JPH06347681A - Lens barrel - Google Patents

Abstract

PURPOSE:To efficiently execute the adjustment work of relative position between a variable power lens group and a correction lens group and to make the adjustment part thereof light in weight and simple. CONSTITUTION:Pins 22 and 32 respectively engaged with the variable power lens group and the correction lens group are made to pierce straight-advance guides 51 and 52 respectively formed on a lens barrel and engaged with the cam groove 61 of a cam member 60 and the cam groove 71 of a cam member 70. When a distance X between the pins 22 and 32 (interval between the variable power lens group and the correction lens group in the case of some magnification) is different from a theoretical value, the cam member 60 is rotated around an optical axis (rotating quantity is dtheta), the relative position between the cam grooves 61 and 71 is adjusted and pin 22 is moved with respect to the pin 32 (moving quantity is dX). Thus, the proper relative interval between the variable power lens group and the correction lens group is set and the cam members 60 and 70 are coupled by a coupling member thereafter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel capable of adjusting the relative positions of a zoom lens group and a correction lens group of a zoom lens.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing the structure of an example of a conventional lens barrel (zoom lens). As shown in FIG. 3, the lens group of the lens barrel includes a front lens group 10 and a rear lens group 50, and a variable power lens group 20 and a correction lens group 30 arranged between them. .
The variable power lens group 20 is a lens group that moves in the optical axis direction during zooming to set a desired magnification. The correction lens group 30 is a lens group that moves in the optical axis direction in conjunction with the variable power lens group 20 during zooming and corrects the focus that changes as the variable power lens group 20 moves.

The variable power lens group 20 is supported by a lens chamber 21. Similarly, the correction lens group 30 is supported by the lens chamber 31. Lens room 21 is screw 2
It is fixed to the moving frame 23 by means of 5.
A pin 22 mounted substantially perpendicular to the optical axis direction is fixed to the outer peripheral portion of the. A pin 32 is fixed to the outer peripheral portion of the lens chamber 31, like the pin 22.

A female thread is formed on the inner diameter side of the lens chamber 11 that holds the front lens group 10, and a male thread is formed on the outside of the lens barrel 50 that holds the rear lens group 40.
These screws are screwed together. The lens barrel 50 has a straight guide 5 that is opened in a substantially oval shape so as to extend in the optical axis direction.
1, 52 are formed.

The cam member 170 is formed in a cylindrical shape and is provided on the outer side of the lens barrel 50, and an outer cylinder 80 is formed by a pin 53.
Operation ring 81 provided on the outer peripheral portion of the zoom lens via
Is connected with. The outer cylinder 80 is a lens barrel 5 with screws 82.
It is fixed at 0.

FIG. 4 is a plan view showing the cam member 170 and the cam grooves 171 and 172 formed therein in a developed manner. The cam groove 171 is opened in a substantially linear shape so as to have a constant pushing angle, and the cam groove 172 is opened so as to have a predetermined curved shape. Cam groove 1
71 and 172 respectively include straight guides 5 of the lens barrel 50.
Pins 22, 32 penetrating through 1, 52 are engaged.

Zooming in the lens barrel described above is performed by rotating the operation ring 81 around the optical axis. That is, when the operation ring 81 is rotated, this rotation is transmitted to the cam member 170 by the pin 53.
At the same time, the cam member 170 also rotates around the optical axis. That is, the cam grooves 171 and 172 rotate around the optical axis. As a result, the rotation of the pins 22 and 32 around the optical axis is restricted by the straight guides 51 and 52, so that the cam groove 17
By the rotation of 1,172, it is moved in the optical axis direction along the straight guides 51,52. Therefore, each of the variable power lens group 20 and the correction lens group 30 is moved in the optical axis direction by a predetermined amount, and a predetermined magnification is set.

As described above, the variable-magnification lens group 20 and the correction lens group 30 of the lens barrel maintain a highly accurate positional relationship for accurate focusing. If these relative positional relationships are not set accurately, the focal plane will be displaced, and the optical performance will deteriorate.

However, it goes without saying that each component of the lens barrel has a manufacturing error during manufacturing. Therefore, even if the manufacturing error of each component is within the allowable range, the accumulated manufacturing error of each component (hereinafter referred to as “cumulative error”) when assembling each component exceeds the allowable range. There were cases. Further, the optical characteristics may change due to the manufacturing error of the lens.

In order to absorb the accumulated error of each component and the change in optical characteristics as described above, as shown in FIG. 3, the lens chamber 21 and the moving frame 23 are provided with a spacer 2 having an appropriate thickness.
4 is attached, and the variable power lens group 20 is moved relative to the correction lens group 30 by the thickness of the spacer 24,
The relative position between the variable power lens group 20 and the correction lens group 30 was adjusted. In addition, the correction lens group 30 is replaced with the variable power lens group 2
In some cases, the correction lens group 30 is supported by a structure similar to that of 0, or both are moved relative to each other for adjustment.

[0011]

However, in the above-mentioned conventional lens barrel, firstly, since the accumulated error and the difference in optical characteristic for each lens barrel are different, the spacers 24 having a plurality of thicknesses are different. Had to be prepared. Secondly, when changing the thickness of the spacer 24, the front lens group 10 is removed to open the inside of the lens barrel 50, and the screw 25 is removed to remove the moving frame 23, the zoom lens group 20, and the lens chamber 21. It has been necessary to disassemble, replace the spacer 24, assemble these parts again, and confirm the performance, which is a troublesome work. further,
If the adjustment was insufficient, such adjustment had to be repeated again. For this reason, there is a problem that the adjustment takes a very long time and the assembling cost increases.

Third, it is desirable that the mechanical portion for moving the variable power lens group 20 be lightweight, and the pin 22 can be fixed directly to the lens chamber 21 if the above adjustment is not necessary. Since the moving frame 23 and the screw 25 are provided in addition to the lens chamber 21 in order to require adjustment,
Mounting these components for adjustment added weight. Due to this weight, the load applied to the cam groove 171 becomes large, the movement of the variable power lens group 20 becomes uncomfortable, the cam groove 171 and the pin 22 are easily worn, or the operating torque during zooming becomes large. There was a problem.

Fourth, since the variable power lens group 20 is supported through various components for adjustment, dimensional errors of these components cause errors in the coaxiality due to shift of the variable power lens group 20 and tilt. There is a problem that an error in the posture due to is likely to occur. Fifth, since the lens barrel 50 is opened during the adjustment, there is a problem that dust and the like enter the inside thereof and further adhere to the lens portion.

The present invention has been made in order to solve the above-mentioned problems, and is a portion for improving the efficiency of the adjustment work of the relative position between the variable power lens group and the correction lens group, and further performing the adjustment. The purpose is to reduce the weight and simplify the.

[0015]

In order to achieve the above-mentioned object, the solution means of the lens barrel according to the present invention has a constant advance angle and moves the variable power lens group (20) in the optical axis direction. The first cam member (60) formed with the first cam (61) to be driven and the first cam member are separate bodies, and the second lens moving the correction lens group (30) in the optical axis direction. A second cam member (70) having a cam (71) formed therein, and a connecting member (62) integrally connecting the first cam member and the second cam member to each other. The relative position of the first cam and the second cam is adjusted by relatively rotating the cam member and the second cam member around the optical axis, and then the first cam member. And the second cam member are connected by the connecting member.

[0016]

In the lens barrel solving means described above, since the first cam member and the second cam member are formed as separate members, the first cam member and the second cam member are relatively disposed. It can be rotated around the optical axis. Therefore, the relative position of the first cam and the second cam can be adjusted. Also, after this adjustment, the connecting member causes the first cam member and the second cam member to
Is connected to the cam member, the relative position between the variable power lens group engaged with the first cam and the correction lens group engaged with the second cam is adjusted, and the adjusted position is held. be able to. As a result, the adjustment can be performed without touching the inside of the lens barrel, and the number of parts for the adjustment can be reduced, the structure can be simplified, and the adjustment work can be facilitated.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the lens barrel according to the present invention will be described below with reference to the drawings. In the embodiment of the present invention, the same parts as those of the conventional lens barrel shown in FIG. Figure 1
FIG. 3 is a sectional view showing a configuration of an embodiment of a lens barrel according to the present invention. As shown in FIG. 1, the variable power lens group 20 includes
It is supported by the lens chamber 21. This lens room 21
A pin 22 is fixed to the outer peripheral portion of the.

The lens barrel of this embodiment has a cam member 60 as a first cam member formed in a cylindrical shape.
And a cam member 70 as a second cam member are provided separately. The cam members 60 and 70 are arranged substantially coaxially, and are fitted so as to be relatively rotatable about the optical axis. The cam members 60 and 70 are formed with cam grooves 61 and 71 as a first cam and a second cam, respectively. The cam grooves 61 and 71 correspond to the cam grooves 171 and 172 shown in the conventional example, respectively.

The cam members 60 and 70 are connected by a connecting member 62 such as a tape so that they can be integrally operated (rotated around the optical axis) during zooming. Further, similarly to the conventional example, the cam 61 of the cam member 60 is
The pin 22 penetrating the linear guide 51 of the lens barrel 50 is engaged with the pin 32, and the pin 32 penetrating the linear guide 52 of the lens barrel 50 is engaged with the cam 71 of the cam member 70.

Next, a method of adjusting the relative positions of the variable power lens group 20 and the correction lens group 30 in the above-mentioned lens barrel will be described. The connecting member 62 is not yet attached before this adjustment.

FIG. 2 is a development view showing the cam members 60 and 70 and the cam grooves 61 and 71 formed therein. It is assumed that the cam members 60 and 70 at a certain magnification are arranged as shown in FIG. 2, and the distance between the pins 22 and 32 at this time is X. At this time, the distance X
Is different from the theoretical value, the cam member 70 is not rotated and only the cam member 60 is rotated around the optical axis. As shown in FIG. 2, for example, when the cam member 60 is rotated about the optical axis by dθ, the position of the cam groove 61 moves to the position shown by the chain double-dashed line in the figure. As a result, the pin 22 is dX in the figure.
However, the distance between the pins 22 and 32 is set to (X-dX).

Therefore, the relative position of the cam grooves 61 and 71 can be adjusted by rotating the cam member 60 in the predetermined direction by an appropriate amount around the optical axis. As a result, even when there are manufacturing errors in the shapes of the cam members 60 and 70, the shapes of the cam grooves 61 and 71, and the forming positions that exceed the allowable range, or when there is a difference in the optical characteristics of the variable power lens group 20. Since the relative positions of the cam grooves 61 and 71 can be adjusted, the distance between the variable power lens group 20 and the correction lens group 30 at a predetermined magnification can be adjusted to an optimum length. Become. The adjustment at this time is performed while forming an image with all the lens groups (10, 20, 30, 40) and confirming the state of the image forming surface.

After the relative positions of the cam members 60 and 70 are adjusted, the cam members 60 and 70 are connected and fixed by the connecting member 62. Therefore, during zooming, the two are integrally rotated about the optical axis without moving relative to each other.

Although one embodiment of the lens barrel according to the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. Is. For example, in the embodiment, adjustment is performed by rotating the variable power lens group 20 without rotating the correction lens group 30, but it is also possible to rotate the correction lens group 30 without rotating the variable power lens group 20. Alternatively, the adjustment may be performed by rotating the both relatively.

The connecting member 62 is not limited to a tape, but various members can be used. Further, the connecting member 62 may connect the cam members 60 and 70 so as to be re-decomposable or non-re-decomposable.

[0026]

As described above, according to the lens barrel of the present invention, the relative positions of the variable power lens group and the correction lens group can be adjusted only by rotating the cam member. First, it is not necessary to prepare a plurality of types of adjusting members such as spacers used in the conventional technique, and
Since it is not necessary to disassemble and reassemble a large number of parts, the time required for adjustment can be shortened. Furthermore, adjustment is performed while confirming the state of the image plane by forming an image with all lens groups. Therefore, the adjustment can be completed once, and the assembling cost can be reduced.

Second, the conventional adjusting mechanism is eliminated,
Since the only component used for adjustment is the connecting member, the weight and structure are simplified, and the load (contact pressure) acting on the contact surface of each component during movement of the zoom lens is reduced. Therefore, it is possible to reduce the operation torque to improve the feeling of operation during zooming, and to improve the durability of the cam and the member that abuts on the cam.

Thirdly, since there is no adjusting member that affects the mounting position of the lens group, it is possible to eliminate errors in the coaxiality and posture of the lens group, and to prevent deterioration of optical characteristics due to mounting of the adjusting member. be able to. Fourth, since the adjustment can be performed without opening the inside of the lens barrel during the adjustment, it is possible to prevent dust from entering the inside of the lens barrel.

[Brief description of drawings]

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

2 is a development view showing a cam member and a cam groove of FIG. 1. FIG.

FIG. 3 is a sectional view showing a configuration of an example of a conventional lens barrel.

FIG. 4 is a development view showing a cam member and a cam groove of FIG.

[Explanation of symbols]

 20 variable power lens group 30 correction lens group 60 cam member (first cam member) 61 cam groove (first cam) 62 connecting member 70 cam member (second cam member) 71 cam groove (second cam)

Claims (1)

[Claims] 1. A first cam member having a constant pushing angle and having a first cam for moving a variable power lens group in the optical axis direction, and a separate member from the first cam member. A second cam member formed with a second cam that moves the correction lens group in the optical axis direction, and a connecting member that integrally connects the first cam member and the second cam member. The first cam member and the second cam member are relatively rotated about the optical axis to adjust the relative position of the first cam and the second cam, and then the A lens barrel characterized in that a first cam member and the second cam member are connected by the connecting member.