JPH05292374A - Zoom lens device - Google Patents

Abstract

PURPOSE:To move a zooming lens only within a range free from eclipse even at the time of setting a teleconversion lens. CONSTITUTION:When it is detected by a switch 14 that a teleconversion lens 8 is set, a microcomputer 19 receives this detection signal to limit the movement of a zooming lens 4 within a range 22 free from eclipse. Thus, a user can operate zooming without a fear of eclipse.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel zoom lens device. Specifically, even when a so-called tele-conversion lens is attached, a new zoom lens device is provided so that the zooming lens does not move only within a range where the screen is not vignetted, and there is no zooming area where the screen is vignetted. Is to provide.

[0002]

2. Description of the Related Art For example, a zoom lens device used for a video camera is shown in FIG.

A zoom lens device a shown in FIG. 7 is an inner focus type zoom lens device having a four-group structure.

In the zoom lens device a, the first lens group b and the third lens group c are fixed, and the second lens group d and the fourth lens group e are movable lenses. And the second
The group lens d is a variator (zooming lens) responsible for zooming, and the fourth group lens e is a focusing lens responsible for focusing on the light receiving surface of the image sensor f such as a CCD image sensor.

Then, while the variator d is moved along the optical axis xx, the zooming is performed, and the focusing lens e is also moved along with the movement of the variator d. This is shown in FIG. In FIG. 8, the vertical axis represents the zoom area of the zoom lens device a, the horizontal axis represents the optical axis direction, and the curve g
Is the movement locus of the variator d, the curve h is the movement locus of the focusing lens e, the range i is the movable range of the variator d, the range j is the movement range of the focusing lens e,
Shown respectively.

[0006]

However, when the tele-conversion lens k for narrowing the angle of view is attached to the front side of the lens system, the effective diameter of the tele-conversion lens k is insufficient and the four corners of the screen on the wide-angle side. So-called vignetting will occur. For example, vignetting occurs in the area 1 in FIG.

Therefore, in the past, the user had no choice but to check the vignetting by looking at the finder and perform a zooming in an area where no vignetting occurred.

However, it is extremely troublesome to perform a zooming operation while always confirming the range in which no vignetting occurs with the viewfinder, and the range seen by the viewfinder and the range seen by the screen of the TV monitor do not always match. , Even if the viewfinder did not show vignetting, there were cases where it was seen on the monitor screen.

[0009]

Therefore, in order to solve the above-mentioned problems, the zoom lens device of the present invention is provided with a detecting means for detecting the attachment of the tele-conversion lens, and the attachment of the tele-conversion lens of the detecting means is carried out. The means for obtaining the confirmed signal and limiting the movable range of the zooming lens is provided.

[0010]

Therefore, in the zoom lens device of the present invention,
When the tele-conversion lens is attached, the movable range of the zooming lens is limited within the range where vignetting does not occur, so the zooming lens does not move to the area where vignetting occurs, and the user can rest assured. You can perform a zooming operation.

[0011]

EXAMPLES The details of the zoom lens device of the present invention will be described below with reference to the illustrated example 1.

The zoom lens device 1 has a four-group structure,
The first lens group 2 and the third lens group 3 are fixed,
The group lens 4 and the fourth group lens 5 are movable lenses. Then, the second lens group 4 is a variator for zooming, and the fourth lens group 5 is a focusing lens (also a master lens for focusing an image of a subject on the light receiving surface of the image pickup element) for focusing. ..

Reference numeral 6 denotes a C arranged behind the fourth lens group 5.
An image pickup device such as a CD image sensor.

Reference numeral 7 denotes a lens barrel that supports the above lens groups 2, 3, 4, and 5, and a teleconversion lens can be detachably attached to the front end of the lens barrel.

Reference numeral 8 is a teleconversion lens for narrowing the angle of view, which is supported by an annular frame 9.

Numerals 10 and 10 are positioning projections projecting rearward from the rear end of the frame body 9, and in positioning recesses 11 and 11 formed on the outer surface of the front end portion of the lens barrel 7. By fitting, the frame 9 is positioned and attached to the lens barrel 7.

A pressing protrusion 12 is provided on the rear end of the frame body 9. An opening 13 is formed at the front end of the lens barrel 7 corresponding to the pressing protrusion 12, and a detection switch 14 is arranged inside the opening 13.

When the tele-conversion lens 8 is attached to the front end of the lens barrel 7, the pressing projection 12 provided on the frame 9 thereof enters the inside of the opening 13 of the lens barrel 7 and the detection switch 14 The pressed element 14a is pressed to short-circuit the contacts of the detection switch 14.

FIG. 4 shows an example of means for detecting the position of the variator 4, and 15 is a potentiometer, which is a resistance film 16 and 16 'arranged in parallel along the moving direction of the variator 4. The brush 17 short-circuits the resistance films 16 and 16 '.

The brush 17 is made of a conductive material, has two contacts 17a and 17b, and is attached to a support frame 18 of the variator 4, the contacts 17a and 17b being the resistive film 1.
It contacts 6 and 16 'separately. Therefore, the electric resistance of the potentiometer 15 changes depending on the position of the variator 4, and therefore the position of the variator 4 can be known from the electric resistance of the potentiometer 15.

A microcomputer 19 controls the position of the variator 4 via the zoom motor 20 and the position of the focusing lens 5 via the focus motor 21. Further, the resistance value of the potentiometer 15 is voltage-converted and input to the microcomputer 19, which detects the position of the variator 4 and controls the position of the focusing lens 5 based on the detected position.

Further, when the ON signal of the detection switch 14 is input to the microcomputer 19, the movable range of the variator 4 corresponds to a certain range, that is, the movable range i in FIG. It is limited to the range 22 excluding the range.

Therefore, when the tele-conversion lens 8 is attached, the variator 4 moves only within the movable range 22 even if the user performs a zooming operation, and the user is wondering whether or not vignetting has occurred. There is no need to operate while doing.

A signal processing circuit 23 processes the output signal of the image pickup device 6.

Reference numeral 24 is an electrical viewfinder, which displays a subject image by the signal processed by the signal processing circuit 23, and the microcomputer 19
A signal regarding the tele-conversion lens 8 is received from and whether or not the tele-conversion lens 8 is mounted is displayed.

5 and 6 show another example of the detecting means for detecting the mounting of the tele-conversion lens 8.

A reflecting plate 25 is attached to the rear surface of the frame 9 of the teleconversion lens 8 at a position corresponding to the opening 13 of the lens barrel 7. A photo coupler 26 is arranged inside the opening 13 of the lens barrel 7.

When the tele-conversion lens 8 is mounted on the front end of the lens barrel 7, the photo coupler 2
The light 27 of the light emitting element 26a of No. 6 is reflected by the reflecting plate 25 and is applied to the light receiving element 26b of the photocoupler 26. Therefore, the output of the photocoupler 26 is different from that when the teleconversion lens 8 is not attached. So
As a result, the microcomputer 19 knows that the teleconversion lens 8 is mounted.

A switch 28 controlled to be turned ON / OFF by the microcomputer 19 is inserted in the circuit of the light emitting element 26a, and the light emitting element is energized once a second, for example. If it is detected, power consumption can be reduced.

[0030]

As is apparent from the above description, in the zoom lens device of the present invention, a teleconversion lens, which is located on the front side of the lens system and has a narrow angle of view, can be detachably mounted and the teleconversion lens can be attached. It is characterized in that detection means for detecting mounting of the version lens is provided, and means for limiting a movable range of the zooming lens by obtaining a signal confirming the mounting of the teleconversion lens of the detection means.

Therefore, in the zoom lens device of the present invention, when the tele-conversion lens is mounted, the movable range of the zooming lens is limited within a range in which vignetting does not occur, so that even an area where vignetting occurs. The zooming lens does not move, and the user can safely perform the zooming operation.

It should be noted that the specific shapes and structures shown in the above embodiments, such as the lens group configuration and the selection of the lens to be moved for focusing, are all examples of the embodiment of the present invention. Nothing but
The technical scope of the present invention is not limitedly interpreted by these.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an example of an embodiment of a zoom lens device of the present invention.

FIG. 2 is a schematic exploded perspective view showing a teleconversion lens and a mounting portion thereof.

FIG. 3 is a diagram showing an example of detection means.

FIG. 4 is a schematic perspective view showing a means for detecting the position of the zooming lens.

FIG. 5 is a schematic exploded perspective view showing another example of a teleconversion lens and its mounting portion.

FIG. 6 is a diagram showing another example of the detection means.

FIG. 7 is a schematic diagram showing an example of a conventional zoom lens device.

FIG. 8 is a graph showing a problem of a conventional zoom lens device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Zoom lens device 4 Zooming lens 8 Tele-conversion lens 14 Detection means 19, 20 Means for limiting the movable range of the zooming lens 24 Viewfinder 26 Detection means

Claims (2)

[Claims] 1. A teleconversion lens, which is located on the front side of the lens system and has a narrow angle of view, is detachably mountable, and a detection means for detecting the mounting of the teleconversion lens is provided, and the teleconversion of the detection means. A zoom lens device comprising means for obtaining a signal confirming that the lens is mounted and limiting a movable range of the zooming lens. 2. The zoom lens device according to claim 1, wherein the mounted state of the tele-conversion lens is displayed in the viewfinder.