KR100470381B1 - The gradient index multifocal lens - Google Patents

Abstract

The present invention relates to a progressive multifocal lens having an optically effective curvature surface over the entire surface of a lens including a far end, a near end, and a progressive part so that an entire field of view can be secured over a long distance, a short distance, and a middle part thereof. It is about. According to the present invention, the curvature of the progressive portion 14 is configured to gradually decrease in consideration of the difference in curvature of the far end portion 12 and the near portion 16 and the vertical width of the progressive portion 14. To this end, in generating the vertical curvature of the progressive portion 14, an arc formed by two curvatures at any element position c2 to which two curvatures a2 and a3 are connected is configured to be inscribed. In addition, in generating the horizontal curvature of the progressive portion 14, the horizontal curvature radius (A ') of the progressive portion 14 forming a boundary line with the original portion 12, and the near portion 16 and the boundary line It forms so that the shape of the horizontal curvature radius B 'of the progressive part 14 to form may correspond. According to the present invention having such a configuration, geometric problems such as protrusions can be solved, and the available optical surface of the lens can be expanded.

Description

Progressive multifocal lens

The present invention relates to a progressive multifocal lens, and more particularly, to improve the geometric problems inevitably generated when minimizing the areas of astigmatism and distortion in order to enlarge the effective optical curvature area. The present invention relates to a progressive multifocal lens that is suitably combined in consideration of the curvature of.

1 and 2 show the configuration of a progressive multifocal lens according to the prior art, and FIG. 3 shows a schematic cross-sectional view of the curvature connected according to the curvature forming method according to the prior art, and FIG. The curvature configuration formed according to the curvature forming method by the technique is shown in schematic perspective.

In general, as shown in FIG. 1, the progressive multifocal lens 10 includes a far vision viewing portion 12 (hereinafter, referred to as a far-field portion) and an area for viewing an intermediate distance (see FIG. 1). 14: an intermediate vision viewing portion (hereinafter referred to as a "progressive portion") and an area for near vision (16: near vision viewing portion (hereinafter referred to as "near portion")) and the like. Here, the intermediate distance refers to a distance of approximately 50cm to 2m, the far distance often refers to a distance farther than this, and the near distance is often closer to this distance, but there is no definite definition.

Therefore, as is well known, the conventional progressive multifocal lens 10 manufactured to simultaneously correct myopia and hyperopia may include the far end 12, the near end 16, and the far end 12 and the near end. It consists of a progressive portion 14 which can see the intermediate distance of 16, and the user can optionally select these root portions 16, the circular portion 12 and the progressive portion 14 in the position and direction of the pupil as needed. By selectively selecting any one of them, it is possible to secure a variety of watches from near to far.

However, the progressive multifocal lens 10 described above has the progressive portion 14 for the purpose of continuously forming the raw portion 12, the progressive portion 14, and the near portion 16 while maintaining the shape of the lens. It is formed by varying the vertical curvature (hereinafter referred to as vertical curvature) and the horizontal curvature (hereinafter referred to as horizontal curvature) at arbitrary element positions. Therefore, as shown in FIG. 2, an unknown region such as the astigmatism portion 20 and the distortion aberration portion 22 occurs at both peripheral portions of the progressive portion 14 and the root portion 16 located on the center line. do.

As such, when the amount of aberration is reduced to maintain the shape of the available general lens, the area of the progressive portion 14 and the approximation portion 16 is narrowed, so that the astigmatism portion 20 and the distortion aberration portion ( As the unknown area as shown in (22) is enlarged, a structural problem occurs that prevents proper visibility due to image distortion. In order to solve this problem, the following solutions have been proposed.

That is, the vertical curvature and the horizontal curvature of the progressive multifocal lens 10 may be formed to be the same, and the progressive part 14 gradually increases the difference between the curvature of the far end part 12 and the curvature of the near part 16. By changing the shape to have been proposed to allow the circular portion 12 and the near portion 16 can be formed continuously.

However, the above-described progressive multifocal lens of the prior art has the following problems.

When the vertical curvature is formed to have a multifocal function of the lens 10, when the curvature of the progressive part 14 is gradually changed by increasing and decreasing the curvature of the optical lens, the surface of the lens 10 may be geometrically formed. Problem occurs. As shown in FIG. 3, the vertical curvature at the vertical center line of the lens 10 is not smoothly connected, resulting in an inflection point a on the surface. Such inflection points deteriorate the function of the lens.

In addition, as shown in Figure 4, in using the horizontal curvature in the same manner as the vertical curvature at any position of the progressive portion 14, when using only one curvature, the progressive portion ( There is a problem in that the protrusion b is formed by the accumulation of the curvature change of 14), thereby impairing the function of the lens.

Accordingly, the present invention has been made to solve the problems of the prior art as described above, an object of the present invention is to solve the geometric problems caused when minimizing the astigmatism and distortion aberration occurred in the conventional progressive multifocal lens To compensate, it is to provide a progressive multifocal lens that combines spherical and aspherical surfaces to attempt various curvature changes.

1 is a front view of a progressive multifocal lens according to the prior art.

2 is a front view of a progressive multifocal lens according to the prior art;

Figure 3 is a schematic cross-sectional view showing the curvature connected according to the curvature forming method according to the prior art.

Figure 4 is a schematic perspective view of the curvature configuration formed according to the curvature forming method according to the prior art.

5 is a schematic cross-sectional view showing the curvature connected according to the curvature forming method according to the present invention.

6A and 6B are cross-sectional views showing a curvature shape of the progressive portion at the boundary line.

** Description of the symbols for the main parts of the drawings **

10: progressive multifocal lens 12: circular part

14: progressive part 16: root part

a2, a3, a4: curvature b1, b2, b3: center of curvature

c1, c2, c3: Element positions A, A ': Radius of curvature of the progressive part at the boundary line with the circular part

B, B '; Radius of curvature of progressive part at boundary line with near part

According to a feature of the present invention for achieving the object as described above, the present invention is a far-end portion that can see the distance, the near-side portion that can see the near, and the progressive to see the intermediate distance between the far-end portion and the near portion In a progressive multifocal lens composed of negative parts, the curvature of the progressive part gradually decreases in consideration of the difference between the curvature of the circular part and the curvature of the near part, and the vertical width of the progressive part; When two curvatures having different magnitudes among the vertical curvatures of the progressive part are connected at one point, the center of the curvature having a small radius is placed on a line connecting the center of the one point and the curvature having the larger radius. An arc formed by two curvatures is configured to be inscribed; An aspherical surface is applied to the entirety of the progressive part such that the horizontal curvature of the progressive part forming the boundary line with the root portion and the horizontal curvature of the progressive part forming the boundary line with the far-end part are coincident with each other.

The aspherical surface is also applied to the root portion and the far portion.

According to the progressive multifocal lens of the present invention having such a configuration, the astigmatism and distortion aberration are reduced, and at the same time, the geometrical problems of the lens can be solved.

Hereinafter, a preferred embodiment of a progressive multifocal lens according to the present invention having the configuration as described above will be described in detail with reference to the accompanying drawings. The same thing as the prior art will be described using the same reference numeral.

FIG. 5 is a schematic cross-sectional view showing a curvature configuration connected according to the curvature forming method according to the present invention, and FIGS. 6A and 6B show a curvature shape of a progressive portion at a boundary line in cross section.

As shown in these figures, if an arc formed by two curvatures is inscribed at any point where two different curvatures are connected, an inflection point does not occur. In detail, as shown in FIG. 5, when the curvature a2 and the curvature a3 are connected at an arbitrary point c2, when the center of the curvature c3 is positioned on a line connecting the c2 and the center b2 of the curvature a2, the curvature a2 and a3 are inscribed so that no inflection point occurs at any one point c2. In addition, since the two arcs are inscribed in the same manner in the connecting portion of the progressive portion 14 and the near portion 16, the occurrence of an inflection point can be prevented.

First, two horizontal curvatures may be formed at any one point. That is, as shown in FIG. 5, the curvature a1 may be formed and the curvature a2 may be formed because the arbitrary point c2 is a boundary where the curvature a2 and a3 are in contact with each other.

When the point where the first horizontal curvature of the progressive part 14 is to be selected in the area where the raw part 12 and the progressive part 14 are connected is c2, the horizontal curvature of the arbitrary element position c2 is set to a2. Once specified, the horizontal curvature at any element position c3 should be set to a3. Similarly, if the horizontal curvature of the arbitrary element position c2 is set to a3, the horizontal curvature of the arbitrary element position c3 will be set to a4.

Also, the center of the horizontal curvature of the element position c2 is not on the line connecting c2 and b2, but on the horizontal line passing through c2. In other words, they are spaced apart by h perpendicularly to c1 and on the line passing through c2.

However, if the curvature of the progressive portion 14 is gradually changed by increasing and decreasing the curvature of the optical lens at the time of forming the vertical curvature, a geometrical problem occurs on the surface of the lens 10. As shown in FIG. 3, the vertical curvature at the vertical center line of the lens 10 is not smoothly connected, resulting in an inflection point a on the surface. Such inflection points deteriorate the function of the lens.

As such, when the curvature is formed in a manner in which the arc is inscribed, geometric problems such as an inflection point will not occur. However, when the lens is manufactured by forming a horizontal curvature with only one curvature selected as described above, the edge of the lens is raised convexly, as shown in FIG. 4 due to the curvature that is changed downward from the center of the lens. In addition, the available area that can be used optically is significantly reduced, and aberrations may not serve as a normal lens.

As shown in FIG. 6A, the curvature radius A of the progressive part at the boundary between the raw part and the progressive part is increased to correspond to the curvature radius of the raw part, and the curvature of the progressive part at the boundary between the near part and the progressive part. The radius B becomes small corresponding to the radius of curvature of the near portion. As such, the sharp difference in the radius of curvature between the boundary region of the far end and the near region does not cause a geometric problem in the region adjacent to the center vertical line of the lens, but protrudes convexly as it goes to the remaining peripheral region. Geometric problems may arise.

Lenses can be roughly classified into spherical lenses and aspherical lenses according to the magnitude of the curvature. In the present invention, the above-mentioned geometrical problems are minimized by replacing the shape of the lens with an aspherical lens having a small curvature of the lens.

Aspheric lenses can vary the curved shape of the lens in addition to the ability to increase the top view of the image or to prevent image distortion when compared to spherical lenses having the same focal length. There is an advantage. Therefore, the above-mentioned geometrical problems can be compensated for by applying the feature of the aspherical lens, which can change the curved shape of the lens, to the progressive multifocal lens.

If you break it down in detail: The curved shape of the spherical lens can be defined by the radius of curvature, but the shape of the aspherical lens is defined by the aspherical formula as follows.

At this time, z (r) is a Seg (Sag) value for an aspherical surface at height r from the optical axis,

,

c is the curvature of the vertex, that is, the curvature of the lens surface from the optical axis,

k is the conic constant, where an ellipsoid with k> 0 short diameter as the optical axis

k = 0 sphere

0> k> -1 Ellipsoid with long diameter as optical axis

k = -1 parabola

k <-1 hyperbolic

A, B, C, etc. mean aspherical coefficients.

Returning back to FIG. 5 and continuing, the curvature a2 or curvature a3, which can be taken at an arbitrary predetermined position c2, is substituted into the above-described aspherical curvature c, and the conic constant k and aspherical coefficient A By appropriately adjusting B, C ...), various aspherical shapes can be obtained. That is, when the aspherical surface is applied to the entire progressive portion and the k value and the aspherical coefficient are gradually changed, the height of the protrusion generated in the spherical shape of the spherical lens is removed or minimized.

This is solved by configuring the horizontal curvature radius A 'of the progressive part forming a boundary line with the circular part and the horizontal curvature radius B' of the progressive part forming a boundary line with the near part in FIG. 6B.

In the above, the present invention has been described with reference to specific preferred embodiments, but the present invention is not limited to the above-described embodiments, and those of ordinary skill in the art belong to the present invention without departing from the gist of the present invention. By the various changes can be made to be possible.

As described above, according to the configuration of the present invention, the following effects can be expected.

Through various curvature changes, the astigmatism and distortion aberrations inevitably generated to maintain the shape of the lens are significantly reduced, and the effective optical curvature surface is enlarged, thereby reducing the unstable state of the dynamic field of view.

In addition, geometrical problems, such as inflection points and protrusions caused by the vertical curvature and the horizontal curvature coincide, are solved, and an effect of improving the function and quality of the lens is expected.

In particular, the focal point is continuously formed in the boundary area between the far end and the progressive part, and the near and the progressive part, thereby improving the stability and reliability of the product.

Claims (2)

In a progressive multifocal lens composed of a far-field unit for viewing the far field, a near-field view for the near field, and a progressive unit for viewing the intermediate distance between the far-field unit and the near field, The curvature of the progressive portion gradually decreases in consideration of the difference between the curvature of the raw material portion and the curvature of the near portion, and the vertical width of the progressive portion; When two curvatures having different magnitudes among the vertical curvatures of the progressive part are connected at one point, the center of the curvature having a small radius is placed on a line connecting the center of the one point and the curvature having the larger radius. An arc formed by two curvatures is configured to be inscribed; The aspherical surface is applied to the whole of the progressive portion so that the horizontal curvature of the progressive portion forming a boundary line with the near portion and the horizontal curvature of the progressive portion forming the boundary line are provided with a non-numeric shape. Focus lens. The progressive multifocal lens according to claim 1, wherein the aspherical surface is also applied to the near portion and the far portion.