JPS6138446B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for holding a movable barrel of a zoom lens, and is intended to provide a simple structure and light and smooth operation.

A zoom lens changes the focal length by moving a part of the optical system in the optical axis direction, and the optical performance is greatly influenced by the precision with which the moving optical system is held.

Conventional methods and devices for holding movable tubes, including movable optical systems, are based on the fact that the inner diameter of the fixed tube and the outer diameter of the movable tube do not play, and in order to achieve smooth movement, processing of matching the actual products, such as wrapping, is required. The necessary accuracy was obtained by compensating for accuracy and performing fitting operations such as wrapping as well as diameter fitting using multiple keyways and keys. All of them are designed to achieve final precision and smooth operation by assembling the actual parts together, and they are not suitable for mass production and cause a large increase in costs.Oil is used on the sliding surfaces. Because it is designed to achieve smooth movement, the operation becomes heavy due to low temperatures, and because it is a sliding fit, even if you try to obtain light operation, there is a limit naturally.

The present invention has been proposed to eliminate such drawbacks, and embodiments will be described below with reference to the drawings.

FIG. 1 is a sectional view of a zoom lens according to an embodiment of the present invention, and the arrangement of parts has been slightly moved in the rotational direction to make the explanation easier to understand.

Although the optical system is not directly related to the present invention, it is an optical system of a general zoom lens.
It has a group type structure. In the figure, 1 is a focus lens, 2 is a variable magnification lens for changing the focal length, 3 is a correction lens for correcting the focus movement caused by the movement of the variable magnification lens 2, and 4
is a general four-group zoom configuration of an imaging lens.
5 holds the focus lens 1 and is connected to a fixed cylinder 6 through a helicoid cylinder 7, and moves the focus lens 1 forward and backward by rotation. Reference numeral 8 denotes a fixed tube main body, in which the fixed tube 6 and a mount tube 9 for attaching to a camera, etc. are integrally connected by screws, etc., and the inner diameter thereof has one or more square grooves 10 according to the present invention. There are several. 11 is a cam cylinder which connects to the variable magnification cylinder 15 via pin 13, and pin 1.
It has respective cams that engage with the correction cylinder 16 via 4.

Reference numeral 12 denotes a zoom operation ring, which is integrally connected to the cam cylinder.

Reference numeral 17 denotes a diaphragm device for adjusting the amount of light, which is constructed so that the amount of light can be adjusted using an iris ring 18. Reference numeral 19 is a tightening ring for attaching to a camera, etc., which can be attached together with the mount 9. The configuration of the movable cylinder and the fixed cylinder main body, which are the key points of the present invention, will be explained with reference to sectional views 2 and 3 and developed view 4. The sectional view in FIG. 2 shows the AA cross section in FIG. 1, and the sectional view in FIG. 3 shows the BB cross section.

Developed view Figure 4 shows the connection relationship with the movable cylinder developed from the outside of the fixed cylinder main body.

There is a square groove 1 on the inside of the fixed cylinder main body 8 as shown in the figure.
One or more zeros are provided parallel to the optical axis. In the movable tube 15, a guide roller 20 that holds the optical axis and guides its movement is rotatably fitted onto a roller shaft 21 fixed to a roller holder 22, and a square groove 10 provided inside the fixed tube body 8. It is placed on one side of the wall and moves while rotating on the wall. To explain the state in more detail with reference to the cross-sectional views 2 and 3 and the developed view 4, the rollers 21 that are rotatably supported are arranged at intervals in the front and rear on the roller holder 22 that is fixed to the movable cylinder 15. Ori,
Moreover, as shown in FIG. 2, they are arranged in two places, on the left and right.

Fig. 2 shows a cross section at the front position of the rollers arranged at intervals, and Fig. 3 shows a cross section at the rear position of the rollers, showing the relationship between the square grooves and the rollers. In FIG. 2, the left roller 20 is in contact with the lower wall surface of the square groove 10. Conversely, the roller on the right is in contact with the upper wall of the square groove. Figure 3 shows the other state of the rollers arranged at intervals; the rollers on the left are in contact with the upper wall of the square groove, and the rollers on the right are in contact with the lower side of the wall of the square groove. . That is, the rollers on the left side shown in sectional view 2 prevent the movable cylinder 15 from falling down, and the rollers on the right side prevent the movable cylinder from falling upward. That is, by twisting and installing the front and rear rollers rotatably provided on the roller stand 22 in the square groove and reversing the left-right relationship, it is possible to move while rolling in the groove and prevent the moving tube from falling vertically. It becomes possible. However, this alone is not enough to maintain the optical axis, and it is only by regulating the left and right inclination of the movable tube that the optical axis can be maintained accurately. As shown in FIGS. 1 and 2, the roller shaft 21' is rotatably arranged on a roller shaft 21' fixed to a roller stand 22' to prevent deflection.
By providing rollers at two places, front and rear, on the anti-flare roller table, and by arranging two sets of anti-flare roller plates at the front and rear in the square groove, the horizontal inclination of the movable tube is restricted.

The developed view in Figure 4 shows the relationship between the square groove and the rollers in an easy-to-understand manner.The rollers installed on the respective roller stands touch different square groove walls within the square groove and move without play while rotating. It allows you to hold the cylinder.

Therefore, the movable cylinder can be moved lightly and smoothly within the fixed cylinder main body, and can be held with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is an axial cross-sectional view of a zoom lens according to an embodiment of the present invention, FIG. 2 is a cross-sectional view along the line A-A in FIG.
The drawings are a sectional view taken along the line B-B in FIG. 1, and FIG. 4 is an exploded view showing the coupling relationship with the movable cylinder from the outside of the fixed cylinder main body. 5... Lens holding member, 6... Fixed tube, 7...
Helicoid tube, 8...fixed tube, 10...square groove, 11...cam tube.

Claims (1)

[Scope of Claims] 1. A movable barrel holding a lens is fitted into a fixed barrel provided with three straight grooves parallel to the optical axis, and on the outer periphery of the movable barrel, the movable barrel is provided on the front and rear sides in the direction parallel to the optical axis. A roller shaft is fixed, and a roller located in the straight groove is fitted onto the roller shaft, and the first and second front rollers fitted in the first and second straight grooves are moved in the same direction of the straight groove. The first and second rear rollers in the direction parallel to the front roller and the optical axis are offset to the wall surface in the opposite direction to the first and second front rollers, and the third straight-moving roller The third front and rear rollers that fit into the grooves are a pair of rollers that are each fitted with a pair of roller shafts, and the front and rear rollers of each pair are aligned on the wall surface in the opposite direction of the straight groove. A holding device for a movable member in a zoom lens, characterized in that the holding device is configured as follows.