JP2000013652A - Lens device for finder and finder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens device for a finder which does not have to make a viewfinder body large even when an image display device of a large size is used in a viewfinder for a video camera, or the like. SOLUTION: This device consists of a convex lens 1 whose focal distance is f1, a concave lens 2 whose focal distance is -f2 (f1<f2) and a lens-barrel 3. The lens 2 is fixed to the side opposite to an eye point A and the lens 1 is supported in a movable way in the direction of an optical axis between the lens 2 and the point A. Because a focal distance of the lenses can be extended in relation to the lens 1, sufficient visual field is secured with a large- sized cathode-ray tube 4 without making the diameter of the lenses large. Thus, it is possible to reduce cost by making parts common. Also, a viewfinder that is small-sized and has good balance against a camera body is obtained because the lenses and the lens-barrel 3 and a finder body 5 do not have to be made large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a viewfinder lens device for a television camera or the like.

[0002]

2. Description of the Related Art Conventionally, as a lens device used for a view finder (hereinafter, referred to as a finder lens device), Japanese Patent Application Laid-Open No. Hei 5-119274 has been disclosed. However, there is no one that specifies the focal length and arrangement of the lenses at the same time.

Hereinafter, a conventional finder lens device will be described with reference to FIG. FIG. 2 is a front view of a conventional finder lens device.

As shown in FIG. 2, the finder lens device includes a convex lens 101 and a lens barrel 103 that supports the convex lens 101 so as to be movable in the optical axis direction. The finder lens device is coupled to the finder body 105 on the side opposite to the eye point a which is the position of the eye. A CRT 104 is arranged in the finder body 105, and the optical axis is bent 90 ° by a mirror 106 on the way.

[0005] In this state, place the eye at eye point a,
The CRT 104 is viewed through the convex lens 101. At this time, since the diopter varies depending on the viewer, the convex lens 10
The diopter is adjusted by moving 1 in the optical axis direction. In other words, when the viewer is farsighted, the convex lens 101 is brought closer to the eye point a, and when the viewer is nearsighted, the convex lens 101 is brought closer to the cathode ray tube 104 to create an easily viewable state.

An example will be described. The focal length of the convex lens 101 is 100 mm, and the movement stroke of the convex lens 101 is 44 mm. Assume that the distance between the eye point a and the convex lens 101 is 82 mm, and the distance between the convex lens 101 and the CRT 104 is 66 mm. The diopter at this time is -3.6 dp according to a known formula. Next, the distance between the eye point a and the convex lens 101 is 38 mm, and the distance between the convex lens 101 and the CRT 104 is 110 mm. The diopter at this time is +0.9 dp. The diopter adjustment range is 4.5 dp.

On the other hand, the diameter of the convex lens 101 is set so that an appropriate field of view can be obtained, that is, when the CRT 104 is viewed at the eye point a, the corners of the CRT 104 are not chipped and a moderate margin is provided. Is decided to have. Here, it is assumed that a diameter of 50 mm is appropriate for a 1.5-inch CRT 104 having an aspect ratio of 4: 3.

However, recently, with the widening of the screen of the television, the view finder has been changed to the 16: 9 wide type.
2 inch cathode ray tubes have come to be used. When this 2-inch wide cathode ray tube is viewed using a conventional finder lens device, there is a problem that corner portions of the cathode ray tube are chipped, or even if they are not cut, the margin is small and it is difficult to see. On the other hand, the convex lens 101
For example, a method of increasing the focal length of the lens and reducing the magnification by, for example, 120 mm can be considered. However, increasing the focal length of the lens causes a problem that the diopter adjustment range becomes narrower. Therefore, a method of increasing the outer diameter of the convex lens 101 in order to make the field of view and the diopter adjustment range compatible is conceivable. However, this requires a new barrel 103, which leads to an increase in the size of the apparatus itself. There is a problem.

[0009]

As described above, the conventional finder lens apparatus has a problem that the size of the lens barrel must be prepared individually according to different CRT sizes. In addition, the size of the viewfinder body also increases with the increase in the size of the cathode ray tube, resulting in a problem that the balance with the camera body deteriorates.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. By using the same lens for different sizes of cathode ray tubes, it is possible to share parts around the viewfinder and to reduce the size of the camera body. It is an object of the present invention to provide a finder lens device capable of realizing a view finder having a good balance with the finder.

[0011]

SUMMARY OF THE INVENTION To solve this problem, the present invention provides a lens barrel, a convex lens having a focal length f1, and
A concave lens having a focal length of -f2 (f1 <f2), wherein the concave lens is fixed on the side opposite to the eye point of the lens barrel, and the convex lens can be moved in the optical axis direction between the eye point and the concave lens. It is.

According to the present invention having the above features,
Parts can be shared, and a compact viewfinder with good balance with the camera body can be obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first aspect of the present invention is an interchangeable lens device used for a viewfinder or the like of a camera, comprising: a lens barrel; a convex lens having a focal length f1; A concave lens that satisfies −f2 (f1 <f2), wherein the concave lens is fixed on the side opposite to the eye point of the lens barrel, and the convex lens can be moved in the optical axis direction between the eye point and the concave lens. Since the concave lens reduces the size of the image, a sufficient field of view can be obtained even if the lens diameter is small.

Further, by providing a concave lens, a convex lens having a short focal length can be used, so that the diopter adjustment range when the convex lens is moved is widened.

According to a second aspect of the present invention, there is provided an interchangeable lens device used for a view finder or the like of a camera, comprising a lens barrel, a convex lens having a focal length of f1, and a focal length of -f2 (f1 <f2). The concave lens is located on the side opposite to the eye point of the lens barrel, and the convex lens is placed between the eye point and the concave lens, and the convex lens and concave lens can move in the optical axis direction in conjunction with Since the concave lens reduces the size of the image, there is an effect that a sufficient field of view can be obtained even if the diameter of the lens is small.

Further, by moving the convex lens and the concave lens in conjunction with each other, the change of the focal length can be increased, so that the diopter adjustment range when the lens is moved is widened.

According to a third aspect of the present invention, there is provided an image display device, a lens barrel, a convex lens having a focal length of f1, and a concave lens having a focal length of -f2 (f1 <f2). The convex lens and the concave lens are disposed apart from each other, and the concave lens reduces the image. Therefore, the concave lens has an effect that a sufficient visual field can be obtained even if the lens barrel is small.

According to a fourth aspect of the present invention, there is provided an image display device, a lens barrel, a convex lens having a focal length of f1, and a concave lens having a focal length of -f2 (f1 <f2). A concave lens is fixed in between, and the convex lens can be moved in the optical axis direction. Since the concave lens reduces the image, it has an effect that a sufficient field of view can be obtained even if the lens barrel is small.

Further, by providing a concave lens, a convex lens having a short focal length can be used, so that the diopter adjustment range when the convex lens is moved is widened.

According to a fifth aspect of the present invention, there is provided an image display device, a lens barrel, a convex lens having a focal length of f1, and a concave lens having a focal length of -f2 (f1 <f2). The convex lens and concave lens are movable in the optical axis direction in conjunction with each other, and the concave lens reduces the image, so that a sufficient field of view can be obtained even if the lens barrel is small. Having.

Further, by moving the convex lens and the concave lens in conjunction with each other, the change of the focal length can be increased, so that the diopter adjustment range when the lens is moved is widened.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 1 is a front view of a finder lens device according to an embodiment of the present invention, and FIG. 2 is a front view of a conventional finder lens device.

As shown in FIG. 1, the finder lens device of the present invention comprises a convex lens 1, a concave lens 2, and a lens barrel 3. Assuming that the focal length of the convex lens 1 is f1 and the focal length of the concave lens 2 is -f2, there is a relationship of f1 <f2, and a combination of both lenses results in a convex lens.

The concave lens 2 is fixed to the lens barrel 3 on the side opposite to the eye point A. The convex lens 1 is supported by the lens barrel 3 so as to be movable in the optical axis direction between the concave lens 2 and the eye point A. The finder lens device thus configured is exchangeably coupled to the finder main body 5 on the side opposite to the eye point A.

A CRT 4 is disposed in the finder body 5 as an image display device.
It is bent at 0 °.

In this state, place the eye at eye point A,
The CRT 4 is viewed through the convex lens 1 and the concave lens 2. According to such a lens arrangement, since the convex lens 1 enlarges the image reduced by the concave lens 2, the convex lens 1
The field of view is wider than in the case of only.

The diopter adjustment is performed by moving the convex lens 1 in the direction of the optical axis. When the viewer is farsighted, the convex lens 1 is brought closer to the eye point A, and when the viewer is nearsighted, the lens is brought closer to the concave lens 2 to create an easily viewable state.

An example will be described. The focal length of the convex lens 1 is 100 mm, and the focal length of the concave lens 2 is -500 m
m, the moving stroke of the convex lens 1 is 36 mm, and the lens diameter is 50 mm. Now, eye point A and convex lens 1
Is 74 mm, and the distance between the convex lens 1 and the CRT 4 is 74 mm. The diopter at this time is -3.7 dp
Becomes Next, the distance between the eye point A and the convex lens 1 is set to 3
8 mm, distance between convex lens 1 and CRT 4 is 110 m
m. The diopter at this time is +0.2 dp. As compared with the conventional example, the moving distance of the convex lens 1 is reduced because the concave lens 2 is provided, and the diopter adjustment range is from 4.5 dp to 3.
It decreased to 9 dp.

However, it is possible to make the focal length longer than the focal length of the convex lens 1, and to use the lens barrel 3 and the finder body 5 of the same size as the lens barrel 103 and the finder body 105 described in the conventional example. Nevertheless 2
A sufficient field of view for the inch cathode ray tube 4 can be secured.

That is, even if the size of the cathode ray tube 4 becomes large, the same convex lens, the same size lens barrel, and the same finder main body can be used, so that it is possible to reduce the cost by sharing the parts. In addition, since the size of the viewfinder with respect to the camera body can be made the same as that of the related art, it is needless to say that the camera does not need to be changed.

Further, by attaching the finder lens device of the present invention to the conventional finder body 105, a viewfinder having a wider field of view than before can be realized.

In the above description, the case where the concave lens 2 is fixed to the lens barrel 3 has been described. However, the present invention can be similarly implemented by moving the concave lens 2 in conjunction with the convex lens 1. In this case, a large diopter adjustment range can be secured by moving the concave lens 2 in the direction opposite to that of the convex lens 1.

[0033]

As described above, according to the present invention, it is not necessary to increase the lens diameter even for a large-sized image display device, so that the same lens, the same lens barrel, and the same finder body can be used. And the cost can be reduced. In addition, a compact viewfinder with good balance with the camera body can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view of a finder lens device according to an embodiment of the present invention.

FIG. 2 is a front view of a conventional finder lens device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Convex lens 2 Concave lens 3 Lens tube 4 CRT 5 Viewfinder body

Claims (5)

[Claims] An interchangeable lens device used for a view finder or the like of a camera, comprising: a lens barrel;
1 and a concave lens with a focal length of -f2 (f1 <f2), wherein the concave lens is fixed on the side opposite to the eye point of the lens barrel, and the convex lens is located between the eye point and the concave lens. A lens device for a finder, wherein the lens device can be moved in the optical axis direction. 2. An interchangeable lens device used for a view finder or the like of a camera, comprising: a lens barrel;
1 and a concave lens with a focal length of -f2 (f1 <f2), wherein the concave lens is disposed on the side opposite to the eye point of the lens barrel, and the convex lens is located between the eye point and the concave lens. Wherein the convex lens and the concave lens are movable in the optical axis direction in conjunction with each other. 3. An image display device, a lens barrel, and a focal length f1.
And a concave lens having a focal length of -f2 (f1 <f2), the concave lens is disposed between the image display device and the convex lens, and the convex lens and the concave lens are disposed separately. A finder device characterized by the above-mentioned. 4. An image display device, a lens barrel, and a focal length f1.
And a concave lens having a focal length of -f2 (f1 <f2), wherein the concave lens is fixed between the image display device and the convex lens, and the convex lens is movable in the optical axis direction. A finder device characterized by the following. 5. An image display device, a lens barrel, and a focal length f1.
, And a concave lens having a focal length of −f2 (f1 <f2), wherein the concave lens is disposed between the image display device and the convex lens, and the convex lens and the concave lens are interlocked with each other to form an optical axis. A finder device which can be moved in any direction.