KR19990003273A - Realistic Finder System - Google Patents

Abstract

The present invention relates to a virtual finder system, comprising: an objective lens unit comprising at least one lens for primary imaging of a subject image from an object side; An inverted right angle triangular prism optical system for inverting the first image formed by the objective lens to an upright image; A prism optical system for shifting an upright image output from the right triangular prism optical system; It comprises an eyepiece lens consisting of one or more lenses for observing the upright image moved by the prism optical system, using an orthogonal triangular prism to shift the optical axis while changing the inverted image formed in the objective lens to the upright image By shortening the overall length of the camera, the camera can be made thinner.

Description

Realistic Finder System

The present invention relates to a real view finder system, and more specifically, in a real view finder, by using a right-angle triangular prism to shift the optical axis while changing the inverted image formed in the objective lens to an upright position to shorten the overall length of the camera. A practical finder system for the present invention.

With reference to the accompanying drawings will be described the operation of the conventional real-type finder system.

1 is a perspective view of a mirror used in a conventional virtual finder system.

In general, the virtual finder is composed of an objective lens unit and an eyepiece unit, and is formed in a form that a user can observe by magnifying the image of an object formed through the objective lens unit through the eyepiece unit.

The image formed in the objective lens unit is reversed, and when viewed through the eyepiece unit, the image inverted from the original subject is seen.

Therefore, an optical system for establishing an image formed through the objective lens unit is required. These real-world finders include the following open technologies.

(1) Japanese Patent Application Publication No. Hei 6-214288

(2) Japanese Patent Application Publication No. Hei 5-93859

(3) Japanese Patent Application Laid-open No. 1-309020

It is equipped with a prism that establishes an image (hereinafter referred to as an erecting prism). This technology has an advantage that the overall length of the camera can be shortened, but it is necessary to secure a space in the lower part from the optical axis of the entire optical system. Difficulties arise in designing the overall configuration, and the overall shape is complicated, which makes it difficult to set molding conditions.

The conventional technique described in (2) is a form in which the role of the sizing frame is half-and-half in the eyepiece portion and the objective lens portion, and generally can be seen in the form of a system of sizing by using two polo prisms. have.

However, the technique described in (2) described above has a disadvantage in that the prism mounting space must secure the spaces on the left, right, and top of the optical axis in the same way as the prior art described in (1).

The conventional technique described in (3) above is a system in which an image is crystallized in the objective lens unit so that the prism of the eyepiece unit transfers the image as it is to the eyepiece.

However, in the technique described in (3) above, by using a right angle mirror as the sizing system, it is easy to shift the optical axis to the left and right by the right angle mirror, so that the overall configuration of the camera can be set by varying the position of the objective lens and the position of the eyepiece. However, it is difficult to form a thin film by thinning the overall length of the camera, that is, the body.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks, by using an orthogonal triangular prism in the actual finder to shorten the overall length of the camera by shifting the optical axis while changing the inverted image formed in the objective lens to an upright image. In addition, the present invention aims to provide a practical finder system capable of thinning the camera.

The configuration of the present invention for achieving the above object,

An objective lens unit comprising at least one lens for primary imaging of an object image from an object side;

An inverted right angle triangular prism optical system for inverting the first image formed by the objective lens to an upright image;

A prism optical system for shifting an upright image output from the right triangular prism optical system;

It includes an eyepiece portion made of one or more lenses for observing the upright image moved by the prism optical system.

1 is a perspective view of a mirror used in a conventional practical finder system,

2 is a block diagram of a virtual finder system according to an embodiment of the present invention;

3 is a perspective view of a right triangular prism according to an embodiment of the present invention;

Fig. 4 is a diagram showing the difference in optical paths when using a mirror and a right triangle prism;

5 is a perspective view of a virtual finder system according to an embodiment of the present invention;

6 is a configuration diagram of the actual finder system at the wide-angle end according to the first embodiment of the present invention;

7 is an aberration diagram of the actual finder system at the wide-angle end according to the first embodiment of the present invention;

8 is a configuration diagram of the actual finder system in the telephoto end according to the first embodiment of the present invention;

9 is an aberration diagram of the actual finder system in the telephoto end according to the first embodiment of the present invention;

Fig. 10 shows the optical axis shift amount by the prism.

With the above configuration, the most preferred embodiment which can be easily carried out by those skilled in the art with reference to the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a virtual finder system according to an embodiment of the present invention;

3 is a perspective view of a right triangular prism according to an embodiment of the present invention;

Fig. 4 is a diagram showing the difference in optical paths when using a mirror and a right triangle prism;

5 is a perspective view of a virtual finder system according to an embodiment of the present invention;

6 is a configuration diagram of the actual finder system at the wide-angle end according to the first embodiment of the present invention;

7 is an aberration diagram of the actual finder system at the wide-angle end according to the first embodiment of the present invention;

8 is a configuration diagram of the actual finder system in the telephoto end according to the first embodiment of the present invention;

9 is an aberration diagram of the actual finder system in the telephoto end according to the first embodiment of the present invention;

Fig. 10 shows the optical axis shift amount by the prism.

As shown in FIG. 2, the configuration of the real-type finder according to the embodiment of the present invention includes the objective lens unit 1, the right triangular prism 2, the penta prism 3, It consists of the lens part 4.

The right triangular prism 2 and the penta prism 3 are made of plastic, but it is also possible to use a material made of another material without departing from the object of the invention.

The objective lens unit 1 and the eyepiece unit 4 are each composed of one or more lenses.

The action of the actual finder according to the embodiment of the present invention by the above configuration is as follows.

In the present invention, a right triangular prism is used to convert the inverted image formed in the objective lens to a sizing phase, and the optical axis can be shifted by the thickness of the cross section while inverting the inverted image formed in the objective lens in the right triangular loop plane of the prism. By forming an image toward the objective lens rather than the reflected optical axis in the absence of a prism, the distance from the objective lens to the eyepiece lens as a whole becomes short.

The optical axis shift amount as described above can be calculated according to the following Equation 1 as shown in FIG.

t = t1 + t2

t1 = dcosθ1 {1- (1 / cosθ2) × sin (θ1-sin ^-1 (sinθ1 / N))}

t2 = dsin (θ1-θ2)

T represents the optical axis shift amount, d represents the thickness of the prism, θ 1 represents the angle of incidence (typically 45 °) to the prism, θ 2 represents the angle of refraction in the prism, N is the refractive index of the prism Indicates.

The operation of the practical finder according to this principle will be described in more detail.

First, light corresponding to an object (not shown) is imaged through the objective lens unit 1 and is incident on the right-angle triangular prism 2.

The image formed through the objective lens unit 1 is an inverted image, in which the original subject is inverted by 180 ° and formed upside down.

The right triangular prism 2 corresponds to the thickness of its cross section while converting the inverted image formed through the objective lens unit 1 into the upright image rotated 180 degrees by inverting the upper and lower sides again and again in the loop surface of the right triangle. Shift the optical axis by

In the case of using a right angle mirror as in the prior art, the incident light is reflected only at right angles to the angle of incidence. However, as shown in FIG. 3, when a right angle triangular prism is used as in the embodiment of the present invention. As the incident light is reflected and output at right angles to the incident angle, the optical axis is shifted.

More specifically, as shown in FIG. 4, when the right triangular prism is not used, the light beam A incident from the left side, that is, the light beam incident from the objective lens unit 1 is reflected on the first surface 11. In the case of using a prism composed of an inclined flat plate having a different refractive index from air, the incident light is reflected on the first surface 11 and then in the second direction C. By outputting, an optical axis shift occurs.

As the optical axis is shifted, the distance from the first lens surface of the objective lens to the eyepiece becomes shorter, making it possible to shorten the overall length of the finder.

The image established through the right triangular prism 2 as described above is incident to the eyepiece part 4 through the penta prism 3 again.

Therefore, the user can observe the enlarged subject image through the eyepiece unit 4.

Embodiment values of the actual finder system according to the embodiment of the present invention, which satisfy the above principles, are as follows.

Next ri (i = 1 to 21) is the radius of curvature of the refractive surface, di (i = 1 to 21) is the thickness of the lens or the distance between the lenses, Nd is the d-line refractive index of the lens, ν is the Abbe number of the lens , m represents the magnification of the entire lens system.

Example values of the actual finder system according to the first embodiment of the present invention are shown in Table 1 below, and the coefficient values of the aspherical surface are shown in Table 3 below.

Face number Radius of curvature (r) Thickness, distance (d) Refractive index (Nd) Abbe (ν) One 29.00000 2.4000 1.49176 57.4 * 2 -15,16000 A * 3 -5.21000 1.1000 1.49176 57.4 * 4 11.51000 B 5 40.00000 2.0000 1.49176 57.4 * 6 -13.90000 C 7 49.60000 1.9000 1.49176 8 -23.00000 5.5000 9 ∞ 7.5840 1.51680 64.2 10 ∞ 7.5840 1.51680 64.2 11 ∞ 4.8000 12 18.00000 2.6000 1.49176 57.4 13 ∞ 2.0000 14 ∞ 0.7000 1.51680 64.2 15 ∞ 0.7000 1.51680 64.2 16 ∞ 3.7000 17 ∞ 34.1400 1.51680 64.2 18 ∞ 3.0000 19 25.00000 2.8000 1.49176 57.4 20 -36.01300 17.0000 21 ∞ 0.0000

The value of the distance change (A, B, C) in Table 1 is shown in Table 2 below.

Wide angle Middle Telephoto A 1.200 7.326 9.318 B 12.500 7.477 1.697 C 2.400 1.297 5.085

Aspheric coefficient of the second side Aspheric coefficient of the third side K -0.2132526000000E + 2 -0.1155358000000E + 2 A4 -0.2863885000000E-3 -0.1011810000000E-2 A6 0.4144859000000E-5 0.5097031000000E-4 A8 -0.3475526000000E-5 Aspheric coefficient of the fourth side Aspheric coefficient of page 6 K 0.8805563000000E + 1 -0.6498840000000E + 1 A4 0.2338287000000E-2 -0.1558744000000E-3 A6 -0.2331343000000E-3 0.2061151000000E-5 A8 -0.1143394000000E-5 -0.3839197000000E-7

As described above, according to the embodiment of the present invention, in the real-type finder, by using the right-angle triangular prism, the inverted image formed by the objective lens is shifted to the upright image by shifting the size of the finder and further, the whole of the camera. Miniaturization becomes possible.

This invention can be used not only in the field of cameras but also in all optical systems for which the subject is to be observed.

Claims (3)

An objective lens unit comprising at least one lens for primary imaging of an object image from an object side; An inverted right angle triangular prism optical system for inverting the first image formed by the objective lens to an upright image; A prism optical system for shifting an upright image output from the right triangular prism optical system; An eyepiece finder system comprising an eyepiece portion made of at least one lens for observing an upright image moved by the prism optical system. The method of claim 1, An actual finder system wherein the prism optical system is composed of a penta prism. The method of claim 1, An actual finder system wherein the prism optical system is made of a plastic.