JP3467784B2 - Camera lens barrel - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel used in an image pickup device such as a video camera, and more particularly to a lens barrel for a camera in which an iris can be attached and detached without disassembling the barrel.

[0002]

2. Description of the Related Art For example, in a video camera, an inner focus type zoom lens mirror for focusing, correcting, and forming an image by moving a focusing master lens group and a zoom variator lens group along an optical axis. The cylinder is known. Further, in this type of lens barrel, there is also known a so-called autofocus system in which focusing, correction, and image formation of a read image are automatically adjusted.

A lens barrel used in a conventional zoom / inner focus type image pickup apparatus is a fourth group lens having a first group and a third group lens as a fixed system and a second group and a fourth group as a movable system. In addition to being composed of a system, for example, a focusing function, a correction function, and an image forming function are given to the movable fourth group lens to automatically control the moving positions of the second group lens and the fourth group lens. There is.

In such a camera lens barrel, an iris (diaphragm device) for automatically adjusting the amount of light is provided, for example, between the second lens group and the third lens group. It is important to match the aperture center of the iris with the optical axis as well as to match the optical axis of the lens barrel. Therefore, conventionally, the position accuracy of the iris with respect to the optical axis is guaranteed by screwing the iris to a lens barrel or the like.

[0005]

However, although the positional accuracy can be guaranteed by screwing the iris to the lens barrel as in the conventional camera lens barrel, the lens barrel must be disassembled when the iris is replaced. Therefore, not only the replacement work time becomes long, but also dust may enter the lens barrel.

Moreover, after the iris is replaced, when reassembling the lens barrel, it is necessary to secure the assembling accuracy of the components such as the lens barrel and other lens groups to the same level as in the initial assembling. there were. Especially for the iris, since the frequency of replacement is higher than that of the lens group which is another component, improvement in maintainability has been demanded.

The present invention has been made in view of the above-mentioned problems of the prior art. It is possible to easily attach and detach the iris without disassembling the lens barrel while ensuring the iris mounting accuracy. With the goal.

[0008]

According to Means for Solving the Problems] The present invention, a lens group composed of beautiful friendly dynamic lens group Oyo stationary lens group along the iris in the optical axis becomes disposed in a lens barrel, the iris A plurality of slide guides, which serve as guides when inserting the iris in a direction substantially perpendicular to the optical axis, are provided in at least one of the adjacent lens group or the lens barrel from the vicinity of the insertion port to the vicinity of the optical axis. Provided in a direction orthogonal to the axis and parallel to the insertion direction, when the iris is inserted, the central axis of the iris is positioned so as to match the optical axis, and the lens group or the lens barrel adjacent to the iris engaging the at least either the iris, detachable engaging portions freely, Ca me provided on at least either said iris of the lens unit or the lens barrel adjacent the iris A use lens barrel, the iris
Of the lens group adjacent to the lens or the lens barrel
One of the engaging parts provided on either side is
A lens barrel for a camera , which is the tip of a guide shaft that supports a lens group, is provided.

Preferably, the iris is inserted in a direction substantially perpendicular to the optical axis, the iris is fixed in position by the engaging portion, and then the bracket portion of the driving means for moving the movable lens group is used. The iris is fixed by pressing the end surface of the iris.

[0010]

[0011]

When the lens group and the iris are provided on the lens barrel along the optical axis, the slide guide formed on at least one of the lens group and the lens barrel adjacent to the iris serves as a guide, and the iris is set on the optical axis. Insert it at a right angle. Then, the engaging portion formed on at least one of the lens group and the lens barrel adjacent to the iris and the engaging portion formed on the iris are engaged with each other. By this insertion and engagement, the iris can be temporarily positioned, and furthermore, the iris can be attached and detached without disassembling the lens barrel and the lens group.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is an exploded perspective view showing an overall configuration of a lens barrel according to an embodiment of the present invention, FIG. 2 is a sectional view showing the lens barrel of the same embodiment, and FIG. 3 is a front view showing an iris according to the same embodiment. It is a figure.

As shown in FIG. 1, the lens barrel according to this embodiment includes a main barrel 5 and a rear barrel 8 which are arranged in the front-rear direction of the optical axis.
The first lens group 1, the second lens group 2, the third lens group 3, and the fourth lens group 4 are sequentially arranged in these two lens barrels along the optical axis I-I '. ing. A CCD (charge couple device, not shown) as an image pickup device is arranged at the focal position of the fourth lens group 4.

[0014] The first lens group 1 is a group lenses for focusing,
It is composed of a plurality of lenses, for example, three lenses, and is fixed in the main lens barrel 5. The second lens group 2 is a zoom (variable magnification) lens group, is composed of a plurality of lenses, for example, three, and is supported by the two guide shafts 6 and 7 and the optical axis. It is provided so as to be movable along the II 'direction.

The third lens group 3 is composed of a single lens or a plurality of lenses, for example, one lens, and the rear lens barrel 8 is provided.
It is fixed inside. Further, the fourth lens group 4 is a focusing lens group, and is composed of a plurality of lenses, for example, two lenses, and is supported by the two guide shafts 12 and 13, and is aligned with the optical axis II ′. It is provided so that it can be moved along.

An iris 9 is provided between the fixed first lens group 1 and third lens group 3 while being sandwiched between the main lens barrel 5 and the rear lens barrel 8. The diaphragm film of the iris 9 is driven up and down by the iris motor 10. “11” is a stepping motor (driving means) which is fixed to the main barrel 5 and moves the second lens group 2, and “18” is a voice coil type linear motor which moves the fourth lens group 4.

The VC linear motor 18 is a linear DC motor comprising a yoke 17 as a stator and a permanent magnet 16 and a mover 15 around which a coil 14 is wound. The yoke 17 has four yokes. A back yoke to which each permanent magnet is attached and a center yoke formed in an annular shape at the center of this back yoke are integrally formed, and a magnetic field is generated by the permanent magnet 16.

On the other hand, the mover 15 to which the fourth lens group 4 is attached is inserted into the lens holder of the third lens group 3 and is installed between the main lens barrel 5 and the rear lens barrel 8. It is supported by the guide shafts 12 and 13 and is slidable along the optical axis I-I '. The mover 15 is inserted through the center yoke with a slight gap, and the current direction of the coil 14 wound around the outer circumference is switched, whereby the mover 15,
That is, the fourth lens group 4 can move forward and backward along the center yoke.

In particular, in the lens barrel of this embodiment, the drive center axis of the mover 15 and the optical axis II 'are aligned.
As a result, the thrust of the VC linear motor 18 is directly transmitted to the mover 15, that is, the fourth lens group 4, so that the center of the fourth lens group 4 does not deviate from the optical axis I-I '. The fourth group lens 4 moves smoothly and at high speed.

On the other hand, one ends of the two guide shafts 6 and 7 for supporting the second group lens are press-fitted in front of the main lens barrel 5, and the holders of the second group lens 2 are attached to the guide shafts 6 and 7. It has been inserted. At the same time, the other ends of the guide shafts 6 and 7 are inserted into the holder of the third lens group 3 and the tips thereof are inserted and fixed in the rear lens barrel 8. In FIG. 2, only one (6) of the two guide shafts 6 and 7 is shown, but the other guide shaft 7 is arranged on the diagonal line of the illustrated guide shaft 6, and this guide shaft 7 is also provided. It is similarly configured.

Similarly, one ends of the two guide shafts 12 and 13 for supporting the fourth group lens 4 are press-fitted to the rear of the rear lens barrel 8 and the holders of the fourth group lens 4 are attached to the guide shafts 12 and 13. Has been inserted. At the same time, the guide shafts 12, 13
The other end of is inserted into the holder of the third lens group 3, and its tip is inserted and fixed to the main lens barrel 5. In FIG. 2, only one (12) of the two guide shafts 12 and 13 is shown, but the other guide shaft 13 is arranged on a diagonal line of the illustrated guide shaft 12, and this guide shaft 13 is also arranged. It is similarly configured.

By the way, these four guide shafts 6, 7,
Since the positional relationship between 12 and 13 is 180 ° out of phase with each other, the four guide shafts 6, 7, 12, 13 interfere at the joint between the main lens barrel 5 and the rear lens barrel 8. There is no such thing.

If the guide shafts 6, 7, 12, and 13 for supporting the movable lens groups 2 and 4 are used to bridge the main lens barrel 5 and the rear lens barrel 8 as described above, Of the main lens barrel 5 and the rear lens barrel 8 and the optical centers of the movable lens groups 2 and 4 and the fixed lens groups 1 and 3 to the optical axis I-I 'of the lens barrel accurately and easily. It is preferable because it can be matched by various operations.

In the lens barrel of the present embodiment, the iris 9 is mounted as follows in view of the fact that the iris 9 is replaced more frequently than the lens groups 1 to 4 constituting the lens barrel. .

First, the slide guides 19 and 19 as shown in FIG. 1 are formed in the holder of the third lens group 3 among the lens groups adjacent to the iris 9, and the iris 9 is shown as shown by the chain line in FIG. Is used as a guide wall when it is inserted in a direction substantially perpendicular to the optical axis II ′ (see the arrow in FIG. 1).
The slide guides 19 and 19 formed on the holder of the third lens group 3 guide the iris 9 to the regular assembly position while slidingly contacting the side surface of the iris 9.

However, the specific shape of the slide guide of the present invention is not limited to the illustrated embodiment, and may be any shape or structure that controls the function of guiding the iris to the regular mounting position. Further, the slide guide is not limited to the third lens group, but may be any component adjacent to the iris. By the work of inserting the slide guides 19 and 19 and the iris 9, the position of the iris 9 with respect to the rotation direction of the optical axis II ′ is determined.

Further, the iris 9 according to this embodiment includes
As shown in FIG. 3, an engaging portion 20 is formed, and this engaging portion 20 is adapted to engage with the tip end of the guide shaft 12 of the fourth group lens 4 described above. That is, as described above, when the iris 9 is inserted in a direction substantially perpendicular to the optical axis II ′, the tip of the guide shaft 12 protruding through the holder of the third lens group 3 is iris. The iris 9 is positioned in the vertical direction of the optical axis I-I 'as a result of being fitted into the engaging portion 20 formed on the optical axis 9.

However, since the center O of the diaphragm film of the iris 9 and the optical axis I-I 'need to coincide with each other with high accuracy, the final positioning in this embodiment is the upper end 21 of the iris 9.
Is abutted on the upper surface of the main lens barrel 5. Since the engaging portion 20 of the iris 9 is composed of a flexible claw piece, when an external force is applied in the direction of arrow A shown in FIG. 2, the engaging portion 20 and the guide shaft 12 are fitted together. Then the iris 9 can be pulled out.

Further, in this embodiment, in order to finally fix the iris 9 to the lens barrels 5 and 8, after the iris 9 is inserted, the lower end surface 22 of the iris 9 is fixed to the second group lens 2
The bracket 23 of the stepping motor 11 of FIG. As a result, the iris 9 is moved to the lens barrels 5 and 8
In contrast, the center O of the diaphragm film of the iris 9 and the optical axis I-
Although it is firmly fixed in a state where it accurately matches with I ′, conversely, the iris 9 can be pulled out only by removing the stepping motor 11 (correctly, the bracket 23).

As described above, in the lens barrel of this embodiment, since the iris 9 is inserted and fitted to be assembled, the work of attaching and detaching the iris 9 becomes extremely easy.
Maintainability is improved. Moreover, even if the iris is attached / detached, the positional relationship of other components is not adversely affected.

It should be noted that the embodiments described above are described for facilitating the understanding of the present invention and not for limiting the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents within the technical scope of the present invention.

For example, in the above-described embodiment, the iris 9 is finally fixed by using the bracket 23 of the stepping motor 11, but it may be fixed by other parts. Further, although the mating engaging portion that fits into the engaging portion 20 formed on the iris 9 is configured by using the tip of the guide shaft 12, for example, even if a protrusion is formed on the holder of the third lens group 3, Good.

[0033]

As described above, according to the present invention, a slide guide is formed on a lens group adjacent to the iris to provide a guide for inserting the iris in a direction substantially perpendicular to the optical axis. Since the iris is positioned by forming an engaging portion between the iris and the lens group adjacent to the iris and engaging them with each other, the iris can be attached and detached without disassembling the lens barrel or lens group. Can be done with extremely easy work. As a result, the maintainability of the iris can be improved while preventing the optical axis shift of the lens barrel.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a configuration of a lens barrel according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a lens barrel of the embodiment.

FIG. 3 is a front view showing an iris of the embodiment.

[Explanation of symbols]

I-I '... optical axis 2 ... Second lens group (movable lens group) 4 ... 4th lens group (movable lens group) 5 ... Main lens barrel 8 ... Rear lens barrel 19 ... Slide guide 20 ... Engagement part 23 ... Bracket

Claims (2)

(57) [Claims] And 1. A lens group including a stationary lens group and allowed dynamic lens group, provided the iris to the lens barrel along the optical axis
From at least one of the lens group adjacent to the iris or the lens barrel, a plurality of slide guides for guiding the iris in a direction substantially perpendicular to the optical axis are provided near the insertion opening. Providing up to the vicinity of the optical axis orthogonal to the optical axis and parallel to the insertion direction, when the iris is inserted, the central axis of the iris is positioned so as to match the optical axis, and the lens group adjacent to the iris or the A detachable engaging portion that engages at least one of the lens barrel with the iris is provided in at least one of the lens group adjacent to the iris or the lens barrel and the iris .
A camera lens barrel, a lens group or the lens barrel adjacent the iris
One of the engaging portions provided on at least one of the
A lens barrel for a camera, which is the tip of a guide shaft that supports the movable lens group . 2. The iris is inserted by a bracket portion of a driving means for moving the movable lens group after inserting the iris in a direction substantially perpendicular to the optical axis and fixing the position of the iris by the engaging portion. and configured to secure the iris elaborate pressing the end face of the camera lens barrel according to claim 1.