JPS61252526A - Progressive multifocus spectacle lens - Google Patents

Abstract

PURPOSE:To decrease the shake of an image, to reduce the astigmatism of a peripheral part and to obtain a physiologically wide distant use visual field, a near use visual field and a wide intermediate progressive band visual field by constituting an aspherical surface as a specified power-function. CONSTITUTION:As for a progressive refracting surface, the respective functions are not determined in each part, the whole progressive refracting surface is determined as one function, and to put it concretely, it is constituted with an n-power function shown as an equation. In this regard, when determining both its shapes, they are determined by executing the evaluation of an astigmatism with regard to a beam passing through an eye-ball winding midpoint of an eye for wearing the lens. By grasping the progressing refractive surface as one function, its surface shape becomes smooth, the astigmatism can be decreased, the shake of an image can be suppressed remarkably, and also a new evaluating method which is called as a spherical aberration spot method is utilized for evaluating the shape of an image. This spherical aberration spot method is a method for making parallel rays incident on the whole surface of a lens L to be inspected and seeing the spot diaphragm of its rays at the place of a prescribed distance P' from the rear surface of the lens. In this way, the shake of an image is decreased remarkably, also the astigmatism of the peripheral part is reduced and a wearing sense and a use sense of the titled lens become better.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a progressive multifocal eyeglass lens, and in particular has a wide distance portion, a wide near portion, and a relatively wide intermediate progressive band portion connecting these. The present invention also relates to a progressive multifocal eyeglass lens that minimizes image blurring that occurs when the line of sight of the wearer's eye moves.

(Prior Art) There have been many proposals and practical applications of progressive multifocal lenses for eyeglass lenses. In particular, the peripheral visual field image in static vision through the distance and near vision areas, the visual field image through the peripheral area, or the visual field image of the eye to be worn from the distance vision area through the intermediate progressive zone to the near vision area. Improvements to so-called "image wobbling" such as distortion, distortion, and undulation of visual fields caused by movement of the line of sight were made in the Special Publication Publication No. 49-35.
No. 95 and Japanese Patent Publication No. 52-20211. The feature of both of these patents is that in order to make the difference between the refractive surface curvature of the distance vision part and the refraction surface curvature of the near vision part closer in the peripheral part, the peripheral curvature becomes stronger in the distance part as it moves away from the principal meridian. However, in the near vision area, on the other hand, the distance from the principal meridian weakens.

With this configuration, although the distance portion and the near portion are narrower than in other conventional examples, it is possible to reduce the curvature of the image in the peripheral portion.

On the other hand, as a technology in contrast to both of the above patents,
-53570 can be mentioned.

A feature of this technology is that each of the refractive surfaces of the distance and near vision sections is formed into a substantially spherical surface, thereby providing optically wider distance and near vision regions compared to those of the above-mentioned patents. Furthermore, as a countermeasure against "image wobbling", the main axis direction of residual astigmatism in the peripheral area is set to the vertical direction.

(Problems to be solved by the present invention) The problems in Japanese Patent Publication No. 57-5357'0 are as follows:
The distance vision area and the near vision area are defined optically (optical means as measured by an optical instrument such as a lens meter, etc.) In contrast, the following describes how the wearer visually and physiologically sees the image. However, in the peripheral part i outside these areas, astigmatism occurs significantly and is measured as a large degree of cylindricity even in optical measurements.

However, the cylindrical axis direction in the peripheral area is aligned horizontally or vertically, so "image wobbling" is not felt so much.

However, in actual wearing, this peripheral astigmatism makes it almost impossible to see the peripheral area.

Furthermore, when using the intermediate progressive zone or the near vision zone, the peripheral visual field is perceived as an image that is hardly focused on the retina of the recipient eye. This out-of-focus state in the periphery already gives a sense of discomfort, and is said to cause a significant slowdown in reading and deciphering text in particular. Additionally, this peripheral out-of-focus state is physiologically perceived as a narrowing of intermediate and near vision. In other words, in the intermediate and near areas, the optically good image is widely measured, but in the peripheral area beyond this, the image is optically significantly poor, so physiologically, the intermediate and near areas are measured. It has the disadvantage that the field of view feels narrow.

On the other hand, the above-mentioned Special Publication No. 49-3595 and Special Publication No. 52-2
Regarding No. 0271, compared to the above-mentioned Japanese Patent Publication No. 57-53570, the distance and near vision areas are optically narrower, but the amount of astigmatism in the peripheral areas is smaller, so it feels physiologically wider. .

However, the amount of astigmatism in the periphery is still large, and although image curvature in static vision through distance and near vision has been improved, "image wobbling" that occurs when the line of sight moves still remains. It cannot be said that it has been sufficiently improved. These problems are caused by the fact that when the principal meridian is cut at a cross section perpendicular to the principal meridian, each cross-sectional curve remains an aspherical shape consisting of a quadratic curve containing at least one circular shape. are doing. Another reason is that the aspherical refractive surface of the conventional example has a surface shape based on the pursuit of what is called a "navel point" in differential geometry. Of course, optically as much as possible
Although it is preferable that the point be the navel point, it cannot necessarily be said to be appropriate from a physiological viewpoint.

Furthermore, in all of the conventional examples described above, the surface shape of the progressive refractive surface is determined by giving a distance portion, a near portion, an intermediate progressive portion, and a peripheral portion each by one function, and defining these boundary portions under certain conditions. It had a kind of polyhedral structure, with smooth ties.

By the way, conventional methods for evaluating a lens with a determined surface shape include evaluating the curvature of an image of a grating object caused by the lens, and evaluating the maximum curvature (Tear) and minimum curvature (Tmin) of each minute region of the refractive surface. (n: refractive index of the lens), and the curvature difference As within the micro region is determined. In other words,
The astigmatism due to the light rays incident in the normal direction to this minute area was determined, and the astigmatism distribution was determined over the entire refractive surface. However, when considering the actual wearing condition of the lens, it is not practical to view objects using light rays from the normal direction, and it cannot necessarily be called a correct evaluation method. Furthermore, conventionally, there has been no sufficient evaluation method for "image wobbling."

(Object of the present invention) The present invention was made to eliminate the above-mentioned conventional drawbacks, and its purpose is to significantly reduce "image wobbling" and to reduce astigmatism in the peripheral area. The object of the present invention is to provide a new progressive multifocal eyeglass lens which can physiologically provide a wide distance visual field, a wide near visual field, and a wide intermediate progressive zone correction field.

(Structure of the Present Invention) A structural feature of the present invention is that instead of determining each function for each part of the progressive refractive surface as in the conventional case, the entire progressive refractive surface is determined as one function.

More specifically, It is an n-th power function expressed as .

In addition, when determining the surface shape, we established and adopted a completely new evaluation method in which the astigmatism of the light ray passing through the midpoint of eyeball rotation of the recipient eye was evaluated. Regarding the smoothness of the refractive surface, it should be noted that the spherical aberration sport method was adopted. Furthermore, it is possible to provide a progressive multifocal eyeglass lens that has less astigmatism in the peripheral area and is more comfortable to wear and use.

(Explanation of Principle of the Present Invention) FIG. 1 is a perspective view schematically showing a progressive refractive surface of a progressive multifocal eyeglass lens according to the present invention. In this embodiment, the progressive refractive surface is configured as the front refractive surface of the lens, and the rear refractive surface is configured as a spherical or toroidal surface. As a result, the spherical refractive power, cylindrical refractive power, and cylindrical axis angle of the lens are determined by changing the radius of curvature of the rear refractive surface.

In the present invention, the front refractive surface may be a spherical or toroidal surface, and the rear refractive surface may be a progressive refractive surface. The following explanation will be made based on the case where the front refractive surface is a progressive refractive surface as described above, and FIG. 1 shows only the progressive refractive surface.

In Fig. 1, in order to make the explanation easier to understand, part A is the distance part, part C is the near part, part B is the intermediate progressive zone, and part D is the peripheral part. , in the present invention, the surface shape of each part is not given as an individual function as in the conventional example, but
The entire progressive refractive surface S is given as one p function described below.

Now, as shown in Figure 1, 3 of X-Y-2 is placed on the progressive refracting surface.
Consider a dimensional coordinate system. The value of 2 at the point on the progressive refractive surface S is
It is given as a function of X and y, Z=f (x-y). This means that, conversely, the shape of the surface S can be uniquely determined by continuously connecting Z given as Z=f(x-y).

Generally, a curved surface can be expressed as an n-th power function. The advantage of considering the progressive refracting surface as a single function in this way is that the surface shape becomes smooth, astigmatism can be reduced, and image blur can be significantly suppressed. However, even in the above function, if the order n is too small, the B part becomes 0
On the other hand, if the order n is increased, optical smoothness decreases and astigmatism increases.

Therefore, a specific example will be shown below regarding the range of the optimum order n. First, a method for evaluating astigmatism of a lens having a progressive refractive surface obtained as one of the functions described above will be described.

FIG. 2a is a diagram schematically showing the evaluation method.

This evaluation method calculates astigmatism for a light ray β that passes through a spectacle lens L and passes through a rotation point Q of the eye E to be worn, using the following formula.

FIG. 2b is a coordinate system showing the relationship between the incident ray β on the refracting surface R and the refracted ray β'. An orthogonal coordinate system x-y-z whose Z-axis is the normal N to the surface R, and an orthogonal coordinate system x-y-z whose Z-axis is the direction of incidence of the incident ray l.

The refracted ray l' of the incident ray l refracted by the curve R is Z'
Consider the orthogonal coordinate system x'-y'-2' with axes. Then, the direction of the incident ray β with respect to the normal N is Φ(i),
Let the direction of the refracted ray β' be Φ(W). If the refractive index of the refractive medium on the side of the incident ray l is n1 and the refractive index of the refractive medium on the refractive surface R is n', the ratio of the two is r=n/n' The refractive surface number is j (j=1.2...n : For eyeglass lenses, if j = 1.2), Ωj 8 γj C, O8Φj (i) + cos
If Φj (wi) is the curvature of the vertical component of the refracted wavefront of the refracted ray L', KI J (w) is KB (kυ = TJ Kat (i> 10).
K5j The curvature of the parallel component of the refracted wavefront of the refracted ray l' is K IIJ (W) = TJ Co52ΦJ (i
) K t l J (i)/cos”Φ, Cvr)+
Ωj Kth J /cos'ΦJ (W) On the other hand, the torsion coefficient τJ
(w> is τj(w)=r> τJ(i) cosΦJ (i)
/cos Φ'J (w)+Ωj τJ /(:0
82ΦJ (w), respectively. Next, the principal curvature is determined using differential geometry based on each of the above components. M4τ2J(W)) K3□(W) are respectively ΦJ (w) =HJ (w) +ξJ (w)
It is expressed as ξSJ (w) =HJ (ν))−ξ, (W). Also, the slope of the principal curvature is sign (τ=
(w) ). Using the ray β' emitted from the j-th refractive surface R1 as the incident ray, the same calculation as above is performed for the j+1-th refractive surface, and the extremum value at the final refractive surface is Φ(W), KS ( W), the image distance from the exit point of the final surface is given as 1/f 5=Ks (w) 1/fΦ= as Φ (W), and the image astigmatism As is As= (1/f s -1/ fΦ) X100O (unit: diopter).

The above image distance 1/fs in the progressive multifocal lens of the present application,
An optical schematic diagram of 1/fΦ is shown in FIG. 2C. The J1#th refractive surface is a progressive refractive surface, and the (J+1)th refractive surface is a spherical surface. In this application, J=1, that is, a two-surface configuration in which the progressive refractive surface is the first surface and the spherical surface is the final surface.

(Evaluation of Prior Art) FIG. 3 shows the astigmatism contour of a conventional progressive multifocal lens based on the above evaluation method. In the lens used here, the front refractive surface is a progressive refractive surface, the distance zone A is spherical (or aspherical), the near zone C is spherical (or aspherical), and the intermediate progressive zone B is for near vision. It is configured to form a ``navel point'' according to the power, and the peripheral portion has a surface shape that smoothly connects these ASB and C portions under a certain predetermined condition. The radius of curvature of the rear refractive surface is rb = 100 m/m, the lens center thickness is t = 2 m1 m, the refractive index of the lens is N f = 1.500, and the distance power of the lens is S.
=0.00 dayopter, near addition power Add=2. O
It is a lens with O diopter.

The contour lines shown in Figure 3 are astigmatism points for each part of the used light beam on the lens surface (progressive refractive surface) due to parallel incident light beams when the eye to be worn rotates around the rotation point and views from a distance through various directions of the lens. These are contour lines connecting the amounts of aberration. 1 in the figure.
A contour line marked with 0 means that the astigmatism is 1.0 diopter. The contour lines are 0.1.0.5.1.0.1.5.
2.0 dayopter is shown (0.1 dayopter first contour line is shown only for near vision area C. The same applies hereinafter).

From the results shown in Figure 3, this conventional lens has zero astigmatism in most of the distance zone A, and zero astigmatism in the near zone C, albeit within a narrow range. There is. In comparison, astigmatism of up to 2.0 dp appears at the periphery, and the play between each contour line is also greatly disturbed. This shows that the surface shape of the peripheral area is extremely poor.

Karu.

(First Example) FIG. 4 is an astigmatism contour diagram of the first example of the progressive multifocal eyeglass lens according to the present invention. In the first embodiment, the front refracting surface is a progressive refracting surface as in the conventional example described above, and the surface shape is such that the order n is n in the linear power function of the above equation (1).
It is configured with a surface shape where =10. The other constituent factors, namely the radius of curvature rb of the rear refractive surface, the refractive index of the central thickness t of the lenses, N1, the near addition power Add, and the distance power S are as described above.

It has the same value as the conventional example (hereinafter, in the second to fourth embodiments, only the order n is changed, and other constituent factors are the same as in the conventional example).

Here, the astigmatism contour lines of the first embodiment of the present application shown in FIG.
When compared with that of the conventional example shown in the figure, it can be seen that there is less astigmatism (the area over which each contour line runs) around the periphery. Furthermore, the intervals between each contour line are wide and the way they run is smooth, which clearly shows that the surface shape is extremely smooth.

As mentioned above, physiological evaluation is required in the evaluation of spectacle lenses, especially progressive multifocal lenses. For example, visual acuity 1
．． When the visual acuity of 2 people is measured by wearing a cylindrical lens with C = + 1.0 dayopters, the person's visual acuity is 0.7.
It decreases to about 0.8, but never reaches zero.

As a result of various wearing tests, the inventor has found that (1) an astigmatism of 0.25 to 0.50 diopter does not cause discomfort to the wearer.

■ Gradual addition of astigmatism (the contour interval of astigmatism changes gradually) does not cause any discomfort to the wearer.

(2) It is possible to perceive that the image is out of focus when the astigmatism is around 1.0 diopter.

From the above physiological wear test results, Fig. 3 and vg4
Comparing the figures, in the present invention (Fig. 4), the several-point aberration contour line is narrower to 0.50 dayopter near the progressive zone B above the near BC, as in the conventional example, but the pupil diameter of the presbyopic wearer ( For example, if we consider the diameter of 4 m1 mΦ), astigmatism of 0.50 diopter is not a physiological problem. This means that even if a surface with an ideal umbilicus point configuration with zero astigmatism is used in the conventional example, it is possible to
When considering a lens with an addition power of 2.0 diopters at a position of , 53Dptr, but it did not pose any physiological problem, and therefore, the present invention.

This confirms that the astigmatism of 0.50 diopter in the progressive band portion is not a problem.

The astigmatism contour lines around the progressive zone are as shown in the conventional example (Fig. 3).
Compared to this, the lens according to the present invention (FIG. 4) has a gentler slope, and in particular, the astigmatism of 1.0 dayopter, which is the evaluation boundary in the out-of-focus state, has been significantly improved. Also, when comparing the near vision area C optically using the 0.5 day-one-astigmatism contour line, it seems that the conventional example (Fig. 3) is wider, but from a physiological point of view as mentioned above, The present invention (FIG. 4) has the advantage that the slope and distribution of the astigmatism distribution line are smoother and can be perceived as a wider near field of vision. However, the contour line area of 0.1 diopter (zero diopter area: shaded area) is narrower than in the conventional example.

This is because the order n is small.

Next, the present invention will be compared with the conventional example regarding "image wobbling". In the present invention, a new evaluation method called the spherical aberration spot method was established and utilized for evaluating "image wobbling." This spherical aberration spot method has conventionally been applied as a method for observing the aberration state of a spherical lens, but as schematically shown in FIG. This method involves viewing the spot diaphragm of the light beam at a certain distance P' from the rear surface of the lens. When this is used to evaluate a lens with a distance power of 0.00 diopters and a near power of 2-00 diopters, as in the conventional example and the present example, the evaluation surface is, for example, P' =
500 m/m, only the rays passing through the near optical center are converged on the evaluation surface, and the degree of diffusion increases as the distance from the near optical center increases in the peripheral area, progressive zone, and distance area. A diagram is obtained. and,
This irregularity in spot diffusion indicates that the surface shape is less smooth. The inventor's wear test revealed that there is a correlation between the irregularity of the spot diagram and the perceived amount of "image wobbling" in the wear test.

Figure 6A shows the evaluation surface distance P'=400, and Figure 6B shows the evaluation surface roughness! A spot diagram of a conventional example when P'=500 is shown.

In addition, FIGS. 7A and 7B each show the evaluation surface distance “P”.
' = 400m/m, P' = 500m/m
1 shows a spot diagram of a lens according to the invention;

As can be seen from FIGS. 68 to 7B, the surface shape of the peripheral portion of the present invention is extremely smooth compared to the conventional example, which indicates that "image wobbling" is extremely small.

(Second Example) Figure 8A is an astigmatism distribution diagram when the order n of equation (1) is set to n=16, and Figure 8B is a spherical aberration spot in this second example. Shows a diagram.

In this second embodiment, the astigmatism distribution below 0.1 diopter in the near vision area C is relatively narrow. When optically measuring refractive power in the near vision area with a lensmeter,
Since astigmatism of 0.1 diopter or more is visible, the narrow range of 0.1 diopter is a disadvantage. Regarding the astigmatism distribution in the near vision area, as the order becomes lower, the astigmatism region of low diopter becomes narrower, and although there is no physiological problem, optically, the order n=16 can be said to be the practical lower limit. Further, as shown in FIG. 8B, it can be seen from the spot diagram that the distribution is slightly curved from the peripheral area to the distance area, and there is a slight "image wobbling".

(Third Embodiment) Figure 9A shows the third embodiment of the present invention.
), the order n of the equation is n=20, rb = 100m/
m5S=0.00 dayopter, t=2m/m,
Add=2. OO diopter, Nji! =1.500
FIG. 9B is an astigmatism contour map of a lens having a progressive refractive surface, and FIG. 9B is a spot diagram thereof.

Note that the coefficient a in this embodiment has a value shown in αβ in 'fal1 diagram. Figure 11 shows the values of α in the horizontal rows and the values of β in the vertical columns, and is expressed as a combination of these α and β. For example, α=2
, the coefficient a23 given by n=3 is as,=-0,
This shows that there are 512x 10' = -51,2 te. The progressive refractive surface of the present invention is shown in FIG. It can be said that it is sufficiently practical optically. It can also be seen that the spot distribution in the spot diagram of FIG. 9B is extremely smooth, and there is extremely little "image wobbling."

(Fourth Example) FIG. 10A is an astigmatism contour diagram of a lens having a progressive refractive surface with the order n=24 in equation (1),
FIG. 10B is a sports/) diagram of the lens.

The width of the 0.1 day optic one-astigmatism contour line in the near area C is wider than that of the third embodiment, but the distribution of the astigmatism contour line in the peripheral area is different from that in the first to third embodiments. It gets worse compared to the previous one, and the smoothness of the surface shape at the periphery decreases.
It can be seen that the amount of astigmatism increases. This is clearly seen in the spot distribution in the spot diagram in Figure 10B.
It can be seen that there is a lot of "image shaking". This increase in astigmatism in the peripheral area and increase in "image wobbling" become more pronounced as the order becomes higher, and it can be said that the optically and physiologically practical limit is at order n=24.

Regarding the coefficient a, the near addition change αβ Add, the curve value (curvature radius rb) of the rear refractive surface, that is, the distance power S and/or the cylindrical power and its axis angle, and the order n of the progressive refractive surface It changes depending on.

I hear it. a when the order n is 10≦n≦24.

are all -102≦ao3, a12, a21 o
ra. It shows that it has a coefficient of ≦102. Note that since the progressive refractive surface of the present invention is constituted by an even function, as described above, all where α is an odd number takes the coefficient value a12=00. Table 2 should be interpreted to include this case. Also, astigmatism.

From the viewpoint of removal, the amount of astigmatism does not become as large as the order n of equation (1).

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the relationship between the progressive refraction surface and the coordinate system;
FIG. 2 is a diagram for explaining the astigmatism evaluation method of the present invention,
3 is an astigmatism contour diagram of the comparative conventional example, FIG. 4 is an astigmatism contour diagram of the first embodiment of the present invention, and FIG. 5 is a diagram for explaining the spherical aberration spot diagram method. 6A
Figure 6B is a spot diagram of the conventional example, and Figure 7A is a spot diagram of the conventional example.
Figure 7B is a spot diagram of the first embodiment, Figure 8A is an astigmatism contour diagram of the second embodiment of the present invention, Figure 8B is its spot diagram, and Figure 9A is the spot diagram of the third embodiment of the present invention. FIG. 9B is a spot diagram thereof, FIG. 10A is an astigmatism contour diagram of the third embodiment of the present invention, 1st (FIG. 18 is its spot diagram, 11L. ...Lens, S...
... Progressive refractive surface, A. Old distance vision part, B... Intermediate progressive zone part, C... Near vision part, D... Peripheral part.

Claims (2)

[Claims] (1) Either the front refractive surface or the rear refractive surface has a distance portion, a near portion, and an intermediate portion where the refractive power of the surface changes continuously from the distance portion to the near portion. In a progressive multifocal lens composed of an aspherical surface having a progressive zone and other refractive surfaces constructed as spherical or toroidal surfaces, the aspherical surface is defined as Z=Σ^α^+^β^=^n_0≦α,β ≦na_α
A progressive multifocal eyeglass lens configured as a power function of _β・x^α・y^β (a_α_β: coefficient) 10≦n≦24. (2) The progressive multifocal eyeglass lens according to claim (1), wherein the order n is 16≦n≦24.