JPH0346616A - Progressive focal lens - Google Patents

Abstract

PURPOSE:To make a light view area wider although an intermediate part is short and to reduce the distortion and fluctuation of an image at the periphery by increasing the radius of longitudinal curvature below the intermediate part and above a short-distance part along a cross-sectional curve from the intersection with a main meridian curve and then decreasing it. CONSTITUTION:The vertical section of a refracting surface is so shaped so that the value of radius of vertical curvature increases along the cross section curve from the intersection with the main meridian curve MM' above a long- distance part F, decreases below the long-distance part F, and is nearly constant along the cross section curve at the center part. Then the radius of the vertical curve decreases from the intersection with the main meridian curve MM' above the intermediate part P, increases along the cross section curve from the intersection with the main meridian curve below the intermediate part and above the short-distance part, and then decreases. Even when the intermediate part as a progressive zone becomes short, the intermediate part having an aberrationally balanced light view area which is wide enough for practical use is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a progressive lens for use as an aid to accommodative power of the eye.

[Prior art]

The upper distance vision correction area (
There are various progressive focus lenses that have a lower near vision correction area (hereinafter referred to as the near vision area), and a progressive area (hereinafter referred to as the intermediate area) in which the refractive power changes continuously between the two. It is being

In a progressive focal length lens, generally, when a wide clear vision area is secured between the distance and near vision areas and a progressive zone is connected between them, lens aberrations will be concentrated in the side areas of the progressive zone. The presence of the area causes image distortion, including blurring of the image, and gives a bad impression to the wearer as the image shakes when the line of sight moves.

In order to solve such problems with visual characteristics, known progressive focus lenses have been designed and evaluated from various viewpoints. Regarding the shape of the lens surface, the line of intersection between the cross section along the meridian running perpendicular to the center of the lens surface and the object-side lens surface is used as a reference line to express specifications such as the addition power of the lens. It is also used as an important reference line in the design of In addition, even in progressive focus lenses where the near vision area is arranged asymmetrically in consideration of the fact that the near vision area is closer to the back side when the lens is worn, a single lens that passes vertically between the center of distance vision and the center of near vision can be used. The center line is treated as the reference line. In the present invention, these reference lines are referred to as principal meridian curves.

As a conventional progressive focus lens, for example,
Those disclosed in Japanese Patent Publication No. 595, Japanese Patent Publication No. 52-20271, and Japanese Patent Publication No. 59-42285 are known.

[Problem to be solved by the invention]

Although it is possible to improve visual performance to a certain extent with the above-mentioned known technology, it is still insufficient for practical use. That is, in Japanese Patent Publication No. 493,595, regarding the shape of the line of intersection formed by the plane perpendicular to the principal meridian curve and the refracting surface, only the line of intersection at a point corresponding to approximately the center of the intermediate part is circular; In the upper part, the radius of curvature of the intersection line decreases as it moves away from the principal meridian curve, and in the lower part, it increases.In this way, only the central part is circular, and the other areas are simple. Because it has a non-circular shape, the clear vision range (range where the astigmatism difference is 0°5 dayopters or less) in the near and far vision areas is narrow, and the field of view becomes narrow due to rapid changes in aberrations, resulting in image distortion. , the shaking was significant.

Furthermore, the method disclosed in Japanese Patent Publication No. 52-20271 is an improvement in dynamic vision that is further improved in addition to the improvement in static vision disclosed in Japanese Patent Publication No. 49-3595. Although it is possible to improve this, it is still difficult to achieve practically sufficient performance.

According to Japanese Patent Publication No. 5 L-42285, regarding the shape of the intersection line formed by the plane perpendicular to the principal meridian curve and the refractive power surface, the radius of curvature decreases as it moves away from the principal meridian curve above the distance viewing portion. The radius of curvature is constant in the upper peripheral part, and the radius of curvature monotonically decreases in the lower part of the distance part. It has a non-circular shape in which the radius of curvature increases and decreases as it moves away from the main meridian curve, except for the connection part with the use part, and the radius of curvature increases and decreases as it moves away from the main meridian curve in the near part. In this case, the above-mentioned Special Publication No. 52-2027
Although the visual characteristics can be improved to some extent compared to those in Publication No. 1, the residual astigmatism difference in the peripheral area of the distance viewing area, especially in the lateral area from the center to the bottom of the distance viewing area, is still significant, and the residual astigmatism difference in the intermediate area is still significant. Image distortion and shaking are large in the lateral areas of the near vision area, and it is still difficult to obtain a sufficiently wide field of view.

Generally, when the intermediate portion as a progressive zone is shortened, the change in refractive power becomes rapid, resulting in a sudden increase in aberrations.

As can be seen from Minkwitz's law, especially in the vicinity of the principal meridian curve, aberrations increase rapidly, not only does the width of the progressive zone tend to become narrower, but also image shaking and distortion increase rapidly. On the other hand, when the progressive zone is relatively long, the change in refractive power is relatively gentle, making it easy to reduce astigmatism, wobbling, and distortion. However, if the progressive band is too long, the desired addition power cannot be obtained unless the line of sight is sufficiently lowered when wearing the device, which poses problems such as making it difficult to use.

The present invention aims to eliminate the above-mentioned conventional drawbacks and provide a progressive focal lens that is aberrationally balanced even when the intermediate portion as a progressive zone is shortened. It has a wide field of view even below the far vision area, and has an intermediate and near vision area that has a clear vision area that is large enough to be practically inconvenient, and also reduces image distortion and shaking as much as possible in the periphery. The object of the present invention is to provide a progressive focus lens that does not cause discomfort even when viewed from the side.

[Means to solve the problem]

The present invention provides a distance part F having a refractive power corresponding to a distant view along a principal meridian curve, a near part N having a refractive power corresponding to a near view, and a distance part F having a refractive power corresponding to a near view, and a distance part F having a refractive power corresponding to a near view, and a distance part F having a refractive power corresponding to a close view, and a distance part F having a refractive power corresponding to a close view, and a distance part F having a refractive power corresponding to a close view, and a distance part F having a refractive power corresponding to a close view. In a progressive focus lens as shown in Fig. 1, which has an intermediate part P that continuously and smoothly connects the refractive powers of both parts, the optimum shape of each part is determined for the vertical cross-sectional shape of the refractive surface when the intermediate part becomes short. The aim is to optimize the aberration balance over the entire refractive surface.

Specifically, in the vertical cross-sectional shape of the refractive surface in the upper part of the distance part F, the value of the vertical curvature radius increases as the distance from the intersection with the principal meridian curve MM'' increases along the cross-sectional curve, The longitudinal cross-sectional shape of the refractive surface at the bottom of The radius of curvature is approximately constant along the cross-sectional curve.The vertical cross-sectional shape of the refractive power surface above the intermediate portion changes as the value of the vertical radius of curvature increases as the distance from the intersection with the principal meridian curve increases along the cross-sectional curve. decreases, and the value of the vertical radius of curvature increases along the cross-sectional curve as it moves away from the intersection with the principal meridian curve below the intermediate section and above the near section, and then decreases.

Here, below the intermediate part and above the near part, the value of the vertical radius of curvature increases as it moves away from the intersection with the principal meridian curve along the cross-sectional curve, and then decreases. It is effective to configure it so that it is located away from the meridian curve, and at least 15 mm away from the main meridian curve in the vertical direction.

Further, near the center of the near portion N, it is effective that the radius of curvature of the longitudinal section of the refractive surface increases as it moves away from the intersection with the principal meridian curve MM' along the cross-sectional curve, and then remains approximately constant.

Further, the position where the radius of curvature of the longitudinal section on the side of the near vision part N changes from increasing to constant is W74 to 3W in the vertical direction from the principal meridian curve, when the radius of the progressive focus lens is W.
It is preferable to have a configuration in which the two regions are located within a region separated by /4.

[Effect]

In the configuration according to the present invention as described above, firstly, above the distance portion, the longitudinal cross-sectional shape of the refractive surface increases along the cross-sectional curve as it moves away from the principal meridian curve, while below the distance portion, this is reversed. This tendency is almost constant at almost the center of the distance vision part, so while ensuring the distance vision part F is extremely wide, it is possible to smoothly connect it with the intermediate part, and to reduce the non-uniformity at the lateral part of the middle part P. It is possible to weaken the concentration of point distance differences, and the value of the radius of vertical curvature increases along the cross-sectional curve as it moves away from the intersection with the principal meridian curve, and then decreases below the intermediate section and above the near section. As a result, even if the intermediate portion is short, the clear visual field at the intermediate portion P can be made wider and image distortion and shaking at the periphery can be reduced.

In addition, at the center of the near portion N, the vertical cross-sectional shape of the refractive surface increases as the distance from the intersection with the principal meridian curve along the cross-sectional curve increases, and then remains almost constant. , despite having a wide distance clear vision area due to the shape of the distance portion as described above, it reduces the concentration of astigmatism difference in the intermediate and near portions in a well-balanced manner, and reduces image fluctuation in the lateral regions. , it softens distortion and makes it possible to improve visual acuity.

〔Example〕

Examples of the present invention will be described below, but first, a cross section and a longitudinal section in the present invention will be explained.

FIGS. 2(A) and 2(B) are perspective views for explaining the cross section and longitudinal section of the refractive surface σ of the lens. The optical axis is set at the geometric center 06 of the lens, and this is taken as the X axis, and the center of curvature of the refractive surface at the geometric center 06 is set as the center O6, and the geometric center ○. The spherical surface whose radius is the radius of curvature R0 of the refractive surface in is used as the reference spherical surface. Therefore, the reference spherical surface is in contact with the refractive surface σ of the lens 1 at the geometric center 06. With the center O0 of the reference spherical surface as the origin, the y-axis is vertical and the two axes are horizontal.

The cross section in the present invention is as shown in FIG. 2(A),
Center of reference sphere ○. A plane (
a plane π perpendicular to the x-y plane).

is the cross section of the refractive surface σ, and the cross section intersection line Φ
, is shown as . In addition, the longitudinal section in the present invention is the center ○ of the reference sphere, as shown in FIG. 2(B). through y
It is a vertical cross section of the refractive surface σ along the plane χ1 including the axis, and is shown as a vertical cross section intersection line Σ.

Such a transverse section intersection line Φ and a longitudinal section intersection line Σ.

FIG. 3 is a plan view showing the planar position of the lens on the refractive surface of the lens. Each cross-sectional intersection line (Φ3Φ
2Φ1. ), the value of the radius of curvature in the vertical direction is
Based on the longitudinal radius of curvature of the principal meridian curve MM′,
FIG. 4 shows changes in the right half of the refractive surface σ. Incidentally, it goes without saying that the cross-sectional intersection line Φ and the vertical cross-section intersection line Σ described here mean the transverse cross-sectional curve and the longitudinal cross-sectional curve in the present invention, respectively.

To explain more specifically, FIG. 4 shows the principal meridian curve MM.
The value of the radius of curvature in the longitudinal direction along each cross-sectional intersection line in seven representative cross-sections intersecting with the main meridian curve MM' This is a plot of the right half of . Here, the values of each radius of curvature plotted are determined by the plane π1 passing through the center O6 of the reference sphere and perpendicular to the plane (xy plane) containing the principal meridian curve MM' in FIGS. 2(A) and (B). Along the cross-sectional intersection line Φ of the refractive surface σ, a vertical plane (χ,
) is the radius of curvature in the vertical direction at the point M1 where the vertical intersection curve Σ1 intersects.

Then, the angle Vy between the optical axis (X-axis) and the plane πj, which passes through the center of the reference sphere and is perpendicular to the plane (x-y plane) containing the principal meridian curve MM', is changed every 5.6 degrees. Surface (π3.
π2. π1π0. π-1, π-2, π3), seven cross-sectional intersection lines (Φ3.Φ2.Φ1.Φ., Φ-1.Φ-
2. Φ-3), on each cross-section, a vertical plane (χ,) containing the y-axis and a plane (x,) containing the principal meridian curve MM'.
The horizontal angle Vz formed with the x-y plane) is taken every 5.6 degrees, and the values of the longitudinal radius of curvature are connected based on the longitudinal radius of curvature of the principal meridian curve MM'. It is a diagram.

As shown in FIG. 4, in this embodiment, the distance portion F
The vertical cross-sectional shape of the refractive surface at the upper part (16,8°) of The vertical cross-sectional shape of the surface is based on the principal meridian curve MM”
The radius of curvature in the longitudinal section of the refractive surface decreases as it moves away from the intersection with F, and the radius of curvature in the longitudinal section of the refractive surface is approximately constant at approximately the center (], 1.2°) of the distance portion F.

And the near center of the near part N ○N (1], 2°)
In the vicinity, the longitudinal cross-sectional shape of the refractive surface has a radius of curvature that increases as it moves away from the intersection with the principal meridian curve MM' along the cross-sectional curve and then remains approximately constant.

The position where the radius of vertical curvature changes almost constantly from the increase in the radius of curvature in the vicinity of the center of near vision 011 is at a position approximately half of W when the radius of the progressive focusing lens is W, and in practical terms, it is located on the principal meridian curve. It is effective to configure the structure to exist in a region spaced apart from W74 to 3W/4 in the lateral direction. Also,
The value that becomes almost constant after increasing the radius of curvature of the longitudinal section in the lateral region of the center of near vision is approximately 13% of the radius of curvature of the longitudinal section at the intersection of the cross section and the principal meridian curve, which is a practical value. 10% to 50%, preferably 10% to 30%
% is effective.

By the way, FIG. 5 shows the change along the vertical intersection line curve Σ1 with respect to the vertical refractive power corresponding to the radius of curvature in the vertical direction. In other words, it is a diagram in which the refractive power in the vertical direction at each point is plotted along the vertical intersection curve Σ1 by the vertical plane (χ1) including the above-mentioned y-axis at the refractive surface σ.
It also shows the vertical change in the longitudinal radius of curvature. That is, there is a close relationship between the radius of curvature and the refractive power, and when the radius of curvature is R and the refractive index of the lens is n, the curvature ρ is expressed as ρ-1/R, and the refraction ED is D = (n-1) 1/R= (n-1,) 0. Here, when the radius of curvature R is expressed in units of meters, the refractive power is expressed in units of diopters.

Vertical section intersection line Σ in FIG. is the principal meridian curve MM”
(Vz = 0°) and the longitudinal power change along this principal meridian curve is curve e. Indicated by And Σ
1. Σ2. Σ3 are Vz=5°6°, ], 1.
2° and 16.8°, and the changes in longitudinal refractive power along the respective longitudinal section intersection lines are represented by curves e1. It is shown as e2el. Here, if Vz=] and 6.8° approximately correspond to the maximum effective aperture as a progressive focus lens, then Σ
1Σ2. Σ3 is W for the radius W of the lens, respectively.
/3.2W/3. This corresponds to W.

As shown at 03 in FIG. 5, above the distance portion F, for the longitudinal refractive power (eo) on the principal meridian curve,
The longitudinal refractive power at the side edge part (Σ3) of the lens is larger, and the longitudinal refractive power (el, e2) at the lateral middle part of the lens (ΣΣ2) is smaller. have almost the same refractive power.

In addition, at the distance eye point position at the lower end of the distance part F, the refractive power (
eo), the refractive power (el, e2) at the lens side intermediate portion (Σ1, Σ2) is greater than the refractive power (el, e2) at the side edge part (Σ
The refractive power in 3) is increased.

Then, at approximately the center of the intermediate portion P, eo+el,
It can be seen that e2 is almost the same, e3 is above the figure, and the longitudinal cross-sectional refractive power is approximately constant along the cross-sectional curve and then decreases. Further, below the intermediate portion P, the refractive power (eo) on the principal meridian curve is maximum, and as it goes to the side, the refractive power decreases and then increases. This tendency continues up to the upper part of the near vision area N.

In the near vision area N, for the longitudinal section refractive power (e.) on the principal meridian curve, which has the maximum refractive power near the center of near vision,
It becomes smaller in the order of e++e2+e+.

Incidentally, in the above embodiment, the distribution of the average refractive power along the principal meridian curve is as shown in FIG. This example is a progressive lens with an average refractive power (base curve) of the distance portion F of 4.0 dayopters and an addition power of 2.5 dayopters, so it is approximately 4.0 dayopters at the distance center O2, The average refractive power at the near center ON is approximately 6.5 dayopters.

When designing a lens surface having such an addition curve, the surface shape should not be designed and evaluated only within the circular shape of the lens, but should be evaluated in a rectangular shape as shown in Figure 3, which includes the circular shape of the lens surface. Assuming this, we designed and evaluated the surface shape within this rectangle. In this way, by optimizing the curved surface of the larger surface that covers the circular shape of the lens, it becomes possible to make the practical lens surface a smoother and better shape.

The isoastigmatism curve diagram in FIG. 7 shows the results of performance evaluation of the progressive focal length lens having the surface shape of the example described above. In this figure, the isostigmatism difference curve has a value every 0.5 diopter.

For comparison with this example, FIG. 8 shows an outline of an isoastigmatism curve diagram and a refractive power distribution curve diagram on a principal meridian curve for a conventional progressive focus lens.

In this figure as well, the isostigmatism difference curve is set to values every 0.5 diopters.

Since the conventional progressive focus lens does not have the above-described configuration according to the present invention, the density of the astigmatism difference becomes high, and the amount of astigmatism difference and the gradient of the astigmatism difference become steep, as shown in FIG. As a result, the distortion of the image becomes large, and you will feel the image shaking when you move your line of sight. In addition, the astigmatism aberration from the intermediate lateral region seeps into the lower lateral region for distance vision, and when you turn your eyes to this region, you will not only see a blurred image, but also a blurred image. Distortion and shaking have become noticeable.

On the other hand, in this example, as shown in FIG. 7, although the middle part of the progressive zone is shortened, the density of the astigmatism difference of the surface refractive power also decreases, and the gradient of the astigmatism difference also decreases. It is clear that the image becomes smoother and the distortion and shaking of the image are reduced.

Here, the main points of the progressive focus lens according to the present invention will be explained using FIG. 6 showing the addition curve of the above embodiment.

The distance center O2 is a position on the principal meridian curve having a predetermined average surface refraction power in the distance portion, and is a point that is practically used as a measurement reference point for the distance portion.

Further, the near vision center ON is a position on the principal meridian curve having a predetermined average surface refractive power in the near vision area, and is a point that is practically used as a measurement reference point for the near vision area.

The distance eye point E is a position that is used as a reference when fitting the lens into the eyeglass frame, and serves as a distance reference point that matches the distance line of sight passing position when the eyeglass frame is worn. The position of such a distance eye point hE is determined independently of the geometric center of the lens, as shown in the average refractive power distribution curve on the principal meridian curve in FIG. Define it as follows. That is, in the addition curve as shown in FIG. 6, in which the average power of the surface refractive power on the principal meridian curve is plotted for each position on the principal meridian curve, the distance center O1 of the distance section F and the center of near vision N are Near center ON
The distance eye point is defined as the intersection point E of the straight line C, which is parallel to the straight line a connecting these lines and touches the addition curve on the distance part F side, and represents the average refractive power at the distance center O2.

In addition, since progressive focus lenses are generally processed to fit the eyeglass frame, the distance, intermediate, and near vision areas, especially the distance and near vision areas including the peripheral area, depend on the shape of the frame. Although it differs depending on the situation, the progressive focus lens before processing is generally a circular lens with a diameter of about 60 mm or more,
This circular shape is supplied to an eyeglass retailer, where it is processed into a desired eyeglass frame shape. Therefore, in defining the surface shape of the progressive focus lens in the present invention, the shape before processing is used as a reference. When designing the optimal surface shape of a progressive focus lens, it is important to balance the aberrations by considering the surface shape not only in the frequently used central region 0 but also in a wider region including the effective region used. It is.

In addition, in general progressive focus lenses, the entire line is a so-called origin curve that is a series of microscopic spherical surfaces along the principal meridian curve, and some areas on the principal meridian curve are not bladder points. Surface shapes with different radii of curvature in directions orthogonal to each other have been proposed. Looking at the surface shapes on the principal meridian curve, there are two types: one where the surface shape is like the origin over the entire principal meridian curve, and one where the radius of curvature is different in directions perpendicular to each other. In some cases, the radius of curvature in the direction along the principal meridian curve and the radius of curvature in the direction perpendicular to the principal meridian curve are different values, instead of the origin. It is also effective in cases where

〔Effect of the invention〕

According to the present invention as described above, even if the intermediate portion as a progressive zone is shortened, the intermediate portion and It has a near vision area, which minimizes image distortion and wobbling in the periphery, causing no discomfort even when viewed from the side, making it possible to create a progressive focal lens with well-balanced aberrations. Therefore, it is possible to achieve a progressive focal length lens that can be worn comfortably even by a person using this type of lens for the first time.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an outline of the area division of the progressive focus lens of the present invention, and FIGS. 2(A) and (B) are perspective views for explaining the cross section and longitudinal section of the refractive surface according to the present invention. ,
FIG. 3 is a plan view showing the cross-sectional intersection line and longitudinal section intersection line according to the present invention; FIG. 4 is a diagram showing changes in the longitudinal radius of curvature along the cross-section of the embodiment according to the present invention; FIG. 5 is a diagram showing the change in longitudinal refractive power along the longitudinal section intersection line, FIG. 6 is a diagram showing the addition curve in the example, and FIG.
The figure is an isoastigmatic difference curve diagram for an example according to the present invention,
FIG. 8 is an isoastigmatism curve diagram for a conventional progressive focus lens. F...Distance part P...Intermediate part N...Near part [Explanation of symbols of main parts] ○,...Distance center ON...Near center E...Distance eye point

Claims (1)

[Scope of Claims] 1) A distance part having a refractive power corresponding to a distant view along the principal meridian curve, and a near part having a refractive power corresponding to a near view;
A progressive focusing lens having an intermediate portion between the distance portion and the near portion that continuously and smoothly connects the refractive powers of both portions, the longitudinal section of the refractive surface above the distance portion; The vertical curvature radius increases as the shape moves away from the intersection with the principal meridian curve along the cross-sectional curve, and the vertical cross-sectional shape of the refractive surface at the lower part of the distance portion changes along the cross-sectional curve. The value of the vertical radius of curvature decreases as it moves away from the point of intersection with the principal meridian curve, and the vertical radius of curvature of the refractive surface is approximately constant along the cross-sectional curve in approximately the central portion of the distance portion, and In the upper part, the vertical cross-sectional shape of the refractive power surface has a radius of vertical curvature that decreases as it moves away from the intersection with the principal meridian curve along the cross-sectional curve,
A progressive focusing lens characterized in that the value of the vertical radius of curvature increases along the cross-sectional curve and moves away from the intersection with the principal meridian curve below the intermediate section and above the near section, and then decreases. 2) Below the intermediate section and above the near section, the value of the vertical radius of curvature increases as it moves away from the intersection with the principal meridian curve along the cross-sectional curve, and then decreases as it approaches the near section. 2. The progressive lens according to claim 1, wherein the progressive focus lens is located away from the meridian curve and is at least 15 mm away from the principal meridian curve in the vertical direction. 3) In the vicinity of the center of near vision in the near vision section, the radius of curvature of the longitudinal section increases as it moves away from the principal meridian curve along the cross sectional curve, and then becomes approximately constant. focal lens. 4) In the near vision section, the position where the longitudinal cross-sectional curvature radius of the refractive surface changes from increasing to constant along the cross-sectional curve is the position in the vertical direction from the principal meridian curve, when the radius of the progressive focusing lens is W. 4. The progressive focus lens according to claim 3, wherein the progressive focus lens exists in a region separated by W/4 to 3W/4.