KR100704761B1 - Real image magnification finder - Google Patents

Abstract

The actual variable displacement finder according to the characteristics of the present invention is composed of a simple structure and inexpensive materials so that the aberration characteristics are good from small to wide angle telephoto end.

The actual variable displacement finder according to the characteristics of the present invention comprises an objective lens unit, an upper inverting unit, and an eyepiece unit, and the objective lens unit has a positive refractive power and a first lens group moving toward an object when shifting, and has a positive refractive power. It consists of a second lens group that moves to the image side at the time of shifting, the eyepiece portion is fixed with a positive refractive power.

Finder, shift, practical, miniaturized, lens

Description

Practical expression change finder {REAL IMAGE MAGNIFICATION FINDER}

Fig. 1 is a lens configuration diagram at each variable stage of the actual variable speed finder according to the first embodiment of the present invention.

2A to 2C are aberration diagrams generated at each shift stage of the actual shift finder according to the first embodiment of the present invention.

3A to 3C are aberration diagrams generated at each shift stage of the actual shift finder according to the second embodiment of the present invention.

4A to 4C are aberration diagrams generated at each shift stage of the actual shift finder according to the third embodiment of the present invention.

The present invention relates to a camera of the present invention, and more particularly, to a practical variable displacement finder.

Recent cameras, especially compact zoom cameras, require miniaturization of the shooting system for miniaturization and light weight, and high magnification and miniaturization are also required in the finder.

The finder is a device that allows the user to set the composition of the subject, and the actual finder is usually composed of an objective part and an eyepiece part. The object portion forms an image of the subject, and the eyepiece portion enlarges an image formed in the object portion so that the user can check it. At this time, the image formed by the objective part is an image which is inverted by 180 ° as in a normalized image system, and when the image is processed into a straight line and enlarged by the eyepiece, the inverted image is enlarged.

Therefore, the practical finder requires a phase inverting portion to invert this inverted image. Here, the image reversal portion of the actual finder is applied not only to the upright image but also to the overall length of the camera, that is, the prism having various shapes, etc., in order to make the camera as compact as possible.

Japanese Laid-Open Patent Publication No. Hei 4-238414 is known as such an actual expression finder.

The Japanese Laid Open Patent discloses four types of negative, positive, positive and positive groups from the object side, in which the second and third lens groups are moved to perform displacement and aberration correction. However, these Japanese published patents are difficult to be miniaturized due to their long overall length, a large amount of movement of the third lens group, and the entire lens is not the same material, resulting in a complicated mechanical structure and a low productivity due to manufacturing difficulties.

In order to solve the conventional problems of the present invention, it is an object of the lens to be simple, miniaturized, and has a high-performance aberration characteristics to make the field of view wide.

In order to achieve the above object, the actual variable speed finder according to a feature of the present invention includes an objective lens unit, an inverting unit, and an eyepiece unit.

In this case, the objective lens unit forms an image of a subject, and the image inverting unit is inverted and established by the object lens unit. The eyepiece unit enlarges an image formed by the image inverting unit and enlarges an image formed by the user. To see.

At this time, the objective lens unit according to the characteristics of the present invention has a positive refractive power sequentially from the object side and moving to the object side along the optical axis when shifting, and a second lens having positive refractive power and moving upward along the optical axis when shifting It is preferably made of a lens group, it characterized by satisfying the following conditional expressions 1, 2, 3.

(Condition 1)

(Condition 2)

(Condition 3)

In the above condition, f1 is the focal length of the first lens, f2 is the focal length of the second lens, fw is the focal length at the wide-angle end of the objective lens portion, ft is the focal length at the telephoto end of the objective lens portion, L is the distance from the object side to the first surface of the upper inverting portion at the telephoto end of the objective lens portion.

Here, in the actual type variable displacement finder according to the characteristics of the present invention, when the upper limit of Conditional Expression 1 exceeds the overall length of the objective lens portion, it becomes difficult to miniaturize, and when the lower limit exceeds, the power of the first lens group and the second lens group increases and the aberration is increased. It becomes bigger. In addition, in the actual expression variable finder according to the characteristics of the present invention, when the upper limit of Conditional Expression 2 is exceeded, the overall length of the objective lens unit is increased, and when the lower limit is exceeded, the power of the first lens group is increased to increase the aberration. In addition, in the real variable displacement finder according to the feature of the present invention, when the upper limit of Conditional Expression 3 is exceeded, the amount of movement of the first lens group is increased, and when the lower limit is exceeded, the power of the first lens group is increased and the aberration is increased.

Here, it is preferable that the first lens group is a first meniscus convex toward the object side and the object side surface is an aspherical surface, and the second lens group is a second lens having both sides convex and the image side surface aspherical.

The eyepiece group includes a third lens in which both sides are convex and the object side is aspheric.

Therefore, the coefficient of the aspherical lens among the lenses of the real variable displacement finder according to the features of the present invention can be expressed by the following equation (1).

                Z = distance from the lens vertex to the optical axis

                h = distance in the direction perpendicular to the optical axis

                c = inverse of the lens radius of curvature

                k = Conic constant

                A, B, C, D: Aspheric coefficient

1A to 1C and FIG. 2, an actual shift finder according to the features of the present invention will be described.

1 is a lens configuration diagram of an actual variable-view finder according to a first embodiment of the present invention, and is a lens configuration diagram at a wide-angle end, an intermediate end, and a telephoto end in order from the top.

As shown in FIG. 1, the actual variable displacement finder according to the exemplary embodiment of the present invention includes an objective lens unit 10, an upper inverting unit 20, and an eyepiece unit 30.

Here, the objective lens unit 10 includes a first lens 11, which is a positive meniscus in which the object side surface is convex from the object side, and a second lens 12 in which both sides are convex. The first lens 11 refracts incident light in the positive direction to enter the second lens 12, and the second lens 12 refracts the incident light in the positive direction once again on the object side surface of the prism. Make the image of the subject image.

The upper inverting unit 20 is a general prism that inverts the image of the subject formed on the object side so that the established image is formed on the upper side. Therefore, the upper inverted portion 20 is referred to as a prism 20.

The eyepiece portion 30 includes a third lens 30 which is convex and fixed at both sides. Therefore, the third lens 30 enlarges the upright image formed on the image side surface of the prism 20.

The virtual variable displacement finder according to the first exemplary embodiment of the present invention configured as described above changes the focal position by moving the positions of the lenses configured for the wide-angle end, the intermediate end, and the telephoto end.

That is, in the intermediate stage shown in FIG. 1B, the first lens 11 moves toward the object side by a predetermined value, and the second lens 12 moves toward the image side by a predetermined value. In addition, in the telephoto end illustrated in FIG. 1C, the first lens 11 moves further toward the object side by a predetermined value, and the second lens 12 moves further toward the image side by a predetermined value.

Herein, the exemplary values for each lens and prism constituting the actual variable displacement finder according to the first exemplary embodiment of the present invention are shown in Table 1 below.

In Table 1, r is the radius of curvature, d is the thickness of the lens and the distance between the lenses, nd is the refractive index, v is the Abbe number, the angle of view (2ω) is 48.90 ° to 20.74 °, and the magnification is 0.37 × 0.87 ×. .

Face number  r (curvature radius) d (thickness, distance)  nd (refractive index) v (Abe number)  Remarks    One      ∞     variable      plane    2    10.328     2.28   1.49176     57.4     Aspheric surface    3   122.949     variable    4    12.646     2.34   1.49176     57.4    5    -6.416     variable     Aspheric surface    6      ∞    27.20   1.49176     57.4 Plane (primary imaging plane)    7      ∞     1.30       plane    8    13.165     4.10   1.49176     57.4      Aspheric surface    9   -36.868    17.00    10      ∞     0.00        plane

In the distance between the lenses of Table 1, the variable d1, d3, and d5 are shown in Table 2 for each variable step.

      Wide-angle end (2ω = 48.90 °)      Medium short (2ω = 32.42 °)      Telescopic end (2ω = 20.74 °)     d1         11.400        3.893         0.000     d3          2.203       11.034        17.384     d5          5.461        3.956         1.500

Accordingly, according to Tables 1 and 2, the focal length f1 of the first lens group 11, which is the first lens group, is 22.776 and the second lens in the actual variable viewfinder according to the first embodiment of the present invention. The focal length f2 of the soldier second lens 12 is 9.021, the focal length fw at the wide-angle end of the objective lens unit 10 is 7.600, and the focal length at the telephoto end of the objective lens unit 10. (ft) is 17.600, and the distance L from the telephoto end of the objective lens unit 10 to the first surface of the prism 20 is 23.500 from the first surface of the first lens 11.

Therefore, the variable L / ft = 23.500 / 17.600 = 1.335 in Condition 1, the variable L / f2 = 23.500 / 9.021 = 2.605 in Condition 2, and the variable f1 / fw = 22.776 / 7.600 = 2.997 in Condition 3, where Satisfy conditional expression.

Herein, aspheric lens coefficients of the lenses 11, 12, and 30 according to the first embodiment are defined by Equation 1 as shown in Table 3 below.

r2  r5  r8 K   0.3265900270705 × 10E + 1   -0.1633896762946 × 10E + 2  -0.1893079748845 × 10E + 1 A   -0.4666605747342 × 10E-3   -0.2562053663833 × 10E-2    0.000000000000    B   -0.9219207744279 × 10E-5    0.1581186289720 × 10E-3    0.000000000000 C    0.9470840603680 × 10E-7   -0.5085463607551 × 10E-5    0.000000000000 D   -0.2946148007395 × 10E-7    0.7609034408556 × 10E-7    0.000000000000

The aberration diagrams generated in the actual type shift finder according to the first embodiment of the present invention configured as shown in Tables 1, 2, and 3 are shown in FIGS. 2A to 2C.

2A to 2C are aberration diagrams generated at each displacement end of the actual displacement finder according to the first exemplary embodiment of the present invention shown in FIG. 1, and FIG. 2A is a view showing spherical aberration, astigmatism, and Fig. 2B shows spherical aberration, astigmatism and distortion occurring in the middle stage, and Fig. 2C shows spherical aberration, astigmatism and distortion occurring in the telephoto end.

1 and 3, a practical variable displacement finder according to a second embodiment of the present invention will be described.

The actual variable displacement finder according to the second exemplary embodiment of the present invention has the same configuration as the lens configuration according to the first exemplary embodiment shown in FIGS. 1A to 1C. However, the actual variable displacement finder according to the second embodiment differs from the first embodiment in the thickness of the lens, the radius of curvature, the distance between the lenses, and the shifting distance at the time of shifting.

An exemplary value of the actual variable displacement finder according to the second exemplary embodiment of the present invention is shown in Table 4 below.

In Table 4, r is the radius of curvature, d is the thickness of the lens and the distance between the lenses, nd is the refractive index, v is the Abbe's number, and the angle of view (2ω) is 48.90 ° to 20.74 ° and the magnification is 0.37 × 0.87 ×. .

Face number  r (curvature radius) d (thickness, distance)  nd (refractive index) v (Abe number)  Remarks    One      ∞     variable      plane    2     7.594     3.50   1.49176     57.4     Aspheric surface    3    25.635     variable    4     9.009     2.50   1.49176     57.4    5    -8.017     variable     Aspheric surface    6      ∞    27.20   1.49176     57.4 Plane (primary imaging plane)    7      ∞     1.30       plane    8    13.165     4.10   1.49176     57.4      Aspheric surface    9   -36.868    17.00    10      ∞     0.00        plane

At the distances between the lenses of Table 4, the variable d1, d3, and d5 are shown in Table 5 for each variable stage.

      Wide-angle end (2ω = 48.90 °)      Medium short (2ω = 32.42 °)      Telescopic end (2ω = 20.74 °)     d1          9.599        3.102         0.000     d3          1.000        9.148        15.000     d5          4.898        3.247         0.499

Accordingly, according to Tables 4 and 5, the focal length f1 of the first lens 11 is 20.624 in the actual variable viewfinder according to the second embodiment of the present invention, and the second lens 12 The focal length f2 is 9.066, the focal length fw at the wide-angle end of the objective lens unit 10 is 7.600, the focal length ft at the telephoto end of the objective lens unit 10 is 17.600, and the objective The distance L from the telephoto end of the lens portion 10 to the first surface of the prism 20 from the first surface of the first lens 11 is 21.500.

Therefore, the variable L / ft = 21.500 / 17.600 = 1.222 of Condition 1, the variable L / f2 = 21.500 / 9.066 = 2.371 of Condition 2, and the variable f1 / fw = 20.624 / 7.600 = 2.714 of Condition 3, Satisfy conditional expression.

Here, aspheric lens coefficients of the lenses 11, 12, and 30 according to the second embodiment as Equation 1 are obtained as shown in Table 6 below.

r2  r5  r8 K   0.5764778303428                                                -0.5747239411743 × 10E + 2   -0.189379748845 × 10E + 1  A   -0.8151482867624 × 10E-3   -0.2787457656219 × 10E-2    0.000000000000     B    0.2021903525278 × 10E-3    0.2359220594991 × 10E-3    0.000000000000  C   -0.3095006797342 × 10E-4   -0.8977029908565 × 10E-5    0.000000000000  D    0.1469670997912 × 10E-5    0.1375808442729 × 10E-6    0.000000000000

3A to 3C show aberration diagrams generated in the actual variable displacement finder according to the first embodiment of the present invention configured as shown in Tables 4, 5, and 6.

3A to 3C are aberration diagrams generated at each variance end of the real-variable finder according to the second embodiment of the present invention shown in FIG. 1, and FIG. 3A is spherical aberration, astigmatism, and distortion occurring at the wide-angle end. 3B shows spherical aberration, astigmatism and distortion occurring in the middle stage, and FIG. 3C shows spherical aberration, astigmatism and distortion occurring in the telephoto end.

Hereinafter, with reference to the accompanying Figures 1 and 4 will be described in the actual type change finder according to a third embodiment of the present invention.

The actual variable displacement finder according to the third exemplary embodiment of the present invention has the same configuration as the lens configuration according to the first and second exemplary embodiments shown in FIGS. 1A to 1C. However, in the actual variable displacement finder according to the third exemplary embodiment, the thickness of the lens, the radius of curvature, the distance between the lenses, and the moving distance in the variable displacement are different from those of the first and second exemplary embodiments.

Example values of the actual type variable finder according to the third exemplary embodiment of the present invention are shown in Table 7 below.

In Table 4, r is the radius of curvature, d is the thickness of the lens and the distance between the lenses, nd is the refractive index, v is the Abbe's number, the angle of view (2ω) is 48.90 ° to 20.74 °, and the magnification is 0.37 × 0.97 ×. .

Face number  r (curvature radius) d (thickness, distance) nd (refractive index) v (Abe number)  Remarks    One      ∞     variable      plane    2    11.805     2.07   1.49176     57.4     Aspheric surface    3   120.889     variable    4    10.335     3.50   1.49176     57.4    5    -6.930     variable     Aspheric surface    6      ∞    27.20   1.49176     57.4 Plane (primary imaging plane)    7      ∞     1.30       plane    8    13.165     4.10   1.49176     57.4      Aspheric surface    9   -36.868    17.00    10      ∞     0.00        plane

At the distances between the lenses of Table 7, the variable d1, d3, and d5 are shown in Table 8 for each variable stage.

      Wide-angle end (2ω = 48.90 °)      Medium short (2ω = 32.42 °)      Telescopic end (2ω = 20.74 °)     d1         15.000        5.817         0.000     d3          1.000       11.482        19.932     d5          5.432        4.132         1.500

Therefore, according to Tables 7 and 8, the focal length f1 of the first lens 11 is 26.437 in the actual variable viewfinder according to the third embodiment of the present invention. The focal length f2 is 9.040, the focal length fw at the wide-angle end of the objective lens unit 10 is 7.600, the focal length ft at the telephoto end of the objective lens unit 10 is 19.098, and the objective The distance L from the telephoto end of the lens portion 10 to the first surface of the prism 20 at the first surface of the first lens 11 is 27.000.

Therefore, the variable L / ft = 27.000 / 17.600 = 1.414 in Condition 1, the variable L / f2 = 27.000 / 9.040 = 2.987 in Condition 2, and the variable f1 / fw = 26.437 / 7.600 = 3.479 in Condition 3, where Satisfy conditional expression.

Here, aspheric lens coefficients of the lenses 11, 12, and 30 according to the third embodiment as Equation 1 are obtained as shown in Table 9 below.

r2  r5  r8 K   0.9604615779383  -0.4064171661386 × 10E + 2  -0.1893079748845 × 10E + 1  A   -0.2247087036918 × 10E-3  -0.4737101644544 × 10E-2    0.000000000000      B    0.1214144131961 × 10E-4   0.4138742636356 × 10E-3    0.000000000000  C   -0.6868879548221 × 10E-6  -0.1786595487138 × 10E-4    0.000000000000  D    0.1284183652213 × 10E-7   0.3152335903889 × 10E-6    0.000000000000

4A to 4C show aberration diagrams generated in the actual type shift finder according to the first embodiment of the present invention configured as shown in Tables 7, 8, and 9.

4A to 4C are aberration diagrams generated at each variance end of the actual shift finder according to the third embodiment of the present invention shown in FIG. 1, and FIG. 4A is spherical aberration, astigmatism, and distortion occurring at the wide-angle end. 4B shows spherical aberration, astigmatism and distortion occurring in the intermediate stage, and FIG. 4C shows spherical aberration, astigmatism and distortion occurring in the telephoto end.

In the first to third embodiments, the surface number 10 is an eye point.

This invention consists of a simple structure and inexpensive material, which is compact and has good aberration characteristics from the wide end to the telephoto end.

Claims (6)

From the object side sequentially, An objective lens unit including a first lens group having positive refractive power and moving toward the object side when changing from the wide-angle end to the telephoto end, and a second lens group having positive refractive power and moving upward when changing from the wide-angle end to the telephoto end; An image inverted image formed by the objective lens unit on an object side surface, and an image inverting unit inverting the image; And It has a positive refractive power, and consists of a fixed eyepiece portion, which enlarges the image inverted by the image inversion, A real variable displacement finder characterized by the following conditional expression

Where: ft is the focal length at the telephoto end of the objective lens section, and L is the distance from the telephoto end of the objective lens section to the first surface of the upper inverted portion at the object side of the first lens. The method of claim 1, Real variable displacement finder characterized by the following conditional expression

Here, f2 is the focal length of the second lens group. The method of claim 2, Real variable displacement finder characterized by the following conditional expression

Here, f1 is a focal length of the first lens group, and fw is a focal length at the wide-angle end of the objective lens unit. The method of claim 1, And the first lens group comprises one lens, wherein the object side is convex positive meniscus, and the object side is aspherical. The method of claim 4, wherein The second lens group includes a single lens, and both sides are convex and the image side is aspherical. The method of claim 5, The eyepiece lens unit comprises a single lens, and both sides are convex, and the object side surface is an aspherical variable finder, characterized in that the aspherical surface.

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