JPH0862711A - Picture size switching device for variable focal distance camera - Google Patents

Abstract

PURPOSE: To attain reliability on actuation and the reduction of cost by adopting a rotary type picture size switching device and to avoid the interference with the lens barrel of a zoom lens moving in accordance with power varying operation so as to set the device compactly. CONSTITUTION: This camera is provided with the zoom lens 16 whose one part of the lens barrel 14 is moved in an optical axis direction in accordance with the power varying operation, and a picture size is switched by turning a mask member 22 having a rotary shaft 21 in parallel with a film surface F. In a full size picture photographing mode in which the mask member 22 is opened to a totally opened state where the picture size is not regulated, the turning position of the rotary shaft 21 is changed between a telephoto state where the focal distance is long and a wide angle state where the focal distance is short, and the mask member 22 is closed within a range where it is retreated from a photographing light beam in the wide angle state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable focal length camera provided with a zoom lens in which a part of a lens barrel moves in the optical axis direction in response to a zoom operation, and a mask having a rotation axis parallel to a film surface. The present invention relates to a screen size switching device that rotates a member to switch the size of an exposure screen on a film.

[0002]

2. Description of the Related Art Conventionally, a zoom lens is provided and the focal length is variable, and the size of an exposure screen can be switched to a full size (Leica size), a panorama size, or another screen size having a different aspect ratio. Cameras equipped with a screen size switching device are commercially available.

Further, in a zoom lens mounted on a small compact camera, a rear lens group which moves according to a zooming operation retracts at a wide angle, and a rear end portion of a lens barrel approaches a vicinity of a film surface. In response to this, as the screen size switching device, blade-shaped mask members are slidably provided above and below the exposure screen, and the upper and lower mask members are slidably linked through a link mechanism or the like to expose the exposure screen. A straight-acting type that is designed to switch sizes is used.

[0004]

However, the above-described rectilinear screen size switching device for sliding the mask member has problems that the operation is unstable and the reliability is low and the manufacturing cost is high. are doing.

Specifically, in order to make the mask members made of thin upper and lower plates slide in a linked manner, a long hole or a pin is provided in a part of the mask member so that the link and the like are linked while the moving direction is regulated. It is configured to move straight according to the actuator operation, there are many linkage sliding parts, it is easy to cause malfunction, there is little freedom in designing the force point and guide method, and secure reliable operation In addition to being difficult to do, machining costs are increasing due to machining and flare prevention coating.

Further, due to the mechanism of the straight-moving type, the mask surface is separated from the film surface, which causes a problem that the vertical size of the exposure screen changes greatly in accordance with the change of the focal length. That is, in the case of a panoramic size because the mask member is away from the film surface, the angle of the ray passing through the edge of the mask member changes depending on the position of the exit pupil between the telephoto end state and the wide-angle end state. In contrast, the exposure screen size in the wide-angle end state where the focal length is short is wider than the exposure screen size in the telephoto end state, which is not preferable.

From the above point of view, there has been proposed a structure in which the mask member of the screen size switching device is rotatably provided. In this rotary structure, a mask member is provided above and below the exposure screen on a rotary shaft parallel to the film surface, and the upper and lower portions of the exposure surface are covered by a predetermined amount by a rotating operation of the rotary shaft.

In the rotary structure, the upper and lower rotary shafts are linked and rotated by gears to perform a switching operation, which ensures reliable operation and the rotary shaft and the mask member are integrally formed of plastic. Molding is possible, and flare can be prevented by roughening the surface of the mask member during molding, which is advantageous in terms of manufacturing cost. Furthermore, the mask position of the mask member can be rotated to approach the film surface, which has the advantage that the change in the exposure screen size is small even if the focal length changes.

On the other hand, in the straight-moving type screen size switching device, it can be installed even when there is a small gap between the film surface and the rear end of the lens barrel which has moved backward in the wide-angle end state of the zoom lens. With the rotary screen size switching device,
In the full-open state where the full-size screen shooting mode is set and the mask member is rotated upright, when the zooming operation is performed to the wide-angle end state where the focal length is short, the rear end of the retracted lens barrel interferes with the mask member. Therefore, it is difficult to install a rotary screen size switching device so as not to interfere with the lens barrel.

Therefore, the present invention has been made in view of the above circumstances, and reduces the reliability of operation and cost by adopting a rotary screen size switching device and avoids interference with the lens barrel of the zoom lens. It is an object of the present invention to provide a screen size switching device for such a variable focal length camera.

[0011]

A screen size switching device for a variable focal length camera according to the present invention, which achieves the above object, includes a zoom lens in which a part of a lens barrel moves in the optical axis direction in response to a zooming operation. At the same time, the mask size having a rotation axis parallel to the film surface is rotated to switch the screen size. In the full-size screen shooting mode in which the mask member is opened in a fully open state without restricting the screen size, the telephoto state has a long focal length. And the rotation position of the rotating shaft is changed in a wide-angle state in which the focal length is short, and the mask member is closed in a range retracted from the photographing light beam in the wide-angle state.

Further, in the full-size screen photographing mode, the rotating shaft is urged in the opening direction of the mask member, and a part of the lens barrel which moves backward in the wide-angle state comes into contact with the mask member, so that the mask member is photographed. It is preferable to provide it in a structure that closes in the range retracted from.

[0013]

According to the above construction, in the state where the rotary shaft is rotated by the operation of the screen size switching device to close the mask member and the exposure screen size is restricted to a small size, the zooming operation is performed to adjust the rear group of the zoom lens. Since the mask member is in a flat state even when the lens moves backward, it can be moved to the wide-angle end state without interfering with the rear end portion of the lens barrel.

On the other hand, in the full-size screen photographing mode in which the rotating shaft is rotated in the opposite direction so that the mask member is set apart from the film surface and fully erected, the zoom lens is operated to the telephoto side and the rear lens group is operated. When moving forward, the position of the exit pupil also moves forward and the angle of the shooting light beam becomes close to the angle perpendicular to the film surface.However, in this telephoto state, the mask member is fully open and retracts from the shooting light beam. The forward movement of the rear lens group does not cause interference with the fully open mask member.

When the zoom lens is operated in the wide-angle end state and the rear lens group moves backward to the rearmost position in the full-size screen photographing mode, the exit pupil also moves backward and the angle of the photographing light beam. Becomes slanted away from the angle perpendicular to the film surface, and by rotating so as to close the mask member within the range for retracting this photographing light beam,
It avoids interference with the lens barrel that has moved backward, and even if the space between them is small, a rotary screen size switching device can be adopted and operation is highly reliable, and the accuracy of the exposure screen size can be secured. It is also advantageous in terms of cost.

Further, when the mask member is closed in a wide-angle state by abutting a part of the lens barrel which has moved backward, the closing operation of the mask member according to the feeding position of the lens barrel can be obtained with a simple structure.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic vertical sectional view of a lens in a variable focal length camera equipped with a screen size switching device according to an embodiment, FIG. 2 is a sectional view showing a telephoto end state in a full size screen photographing mode, and FIG. It is the same cross section diagram which shows the wide angle end state in size picture photographing mode.

In the camera 10 of this example, a back cover 12 is provided on the back surface of the camera body 11, the lens barrels 14 and 15 of the camera body 11 are equipped with a zoom lens 16, and a film is provided on the back of the rear surface. An aperture member 17 that forms an exposure screen for F is provided, and an aperture opening 17a of this aperture member 17 is provided in a predetermined rectangular shape for a full size screen. Further, a pressure plate 18 is arranged on the back cover 12,
A film F is held on the back part of the aperture member 17 by means of 18. The optical axis S of the zoom lens 16 is configured to pass through the center of the aperture opening 17a.

In the zoom lens 16, the rear lens group 16a is held by a moving frame 19 installed in the first lens barrel 14 held by the camera body 11 so as to be movable back and forth, and the first group lens 16a is held by the moving frame 19. Second movable inside lens barrel 14 in the front-back direction
The lens barrel 15 is held, and the front lens group 16b is held by the second lens barrel 15.

When the zooming operation is performed from the lens housed state of FIG. 1 to the telephoto end, the first mechanism is driven by a driving mechanism (not shown).
The lens barrel 14 and the second lens barrel 15 are moved forward, respectively.
As shown in (4), it is extended from the camera body 11 and extends, and the moving frame 19 of the rear group lens 16a moves to the front end position. Also,
When operated to the wide-angle end, the first lens barrel 14 and the second lens barrel 15 are operated.
Of the rear lens group 16a are moved backwards and are retracted into the camera body 11 as shown in FIG.

On the other hand, a screen size switching device 20 for restricting the size of the exposure screen from the full size to the panoramic size is arranged on the front side portion of the aperture member 17.

As shown in the enlarged view of FIG. 4, the screen size switching device 20 includes a rotating shaft 21 which is vertically parallel to the film surface F.
And a mask member 22 extending in the lateral direction are integrally formed on the rotary shaft 21. The upper and lower portions of the exposure surface are covered by a predetermined amount by rotating the rotary shaft 21.

That is, the rotary shaft 21 is disposed in parallel with the upper and lower parts of the aperture opening 17a along the lateral direction at a position slightly apart from the aperture member 17, and a drive mechanism (not shown) is connected to The upper and lower rotating shafts 21 are provided so as to be linked and rotate in opposite directions in response to the operation of the size switching button.

In the mask member 22, the connecting portion 22a extends from the rotary shaft 21 to the edge portion of the aperture opening 17a.
Of the aperture opening from this connection 22a.
The distal end plate portion 22b is formed so as to extend in the lateral direction in the aperture opening 17a while bending toward the inside of 17a, and the inner surface of the plate portion 22b is formed as an antireflection surface 22c for flare prevention. The mask member 22 and the rotating shaft
21 is integrally formed of plastic.

Further, the rotating shaft 21 is constantly urged toward the fully opening direction of the mask member 22 by urging means such as a spring (not shown). An engaging projection 23 is provided on the rotary shaft 21 while a stopper 24 is provided as a recess in the aperture member 17, and the engaging projection is provided on the stopper 24.
It is provided in a structure in which the maximum rotation position of the mask member 22 is regulated by engaging with 23. As shown in FIG. 2, the maximum rotation position of the mask member 22 is such that the zoom lens 16 rotates to a position retracted from the photographing light beam at the maximum focus at the telephoto end.

Then, in the full-size screen photographing mode in which the mask member 22 is opened in an open state in which the screen size is not restricted, in the telephoto state of FIG. 2 where the focal length is long and the wide angle state of FIG. 3 where the focal length is short, The rotation position of the rotary shaft 21 is changed, and in the wide-angle state, the mask member 22 is closed in a range retracted from the photographing light beam in accordance with the extension.

That is, in the wide-angle state of FIG. 3, a part of the light shield plate 26 at the rear end of the first lens barrel 14 which moves backward is partially covered by the mask member 22.
The mask member 22 is rotated in the closing direction by abutting on the tip end thereof, and even in this state, the closing operation is performed within the range retracted from the photographing light beam at the wide angle. The range of the photographing light beam at wide angle becomes narrower than the maximum rotation position of the mask member 22 as the focal length becomes shorter as described above, and the closing operation can be performed correspondingly. .

As a result, in the full-size screen photographing mode, the rotation axis is irrelevant regardless of the feeding positions of the lens barrels 14 and 15.
Reference numeral 21 indicates that the engaging projection 23 comes into contact with the fixed stopper 24 by its urging force, and the mask member 22 can be rotated to a position retracted from the photographing light beam at the longest focus. The mask member 22 comes into contact with the light shield plate 26 at the rear end of the first lens barrel 14 that has moved backward in accordance with the extended position, and the mask member 22 closes at least in the range retracted from the photographing light beam to change the rotation angle. When it is operated in the retracted state as shown in 1, the first lens barrel 14 is further moved backward to move the mask member 22.
Is a closed operation.

The mask member 22 is in a fully closed state shown in FIG. 1 in a panoramic size screen state in which the plate portion 22b is rotated so as to close substantially parallel to the aperture member 17 and the exposure screen size is restricted to a small size.

[0030]

As described above, according to the present invention, the screen size is switched by the rotary mask member, and in the full-size screen photographing mode in which the mask member is fully opened, the telephoto lens has a long focal length. The range in which the mask member is retracted from the shooting light beam in the wide-angle state as the angle of the shooting light beam changes according to the change in the focal length by changing the rotational position of the rotating shaft depending on the state and the wide-angle state in which the focal length is short. Since it is possible to avoid interference with the lens barrel that has moved backwards, even if the space between them is small, a rotary mask member can be installed, which enables compactness and screen size switching. The reliability of the operation is high, the accuracy of the exposure screen size can be secured, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing a lens accommodation state of a variable focal length camera equipped with a screen size switching device of the present invention.

FIG. 2 is a sectional view showing a telephoto end state in a full-size screen shooting mode.

FIG. 3 is a cross-sectional view showing a wide-angle end state in a full-size screen shooting mode.

FIG. 4 is an enlarged cross-sectional view of an essential part of the screen size switching device of FIG.

[Explanation of symbols]

 10 Camera 12 Back cover 14,15 Lens barrel 16 Zoom lens 16a Rear lens group 17 Aperture member 17a Aperture opening 18 Pressure plate 20 Screen size switching device 21 Rotation axis 22 Mask member 23 Engagement projection 24 Stopper 26 Light-shielding plate F film

Claims (2)

[Claims] 1. A focus for switching a screen size by providing a zoom lens in which a part of a lens barrel moves in an optical axis direction according to a zooming operation, and rotating a mask member having a rotation axis parallel to a film surface. In a screen size switching device for a variable distance camera, in a full size screen shooting mode in which the mask member is opened in a fully open state in which the screen size is not restricted, the rotation axis is rotated in a telephoto state with a long focal length and a wide angle state with a short focal length. A screen size switching device for a variable focal length camera, characterized in that a moving position is changed and the mask member is closed in a wide-angle state within a range retracted from a photographing light beam. 2. The rotating shaft is urged in the opening direction of the mask member in the full-size screen photographing mode, and a part of the lens barrel that moves backward in the wide-angle state comes into contact with the mask member, so that the mask member is photographed with a light beam. 2. The screen size switching device for a variable focal length camera according to claim 1, wherein the closing operation is performed in a range retracted from the position.