cam ring, and having a bending portion that urges the cam ring in one direction along the optical axis with respect to the lens barrel body;
Of the one end face of the cam ring on which the biasing means is disposed, a storage portion for storing the biasing means is formed at a place avoiding a position where the track of the cam groove is closest to the end face,
2. A lens barrel according to claim 1 , wherein a biasing force is applied by the biasing means in a state where substantially the entire deflection portion of the biasing means is stored in the storage portion .   The lens barrel according to claim 1, wherein an elastic member separate from the cam ring is used as the biasing means.   2. The lens barrel according to claim 1, wherein a spring member is used in which a plurality of flexure portions corresponding to the plurality of urging means are integrally provided.   2. The lens barrel according to claim 1, wherein the urging means is formed integrally with the cam ring.   2. The lens barrel according to claim 1, wherein the plurality of urging means are arranged at symmetrical positions that equally distribute the circumference of the cam ring at a predetermined angle.

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