JPH02267531A - Optical system driving device of camera - Google Patents

Abstract

PURPOSE:To prevent the deterioration of optical accuracy caused by a fact that an optical system is inclined due to a contact load to a light shielding material by providing a guide means for the movement in the vicinity of a position which is subject to an action of a driving means for moving an optical system holding means. CONSTITUTION:When a zoom use cam plate 18 is rotated by a driving source, front and rear group base boards 1, 16 are moved in relation to each other so as to become a prescribed zooming ratio, respectively by rollers 2, 17 engaged into its cam groove and a focal distance is varied. In this case, between a body cover 15 to which a light shielding material 19 is fixed and a lens-barrel cover 9 attached to the base board 1, a load caused by friction is applied and on the side of the roller 2 and on its opposite side, the moving amounts are different and an inclination is generated in the base board 1. However, since a holding bar 5 of a front group lens-barrel 3 is placed near a guide bar 12 of the base board 1, this inclination can be prevented. Accordingly, a front group lens L1 is not inclined either and the optical performance is not deteriorated.

Description

Detailed Description of the Invention (Field of Application in Industry A) The present invention relates to a drive device for moving an optical system, and in particular, a drive device that maintains the tilt of the optical system even when a load is applied when moving the optical system. This invention relates to an optical system drive device for a camera that can prevent the above problems.

(Prior Art) Conventionally, as a low-cost zoom drive system, one in which the focal length of a photographic lens is changed by rotating a single zoom cam and moving the front and rear groups of the lens, respectively, is known. In addition, a light-shielding material is placed around the outer periphery of the front lens barrel that protrudes outside the camera to prevent outside light from entering the camera, no matter where the front lens barrel moves during zooming, or even during movement. It is also known to prevent

By the way, since the above-mentioned conventional lens has one zoom drive cam, its driving force acts only on one side of the front lens barrel to move the lens barrel. On the other hand, since the above-mentioned light-shielding material is arranged all around the outside of the front lens barrel, when the lens barrel moves in the U direction, the side of the front lens barrel on which the zoom drive cam acts moves the normal stroke, but the other side Due to the load of the light-shielding material, the amount of stroke is less than the normal stroke on the side where the zoom drive cam acts, especially on the side opposite to the side where the zoom drive cam acts.As a result, the front lens barrel is tilted, and the front lens group is also tilted. This has the disadvantage that the optical accuracy of the zoom lens becomes unsatisfactory.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and includes a holding means for holding an optical system, a driving means for moving the holding means in g, and a drive means that moves integrally with the holding means and makes contact with a light shielding material. a cover means for applying a load to the movement of the holding means by means of the optical system; and a guide means provided near a position where the holding means receives the action of the driving means to guide movement of the holding means by the driving means; Provided is an optical system drive device for a camera that prevents the optical system from being tilted due to the load of the light shielding material when moving the system, thereby preventing deterioration of optical accuracy due to the light shielding material when moving the optical system. This is what I am trying to do.

In addition, the present invention includes a holding means for holding an optical system, a driving means for moving the holding means, and an optical system that is held only in the vicinity of a position of the holding means that is acted upon by the driving means, and that is caused by contact with a light shielding material. A cover means is provided which moves integrally with the holding means while a load is applied, and the optical system is prevented from being tilted due to the load of the light shielding material when the optical system is moved. It is an object of the present invention to provide an optical system drive device for a camera that prevents deterioration of optical accuracy due to a light shielding material.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a longitudinal cross-sectional view of a lens barrel constituting a photographing optical system of a camera according to the present invention, and FIG. 2 is a view of the lens barrel shown in FIG. 1 viewed from direction D with the lens barrel cover removed. In FIGS. 1 and 2, 1 is the front base plate, which has a hole 1a that is slidably held by a kite bar 12 (described later), and a rotation prevention part 1b on the opposite side of the hole 1a. Furthermore, a roller 2 is fixed to the side surface with screws. Reference numeral 3 denotes a front group lens barrel, which holds the front group lens L1 and is slidably held by a bar 5, which will be described later, through a hole 3a. Reference numeral 4 denotes a focus adjustment screw, which is screwed into the front lens barrel 3, and the reference focus position can be adjusted by adjusting the feed rate of the screw. Reference numeral 5 denotes a bar for holding the front group lens barrel 3, which is fixedly held between the front group base plate 1 and a fixing plate 6 provided integrally with the front group base plate 1. 7 is a cam ring with a lead cam part 7a on the top surface and a ratchet 7b on the outer periphery.
is formed and rotatably held by the bar 5.

A spring 8 is disposed between the fixed plate 6 and the front lens barrel 3, and brings the focus adjustment screw 4 into contact with the cam surface 7b of the cam ring 7. Reference numeral 9 denotes a lens barrel cover as a cover means, which has a lens barrel hole 9a in the center and is fixed to the front group base plate 1 with screws 11 near where the roller 2 of the front group base plate 1 is attached. The remaining part of 9 is also attached to the front group base plate l with screws not shown.
is fixed all around. Reference numeral 12.13 denotes a guide bar which is sandwiched and fixed between the camera body 14 and the camera body cover 15, and the guide bar 12 serves as a holding means to slidably hold the front group base plate 1 and the rear group base plate 16 to be described later. The guide bar 13 serves as a rotation-preventing guide bar and engages with the forked portions of the front group base plate 1 and the rear group base plate 16 to prevent the front group base plate 1 and the rear group base plate 16 from rotating. . 16 is a rear group base plate that holds the rear group lens L, and has a hole lea that engages with the guide bar 12 and a rotation-preventing forked portion 16b that fits into the guide bar 13 on the opposite side of the hole 16a; Furthermore, a roller 17 is screwed to the side surface. 18
is a zoom cam plate as a driving means, and rollers 2 and 17
When these are fitted together and the zoom cam plate 18 is moved by a drive source (not shown), the rollers 2 and 17 move along the cam grooves of the zoom cam plate 18, and the front group base plate 1 and the rear group base plate 16 are moved. performs a zooming operation, and 19 is a sheet-like material flocked with light-shielding material that is glued to the inside of the camera body cover 15.
Moreover, the inner circumferential side thereof is crimped to the outer circumference of the lens barrel cover 9, and prevents light from entering the camera body through the gap between the lens barrel cover 9 and the camera body cover 15 over the entire circumference. .

Next, the operation of the above configuration will be explained. First, when a zoom button (not shown) is pushed to the long focal length 111K (hereinafter referred to as tele) side or to the short focal length all (hereinafter referred to as wide) side, the zoom cam plate 18 is rotated by a driving source (not shown). The roller 2.17 is fitted into the cam groove of the zoom cam plate 18, so the front.

The rear group base plates 1.16 move in association with each other to achieve a predetermined zoom ratio, thereby changing the focal length.

At this time, when the front group base plate 1 moves in the direction of FIG. 1, the lens barrel cover 9 also tries to move. However, since the camera body cover 15 does not work B, the light blocking material 19 is fixed in that position, and friction occurs between the light blocking material 19 and the lens barrel cover 9, and a certain load is applied to the lens barrel cover 9 from the light blocking material 19. join. At this time, the amount of movement of the lens barrel cover 9 differs between the side where the roller 2 is provided (arrow B) and the opposite side (arrow C) as shown in FIG. That is, the amount of movement indicated by arrow C is smaller than the normal amount of movement, and as a result, the lens barrel cover 9 and the front group base plate 1 are tilted.

However, in this embodiment, the holding bar 5 of the front group lens barrel 3 is arranged near the guide bar 12 of the front group base plate 1, and as shown in FIG. Not tilted by the bar 12, thus retaining bar 5. The front lens barrel 3 does not tilt, so the front lens L1 also does not tilt, and optical performance does not deteriorate.

FIG. 4 is a longitudinal cross-sectional view of a lens barrel constituting a photographing optical system of a camera showing another embodiment of the present invention. In Figure 4, M
For the sake of IL, the same components as in FIG. 1 are given the same numbers and their explanations are omitted, and only the points that are different from the embodiment in FIG. 1 will be explained.

The lens barrel cover 51 is fixed to the front group base plate 1 with screws 11 only near the guide bar 12, and a gap 10 is provided between the lens barrel cover 51 and the other front group base plate 1. The other configurations are the same as in FIG.

The feature of this embodiment is that the lens barrel cover 51 is attached to the front group base plate 1 only in the vicinity of the guide bar 12, and a gap is provided between the other front group base plate 1 and the lens barrel cover 51.

To explain the operation of the above configuration, the front group base plate 1 and the lens barrel cover 51 move in the E direction due to the zoom operation. At this time, the load on the light shielding material 19 causes the lens barrel cover 51 to tilt as shown in FIG. 5, as in the previous embodiment. but%
Since the lens barrel cover 51 is fixed to the front group base plate 1 with screws only near the guide bar 12, even if the lens barrel cover 51 is tilted, the tilt of the lens barrel cover 51 will be reduced by the gap between it and the front group base plate 1. 10, the front group base plate 1 itself will not be tilted by the guide bar 12, and the gap 10 is just enough to prevent it from coming into contact with the front group base plate 1 even if the lens barrel cover 51 tilts and approaches the front group base plate 10. is provided.

As described above, in this embodiment as well, the lens barrel cover 51 tilts due to the load on the light shielding material 19, but the front group base plate l does not tilt. The group lens L is also not tilted, and deterioration of optical performance can be prevented.

In this embodiment, the mechanism for advancing the front group lens barrel uses a holding bar 5 and a cam ring 7, but in this embodiment, since the front group main plate 1 can be kept in a horizontal state, for example, a helicoid, three cams, etc. It is also possible to arrange the drive mechanism on the outer periphery of the front lens barrel.

Further, in each of the above embodiments, the optical system is moved for zooming, but it goes without saying that the present invention is also applicable to moving the optical system for multi-focal switching, collapsing, etc.

Further, although each of the above embodiments is directed to driving a photographing optical system, it goes without saying that the present invention is applicable to other optical systems or optical devices other than cameras.

(Effects of the Invention) As explained above, according to the present invention, it is possible to prevent the optical system from being tilted due to the load of the light shielding material when moving the optical system, so that the optical system can be moved by 8'JJJ. In this case, the light shielding material can prevent optical precision from deteriorating, and its effectiveness is extremely high.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of the lens barrel according to an embodiment of the present invention, FIG. 2 is a view of the lens barrel shown in FIG. 1 viewed from direction D with the lens barrel cover removed, and FIG. FIG. 4 is a vertical cross-sectional view of the lens barrel according to another embodiment of the present invention, and FIG. 5 is a vertical cross-sectional view of the lens barrel of FIG. 4 after the zoom operation. It is a diagram. 1 is the front group base plate, 2 is the roller, 3 is the front group lens barrel, 4 is the focus adjustment screw, 5 is the bar, 6 is the fixing plate, 7 is the cam ring, 8 is the spring, 9 is the lens barrel cover, 10 is the gap, 11 is Bis, 12
is the guide bar 1°3 is the guide bar 14 is the camera body, 15 is the camera cover, 16 is the rear group base plate, 17 is the roller, 18 is the zoom cam plate, 19 is the light shielding material, L is the front group lens, L2 is the Rear group lens, 51 is lens barrel cover

Claims (2)

[Claims] (1) A holding means for holding the optical system, a driving means for moving the holding means, and a cover that moves integrally with the holding means and applies a load to the movement of the holding means through contact with the light shielding material. 1. An optical system drive device for a camera, comprising: a means for driving an optical system; and a guide means provided near a position where the holding means receives the action of the driving means, and guiding the movement of the holding means by the driving means. (2) A holding means for holding the optical system, a driving means for moving the holding means, and the holding means is held only in the vicinity of the position where it is acted upon by the driving means, and a load is applied by contact with a light shielding material. 1. An optical system drive device for a camera, comprising: a cover means that moves integrally with the holding means while being held.