JPH03210541A - Zoom lens barrel - Google Patents

Abstract

PURPOSE:To unnecessitate a bar used exclusively for the prevention of vibration by allowing the 1st guide bar to guide the 1st lens frame and prevent the vibration of the 2nd lens frame and allowing the 2nd guide bar to guide the 2nd lens frame and prevent the vibration of the 1st lens frame. CONSTITUTION:The zoom lens barrel is provided with a fixed cylinder 10, a cam cylinder 24 having the 1st and 2nd cam grooves 32, 38 and supported by the fixed cylinder 10 so as to be optionally rotated, the 1st lens frame 28 having the 1st driven pin 30 to be engaged with the 1st cam groove 32 of the cam cylinder 24 so as to move back and force in accordance with the rotation of the cam cylinder 24, and the 2nd lens frame 34 having the 2nd driven pin 36 to be engaged with the 2nd cam cylinder 38 so as to move back and force in accordance with the rotation of the cam cylinder 24. In addition, the 1st guide bar 40 engaged with the guide hole of the 1st lens frame 28 and the vibration preventing recessed part of the 2d lens frame 34 and fixed to the fixed cylinder 10 in its axial direction and the 2nd guide bar 42 engaged with the guide hole of the frame 34 and the vibration preventing recessed part of the frame 28 and fixed to the fixed cylinder 10 in its axial direction are also include. Consequently, the vibration preventing bar can be made unnecessary and the number of parts and manhour can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a zoom lens barrel, and particularly to a zoom lens barrel suitable for a video camera.

[Conventional technology]

2. Description of the Related Art There is a zoom mechanism for a photographic lens in which a first zoom lens group and a second zoom lens group are moved back and forth to perform a zooming operation. In such a zoom lens barrel, a guide hole and a steady rest concave portion are formed in the first movable lens frame, and the first guide bar is fitted into the guide hole.
It guides the first movable lens frame and also fits into the common steady rest par ρI steady rest recess to prevent the first movable lens frame from steadying. Further, a guide hole and a steady rest recess are formed in the second movable lens frame, and the second guide bar is fitted into the guide hole to guide the second movable lens frame, and the common steady rest bar is formed in the steady rest recess. The second movable lens frame is fitted into the frame to prevent the second movable lens frame from steadying. Further, a relief is formed in the second movable lens frame to prevent interference with the first guide bar, and a relief is formed in the first lens frame to prevent interference with the second guide bar.

[Problem to be solved by the invention]

However, the conventional zoom lens barrel has the following problems:
In addition to the second guide bar, a steady rest bar is required, and relief recesses must be formed in each of the first and second lens frames. For this reason, conventional zoom lens barrels have the drawbacks of having a large number of parts and requiring a large number of processing steps.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to propose a zoom lens barrel with a small number of parts and a small number of processing steps.

[Means to solve problems]

In order to achieve the above object, the present invention provides a fixed cylinder, a cam cylinder having a first cam groove and a second cam groove and rotatably supported by the fixed cylinder, and a first cam groove of the cam cylinder. A first lens frame has a first driven pin that fits into the cam barrel and moves back and forth as the cam barrel rotates, and a second driven pin that fits into a second cam groove of the cam barrel, and the cam barrel rotates. a second lens frame that moves back and forth as a result of this; a first guide bar that fits into the guide hole of the first lens frame, fits into the steady rest recess of the second lens frame, and is attached to the fixed barrel in the axial direction; It is characterized by comprising a second guide bar that fits into the guide hole of the second lens frame and the steady rest recess of the first lens frame, and is attached to the fixed barrel in the axial direction.

[Effect]

The present invention has a first guide bar that guides the first lens frame and prevents the second lens frame from steadying, and a second guide bar that guides the second lens frame and prevents the first lens frame from steadying. This eliminates the need for a dedicated steady rest bar, and also eliminates the need for relief machining.

〔Example〕

Preferred embodiments of the zoom lens barrel according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a zoom lens barrel to which the present invention is applied. (in Fig. 1), the fixed cylinder 10 has a first
Fixed lens group 12, first zoom movable lens group 14, second
Zoom moving lens group 16, focus moving lens group 18
, a second fixed lens group 20, five lens groups are arranged. Further, a diaphragm plate 1 is provided at the front of the second zoom movable lens group 16.
7 is provided.

The first fixed lens group 12 has a lens frame 2 at the front of the fixed barrel 10.
It is fixed via 2. A cam cylinder 24 is rotatably supported inside the center of the fixed cylinder 10.
4 is adapted to receive rotational driving force from a motor (not shown) via a gear 26 provided at its rear end.

The first zoom movable lens group 14 is mounted on a first lens frame 28 , and a driven pin 30 projects from the top of the first lens frame 28 . has been incorporated into. On the other hand, the second zoom movable lens group 16 is attached to the second lens frame 34, and
A driven pin 36 projects from the lower part of the lens frame 34, and this driven pin 36 is fitted into a cam groove 38 of the cam barrel 24.

A first guide bar 40 is provided at the upper part of the fixed barrel 10 in the axial direction of the fixed barrel 10, and a second guide bar 42 is further provided at the lower part of the fixed barrel 10.

The front end of the first guide bar 40 is inserted into a hole 46 of a support piece 44 provided at the upper front surface of the fixed cylinder 10 and is supported.
A rear end portion of the first guide bar 40 is inserted into a hole 48 formed in a stepped portion of the fixed cylinder 10 and is supported. Further, the front end of the second guide bar 420 is supported by the hole 52 of the support piece 50 formed at the front lower part of the fixed tube lO, and the rear end of the second guide bar 420 is supported by the hole 52 of the support piece 50 formed at the rear end of the fixed tube 10. Hole 5
Supported by 4. Support pieces 44.50 of the guide bar 40.42 formed on the fixed cylinder 10 are formed above and below the fixed cylinder 10, as shown in FIG. 2, and form fixed aperture pieces. This prevents unnecessary light from entering and reflection of so-called shiny objects such as the guide bar 40.42 and the driven pin 30.36.

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, 42. That is, the first guide bar 40 is fitted into the guide hole 56 formed at the upper part of the first lens frame 28 and is guided in the front-rear direction, and the steady rest recess 58 formed at the lower part of the first lens frame 26 is fitted with the first guide bar 40 . The second guide bar 42 is inserted into the
1. The zoom lens frame 28 is stabilized. Therefore, when the cam barrel 24 rotates in this state, the first zoom lens frame 24
8 moves back and forth while being guided by guide bars 40 and 42. On the other hand, a guide hole 60 is formed in the lower part of the second zoom lens frame 34, and a second
The guide bar 42 is fitted into the second zoom lens frame 3.
A steady rest recess 62 is formed in the upper part of the guide bar 4, and the first guide bar 40 is fitted into the recess 62. 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. In this way, the first guide bar 40 is fitted into the guide hole 56 of the first zoom lens frame 28, and the gJ1
While guiding the zoom lens frame 28, the second zoom lens frame 3 is positioned in the recess 62 of the second zoom lens frame 34.
It forms a steady rest for 4. The second guide bar 42 guides the hole 60 of the second zoom lens frame 34 and also serves as a steady rest for the first zoom lens frame 28, so the number of parts and processing steps are reduced compared to conventional zoom lens barrels. effective.

As shown in FIG. 1, the focus moving lens group 18 is mounted on a lens frame 63, and the second guide bar 42 is fitted into a guide hole 64 at the bottom of this lens frame 63. Further, a recess 66 is formed in the upper part of the focus lens frame 63, and the first guide bar 40 is fitted into the recess 66 to prevent the lens frame 63 from steadying. In this way, the focus lens frame 63 is attached to the guide bar 40 of the zoom lens system.
42 in common, it becomes easy to adjust the optical axes of the zoom lens system and the focus lens system, and the number of parts can be reduced.

Next, the drive mechanism of the focus lens will be explained.

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 around the pulley 70, and this belt 72 rotates a pulley 74. A screw shaft 76 is fixed to the pulley 74, and a nut member 78 is screwed onto the screw shaft 76. As shown in FIGS. 5 and 6, the nut member 78 is formed with a pair of forked locks 8B80.

A long hole 82.
82 is formed, and locking pieces 84, 84 are formed to be elastically deformable. This bifurcated locking portion 82 is engaged with a connecting piece 86 integral with the focus lens frame 63 shown in FIGS. 5 and 6. That is, the connecting piece 86 is formed from pins 88, 88 on both sides and a spherical piece 90. To attach the connecting piece 86, insert the pin 88.88 into the elongated hole 82.82 between the pair of forked locking parts 80, and insert the spherical piece 90 into the groove between the locking pieces 84.84. insert. The connection structure assembled in this way is shown in FIG.

In such a connection structure, the rotational force from the motor 68 is transmitted to the screw shaft 76, thereby causing the nut member 78 to move back and forth. When the nut member 78 moves back and forth, the nut member 78 and the focus lens frame 63 are connected through a spherical structure.

Therefore, the deviation in parallelism between the screw shaft 76 and the guide bar 40, 42 can be absorbed by this spherical contact portion, and the movement of the nut member 78 is not hindered.

Behind the focus moving lens 18, a second fixed lens group 20 is fixed to the fixed barrel 10 via a lens frame 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, a CCD 94 is disposed.

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

Also, the motor 68 rotates and the focus lens frame 6
3 moves to adjust the focus.

The photographed image light passes through a low-pass filter 92 and enters the CCD 94.
will be imaged.

〔Effect of the invention〕

According to the invention! The Jl guide bar guides the first lens frame and prevents the second lens frame from steadying, and the second guide bar guides the second lens frame and prevents the first lens frame from steadying. There is no longer a need for a dedicated steady rest bar, which was previously necessary, and there is also no need for relief machining.

[Brief explanation of drawings]

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 ■-■ in FIG. 1; The figure is a perspective view showing the relationship between the zoom lens frame and the guide bar, FIG. 4 is a sectional view showing the focus lens drive mechanism within the zoom lens barrel according to the present invention, and FIG. 5 is the same focus lens drive mechanism. FIG. 6 is a cross-sectional view seen from a different angle from FIG. 4, and FIG. 6 is a perspective view showing the structure of a connecting portion of the focus lens drive mechanism. 10... Fixed barrel, 24... Cam barrel, 8...
・First lens frame, 30... Followed pin, 2... Cam groove, 34... Second lens frame, 6... Followed pin, 38... Cam groove, 0... First guide Bar 2...Second guide bar

Claims (1)

[Claims] (1) A fixed cylinder, a cam cylinder having a first cam groove and a second cam groove and rotatably supported by the fixed cylinder, and a first driven pin fitted into the first cam groove of the cam cylinder. and a second lens having a first lens frame that moves back and forth as the cam barrel rotates, and a second driven pin that fits into a second cam groove of the cam barrel, and that moves back and forth as the cam barrel rotates. a frame; a first guide bar that fits into the guide hole of the first lens frame and the steady rest recess of the second lens frame; and a first guide bar that is attached to the fixed barrel in the axial direction; and a first guide bar that fits into the guide hole of the second lens frame. and a second guide bar that is fitted into the steady rest recess of the first lens frame and attached to the fixed barrel in the axial direction.