JPH01277810A - Zoom lens - Google Patents

Abstract

PURPOSE:To reduce the size and weight of the zoom lens by providing motors which drive and rotate a focus lens and a cam cylinder within the range of rotating cam cylinder cut parts and not on an optical path of photography in the direction of the optical axis. CONSTITUTION:The focusing motor 21 and zooming motor 22 which drive and rotate the focus lens 1 and cam cylinder 18 are provided within the range of the cut parts 18a and 18b of the rotating cam cylinder 18 and not on the optical path of photography in the direction of the optical axis. Consequently, the focusing motor 21 and zooming motor 22 can be incorporated in a zoom lens barrel at a position where a photographic image plane is not eclipsed in the wide space where a power varying lens 2 and a compensating lens 3 move, and the zoom lens structure is simplified. Further, the zoom lens which can be operated remotely can be compacted to nearly the same size with a manual lens.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a zoom lens, particularly a remotely controllable zoom lens that is used by being attached to a surveillance television camera or the like.

[Conventional technology]

Conventionally, this type of zoom lens has a focus ring, a zoom ring, and an aperture ring rotatably provided on the outer periphery of the lens barrel, which are remotely controlled, so the focus ring is driven outside of the manual operation ring.

Motors for driving the zoom ring and for driving the aperture ring are provided, and the outer peripheries of these motors are further covered with a protective cover.

As a result, the zoom lens becomes significantly larger and heavier, making it difficult to attach and detach it from the TV camera.

There was a drawback that the appearance was also impaired.

In order to solve such drawbacks, for example, Japanese Patent Application Laid-Open No. 61-1
As shown in Publication No. 24910.

A focus ring is attached to the outer periphery of the small diameter relay lens frame fixed to the mount side of the zoom lens barrel.

Three motors capable of driving the zoom ring and the aperture ring are provided, the zoom lens barrel is extended to the rear end while maintaining its maximum diameter, and these motors and their interlocking mechanism are installed in the extended part. It is known that it is designed to be stored.

[The problem that the invention aims to solve]

However, the zoom lens disclosed in the above publication is
Since each motor is arranged around the outer periphery of the relay lens frame that is fixed at the rear end of the zoom lens barrel, there is a complicated In addition to requiring an interlocking mechanism, each interlocking mechanism suffers a large loss of force, requires a large motor with a large drive torque, produces high driving noise, and has problems with durability.

Also, the rear end of the zoom lens barrel becomes larger.

For those with a tightening ring near the mount,
There was also a problem that fingers could not be inserted into this part.The object of the present invention is to solve these problems and provide a zoom lens that is small and lightweight and can improve operability when attaching and detaching the lens.

[Means for resolving issues]

In order to achieve the above object, the zoom lens according to the present invention is provided with a focus lens, a variable power lens, and a correction lens movable in the optical axis direction in front of the relay lens, and rotated by a predetermined angle around the optical axis. In a zoom lens in which a variable magnification lens and a correction lens are driven by a cam barrel while maintaining predetermined relative positions, the cam barrel is provided with a notch, and the cam barrel is provided with a notch, and the lens is rotated within the range of this notch and out of the photographing optical path. , a focusing motor and a zooming motor are provided along the optical axis direction to rotate the focusing lens and the cam barrel, respectively.

Further, it is preferable that both ends in the circumferential direction of the motor holder holding the focusing motor and the zooming motor be used as stoppers for regulating the rotation range of the cam cylinder.

Furthermore, it is preferable to provide a potentiometer whose output changes according to the rotation of the focus lens within the notch of the cam barrel that rotates once and outside the photographing optical path. It is preferable to keep the ratio of the helicoid to the lead moved in the axial direction constant.

Furthermore, a potentiometer whose output changes according to the rotation of the cam cylinder may be provided along the optical axis direction within the range of the rotating cam cylinder notch and outside the photographing optical path.

[For production]

By configuring as described above, the focus motor and zoom motor can be built in at a position where the photographing screen will not be vignetted in the vast space where the variable magnification lens and correction lens of the zoom lens barrel move. It becomes possible to obtain a zoom lens that has almost the same size as a manual lens and allows remote control of focusing and zooming.

In such a configuration, if the circumferential ends of the motor holder that holds the focus motor and the zoom motor are used as stoppers to restrict the rotation range of the cam cylinder, there is no need to provide a separate stopper. , the structure can be simplified.

Further, by providing a potentiometer whose output changes according to the rotation of the focus lens near the focus motor and zoom motor, it becomes possible to accurately know the distance to the object from a remote location. At this time, if the ratio between the amount of extension of the focus lens and the lead of the helicoid that moves the focus lens in the optical axis direction is kept constant, the potentiometer will correspond to the same subject distance even when using various lenses with different extension amounts. The output will be the same and you will always get accurate distance information.

Furthermore, by providing a potentiometer whose output changes according to the rotation of the cam cylinder, zooming information can also be obtained from a remote location.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the present invention, and for convenience of illustration, parts that are not necessarily in the same cross section are also shown on the same drawing.

This zoom lens consists of a focus lens 1.0 held by a focus lens frame 1a from the front (object side). A variable power lens 2 held in a variable power lens frame 2a. Correction lens frame 3
A correction lens 3 held by a and a relay lens 4 held by a relay lens frame 4a are sequentially disposed.

Then, focus lens 1. A variable magnification lens 2 and a correction lens 6 are provided movably in the optical axis direction on the side of a fixed lens barrel 11, and a relay lens 4 is fixed to a body plate 12 and a body frame 13 that are integral with the fixed lens barrel 11. .

A distance ring 14 is integrally fixed to the outer peripheral surface of the focus lens frame 1a, and a toothed portion 14 is partially provided on the inner peripheral surface of the distance ring 14.
b, a helicoid screw 14a is provided on the outer periphery, the helicoid screw 14a is screwed into a vericoid screw lla provided on the inner periphery of the net barrel 11, and focus is set by rotating the distance ring 14. Focusing is performed by moving the lens 1 in the optical axis direction.

Note that, when the amount of extension of the focus lens 1 is X and the lead of the helicoid screw 14a is Ω, the pitch and thread of the helicoid screws 11a and 14a are determined so that x/Q is constant.

On the other hand, the variable power lens frame 2a and the correction lens frame 3a are held by a plurality of poles 16 fixed between the body plate 12 and the pole support plate 15 so as to be able to slide in the optical axis direction but not to rotate. .

A gutter-shaped guide member 17 with a part (the upper part in the figure) cut out is integrally fixed to the inner circumferential surface of the fixed lens barrel 11. The outer circumferential surface of the cam cylinder 18, which has a notch in a part, is rotatably brought into sliding contact, and both ends are brought into sliding contact with the body plate 12 and the ball support plate 15 to prevent movement in the optical axis direction. There is.

The cam tube 18 has a first cam groove 18a into which a cam sleeve 1, which is protruded from the variable power lens frame 2a, is fitted, and a second cam groove 18b, into which a cam sleeve 20 which is protruded from the correction lens frame 3a is fitted. The first cam groove 18a and the second cam groove 18b are provided at a predetermined angle (for example, 40 degrees) in the circumferential direction, as shown in the developed view of FIG. By extending one end of the second cam groove 18b to a protruding portion 18c provided in a part of the lens 18, the correction lens frame 3a can be guided to a position where a desired zoom magnification can be obtained.

Further, a focusing motor 21 and a zooming motor 22 are arranged along the optical axis direction at a position that is within the range of the notch even when the cam cylinder 18 rotates by a predetermined angle and outside the photographing optical path. The motors 21 and 22 are fixed to a motor holder 23 fixed to the inner circumference of the fixed lens barrel 11, and a potentiometer 24 for distance information is fixed to the middle part of the motors 21 and 22, as shown in FIG. In addition, radial surfaces 23a and 23b are provided at both ends of the motor holder 23 in the circumferential direction to serve as stoppers for regulating the rotation range of the cam cylinder 18.

A pinion 2 is attached to the rotation axis of the focusing motor 21.
1a, and a pinion 22a on the rotation shaft of the zoom motor 22.
and a pinion 24. to the rotating shaft of the potentiometer 24. A reinforcing ring 2 in which the pinions 21a and 24a are both connected to the teeth 14b of the distance ring 14, and a pinion 228 is fixed to the outer periphery of the cam cylinder 18.
It is connected to the tooth portion 25a of No. 5.

Here, as shown in FIG. 5, the pinions 21a and 24a are arranged on the front side of the lens barrel, the pinion 22a is arranged on the rear side, and the protrusion 18c of the cam barrel 18 is placed behind the focusing motor 21. space for rotation is secured.

Note that it is also possible to arrange a potentiometer 28 for zooming information in a space behind the potentiometer 24 for distance information, and to connect a pinion 26a fixed to the rotation shaft of the potentiometer 28 to the teeth 25a of the reinforcing ring 25.

Further, a ring servo device 27 is provided on the outer periphery of the relay lens frame 4a, and the aperture 28 is narrowed down to an appropriate aperture value depending on the brightness of the subject.

Note that 29 in FIG. 1 is a tightening ring for fixing this zoom lens to a television camera.

In the embodiment configured as described above, the zoom motor 2 is controlled by remote control while looking at a monitor screen (not shown).
When the cam barrel 18 is rotated by rotating the zoom lens 2 in a desired direction, the variable power lens 2 and the correction lens 3 are moved in the optical axis direction, and an appropriate zoom ratio can be set.

Furthermore, when the focus motor 21 is rotated in a desired direction to rotate the focus lens frame 1a, the focus lens 1 is moved in the optical axis direction and focus adjustment is performed.

When the focus lens frame 1a rotates, the output of the distance information potentiometer 24 changes according to the amount of rotation, and the object distance is detected. At this time, if the ratio between the amount of extension of the focus lens 1 and the lead of the helicoid 14a of the distance ring 14 is set constant, the amount of extension of the focus lens 1 corresponding to the same subject distance can be adjusted depending on the type of zoom lens. Even if the distance changes, the output of the potentiometer 24 remains the same for the same subject distance, so accurate distance information can always be obtained even if the lens is replaced.

In addition, a focus motor 21 and a zoom motor 22
Since the motor holder 23 with the fixedly attached motor holder 23 is also used as a stopper for the cam cylinder 18, there is no need to provide a separate stopper.

Furthermore, if a potentiometer whose output changes according to the rotation of the cam cylinder is also provided, zooming information can be obtained in addition to distance information at a remote location.

According to this embodiment, the protrusion 18c is provided on the cam cylinder 18 by utilizing the space at the rear of the focusing motor 21, and the second cam groove 18b is formed in the protrusion 18c. It becomes possible to set the rotation angle of the cam barrel 18 to an angle necessary to obtain a desired zoom ratio.

〔Effect of the invention〕

As described above, in the zoom lens according to the present invention, the cam barrel is provided with a notch portion that moves the variable power lens and the correction lens in the optical axis direction by rotating a predetermined angle.
Since the focus motor and zoom motor are provided within the range of this rotating notch and outside the photographing optical path, there is no need to provide extra space for these motors, and the remote-controllable zoom lens can be used as a manual lens. can be combined into approximately the same size.

If both circumferential ends of the motor holder that holds the focus and zoom motors are used as stoppers to restrict the rotation range of the cam cylinder, there is no need to provide a separate stopper, and the structure of the zoom lens can be improved. It becomes possible to simplify.

In addition, by providing a potentiometer whose output changes according to the rotation of the focus lens, it is convenient to be able to know the subject distance from a remote location. If the ratio of the lead of the helicoid to the helicoid that is moved is constant, the output of the potentiometer corresponding to the same subject distance will be the same even when using various zoom lenses with different extension amounts. Accurate distance information can always be obtained no matter what lens is used.

Furthermore, if a potentiometer whose output changes according to the rotation of the cam cylinder is provided, zooming information can also be obtained from a remote location.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a perspective view showing the shape of the cam cylinder. FIG. 3 is a developed view thereof, FIG. 4 is an explanatory diagram showing the relationship between the cam barrel and the motor holder, and FIG. 5 is a schematic plan view showing the arrangement of the motor and potentiometer in relation to the cam barrel. 1... Focus lens 2... Variable magnification lens 3.
...Correction lens 4...Relay lens 11.
... Fixed lens barrel 14 ... Annular ring 14a ...
Helicoid screw 1st...Ball 18...Cam cylinder
18a...first cam groove 18b...second
Cam groove 21... Focus motor 22... Zoom motor 23... Motor holder 2
4...Potentiometer (for distance information) 26...Potentiometer (for zooming information) 27...Ring servo device 28...Aperture 2nd...Tightening ring Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] 1. A focus lens, a variable magnification lens, and a correction lens are provided movably in the optical axis direction in front of the relay lens, and the variable magnification lens is controlled by a cam tube that rotates at a predetermined angle around the optical axis. and a zoom lens in which the correction lens is driven while maintaining a predetermined relative position, wherein the cam barrel is provided with a notch, and the focus lens and the above are provided within the rotating notch and outside the photographing optical path. A zoom lens characterized in that a focusing motor and a zooming motor are provided along an optical axis direction to rotate respective cam cylinders. 2. The zoom lens according to claim 1, wherein both ends in the circumferential direction of the motor holder holding the focusing motor and the zooming motor are stoppers for regulating the rotation range of the cam barrel. 3. Claim 1 or 2, wherein a potentiometer whose output changes according to the rotation of the focus lens is provided along the optical axis direction within the range of the rotating cam cylinder notch and outside the photographing optical path.
Zoom lens listed. 4. The zoom lens according to claim 3, wherein the ratio between the amount of extension of the focus lens and the lead of the helicoid that moves the focus lens in the optical axis direction is constant. 5. A potentiometer according to claim 1, 2, 3, or 4, wherein a potentiometer whose output changes according to the rotation of the cam tube is provided within the range of the rotating cam tube cutout and outside the photographing optical path along the optical axis direction. zoom lens.