JP4656597B2 - Zoom lens barrel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a zoom lens barrel that is provided with a plurality of freely retractable / collapseable tubes and is suitable for a compact camera.
[0002]
[Prior art]
Compact cameras are used by a wide range of users because of their compact body and excellent storage and portability. Here, even with a compact camera, there is a demand for shooting various scenes by changing the shooting angle of view. Therefore, a compact camera equipped with a zoom lens has become the mainstream.
[0003]
Here, in the zoom lens, a plurality of lens groups must be moved in the optical axis direction, so that a so-called zooming ratio can be kept large, and a retractable telescopic type can be secured to ensure compactness during storage. Often provided with a lens barrel. In general, assuming that the maximum lengths are equal, the three-stage extension zoom lens barrel has an advantage that the length in the optical axis direction during storage can be shortened than the two-stage extension zoom lens barrel.
[0004]
[Problems to be solved by the invention]
Here, compared with the two-stage extension type lens barrel, the three-stage extension type lens barrel should theoretically have an effect of shortening the length in the optical axis direction by 33%. Due to various limitations, it is difficult to say that the length in the optical axis direction can be shortened as calculated. For example, when it is necessary to provide protrusions or ribs for restricting the movement of each cylinder at the time of feeding at the end of the cylinder, the provision of such protrusions or ribs causes a problem that the cam groove cannot be disposed at an optimal position. Because.
[0005]
The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a zoom lens barrel that can shorten the length in the optical axis direction during storage while ensuring zoom performance.
[0006]
[Means for Solving the Problems]
The zoom lens barrel according to claim 1,
A cam cylinder having cam grooves and protrusions formed on the same side of the inner periphery or outer periphery;
A rectilinear guide ring rotatable relative to the cam cylinder;
A cam pin that engages with the cam groove, and a lens frame that moves in the optical axis direction according to the shape of the cam groove when rotating relative to the cam cylinder;
The protrusion formed on the cam cylinder and the rib formed on the rectilinear guide ring engage with each other, so that the movement of the cam cylinder and the rectilinear guide ring in the optical axis direction is limited. cage, the projection is formed by spaced apart two or more circumferentially, between the protrusions adjacent in the circumferential direction, a portion of the cam groove of the cam barrel enters the overlapping positions in the optical axis direction It is characterized by being.
[0007]
[Action]
According to the zoom lens barrel of the present invention, the cam cylinder having the cam groove and the protrusion formed on the same side of the inner periphery or the outer periphery, the linear guide ring rotatable relative to the cam cylinder, and the cam groove are engaged. A cam frame having a lens frame that moves in an optical axis direction according to the shape of the cam groove when the cam pin rotates relative to the cam cylinder, and the protrusion formed on the cam cylinder; The ribs formed on the guide ring engage with each other so that the movement of the cam cylinder and the linear guide ring in the optical axis direction is restricted, and there are two or more protrusions in the circumferential direction. spaced and are formed, between the protrusions adjacent in the circumferential direction, a part of the cam groove of the cam barrel is enters the overlapping positions in the optical axis direction, the so as to avoid the protrusion cam By forming the groove, the cam groove is sufficiently Even while securing the optical axis direction length, the it is possible to shorten the optical axis direction length of the cam barrel, thus providing a zoom lens barrel to be compactly when storing.
[0008]
Furthermore, it is preferable that two or more protrusions are formed in the circumferential direction. In particular, if a plurality of protrusions are formed apart from each other, the relative movement in the optical axis direction between the cam cylinder and the linear guide ring can be suppressed with a good balance.
[0009]
Further, it is preferable that the interval between at least one of the adjacent protrusions is different because the cam cylinder and the linear guide ring can be assembled at a predetermined rotational phase.
[0010]
Further, when a plurality of the protrusions are provided, it is preferable that at least one protrusion has a different circumferential length because the cam cylinder and the linear guide ring can be assembled at a predetermined rotational phase.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described with reference to embodiments.
FIG. 1 is a cross-sectional view of the zoom lens barrel according to the present embodiment, showing a state where the lower half is at the telephoto end and a state where the upper half is at the wide-angle end. FIG. 2 is a cross-sectional view of the lens barrel according to the present embodiment when retracted (completely retracted). FIG. 3 is a perspective view showing the assembly relationship of the cam cylinder 4, the rectilinear guide ring 6, the second lens frame 11, and the front cylinder 7.
[0012]
1 and 2, a cylindrical helicoid member (fixing member) 1 fixed in a camera body (not shown) forms a female helicoid 1a on the inner peripheral surface thereof. A rotating cylinder 2 in which a male helicoid 2 a that engages with a female helicoid 1 a is formed on the outer peripheral surface is attached so as to be enclosed in the helicoid member 1.
[0013]
A rectilinear cylinder (first cylinder) 3 included in the rotating cylinder 2 is disposed so as to move integrally with the rotating cylinder 2 in the optical axis direction. A protrusion (not shown) is formed on the outer periphery of the straight tube 3 on the film surface side (right side in FIG. 1) of the optical axis direction, and the protrusion is formed on the inner periphery of the helicoid member 1 and extends in the optical axis direction. Since it is engaged with an existing guide groove (not shown), the rectilinear cylinder 3 is supported non-rotatably with respect to the helicoid member 1 regardless of the rotation of the rotating cylinder 2 and moves only along the optical axis direction. It is possible.
[0014]
A female helicoid 3 a is formed on the inner periphery of the rectilinear cylinder 3, and a cam cylinder 4 in which a male helicoid 4 a that engages the female helicoid 3 a is formed on the outer periphery of the film side end is enclosed in the rectilinear cylinder 3. Therefore, it is arranged so as to be movable in the optical axis direction.
[0015]
As shown in FIG. 2, the drive pin 5 provided on the outer periphery of the cam cylinder 4 engages with a groove 2b formed on the inner periphery of the rotary cylinder 2, whereby the cam cylinder 4 and the rotary cylinder 2 are the same. It is designed to rotate in phase.
[0016]
As shown in FIG. 3, on the inner periphery of the end of the cam cylinder 4 on the film surface side, three protrusions 4 d formed in the circumferential direction are separated from the optical axis by ribs 6 b formed on the outer periphery of the rectilinear guide ring 6. The direction position is limited (see FIG. 2). In order to assemble the cam cylinder 4 and the straight guide ring 6 in the direction shown in FIG. 3 with the projection 4d facing the film surface (the back side in FIG. 3), the rib 6b has a projection 4d. A notch 6c corresponding to is formed. After the assembly, the protrusion 4d can arbitrarily move in the rotational direction between the rib 6b and the flange 6d, so that the rectilinear guide ring 6 moves integrally with the cam cylinder 4 in the optical axis direction and is relatively rotatable. It has become. The cam cylinder 4 and the linear guide ring 6 can be assembled at a predetermined rotational phase shown in FIG. 3 by changing the interval between the adjacent protrusions 4d or changing the circumferential lengths of the protrusions 4d.
[0017]
In FIG. 2, since the projection 6 a formed on the outer periphery of the film surface side end portion of the rectilinear guide ring 6 is fitted in the rectilinear groove 3 b of the rectilinear cylinder 3, the rectilinear guide ring 6 is in contact with the rectilinear cylinder 3. It moves in the optical axis direction without relative rotation. The straight guide ring 6 is provided with a notch (not shown) that avoids interference with the second lens frame 11 that holds the second lens group 10.
[0018]
Returning to FIG. 1, a female helicoid 4 b and a cam groove 4 c are formed on the inner peripheral surface of the cam cylinder 4. A front cylinder (second cylinder) 7 in which a male helicoid 7 a that engages with a female helicoid 4 b of the cam cylinder 4 is formed on the outer peripheral surface is disposed so as to be included in the cam cylinder 4. The front cylinder 7 is configured to be fitted with a key portion (not shown) of the straight guide ring 6 so as to be able to go straight.
[0019]
A shutter unit 8 that opens and closes a shutter blade 8 a and a first lens frame 12 that holds a first lens group 9 are attached to the front cylinder 7. Further, a key portion (not shown) of the second lens frame 11 is fitted into a straight groove (not shown) of the front cylinder 7, and the cam pin 11 a is fitted into a cam groove 4 c inside the cam cylinder 4.
[0020]
A thin and thin plate-like flexible printed wiring 15 is folded from the shutter unit 8 serving as a drive unit along the inner circumference of the front cylinder 7 and the inner circumference of the cam cylinder 4 at the straight cylinder 3, and from there the helicoid member 1 Extends through the opening 1b of the helicoid member 1 to the outer peripheral surface side, and its end is connected to a CPU of a camera body (not shown). The folded portion of the flexible printed wiring 15 is held by the attachment plate 14 and attached to the straight cylinder 3 with an adhesive tape (not shown).
[0021]
The operation of the present embodiment will be described. When the drive shaft 13 rotates in any direction by the power from a motor (not shown), the pinion 13a formed on the outer periphery of the drive shaft 13 rotates and meshes with the gear portion 2c. When the rotating cylinder 2 is rotated by receiving the rotational force via the, the rotating cylinder 2 is drawn out with respect to the helicoid member 1 by the action of the helicoids 1a and 2a (moves to the left in FIG. 1).
[0022]
When the rotary cylinder 2 is extended, the rectilinear cylinder 3 is extended integrally without rotating. At this time, the cam cylinder 4 is extended while rotating by the action of the helicoids 3a and 4a. When the cam cylinder 4 rotates, the front cylinder 7 is extended by the action of the helicoids 4b and 7a. The first lens group also moves with the movement of the front tube 7. On the other hand, since the cam pin 11a of the second lens frame 11 moves along the cam groove 4c by the rotation of the cam cylinder 4, the second lens frame 11 moves relative to the cam cylinder 4 in the optical axis direction accordingly. Therefore, the amount of movement in the optical axis direction of the first lens group 9 and the second lens group 10 is different, so that the subject image can be properly focused on the film surface. The above operation is reversed by reversing the drive shaft 13, and the zoom lens barrel is retracted.
[0023]
When the photographer presses a release button (not shown), the CPU in the camera body calculates an appropriate exposure amount and sends a signal corresponding to the exposure amount to the shutter unit 8 via the flexible printed wiring 15. The shutter unit 8 drives the shutter blade 8a at an appropriate shutter speed.
[0024]
FIG. 4 is a development view of the inner peripheral surface of the cam barrel of the zoom lens barrel of the present embodiment, and FIG. 5 is a development view of the inner peripheral surface of the cam barrel of the zoom lens barrel according to the comparative example. The direction is the optical axis direction. In the cam cylinder 4 (FIG. 4) of the present embodiment, the projection 4d formed at the end of the cam cylinder 4 and the cam groove 4c have a positional relationship in which a part thereof overlaps in the vertical direction (optical axis direction). It has become.
[0025]
On the other hand, in the cam cylinder 4 ′ (FIG. 5) of the comparative example, the protrusion 4d ′ formed at the end of the cam cylinder 4 ′ has a rib shape provided on substantially the entire circumference, and the circumferential direction A notch 4e ′ is formed at intervals. In this case, the rib (corresponding to 6b) of the straight guide ring combined with the cam cylinder 4 'needs to be small enough to correspond to the notch 4e'. Since the protrusions 4d ′ are provided on substantially the entire circumference, the protrusion 4d ′ and the cam groove 4c ′ of the cam cylinder 4 ′ of the comparative example are spaced apart in the vertical direction (optical axis direction) (not overlapping). ).
[0026]
In any of the cam cylinders 4 and 4 ′, when the maximum movement amount S of the cam pin 11a (second lens frame 11) is to be secured, the shapes of the cam grooves 4c and 4c ′ are the same. However, as apparent from a comparison between FIGS. 4 and 5, in the cam cylinder 4 (FIG. 4) of the present embodiment, the protrusion 4d and the cam groove 4c have a positional relationship in which a part thereof overlaps in the vertical direction. Therefore, as compared with the length L ′ of the cam cylinder 4 ′ of the comparative example in which they are spaced apart from each other, the length L of the cam cylinder 4 in the optical axis direction is shortened only in the overlapping portion (L <L )can do. The length of the zoom lens barrel in the optical axis direction when retracted is often determined by the length of the cam barrel 4 in the optical axis direction. In such a case, the zoom lens barrel is shortened by shortening the cam barrel 4. It can be said that overall compactness can be achieved.
[0027]
The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. For example, one or more protrusions 4d on the cam cylinder 4 are sufficient. The rectilinear guide ring 6 may have a cylindrical shape, and the projection 4d of the cam cylinder 4 and the rib 6b of the rectilinear guide ring 6 are provided on the subject side, and the projection 4d and the cam groove 4c are provided. As long as they overlap in the optical axis direction, they are included in the scope of the present invention. The present invention can be applied not only to a three-stage zoom lens barrel, but also to a two-stage zoom lens barrel and a multi-stage zoom lens barrel having four or more stages.
[0028]
【The invention's effect】
According to the present invention, it is possible to provide a zoom lens barrel that can shorten the length in the optical axis direction during storage while ensuring zoom performance.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a zoom lens barrel according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the lens barrel according to the present embodiment when retracted (completely retracted).
FIG. 3 is a perspective view showing an assembling relationship between a cam cylinder 4, a rectilinear guide ring 6, a second lens frame 11, and a front cylinder 7. FIG.
FIG. 4 is a development view of an inner peripheral surface of a cam barrel of the zoom lens barrel of the present embodiment.
FIG. 5 is a development view of an inner peripheral surface of a cam barrel of a zoom lens barrel according to a comparative example.
[Explanation of symbols]
Reference Signs List 1 helicoid member 2 rotating cylinder 3 rectilinear cylinder 4 cam cylinder 5 drive pin 6 rectilinear guide cylinder 7 front cylinder 8 shutter unit 9 first lens group 10 second lens group 11 second lens frame 12 first lens frame 13 drive shaft 14 Board 15 Flexible printed wiring

Claims (3)

A cam cylinder having cam grooves and protrusions formed on the same side of the inner periphery or outer periphery;
A rectilinear guide ring rotatable relative to the cam cylinder;
A cam pin that engages with the cam groove, and a lens frame that moves in the optical axis direction according to the shape of the cam groove when rotating relative to the cam cylinder;
The protrusion formed on the cam cylinder and the rib formed on the rectilinear guide ring engage with each other, so that the movement of the cam cylinder and the rectilinear guide ring in the optical axis direction is limited. cage, the projection is formed by spaced apart two or more circumferentially, between the protrusions adjacent in the circumferential direction, a portion of the cam groove of the cam barrel enters the overlapping positions in the optical axis direction A zoom lens barrel characterized by that. The zoom lens barrel according to claim 1 , wherein an interval between at least one of the adjacent protrusions is different. 3. The zoom lens barrel according to claim 1, wherein when a plurality of the protrusions are provided, at least one protrusion has a different circumferential length. 4.

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