JPH04157409A - Zoom lens tracking adjusting device - Google Patents

Abstract

PURPOSE:To eliminate need for rotating a rear group lens in relation to a light axis and to certainty prevent light axis deviation of a zoom lens as caused by such rotating adjustment by adjusting the initial position of a cam face with a cam member rotated in relation to a movable cylinder in the end section of a variable power area. CONSTITUTION:Tracking adjustment for a zoom lens is sperformed with a cam member 27 rotated corresponding to the movement of an adjusting plate 29 by shifting a movable cylinder 16 to a wider end. The cam member 27 is rotated by the rotation of this adjusting plate 29 and the rotation of the cam member 27 is smoothly performed with a cylindrical section 27c sliding on the inner periphery of a plate 28 for preventing the cylindrical section 27c from coming out. Since the rear group driving frame 25 and a rear group lens frame 13 are advanced and retreated in the direction of a light axis corresponding to the displacement of a cam face 27a due to the rotation of the cam member 27, the tracking of the rear group lens can be adjusted. After the adjustment, when the screws loosened are fastened again, the cam member 27 is fixed to the movable cylinder 16, the tracking adjustment for the rear group lens is completed. This constitution prevents the light axis of the zoom lens from deviating and eliminates light axis adjusting required.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a tracking adjustment device for a zoom lens.

[Conventional technology]

Zoom lenses incorporated into compact cameras are required to be low cost and compact.

As a zooming method that meets these requirements, a front group lens and a rear group lens are built into a movable tube, and when the movable tube is moved during zooming, the front group lens is moved integrally with the movable tube, and the rear group lens is assembled into a movable tube. There is a type of group lens that moves within a movable tube in conjunction with the movement of the movable tube.

When assembling such a zoom lens, after adjusting the optical axis of the zoom lens, the position of the rear group lens is determined while the movable barrel is moved to the wide end or telephoto end.

Such positioning of the rear group lens is called tracking adjustment, and conventionally, a lens holder incorporating the rear group lens and a lens frame holding the lens holder have been fitted with a helicoid. Therefore, the tracking adjustment of the rear group lens is performed by rotating the lens holder with respect to the lens frame, and then it is fixed by a locking means.

[Problems to be Solved by the Invention] However, the helicoid for fitting the lens holder and the lens frame is of a screw type and is formed with a margin for fitting tolerance. Therefore, when the lens holder is rotated to adjust the tracking of the rear lens group, the rear lens group tilts with respect to the optical axis, and it is necessary to adjust the optical axis of the zoom lens again.

(Object of the Invention) The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide a tracking adjustment device for a zoom lens that can simplify adjustment work.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a movable front lens group that incorporates a front group lens that moves forward and backward in response to the displacement of the cam surface by rotating a cam cylinder on which a cam surface is formed. a rear group lens frame that is movable in the movable tube and holds the rear group lens; a cam member that is fixed to the movable tube and moves the rear group lens forward and backward; and adjusting means for rotating the cam member relative to the movable cylinder to adjust the initial position of the cam surface of the cam member.

[Operation] According to the above configuration, for example, the cam barrel is rotated to set the movable barrel at the wide end, and the rear group lens is positioned. This positioning involves rotating the cam barrel relative to the movable barrel to adjust the initial position of the cam surface of the cam barrel, so that the rear group lens does not rotate but moves relative to the optical axis.

An embodiment of the present invention will be described below with reference to the drawings.

〔Example〕

FIG. 1 shows a cross section of a main part of a zoom lens using the present invention;
In FIG. 2, a zoom lens using a zoom lens barrel has a front group lens frame 12 in which five lenses are incorporated.
The front group lens frame 12, which is a two-group zoom system focusing section, is made up of a rear group lens frame 13 in which three lenses are incorporated, and is fitted into a holding frame 14 in a helicoidal manner. 16 at the front end.

This movable cylinder 16 has three threaded parts 16a formed on the outside and is housed inside the fixed frame 17.

A spring retainer 18 is provided on the outside of the fixed frame 17. Cam holder 19
are inserted in order, and the pins 20 are respectively locked to the threaded portions 16a through the three straight grooves 17a provided in the fixed frame 17. The tips of these pins 20 protrude from the linear groove 17a and abut on three cam surfaces 21a provided on a cam cylinder 21 that is then inserted outside the fixed frame 17, respectively. As a result, when the cam barrel 21 is rotated by the drive of the lens motor 22, the movable barrel 16 moves back and forth in the optical axis direction in response to the displacement of the cam surface 21a of the cam barrel 21, and the front group lens is extended. There is.

The cam holder 19 is provided with three lips 19a on the rear end side for holding the springs 23, and the springs 23 are inserted into each lip and held by the spring holder 18. This spring holder 18 is engaged with the cam cylinder 21, and this and the cam holder 19 rotate together with the cam cylinder 21. And the above-mentioned wing 2
The pin 20 and the cam surface 21a are designed to constantly slide due to the urging force of the cam surface 21a.

A spring 24° is attached to the rear end of the movable barrel 16, and a rear group lens frame 13. Rear group drive frame 25. Cam member 27, removal prevention plate 28. The adjusting plate 29 is then assembled in order.

The spring 24 has one end attached to the shutter block 1.
5, and the other end engages with the front end of the rear group lens frame 13.

The rear group lens frame 13 is formed with three key parts 13a, and a key groove 16 provided inside the movable barrel 16.
c and are inserted so that they can move forward and backward in the optical axis direction.

The front end side of the rear group drive frame 25 contacts the rear end side of the key portion 13a, and the three ribs 25a provided inside the rear group drive frame 25 contact the three cam surfaces 27a of the cam member 27, respectively. come into contact with

Furthermore, a pin 26 is attached to the outer periphery of the rear group drive frame 25. This pin 26 is inserted into the cam holder 1 through relief holes 16d and 17d provided in the movable cylinder 16 and the fixed frame 17.
9 and rotates the rear group drive frame 25 together with the cam retainer 19. In addition, the cam groove 166
．． 17d has a length that allows the pin 260 to rotate.

A locking hole 27b is provided on the rear end side of the cam member 27, into which a locking pin 29a of the adjustment plate 29 is engaged via an elongated adjustment hole 28a provided in the removal prevention plate 28. match. Also, inside the cam member 27 is the above-mentioned removal prevention plate 2.
A cylindrical portion 27c that fits into the inner circumferential surface of 8 is provided.

The removal prevention plate 28 is fixed to the rear end side of the movable cylinder 16 with screws, and the adjustment plate 29 is fixed to the removal prevention plate 28 with screws through an elongated hole 29b provided therein. As a result, the cam member 27 is fixed to the movable cylinder 16, and the rear group drive frame 2
5 rotates, which moves the rear group lens frame 13 forward or backward in response to the displacement of the cam surface 27a.

The zoom lens is extended as follows.

First, when zooming from the wide side shown in FIG. 1(A) to the telephoto side shown in FIG. 1(B), the lens motor 22
drive. The lens motor 22 is driven to rotate the cam cylinder 21, and the movable frame 16 moves in the optical axis direction in response to the displacement of its cam surface 21a. This determines the position of the front group lens on the telephoto side.

Further, since the rear group drive frame 25 is engaged with the cam retainer 19 which rotates together with the cam cylinder 21 via the locking pin 26, the rear group drive frame 25 rotates in conjunction with the cam retainer 19. Note that the rear group drive frame 25 may be rotated integrally with the cam cylinder 21 by engaging the pin 26 attached to the rear group drive frame 25 with the cam cylinder 21.

The rear group drive frame 25 moves in the optical axis direction along the displacement of a cam surface 27a provided on the cam member 27 by its own rotation. Then, in response to the movement of the rear group drive frame 25, the rear group lens frame 13 moves along the keyway 16c, and the position of the rear group lens at the telephoto end is determined. In addition, the rear group lens frame 13
Since the spring 24 constantly urges the rib 25a against the cam surface 27a, the movement is performed smoothly in response to the displacement of the cam surface 27a.

Tracking adjustment of such a zoom lens is performed as follows. For example, the movable cylinder 16 is moved to the wide end shown in FIG. 1(A). In this state, the rib 25a of the rear group drive frame 25 contacts the wide end position of the cam surface 27a, and the wide end position of the rear group lens is determined with respect to the front group lens. In this state, loosen the screws fixing the adjustment plate 29 and the removal prevention plate 28, and move the adjustment plate 29 within the range of the adjustment elongated hole 28a. As a result, the cam member 27 rotates in response to the movement of the adjustment plate 29.

This rotation of the adjusting plate 29 causes the cam member 27 to move towards the locking pin 2.
It rotates via 9a. The cam member 27 rotates smoothly as the cylindrical portion 27c slides on the inner periphery of the retaining plate 28.

By rotating this cam member 27, the rear group drive frame 25 and the rear group lens frame 1 are moved in response to the displacement of the cam surface 27a.
3 moves back and forth in the optical axis direction, making it possible to adjust the tracking of the rear group lens. After adjustment, by tightening the loosened screw, the cam member 27 is fixed to the movable barrel 16, and the tracking adjustment of the rear group lens is completed.

As described above, in the zoom lens according to the present invention, the tracking adjustment of the rear group lens adjusts the initial position of the cam surface 27a at the wide position of the rear group lens, and the rear group lens frame 13 is adjusted relative to the optical axis. Since the zoom lens moves forward and backward without rotating, the optical axis of the zoom lens does not shift, and there is no need for the associated optical axis adjustment work.

It goes without saying that tracking adjustment of the rear group lens can also be performed at the telephoto end.

Further, in this embodiment, the rear group drive frame 27 between the rear group lens frame 13 and the cam member 27 is provided with a rib 25a so as to come into contact with the cam surface 27a, but the present invention is not limited to this. A rib 25a for contacting the cam surface 27a is provided on the rear end side of the rear group lens frame 13.
may be rotated integrally with the cam cylinder 21 or the cam retainer 19. According to this, when changing magnification, the cam surface 27a
The rear group lens frame 13 moves forward and backward directly in response to the inclination of the rear group lens, and when adjusting the tracking of the rear group lens, it can be adjusted in the same manner as in this embodiment. This eliminates the need to use the rear group drive frame 25 used in this embodiment, resulting in cost reduction.

〔Effect of the invention〕

As explained above, the zoom lens tracking adjustment device of the present invention has a structure in which the initial position of the cam surface of the cam member is adjusted by rotating the cam member relative to the movable barrel at the end of the variable power range. Therefore, the rear lens group does not need to be rotated with respect to the optical axis (this has the effect of reliably preventing the optical axis shift of the zoom lens caused by this).

[Brief explanation of drawings]

FIGS. 1A and 1B are sectional views of essential parts showing an embodiment of the present invention. FIG. 2 is a perspective view showing the structure of the movable tube used in this example. 12... Front group lens frame 13... Rear group lens frame 16... Movable barrel 17... Fixed frame 21... Cam barrel 25... Rear group drive frame 27... Cam member 28... Removal stop plate 29・Adjustment board. Procedural amendment (method) February 14, 1991 1990 Patent Application No. 282923 2 Name of the invention Zoom lens tracking adjustment device 3 Relationship with the person making the amendment Patent applicant address Minamiashigara City, Kanagawa Prefecture Nakanuma 210 address name (520)
Fuji Photo Film Co., Ltd. Taiyo Life Otsuka Building 3rd floor
3917) 1917 (752B) Patent attorney Kazunori Kobayashi (and one other person), Layer - (2) "Brief explanation of the drawings" section of the specification (3) "Figure 1" of the drawings 7. Contents of amendment (1) ) In the second line of page 8 of the specification, the phrase ``When zooming from the wide side shown in Figure 1 (A) to the telephoto side shown in Figure 1 (B)'' has been changed to [In Figure 1, When zooming from the wide position shown above the center line to the tele position shown below the center line in the figure, the correction is made as follows. (2) [Move to the wide end shown in FIG. 1(A) on page 9, line 7 of the specification. " is moved to the wide position shown above the center line in Figure 1.
and correct it. (3) "Tele end" on page 10, line 15 of the specification is corrected to "tele position." (4) “Figure 1 (A) 9 (
``B)'' should be corrected to ``Figure 1 is''. (5) [Figure 1 J is corrected as shown in the attached sheet. that's all

Claims (1)

[Claims] (1) In a zoom lens in which a movable barrel incorporating a front lens group moves back and forth in response to displacement of the cam surface by rotating a cam barrel on which a cam surface is formed, the movable barrel is provided in the movable barrel so as to be movable back and forth. , a rear group lens frame that holds the rear group lens; a cam member fixed to the movable tube that moves the rear group lens forward and backward; and a cam member that rotates the cam member with respect to the movable tube at an end of a variable power range. A tracking adjustment device for a zoom lens, comprising: adjustment means for adjusting the initial position of a cam surface of the lever.