JPH03210542A - Zoom lens barrel - Google Patents

Abstract

PURPOSE:To obtain a compact and high magnification zoom lens barrel by arranging a diaphragm member in the front of the 2nd zoom moving lens to move the diaphragm member back and force together with the 2nd zoom moving lens and arranging a focus moving lens group between the zoom lens group and the 2nd fixed lens group. CONSTITUTION:The zoom lens barrel is provided with a fixed cylinder 10, the 1st fixed lens group 12 arranged in the front of the fixed cylinder 10, the 1st zoom moving lens group 14 arranged on the back of the group 12 so as to be optionally moved back and force in the cylinder 10, and the 2nd zoom moving lens group 16 arranged on the back of the group 14 so as to be optionally moved back and force in the cylinder 10. In addition, the diaphragm member 17 arranged in the front of the group 16 so as to be moved together with the group 16 and the focus moving lens group 18 arranged on the back of the group 16 so as to be optionally moved in the cylinder 10 and the 2nd fixed lens group 20 arranged on the back of the lens 18 in the rear part of the cylinder 10 are also included. Consequently, high power can be obtained in spite of using the compact zoom lens barrel.

Description

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

[Conventional technology]

Zoom lens barrels used in conventional video cameras generally employ a front lens focusing method, and furthermore, the iris is fixed between the zoom lens group and the master lens group.

[The invention seeks to solve rlAM”J However,
When the front lens focusing method is adopted, the front lens is moved out during focusing, so if you try to increase the angle of view on the wide-angle side, the front lens has the disadvantage of increasing diameter and making it heavier.

Furthermore, if the iris is fixedly disposed between the zoom lens and the master lens, there is a drawback that the zoom lens barrel becomes large in order to obtain high magnification.

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 that is compact and provides high magnification.

[Means to solve problems]

In order to achieve the above object, the present invention includes a fixed barrel, a first fixed lens group provided at the front of the fixed barrel, and a lens group provided within the fixed barrel so as to be movable back and forth behind the first fixed lens. a first zoom movable lens group; a second zoom movable lens group provided on a fixed barrel behind the first zoom movable lens group so as to be movable back and forth; and a second zoom lens group provided in front of the second zoom movable lens group; a diaphragm member that moves together with the movable lens group;
It is characterized by comprising a focus moving lens group movably provided on a fixed barrel behind the zoom moving lens group, and a second fixed lens group provided at the rear of the fixed barrel behind the focus moving lens group. do.

[Effect]

In the present invention, the diaphragm member is provided in front of the second zoom movable lens, and the diaphragm member is moved back and forth together with the second zoom movable lens, so that a high magnification can be obtained with a small size. Furthermore, since the lens is of an inner focus type and the focus moving lens group is provided between the zoom lens group and the second fixed lens group, high magnification can be obtained.

〔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 barrel 10 includes, from the front, a first fixed lens group 12, a first zoom movable lens group 14, a second zoom movable lens group 16, a focus movable lens group 18,
Five lens groups of the second fixed lens group 20 are arranged.

In addition, an aperture plate 17 is provided at the front of the second zoom movable lens group 16.
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 3 is inserted from the top of the first lens frame 28.
0 is provided in a protruding manner, and this driven pin 30 is fitted into a cam groove 32 of the cam cylinder 24. On the other hand, the second zoom movable lens group 16 is attached to a second lens frame 34 , and a driven pin 36 is protruded from the lower part of the second lens frame 34 . It is inserted inside.

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 400 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 lower front of the fixed cylinder 10, and the rear end of the second guide bar 420 is supported by the hole 52 of the support piece 50 formed at the lower front of the fixed cylinder 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 second lens frame 28 and is guided in the front-rear direction, and the steady rest recess 58 formed at the lower part of the second lens frame 34 has a second guide bar 40 fitted therein. 2 guide bar 42 is inserted into the first
The zoom lens frame 28 is stabilized. Therefore, when the cam barrel 24 rotates in this state, the first zoom lens frame 28
will move 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 the second guide bar 42 is fitted into the guide hole 60 .
A steady rest recess 62 is formed in the upper part of the recess 6.
2 has a first guide bar 40 fitted therein. Therefore, when the cam barrel 24 rotates in this state, the second zoom lens frame 3
4 moves back and forth while being guided by guide bars 40 and 42. In this way, the first guide bar 40
It fits into the guide hole 56 of the zoom lens frame 28 to guide the first zoom lens frame 28, and is located in the recess 62 of the second zoom lens frame 34 to form the [14th] part of the second zoom lens frame 34. The second guide bar 40 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 attached to 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 1o, a belt 72 is stretched around the pulley 7o, 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 B80.

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.

4 and 7, a drive mechanism for the aperture plate 17 is shown. That is, a lever 102 is provided on the output shaft of the iris meter 100, and a pin 1 is attached to the tip of the lever 102.
04 is provided protrudingly.

A lever 108 is pivotally supported on the side leg lO via a shaft 106, and a pin 104 of the lever 102 is fitted into an elongated hole 110 formed at one end of the lever 108. Lever 1
A pin 112 is provided protruding from the other end of 08, and this pin 112
is the elongated hole 11 formed in the rotating ring 114 of the aperture plate 17.
6 is included. A plurality of aperture blades having a known structure are pivotally supported on the rotation ring 114.

In the aperture plate drive device configured as described above, the lever 102 of the iris meter 100 is adjusted depending on the surrounding brightness.
When the lever 108 rotates, the rotation ring 11
Rotate 4. This causes the aperture blades (not shown) to open and close, thereby determining the aperture opening degree. Note that the aperture plate 17 moves together with the second zoom moving lens frame 34, but since the pin 112 is fitted into the elongated hole 116 of the rotation ring 114, the state of engagement between the lever 108 and the aperture plate 17 is fixed. maintained. The aperture plate 17 is connected to the lever 102 of the iris meter 100.
Since the lever 102 is engaged via the lever 108 without being directly engaged with the lever 102, the lever 102 can be made smaller, which has the effect of improving accuracy accordingly.

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 provided with power.

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〕

In the present invention, the diaphragm member is provided in front of the second zoom lens group so that the diaphragm member is moved back and forth together with the second zoom lens group, and the focus movement lens group is of an inner focus type and the second zoom lens group is Since it is placed between the fixed lens group, high magnification can be obtained despite the small zoom lens barrel.

[Brief explanation of drawings]

1 is a sectional view showing the structure of a zoom lens barrel to which the present invention is applied; FIG. 2 is a sectional view showing the shape of the front surface of the zoom lens barrel taken along the line ■-■ 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 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 perspective view showing the structure of the connection part of the focus lens drive mechanism, and FIG. 7 is an explanatory diagram showing the aperture plate drive mechanism. It is. DESCRIPTION OF SYMBOLS 10... Fixed barrel, 12... First fixed lens group, 14... First zoom moving lens group 16... Second zoom moving lens group, 17... Aperture plate, 18... Focus moving lens group, 20... second fixed lens group;

Claims (1)

[Claims] (1) a fixed barrel; a first fixed lens group provided in the front part of the fixed barrel; a first zoom movable lens group provided in the fixed barrel so as to be movable back and forth behind the first fixed lens; a second zoom movable lens group provided on a fixed barrel behind the first zoom movable lens group so as to be movable back and forth; and an aperture member provided in front of the second zoom movable lens group and moved together with the second zoom movable lens group. , a focus moving lens group movably provided on a fixed barrel behind the second zoom moving lens group, and a second fixed lens group provided at the rear of the fixed barrel behind the focus moving lens group. lens barrel.