JPH07199019A - Lens barrel - Google Patents

Abstract

PURPOSE:To miniaturize a camera and to reduce the diameter of the lens barrel by forming a D cut outside the effective diameter of the lens and switching an inner converter lens between a position on an optical axis of photography and a stand-by position in a space formed of the D cut. CONSTITUTION:A part outside the effective diameter where the photographic light of the two-group lens 5 passes is the D cut 5a, and the inner converter 11 stands by in the space formed of the D cut 5a. A holder 12 is held rotatably by 90 deg. around an axis 6b perpendicular to the optical axis of photography, and the inner converter lens 11 is movable between the position on the optical axis of photography and a position off the optical axis of photography. Consequently, a one-point focal length can be set in addition to a variable focal length area formed by normal zooming nearly without an increase in size as compared with the size of the lens barrel of constitution that uses only a zoom optical system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens which changes a focal length, and more particularly to a lens barrel which holds a zoom lens of a type in which an inner converter lens is inserted on a photographing optical axis at a short focal length.

[0002]

2. Description of the Related Art In a conventional lens barrel of this type, as described in US Pat. No. 5,166,716, an inner converter lens is normally retracted to the outside of the barrel, and a zoom in the barrel is performed. When the lens reaches a predetermined position, the inner converter lens slides in the direction orthogonal to the photographing optical axis and enters the lens barrel.

An inner converter lens is supported inside the lens barrel so as to be rotatable about an axis parallel to the photographing optical axis.
Normally, it is held at a position retracted from the photographing optical path, and is rotated around the axis to be inserted into the photographing optical path at wide angle.

[0004]

However, among the above-mentioned conventional examples, in US Pat. No. 5,166,716, a space for retracting the inner converter lens is required outside the lens barrel, and the camera becomes large in size. .

Further, in the conventional example in which the inner converter lens moves parallel to a direction perpendicular to the photographing optical axis and retracts from the photographing optical path, the diameter of the lens barrel frame holding the zoom lens includes the retracting space of the inner converter lens. However, there is a problem in that the diameter of the lens barrel frame becomes large.

An object of the present invention is to obtain a lens barrel which solves the above problems.

[0007]

According to the first aspect of the present invention, there is provided a zoom photographing optical system including at least two lens groups, a first lens group and a second lens group, a position on the photographing optical axis, and a position on the photographing optical axis. In a zoom lens barrel having an inner converter lens that can be switched to a retracted position, a D cut is formed outside the effective diameter of the second group lens, and the inner converter lens is positioned at a position on the photographing optical axis and the D position. Since the holder of the inner converter lens is held by the holder of the second group lens so as to be rotatable in a direction perpendicular to the photographing optical axis, the lens barrel diameter can be switched to the retracted position in the space formed by cutting. It became possible to arrange the inner converter lens inside the lens barrel without increasing the size.

According to the second aspect of the present invention, a fixed diaphragm that determines an open diaphragm when the inner converter lens is used is fixed to the inner converter lens. It has become possible to switch the diameter of the aperture.

[0009]

1 to 4 show an embodiment of the present invention, FIG. 1 is a vertical sectional view of a lens housed state, FIG. 2 is a vertical sectional view of a short focal length state, and FIG. 3 is a vertical section of a medium focal length state. FIG. 4 is a vertical sectional view in a long focal length state. 5 is a cross-sectional view taken along the line AA of FIG. 1, FIG. 6 is a cross-sectional view taken along the line BB of FIG.
FIG. 7 is a development view of the straight guide cylinder of the zoom lens as seen from the inside.

In the figure, reference numeral 1 denotes a first group lens held by a first group holder 2, and this first group holder 2 is held by a shutter unit 3. The shutter unit 3 has an edge 3a that determines the open aperture and is fixed to the lens barrel frame 4. Pins 4a are provided at three locations on the outer circumference of the lens barrel frame 4.

Reference numeral 5 denotes a second lens group held by a second lens group holder 6, and pins 6a are provided at three locations on the outer circumference of the second lens group holder 6. The second group holder 6 is provided with two shafts 6b perpendicular to the photographing optical axis. 11 is an inner converter lens held by a holder 12,
The tip of the arm 12a of the holder 12 is fitted to the shaft 6b of the second group holder 6, and the fixed diaphragm 13 having the edge 13a is fixed to the front surface of the holder 12.

The holder 12 is held so as to be rotatable about an axis 6b perpendicular to the photographing optical axis by about 90 °, and the inner converter lens 11 is located on the photographing optical axis and at a position retracted from the photographing optical axis. You can move to and.

A part outside the effective diameter of the second group lens 5 through which the photographing light passes is D-cut 5a as shown in FIGS. 5 and 6, and an inner converter is formed in a space 19 formed by the D-cut 5a. The lens 11 retracts. A pin 12b is attached to the tip of the arm 12a of the holder 12.
Is fixed, and a spring 14 is applied in the vicinity thereof to urge the inner converter lens 11 to be positioned on the photographing optical axis.

Reference numeral 7 denotes a straight guide cylinder fixed to a camera body (not shown), and a cam cylinder 8 is rotatably fitted to the outer periphery of the straight guide cylinder. A groove 7 parallel to the photographing optical axis is formed in the straight guide cylinder 7.
a, 7b are provided for 3 respectively, 7c is provided for 2,
The three pins 4a of the lens barrel frame 4 are fitted into the groove 7a, and the groove 7b
Is fitted with three pins 6a of the second group holder 6, and two pins 12b of the holder 12 of the inner converter lens 11 are fitted into the grooves 7c, and are respectively guided so as to go straight in the optical axis direction of photographing. .

The cam barrel 8 is provided with three cam grooves 8b and 8c, and the cam groove 8b has a pin 4 of the lens barrel frame 4.
a is fitted, and the pin 6a of the second group holder 6 is fitted in the cam groove 8c.
Are fitted. Therefore, when the cam barrel 8 rotates,
The lens barrel frame 4 is driven by the cam groove 8b, and the second group holder 6 is driven by the cam groove 8c, so that the lens barrel frame 4 moves straight in a predetermined amount in the photographing optical axis direction.

Since the pin 12b at the tip of the arm 12a of the holder 12 of the inner converter lens 11 does not reach the cam barrel 8, it does not interfere with the cam barrel 8. A gear portion 8 a is provided on the outer circumference of the cam barrel 8 and meshes with the gear 9. The gear 9 is connected to the motor 10 via a reduction gear train, and the cam barrel 8 is rotated by the motor 10. Since the control of the zoom lens by the motor 10 is known, its description is omitted here.

Next, the operation of the above embodiment will be described. FIG. 1 shows a retracted state in which the first-group lens 1 and the second-group lens 5 are most retracted to the film surface 15 side.
7 and the pin 6a of the second group holder 6 are held at the respective positions 4b and 6c in FIG.

In this collapsed state, the second group holder 6
The inner converter lens 11 held by the second group holder 6 is also most retracted, so that the pin 12b at the tip of the arm 12a of the holder 12 is retracted.
7 is located at a position 12c in FIG. 7, and is rotated by the slope of the groove 7c against the force of the spring 13, and the inner converter lens 11 causes the second group lens 5 to be D-cut 5a.
The space 19 has been evacuated.

When the cam barrel 8 is rotated by the motor 10 from the retracted state of FIG. 1, the pin 4a of the lens barrel frame 4 and the pin 6a of the second group holder 6 are respectively extended according to the cam grooves 8b and 8c, and the cam barrel 8 is pulled out. And stop at the solid line positions 4a and 6a. The pin 12b at the tip of the arm 12a of the holder 12 of the inner converter lens 11 is also extended together with the second group holder 6, and comes to the solid line position 12b in FIG. 7 according to the groove 7c. The holder 12 of the inner converter lens 11 is biased by a spring 14 and is positioned by abutting a stopper (not shown). This stopper (not shown) may be provided on the second group holder 6 or the shutter unit 3.

At this time, the optical axis of the inner converter lens 11 and the photographing optical axis of the optical system constituted by the first group lens 1 and the second group lens 5 coincide with each other, thus forming a wide-angle photographing optical system.

In this wide-angle photographic optical system, it is the edge 13a of the fixed diaphragm 13 that determines the aperture to be opened when the shutter of the shutter unit 3 is fully opened, and the diameter is larger than that of the edge 3a of the shutter unit 3. It is small, and it is possible to switch the open aperture diameter when the inner converter lens 11 is on the photographing optical path and when it is retracted.

When the cam barrel 8 is further rotated by the motor 10 from this wide-angle photographing state, the first lens group 1 and the second lens group 5 are further extended along the cam grooves 8b and 8c, and the pins 4a and 2 of the lens barrel frame 4 are moved. The pin 6a of the group holder 6 comes to positions 4c and 6d in FIG. Pin 12b at the tip of arm 12a of holder 12 of inner converter lens 11
Since it is extended together with the second group lens 5, it is displaced along the slope of the groove 7c, and the holder 12 of the inner converter lens 11 rotates again in the retreat direction against the spring 14 and becomes the state of FIG. In this state, the first lens group 1
And the second group lens 5 constitute a photographing optical system, which is a medium focal length photographing system.

When the cam barrel 8 is further rotated by the motor 10, the pin 4a of the lens barrel frame 4 and the pin 6a of the second group holder 6 are further extended and come to positions 4d and 6e, respectively, in FIG. Inner converter lens 11
The pin 12b at the tip of the arm 12a of the holder 12 of
2e, as in FIG. 3, the inner converter lens 11 is held at the position retracted from the photographing optical path, and the state shown in FIG. 4 is obtained. In this state, the most extended lens group 1 and second lens group 5 constitute a photographic optical system, which is a long focal length photographic optical system.

Between the medium focal length photographing system of FIG. 3 and the long focal length photographing system of FIG. 4, it is possible to stop at an arbitrary focal length by a zooming operation, but the shorter focal length side is the wide angle photographing state 1 of FIG. Only points can be stopped. For example, in addition to a continuous zoom with a focal length of 35 m to 70 mm, a photographic optical system with a focal length of 28 mm at one point will be used. However, changing the size of the lens barrel from a zoom photographic system with a focal length of 35 m to 70 mm Without, focal length 28mm
It is possible to add.

[0025]

As described above, according to the first aspect of the present invention, a D-cut is made outside the effective diameter of the second lens group of the zoom photographing optical system including at least two lens groups of the first and second lens groups. At the same time as forming, the holder of the inner converter lens is held in the holder of the second group lens so as to be rotatable around the axis perpendicular to the photographing optical axis, and this inner converter can be formed at the position on the photographing optical axis and the above D cut. Since it is configured to be able to switch to a retracted position in a separate space, it is possible to add a one-point focal length in addition to the variable focal length area by normal zoom without increasing the size of the lens barrel when only the zoom optical system is used. It became possible to set.

Further, according to the second aspect of the present invention, since the fixed diaphragm is fixed to the inner converter lens, the open diaphragm diameter can be changed between when the inner converter lens is used and when it is not used, without using a complicated mechanism. The effect that it is possible to switch is obtained.

[Brief description of drawings]

FIG. 1 is a simplified sectional view showing a lens housing state of a lens barrel embodying the present invention.

FIG. 2 is a simplified sectional view showing a wide-angle shooting state of the lens barrel.

FIG. 3 is a simplified cross-sectional view showing the middle focus state of the lens barrel.

FIG. 4 is a simplified sectional view showing a long focus state of the lens barrel.

5 is a cross-sectional view taken along the line AA of FIG.

6 is a cross-sectional view taken along the line BB of FIG.

FIG. 7 is a developed view of the inner surface of the zoom linear guide tube.

[Explanation of symbols]

 1 1st group lens 2 1st group holder 5 2nd group lens 5a D cut 6 2nd group holder 11 Inner converter lens 12 Holder 13 Fixed diaphragm 19 Space

Claims (2)

[Claims] 1. A zoom photographing optical system comprising at least two lens groups, a first lens group and a second lens group, and an inner converter lens capable of switching between a position on the photographing optical axis and a position retracted on the photographing optical axis. In the lens barrel having the above, a D cut is formed outside the effective diameter of the second group lens, and the inner converter lens can be switched between a position on the photographing optical axis and a retracted position in the space formed by the D cut. A lens barrel, wherein the holder of the inner converter lens is held by the holder of the second group lens so as to be rotatable in a direction perpendicular to a photographing optical axis. 2. The lens barrel according to claim 1, wherein a fixed diaphragm that determines an open diaphragm when the inner converter lens is used is fixed to the inner converter lens.