JP3139753B2 - Zoom lens barrel - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a zoom lens barrel suitable for a video camera or the like.

[Conventional technology]

Some zoom lens barrels include a zoom lens driving mechanism and a focus lens driving mechanism. The zoom lens driving mechanism is provided with a movable lens frame, and the movable lens frame is guided by a guide rod and moves back and forth to perform a zooming operation. On the other hand, a moving lens frame is also provided in the focus lens driving mechanism, and the moving lens frame moves back and forth by being guided by a guide rod, and performs focus adjustment.

[Problems to be solved by the invention]

However, in the conventional zoom lens barrel, the movable lens frame of the zoom lens system and the movable lens frame of the focus lens system are guided by different guide rods. Therefore, there is a disadvantage that it takes time to adjust the optical axes of the zoom lens system and the focus lens system. Further, if guide rods are provided in each of the focus lens system and the zoom lens system, there is a disadvantage that the number of parts increases.

The present invention has been made in view of such circumstances,
It is an object of the present invention to propose a zoom lens barrel having a small number of components and capable of easily adjusting the optical axes of a zoom lens system and a focus lens system.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a first fixed lens group fixed to a fixed cylinder, and is disposed behind the first fixed lens group, and is moved back and forth within the fixed cylinder via a guide rod. A zoom lens system including a first zoom movable lens group and a second zoom movable lens group for performing zooming, and a focus adjustment performed by moving the zoom lens system back and forth within a fixed cylinder via a guide rod of the zoom lens system; The zoom lens system includes a focus lens system arranged behind the lens system and a second fixed lens group arranged behind the focus lens system. The entire zoom lens system and the entire focus lens system are supported by the common guide rod. It is characterized by the following.

[Action]

According to the present invention, the moving lens frame of the focus lens system is guided by the guide rod of the zoom lens system. Therefore, it is easy to adjust the optical axis of the zoom lens system and the focus lens system, and the number of components is reduced because the guide rod is shared.

〔Example〕

Hereinafter, preferred embodiments of a zoom lens barrel according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a zoom lens barrel to which the present invention is applied. In FIG. 1, a fixed barrel 10 includes a first fixed lens group 12, a first zoom moving lens group 14, a second zoom moving lens group 16, a focus moving lens group 18, and a second fixed lens group 20 from the front. Five lens groups are arranged. An aperture plate 17 is provided in front of the second zoom moving lens group 16.

The first fixed lens group 12 is fixed to the front of the fixed cylinder 10 via a lens frame 22. A cam cylinder is located inside the center of the fixed cylinder 10.
A cam cylinder 24 is rotatably supported, and the cam cylinder 24 is provided with a rotational driving force from a motor (not shown) via a gear 26 provided at a rear end thereof.

The first zoom moving lens group 14 is mounted on a first lens frame 28, and a driven pin 30
The driven pin 30 is fitted in the cam groove 32 of the cam cylinder 24. On the other hand, the second zoom moving lens group 16 is mounted on a second lens frame 34, and a driven pin 36 projects from a lower portion of the second lens frame 34, and the driven pin 36
The cam grooves 38 are fitted into the 24 cam grooves 38.

A first guide bar 40 is provided in an upper part of the fixed cylinder 10 in an axial direction of the fixed cylinder 10, and a second guide bar 42 is provided in a lower part of the fixed cylinder 10. The front end of the first guide bar 40 is inserted into and supported by the hole 46 of the support piece 44 provided on the upper front surface of the fixed cylinder 10, and the rear end of the first guide bar 40 is formed at the step of the fixed cylinder 10. The hole 48 is inserted and supported. Also,
The front end of the second guide bar 42 is supported by a hole 52 of a support piece 50 formed at the lower part of the front surface of the fixed cylinder 10, and the rear end of the second guide bar 42 is formed at the rear end of the fixed cylinder 10. Supported by holes 54. A guide bar 40 formed on the fixed cylinder 10,
As shown in FIG. 2, the support pieces 44 and 50 of the 42 are formed above and below the fixed cylinder 10 so as to form a fixed throttle piece. This prevents unnecessary holes from entering and guide bar
The reflection of so-called light objects such as 40, 42 and driven pins 30, 36 is prevented.

FIG. 3 shows the relationship between the first zoom lens frame 28, the second zoom lens frame 34, and the first and second guide bars 40 and 42. That is, a guide hole formed in the upper part of the first lens frame 28
A first guide bar 40 is fitted into 56 and guided in the front-rear direction, and a steady rest recess formed in the lower and lower part of the first lens frame 26.
The second guide bar 42 fits into the 58 and the first zoom lens frame
Perform 28 steady rest. Therefore, when the cam barrel 24 rotates in this state, the first zoom lens frame 28 moves back and forth while being guided by the guide bars 40 and 42. On the other hand, a guide hole 60 is formed in a lower portion of the second zoom lens frame 34, a second guide bar 42 is fitted in the guide hole 60, and
In the upper part of the zoom lens frame 34, there is formed an anti-sway concave portion 62, into which the first guide bar 40 is fitted.
Therefore, when the cam barrel 24 rotates in this state, the second zoom lens frame 34 moves back and forth while being guided by the guide bars 40 and 42. Thus, the first guide bar 40 is
The first zoom lens frame 28 is guided by being fitted into the guide hole 56 of the zoom lens frame 28, and is positioned in the concave portion 62 of the second zoom lens frame 34 to prevent the second zoom lens frame 34 from oscillating. The second guide bar 42 guides the hole 60 of the second zoom lens frame 34 and also serves to prevent the first zoom lens frame 28 from swaying.
This has the effect of reducing the number of processing steps.

As shown in FIG. 1, the format moving lens group 18 is mounted on a lens frame 63, and a second guide bar 42 is fitted into a guide hole 64 below the lens frame 63. In addition, a concave portion 66 is formed in the upper part of the focus lens frame 63, and the first guide bar 40 is fitted into the concave portion 66 to prevent the lens frame 63 from oscillating. Focus lens frame like this
Since 63 shares the guide bars 40 and 42 of the zoom lens system, it is easy to adjust the optical axis of the zoom lens system and the focus lens system, and the number of parts is reduced.

Next, the drive mechanism of the focus lens will be described. As shown in FIG. 4, a pulley 70 is provided on the output shaft of the focus motor 68 attached to the fixed cylinder 10.
A belt 72 is stretched on 70, and the belt 72 rotates a pulley 74. A screw shaft 76 is fixed to the pulley 74,
A nut member 78 is screwed onto the screw shaft 76. The nut member 78 has a pair of forked locking portions 80 as shown in FIGS. Slots 82 are formed between the pair of forked locking portions 80, respectively.
4, 84 are formed so as to be elastically deformable. The forked locking portion 82 is engaged with a connecting piece 86 integral with the focus lens frame 63 shown in FIGS. That is, the connecting piece 86 is formed by the pins 88 on both sides and the spherical piece 90. The mounting pins 88, 88 of the connecting piece 86 are fitted into the elongated holes 82, 82 between the pair of forked locking portions 80, and the spherical piece 90 is
Fit into the groove between 84,84. The connecting structure thus assembled is shown in FIG.

In such a connection structure, the rotational force from the motor 68 is transmitted to the screw shaft 76, whereby the nut member 78 moves back and forth. When the nut member 78 moves back and forth, the nut member 78
And the focus lens frame 63 are connected via a spherical structure. Therefore, the deviation of the parallelism between the screw shaft 76 and the guide bars 40 and 42 can be absorbed by the spherical contact portion, and the movement of the nut member 78 is not hindered.

Behind the focus moving lens 18, the second fixed lens group 20 is fixed to the fixed cylinder 10 via the lens group 79.

As shown in FIG. 1, a low-pass filter 92 is provided at the rear of the fixed cylinder 10, and further behind the low-pass filter 92.
CCD94 is arranged.

In the lens barrel according to the present invention configured as described above, when the cam barrel 24 rotates, the zoom lens group 14,
16 moves as shown by the dashed line in FIG. 1 to perform zooming.

Further, the motor 68 is driven to rotate, and the focus lens frame 63 is rotated.
Moves to perform focus adjustment.

The captured image light passes through the low-pass filter 92 and is captured by the CCD 94.

〔The invention's effect〕

According to the present invention, since the entire zoom lens system and the entire focus lens system are supported by the common guide rod, the number of parts constituting the zoom lens barrel is reduced, and the light of the zoom lens system and the focus lens system is reduced. Axis adjustment is easy, and the focus lens system is placed behind the zoom lens system, and the entire zoom lens system and the entire focus lens system are supported by a common guide rod, so that the focus lens system can be made smaller. Thus, a high-magnification zoom lens barrel can be obtained. Therefore, a small and high-magnification zoom lens barrel can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the structure of a zoom lens barrel to which the present invention is applied, FIG. 2 is a cross-sectional view showing the shape of the front surface of the zoom lens barrel along the line II-II in FIG. 3 is a perspective view showing the relationship between the zoom lens frame and the guide bar, FIG. 4 is a sectional view showing a focus lens driving mechanism in the zoom lens barrel according to the present invention, and FIG. And FIG. 6 is a perspective view showing a structure of a connecting portion of a focus lens driving mechanism. 10: fixed cylinder, 14: first zoom moving lens group, 16: second zoom moving lens group, 18: focus lens group, 40, 42: guide bar.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-95409 (JP, A) JP-A-64-59310 (JP, A) JP-A-61-67011 (JP, A) JP-A 55-95 67716 (JP, A) JP-A-63-314511 (JP, A) JP-A-63-52111 (JP, A) JP-A-64-35516 (JP, A) Japanese Utility Model Showa 62-99021 (JP, U) Shokai Sho 61-148026 (JP, U)

Claims (1)

(57) [Claims] A first fixed lens group fixed to a fixed cylinder;
A first lens arranged rearward of the first fixed lens group and moved back and forth in a fixed cylinder via a guide rod to perform zooming
A zoom lens system including a zoom moving lens group and a second zoom moving lens group; and a focus adjustment performed by moving the zoom lens system back and forth in a fixed cylinder via a guide rod of the zoom lens system, and disposed behind the zoom lens system. And a second fixed lens group disposed behind the focus lens system, wherein the entire zoom lens system and the entire focus lens system are supported by the common guide rod. Lens barrel.