JPH043289Y2 - - Google Patents

Description

[Detailed description of the invention] "Technical field" This invention is a so-called floating lens that changes the air spacing between the constituent lens groups according to the shooting distance in order to correct aberrations that increase at close distances. The present invention relates to a lens barrel structure, and particularly relates to a lens barrel structure suitable for a floating lens system in which the amount of movement of the entire optical system is significantly larger than the amount of air gap that is changed for aberration correction.

"Prior Art and its Problems" Many so-called floating lens lens barrels have been proposed in the past. Actual Public Showa 50-11370
No. 52-51787, No. 54-7791, No. 55-31521
No. 56-50485 is an example, but all of these use a helicoid or similar screw structure to extend the entire lens system. The ratio of the amount of change in air spacing is about 5:1 at most. For this reason, it is extremely difficult to apply these conventional structures to lens barrels such as macro lenses, where the ratio of the amount of change in the air spacing of the constituent lens groups to the amount of extension of the entire lens system is approximately 10:1 to 20:1. It is difficult to
If this were to be applied, the threaded part of the helicoid or the like would have to be set long, making the entire lens barrel thick and long, and the operability would be poor, making it impractical. If the length is further increased, the center of the lens tends to shift, tilt, etc., and the image performance deteriorates.

``Purpose of the invention'' The invention aims to develop a lens barrel suitable for floating lenses in which the entire lens system has a large amount of extension.In other words, even with a large amount of extension, the lens barrel becomes larger, has a more complicated structure, and becomes heavier. The object of the present invention is to provide a lens barrel that is free from problems and has excellent precision.

"Summary of the invention" The lens barrel of this invention has a threaded joint only between the front lens barrel and the rear lens barrel, and either one of the front lens barrel or the rear lens barrel is connected to the mount barrel. The other is a rotating lens barrel that rotates and moves back and forth according to the screw, and the interlocking pin implanted in this sliding lens barrel is
It is characterized in that it fits into the front and rear guide grooves formed on the mount fixed tube and the focusing groove formed on the operation ring, and the interlocking pin implanted in the rotating lens tube is fitted into the correction groove formed on the mount fixed tube. . Since the length of the front and rear guide grooves and focusing grooves in the optical axis direction can be made sufficiently long, the amount of movement of the entire lens system can be easily increased, and the distance between the correction groove and the front and rear guide grooves in the circumferential direction can be easily increased. Due to this relationship, aberrations can be corrected by freely changing the distance between the front group lens and the rear group lens either linearly or nonlinearly with respect to the rotation angle of the operation ring or the amount of movement of the entire lens system.

``Embodiments of the invention'' The invention will be described below with reference to illustrated embodiments. 1 and 2 show a first embodiment of the present invention, in which the upper half of FIG. 1 shows the infinity photographing state, and the lower half shows the shortest photographing state. The front group lens L1 and the rear group lens L2 each have a front group lens barrel 11,
It is held in a rear group lens barrel 12, and the front group lens barrel 11 and the rear group lens barrel 12 are screwed together with a screw S. In this lens barrel, there is only one screw connection. In this lens barrel, the entire lens system is extended by a distance dx, and during that time the distance between the front group lens L1 and the rear group lens L2 changes from l to l+Δl.
Changes to The ratio of dx and Δl is approximately 20:1.

The rear lens barrel 12 is slidably fitted into the inner periphery of a fixed mount barrel 13 attached to the camera body, and is hereinafter referred to as a sliding lens barrel. On the other hand, the front group lens barrel 11 has a screw S with respect to the sliding lens barrel 12.
Since it rotates according to the following, it is hereinafter referred to as a rotating lens barrel.
An operating ring 14 is fitted around the outer periphery of the mount fixing tube 13 so as to be rotatable only.

Radial interlocking pins 15 and 16 are implanted in the sliding lens barrel 12 and the rotating lens barrel 11, respectively. The interlocking pins 15 and 16 are connected to the front and rear guide grooves 13a and the correction grooves 13 formed in the mount fixed cylinder 13.
b, respectively, and the interlocking pin 15 further fits into the focusing groove 14 bored in the operation ring 14.
It fits into a.

FIG. 2 shows the front and rear guide grooves 13a and the correction grooves 13.
14b shows an example of the planar shape of the focusing groove 14a and the focusing groove 14a. The front and rear guide grooves 13a are straight grooves parallel to the optical axis, and simply guide the sliding lens barrel 12 in the optical axis direction. The focusing groove 14a is connected to the operating ring 1.
4 moves the sliding lens barrel 12 (and rotating lens barrel 11) in the optical axis direction, and is inclined with respect to the optical axis direction. Correction groove 13b
The rotary lens barrel 11 is rotated with respect to the sliding lens barrel 12 to change the distance between the front group lens L1 and the rear group lens L2 according to the screw S, which is also inclined with respect to the optical axis direction.

The inclinations of the correction groove 13b and the focusing groove 14a are determined according to the amount of lens extension with respect to the rotation angle of the operating ring 14, and the amount of correction of the air gap between the front group lens L1 and the rear group lens L2 with respect to the amount (position) of lens extension. . If the inclination angle of the correction groove 13b is not constant as shown in the figure, the change in Δl with respect to dx will be a nonlinear change, and if the inclination angle is constant, it will be a linear change. Similarly, if the inclination angle of the focusing groove 14a is not constant as shown in the figure, the amount of change in dx and Δl with respect to the rotation angle of the operating ring 14 will be non-linear; if this inclination angle is constant, the relationship between the two will be linear.

Therefore, in this lens barrel having the above configuration, when the operating ring 14 is rotated, the focusing groove 14a
The sliding lens barrel 12 moves linearly back and forth due to the slope and the front and rear guide groove 13a guide, and the rotating lens barrel 11 is screwed onto the sliding lens barrel 12 with a screw S.
It also moves back and forth. As the rotating lens barrel 11 moves back and forth, the interlocking pin 16 moves within the correction groove 13b, so the rotating lens barrel 11 rotates relative to the sliding lens barrel 12 according to the inclination of the correction groove 13b, and the screw Following the lead of S, the rotating lens barrel 11 moves to the sliding lens barrel 1.
Move back and forth relative to 2. In other words, the front lens group L
1 and the rear group lens L2 changes by a maximum of Δl.

The relationship between the front and rear guide grooves 13a and the correction grooves 13b changes as the circumferential distance between them changes.
The rotating lens barrel 11 rotates relative to the sliding lens barrel 12, and as a result, the front group lens L1 rotates according to the screw S.
Since the distance between the rear lens group L2 and the rear lens group L2 changes, the correction groove 13b is formed in a straight line parallel to the optical axis.
A similar effect can be obtained even if the front and rear guide grooves 13a are inclined.

3 and 4 show a second embodiment of the present invention. In this embodiment, the front lens barrel is a sliding lens barrel 12 that is slidably fitted into a fixed mount barrel 13, and the rear lens barrel is a sliding lens barrel 12.
The rotating lens barrel 11 is screwed onto the lens barrel 2 with a screw S, and the interlocking pin 1 embedded in the sliding lens barrel 12
7, in the front and rear guide groove 13a of the mount fixed cylinder 13 and in the focusing groove 14a of the operation ring 14,
Interlocking pins 18 implanted in the rotary lens barrel 11 are fitted into the correction grooves 13b, respectively. This embodiment also provides the same effect as the first embodiment.

"Effect of ideas" Next, the effects of the lens barrel of the present invention will be listed.

(1) Since the entire lens system is moved by moving the sliding lens barrel that is slidably fitted into the fixed mount barrel, the amount of lens extension can be easily increased, and focusing operations can be performed using the operating ring. It can lighten the force. Furthermore, even if tilting or eccentricity from the optical axis occurs, the lens group supported by the sliding lens barrel and the lens group supported by the rotating lens barrel screwed into this sliding lens barrel Because all lens systems in the camera are affected equally, there is almost no deterioration in image performance. Therefore, it is possible to shorten the sliding fitting length, which further helps to reduce the operating force.

(2) Therefore, even if the amount of lens extension is large, a lightweight and compact lens barrel can be obtained.

(3) The screw connection is only between the sliding lens tube and the rotating lens tube screwed into it, and aberrations are corrected by the relative rotation of both lens tubes due to this screw connection, making it easy to maintain accuracy. It is.

(4) By setting the shapes of the front and rear guide grooves and correction grooves formed on the fixed mount barrel, and the focusing groove formed on the operating ring, the air spacing of the constituent lens groups changes with respect to the rotation angle of the operating ring or the amount of movement of the entire lens system. Since the amount can be freely configured to be linear or nonlinear, aberration correction can be performed with extremely high accuracy.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing the first embodiment of the present invention, with the upper and lower sections shown in different operating states, and Fig. 2 shows an example of the shape of each groove formed in the mount fixing cylinder and operating ring. 3 is a longitudinal sectional view similar to FIG. 1 showing a second embodiment of the present invention, and FIG. 4 is a developed view similar to FIG. 2. 11... Rotating lens barrel, 12... Sliding lens barrel, 13... Fixed mount barrel, 13a... Front and rear guide groove, 13b... Correction groove, 14... Operation ring, 14
a...Focusing groove, 15, 16, 17, 1
8...Interlocking pin, S...screw, L1...front group lens, L2...rear group lens.

Claims (1)

[Scope of claim for utility model registration] Either the front group lens barrel that holds the front group lens or the rear group lens tube that holds the rear group lens,
One is a sliding lens barrel that is slidably fitted to the fixed mount barrel, and the other is screwed to this sliding lens barrel to form a rotatable lens barrel, which can be rotated freely to the fixed mount barrel. Fit the operating ring into the sliding lens barrel, fit the interlocking pin implanted in the sliding lens barrel into the front and rear guide groove formed in the mount fixed barrel and the focusing groove formed in the operating ring, and insert the interlocking pin implanted into the rotating lens barrel. The provided interlocking pin is fitted into the correction groove formed in the mount fixing tube, and by rotation of the operation ring, the sliding lens tube is moved back and forth through the front and rear guide groove and the focusing groove, and the correction groove The rotating lens barrel is configured to be rotated relative to the sliding lens barrel through the lens barrel and moved back and forth according to the screw;
A lens barrel featuring: