JP2503664B2 - Progressive focus lens - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a progressive focus lens used as an auxiliary to the accommodation power of the eye.

[Prior art]

As an eyeglass lens for assisting the accommodation power when the accommodation power of the eye declines and near vision becomes difficult, an upper distance vision correction region (hereinafter referred to as a distance portion) and a lower near vision correction region ( Various progressive focus lenses having a progressive region (hereinafter referred to as an intermediate part) in which the refracting power continuously changes between the two are known.

In a progressive-focus lens, generally, a wide viewing zone between the distance portion and the near portion is secured, and if a space between them is connected by a progressive zone, lens aberrations will be concentrated in the lateral area of the progressive zone.
The presence of this region causes image blurring and image distortion, and gives a bad impression to the wearer when the eyes move.

In order to solve such a problem of visual characteristics, known progressive lenses have been designed and evaluated from various viewpoints. Then, regarding the shape of the lens surface, an intersection line between a cross section along a meridian running substantially perpendicular to the center of the lens surface and the object side lens surface is used as a reference line for representing specifications such as addition of the lens, It is also used as an important reference line in the design. In addition, even in a progressive lens in which the near portion is asymmetrically arranged in consideration of the near portion approaching the nose side in the wearing state of the lens, one lens that passes vertically through the distance center and the near center is also used. The center line is treated as the reference line. In the present invention, these reference lines are called main meridian curves.

As a conventional progressive-focus lens, for example, Japanese Patent Publication No. 49-35
Japanese Patent Publication No. 95, Japanese Patent Publication No. 52-20271 and Japanese Patent Publication No. 59-42285.
The one disclosed in Japanese Patent Publication is known.

[Problems to be Solved by the Invention]

Although it is possible to improve the visual performance to some extent in the above-mentioned known techniques, it is still insufficient for practical use. That is, in JP-B-49-3595, the shape of the line of intersection between the plane perpendicular to the main meridian curve and the refracting surface is circular only at the point corresponding to approximately the center of the middle portion, Above that, the radius of curvature of the intersecting line decreases with increasing distance from the main meridian curve, and increases with the lower part, both of which have non-circular shapes. As it has a simple non-circular shape, it has a clear vision area for near and far vision areas (with an astigmatic difference of 0.5 diopter or less).
Is narrow, and the field of view is narrowed due to the abrupt change in aberration, resulting in significant image distortion and fluctuation.

In addition, Japanese Patent Publication No. 52-20271 discloses the above-mentioned Japanese Patent Publication No.
This is a modification of the static vision disclosed in Japanese Patent Publication No. 9-3595 with further improvement of dynamic vision.Although it is possible to improve dynamic vision to some extent, it achieves practically sufficient performance. It's still difficult to do.

In the case of Japanese Patent Publication No. 59-42285, similarly, regarding the shape of the line of intersection between the plane perpendicular to the main meridian curve and the refracting power surface, the radius of curvature decreases with increasing distance from the main meridian curve above the distance portion. , The decreasing rate approaches 0 as it goes up in the distance portion, and the radius of curvature is constant in the upper peripheral portion, and the radius of curvature monotonically decreases in the lower portion of the distance portion. The non-circular shape in which the radius of curvature increases and decreases as the distance from the main meridian curve is increased, except for the connecting portion with the portion, and the radius of curvature increases and decreases in the near portion, as the distance from the main meridian curve increases. Although the visual characteristics can be improved to some extent as compared with the Japanese Patent Publication No. 52-20271, the residual astigmatism in the peripheral region of the distance portion, particularly in the lateral region from the center to the lower portion of the distance portion, is improved. The gap is still significant, and the image is greatly distorted and shaken in the lateral regions of the middle portion and the near portion, and it is still difficult to obtain a sufficiently wide field of view.

Generally, when the middle part of the progressive zone is shortened, the change in the refractive power becomes rapid, so that the aberration sharply increases. As can be seen from Minkwitz's law, especially near the main meridian curve, the aberration increases rapidly, and not only the width of the corridor tends to be narrowed, but also the image distortion and distortion increase rapidly. On the other hand, when the corridor is relatively long, the change in refractive power is relatively gentle, so that astigmatism, shaking, and distortion are easily reduced. However, if the corridor is too long, a desired addition degree cannot be obtained unless the line of sight is lowered sufficiently at the time of wearing.

The present invention intends to solve the above-mentioned conventional drawbacks and to provide a progressive focus lens that is well-balanced in terms of aberrations even when the intermediate portion as a progressive zone is shortened. Has a wide field of view even below the distance part, and has an intermediate part and a near part having a clear viewing area that is practically inconvenient, and also reduces the image distortion and shake in the periphery as much as possible. It is an object of the present invention to provide a progressive-focus lens that does not cause discomfort even when viewed laterally.

[Means for solving the problem]

The present invention provides a distance portion F having a refractive power corresponding to a distant view along a main meridian curve, a near portion N having a refractive power corresponding to a near view, and between the distance portion and the near portion. In a progressive-focus lens as shown in FIG. 1 having an intermediate portion P that continuously and smoothly connects the refracting powers of both portions, when the intermediate portion becomes short, the optimum cross-sectional shape of each portion is defined as the longitudinal cross-sectional shape of the refracting surface. The finding is to optimize the aberration balance in the entire refracting surface.

Specifically, in the upper portion of the distance portion F, the longitudinal cross-sectional shape of the refracting surface has a value of the longitudinal curvature radius that increases as the distance from the intersection with the main meridian curve MM ′ along the transverse sectional curve increases, The vertical cross-sectional shape of the refracting surface in the lower part of is such that the value of the longitudinal curvature radius decreases as the distance from the intersection with the main meridian curve MM ′ along the cross-sectional curve increases, and the longitudinal length of the refracting surface is approximately at the center of the distance portion F. The radius of curvature is almost constant along the curve of the cross section. Then, the vertical cross-sectional shape of the refractive power surface above the middle portion decreases in value of the vertical curvature radius as it goes away from the intersection with the main meridian curve along the cross-section curve, and below the middle portion and above the near portion. The value of the vertical curvature radius increases along the cross-section curve as it moves away from the intersection with the main meridian curve, and then decreases.

Here, in the lower part of the middle part and the upper part of the near portion, the value of the vertical curvature radius increases along the transverse curve with increasing distance from the intersection with the main meridian curve, and then the position where it decreases decreases toward the near portion. It is effective to be located away from the meridian curve and at least 15 mm away from the main meridian curve in the vertical direction.

Further, in the vicinity of the center of the near portion N, it is effective that the radius of curvature of the longitudinal section of the refracting surface increases along the transverse section curve as the distance from the intersection with the main meridian curve MM ′ increases, and then becomes substantially constant.

In addition, the position where the radius of curvature of the vertical section on the side of the near portion N becomes constant from the increase is W / 4 to 3W / 4 in the vertical direction from the main meridian curve when the radius of the progressive-focus lens is W.
It is preferable to have a configuration in which the regions are separated from each other.

[Action]

In the structure according to the present invention as described above, first, above the distance portion, the vertical cross-sectional shape of the refracting surface increases as the distance from the main meridian curve along the cross-section curve increases, while on the other hand, below the distance portion, the reverse. Has a tendency to be almost constant in the center of the distance portion. Therefore, while ensuring the distance portion F to be extremely wide, a smooth connection with the middle portion is possible, and non-contact at the side portion of the middle portion P is possible. It is possible to weaken the concentration of point gaps, and the value of the longitudinal curvature radius below the middle part and above the near vision part increases and decreases as it goes away from the intersection with the main meridian curve along the cross-section curve. As a result, even if the intermediate portion is short, the clear vision area in the intermediate portion P is widened, and distortion of the image in the periphery and reduction of the fluctuation are achieved.

Also, at the center of the near portion N, since the vertical cross-sectional shape of the refracting surface increases along with the horizontal cross-section curve and away from the intersection point with the main meridian curve, the value of the vertical curvature radius increases and becomes substantially constant thereafter. , In spite of having a wide distance clear vision area due to the shape of the distance portion as described above, the concentration of astigmatic difference in the middle portion and the near portion is reduced in a well-balanced manner, and the image shake in the lateral region is reduced. , Softens distortions and enables visual improvement.

〔Example〕

Examples of the present invention will be described below. First, the cross section and the vertical section of the present invention will be described.

FIGS. 2A and 2B are perspective views for explaining a horizontal section and a vertical section of the refracting surface σ of the lens.
The geometric center O _G of the lens takes the optical axis which is x-axis, the center O _O curvature center position of the refractive surface in the geometric center O _G,
A spherical surface having a radius of curvature R ₀ of the refracting surface at the geometric center O _G as a reference spherical surface. Therefore, the reference spherical surface is in contact with the refracting surface σ and the geometric center O _G of the lens. With the center O _{O of the} reference spherical surface as the origin, the y axis is taken in the vertical direction and the z axis is taken in the horizontal direction.

The cross section in the present invention means, as shown in FIG. 2 (A), a refraction surface σ by a plane π _j that passes through the center O _{0 of the} reference sphere and is orthogonal to the plane containing the main meridian curve MM '(X-y plane). Of the cross section and is shown as a cross section intersection line Φ _j . Further, the vertical section in the present invention is a vertical section of a refracting surface σ by a plane χ _j passing through the center O _{0 of the} reference sphere and including the y axis, as shown in FIG. 2 (B). Line Σ _j
Is shown as.

FIG. 3 is a plan view showing the planar positions of the intersection line Φ _j of the transverse section and the intersection line Σ _j of the longitudinal section on the lens refracting surface. Each cross-section intersection line (Φ ₃ , Φ ₂ ,
Fig. 4 shows the variation of the radius of curvature in the vertical direction along Φ ₁ , ...) with reference to the radius of curvature of the main meridian curve MM 'in the right half of the refraction surface σ. Is.
Needless to say, the cross-section line Φ _j and the vertical cross-section line Σ _j described here mean the cross-section curve and the vertical cross-section curve of the present invention, respectively.

More specifically, FIG. 4 shows the main meridian curve M
The values of the vertical radii of curvature along the intersection lines of the seven representative cross-sections that intersect M'are the main meridian curve MM based on the vertical radii of curvature of the main meridian curve MM '. This is a plot of the right half of ′. Here, the plotted values of the respective radii of curvature are planes π orthogonal to the plane (xy plane) passing through the center O _O of the reference sphere and including the main meridian curve MM 'in FIGS. 2 (A) and 2 (B). along a transverse plane intersection line [Phi _j refractive surface σ by _j, the vertical intersection line curve sigma _i is the longitudinal direction of the radius of curvature at M _j point of intersection by the vertical plane including the y-axis (χ _j).

Then, the angle Vy formed by the plane π _j with the optical axis (x-axis) passing through the center of the reference sphere and orthogonal to the plane containing the main meridian curve MM ′ (xy plane) is changed every 5.6 °. (Π ₃ , π ₂ ,
7 cross-section intersection lines (Φ ₃ , Φ ₂ , Φ ₁ , Φ ₀ , Φ _-1 , Φ _-2 , Φ _-3 ) by π ₁ , π ₀ , π _-1 , π _-2 , π _-3 ) ), On each cross-section, in the vertical plane (χ _j ) containing the y-axis
The angle Vz in the lateral direction formed by the plane including the main meridian curve MM '(xy plane) is taken every 5.6 °, and the main meridian curve MM' is obtained.
FIG. 4 is a diagram in which the values of the vertical radius of curvature are connected with reference to the vertical radius of curvature.

As shown in FIG. 4, in the present embodiment, the vertical cross-sectional shape of the refracting surface at the upper portion (16.8 °) of the distance portion F is:
The value of the radius of curvature increases as the distance from the intersection with the main meridian curve MM ′ increases, and the vertical cross-sectional shape of the refracting surface at the lower portion (5.6 °) of the distance portion F increases as the distance from the intersection with the main meridian curve MM ′ increases. The radius of curvature in the longitudinal section of the refracting surface is almost constant in the central portion (11.2 °) of the distance portion F.

Then, in the vicinity of the near center O _N (−11.2 °) of the near portion N, the vertical cross-sectional shape of the refracting surface has a value of the radius of curvature as the distance from the intersection with the main meridian curve MM ′ along the horizontal cross-sectional curve increases. It has increased and has been almost constant since then. The position near the near center O _N , where the vertical curvature radius increases and changes almost constantly, is about half of W when the radius of the progressive-focus lens is W, and practically the main meridian. It is effective to adopt a configuration in which it exists in a region distant from the curve by W / 4 to 3W / 4 in the lateral direction. Further, the value which becomes almost constant after the increase of the radius of curvature of the vertical section in the lateral region of the near center is about 13% with respect to the radius of curvature of the vertical section at the intersection of the horizontal section and the main meridian curve, Practically 10% to 50
%, Preferably 10% to 30% is effective.

By the way, FIG. 5 shows changes in the vertical refracting power corresponding to the radius of curvature in the vertical direction along the vertical intersection curve Σ _i . That is, it is a diagram in which the refractive power in the vertical direction at each point is plotted along the vertical intersection curve Σ _i by the vertical plane (χ _j ) including the above-mentioned y axis on the refractive surface σ.
It also indicates the vertical change in the radius of curvature in the vertical direction. 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 represented by ρ = 1 / R, and the refractive power D has a relationship of D = (n−1) 1 / R = (n−1) ρ. Here, when the radius of curvature R is in units of meters, the refractive power D is expressed in units of diopters.

The vertical cross section Σ ₀ in Fig. 5 is the main meridian curve MM '(V
z = 0 °), and the change in refractive power in the longitudinal direction along this main meridian curve is shown by the curve e ₀ . And Σ ₁ , Σ ₂ , Σ
₃ corresponds to Vz = 5.6 °, 11.2 °, 16.8 °, respectively, and shows the change in the longitudinal refractive power along each vertical cross-section line.
It is shown by e ₁ , e ₂ , and e ₃ . Assuming that Vz = 16.8 ° corresponds to the maximum effective aperture of the progressive-focus lens, Σ ₁ , Σ ₂ , and Σ ₃ are W / 3 and 2W / with respect to the radius W of the lens, respectively. It corresponds to 3, W.

As shown by e ₃ in FIG. 5, above the distance portion F, the longitudinal refraction at the side edge portion (Σ ₃ ) of the lens with respect to the longitudinal refracting power (e ₀ ) on the main meridian curve is increased. force greater, the lens side middle part (Σ _1, Σ ₂₎ vertical direction power in (e _1, e ₂₎ has become smaller, substantially equal refractive power thereof in the middle of the distance portion F and Has become.

Further, at the distance eyepoint position at the lower end of the distance portion F, the lens lateral side intermediate portions (Σ ₁ , Σ ₂ ) are different from the refractive power (e ₀ ) on the main meridian curve having the smallest refractive power. The refractive power at the side edge portion (Σ ₃ ) of the lens is larger than the refractive power (e ₁ , e ₂ ).

Then, at the approximate center of the intermediate portion P, e ₀ , e ₁ , e ₂
It can be seen that is almost the same, e ₃ is higher than in the figure, and the refractive power in the longitudinal section is almost constant along the curve of the transverse section and then decreases. Further, below the middle portion P, the refracting power (e ₀ ) on the main meridian curve becomes maximum, and the refracting power decreases as it goes to the side and then increases. This tendency continues above the near portion N.

In the near vision portion N, with respect to the longitudinal cross-section refractive power (e ₀ ) on the main meridian curve having the maximum refractive power in the vicinity of the near vision center,
It becomes smaller in the order of e ₁ , e ₂ , and e ₃ .

By the way, in the embodiment as described above, the distribution of the average refractive power along the main meridian curve is as shown in FIG. This embodiment is an average refractive power (base curve) is 4.0 diopter distance portion F, from a progressive lens addition power 2.5 diopters, approximately in the far viewing center O _F
It is 4.0 diopters, and the average refractive power is about 6.5 diopters in the near center O _N.

In the design of the lens surface having such an addition curve, the surface shape is not designed and evaluated only within the range of the circular shape as the lens, but the square shape as shown in FIG. As a result, the design and evaluation of the surface shape within this square were performed. Thus, by optimizing the curved surface on a larger surface covering the circular shape of the lens, it becomes possible to make the practical lens surface smoother and superior.

The result of performance evaluation of the progressive-focus lens having the surface shape of the above-described embodiment is shown in the isoastigmatic difference curve diagram of FIG. In this figure, the equi-astigmatic difference curve is a value for each 0.5 diopter.

For comparison with the present embodiment, FIG. 8 shows an outline of an isoastigmatic difference curve diagram and a refractive power distribution curve diagram on the main meridian curve for a conventional progressive-focus lens. Also in this figure, the isoastigmatic difference curve is set to a value every 0.5 diopter.

Since the conventional progressive-focus lens does not have the above-mentioned configuration according to the present invention, as shown in FIG. , As a result, the distortion of the image becomes large,
When you move your line of sight, you will feel the shaking of the image. Also, astigmatism aberration seeps out from the lateral region of the middle portion in the lateral region below the distance portion, and when the eye is directed to this region, not only the image blur, but also the image Distortion and shaking are noticeable.

On the other hand, in this embodiment, as shown in FIG.
Despite the shortening of the intermediate part of the progressive zone, the astigmatic density of the surface refractive power also decreases, the astigmatic gradient becomes gentle, and the distortion and shake of the image are reduced. it is obvious.

Here, the main points of the progressive-focus lens according to the present invention will be described with reference to FIG. 6 showing the addition curve of the above-mentioned embodiment.

The distance center O _F, a position on the principal meridional curve having a predetermined surface refractive average power in the distance portion, practically is that it is a reference point of the distance portion. Further, the near vision center O _N, a position on the principal meridional curve having a predetermined surface refractive mean power in the near portion, practically is that it is a reference point of the near portion.

The distance eye point E is a position used as a reference when the lens is framed in the spectacle frame, and is a distance reference point that matches the distance line of sight passage position when the spectacle frame is worn. The position of such a distance eye point E is determined independently of the geometric center of the lens as shown in the average refractive power distribution curve on the main meridian curve in FIG. Defined in That is, in the addition curve as shown in FIG. 6 in which the average power of the surface refractive power on the main meridian curve is plotted for each position on the main meridian curve, the distance center OF of the distance portion _F and the near portion N Parallel to the straight line a connecting the near center O _{N of}
Line b in contact with the side is, the distance eye point to the intersection E between the straight line c representing an average refracting power of the far viewing center O _F.

In addition, since a progressive-focus lens is generally processed according to the spectacle frame, each region of the distance portion, the middle portion, and the near portion,
In particular, the distance portion and the near portion including the peripheral portion will differ depending on the shape of the frame, but the progressive lens before processing is generally a circular lens with a diameter of about 60 mm or more, and this circular shape is used for glasses. It is supplied to retailers and processed at retailers to have a desired spectacle frame shape.
Therefore, the definition of the surface shape of the progressive lens in the present invention is based on such a shape before processing. In designing the optimal surface shape of the progressive-focus lens, it is important to balance aberrations by considering not only the central region that is frequently used but also the surface shape in a wider region including an effective region to be used. .

Further, in a general progressive-focus lens, along the main meridian curve, a so-called umbilical point curve in which all lines are continuous microscopic spherical surfaces, or not a umbilical point in a part of the main meridian curve , It is proposed to have surface shapes with different radii of curvature in the directions perpendicular to each other. Regarding surface shapes on the main meridian curve, umbilical points are formed over the whole line of the main meridian curve and on the main meridian curve. At least part of which is not an umbilical point, but is roughly divided into a radius of curvature in a direction along the main meridian curve and a radius of curvature in a direction perpendicular to the main meridian curve, which are different values in the present invention. It is effective in both cases.

〔The invention's effect〕

According to the present invention as described above, even if the intermediate portion as a progressive zone is shortened, it has a wide field of view even below the distance portion,
It has an intermediate part and a near part that have a clear vision area that is practically inconvenient, and image distortion and shake in the periphery are reduced as much as possible, and there is no discomfort in side view, and aberration It is possible to realize a well-balanced progressive-focus lens, and it is possible to achieve a progressive-focus lens that can be worn by a person who is new to this type of lens without feeling uncomfortable.

[Brief description of drawings]

FIG. 1 is a plan view showing the outline of the area division of the progressive-focus lens of the present invention, and FIGS. 2 (A) and 2 (B) are perspective views for explaining a transverse section and a longitudinal section of a refracting surface according to the present invention. ,
FIG. 3 is a plan view showing a state of a cross section intersection line and a vertical section intersection line according to the present invention, and FIG. 4 is a view showing a change of a longitudinal curvature radius along a cross section of an embodiment according to the present invention, FIG. 5 is a diagram showing a change in longitudinal power along an intersection line of a longitudinal section, FIG. 6 is a diagram showing an addition curve in the embodiment, and FIG.
The figure is an isoastigmatic difference curve diagram for an embodiment according to the present invention,
FIG. 8 is an isoastigmatic difference curve diagram for a conventional progressive-focus lens. Description of reference numerals of main parts] F ...... distance portion, O _F ...... distance center P ...... intermediate portion, O _N ...... center N ...... near portion for near, eye point distance E ......

Claims (4)

(57) [Claims] 1. A distance portion having a refractive power corresponding to a distant view along a main meridian curve, a near portion having a refractive power corresponding to a near view, and between the distance portion and the near portion. A progressive-focus lens having an intermediate portion that continuously and smoothly connects the refracting powers of both portions, wherein the longitudinal cross-sectional shape of the refracting surface above the distance portion is a main meridian curve along a transverse sectional curve. The value of the vertical radius of curvature increases as the distance from the intersection with and the vertical cross-sectional shape of the refracting surface in the lower portion of the distance portion is longer than the intersection with the main meridian curve along the cross-section curve. The radius of curvature of the refracting surface is substantially constant along the transverse section curve in the substantially central portion of the distance portion, and the longitudinal cross-sectional shape of the refracting surface is above the intermediate section. Is it the intersection with the main meridian curve along the curve? The value of the longitudinal radius of curvature decreases as the distance increases, and the values of the longitudinal radius of curvature in the lower part of the middle part and the upper part of the near part increase along the transverse section curve from the point of intersection with the main meridian curve, and then decrease. Characteristic progressive lens. 2. The lower part of the middle portion and the upper part of the near portion, the value of the longitudinal curvature radius increases along the transverse curve with increasing distance from the intersection with the main meridian curve, and the position where the value decreases thereafter is in the near portion. As it gets closer, it moves away from the main meridian curve and at least 15 vertically from the main meridian curve.
The progressive-focus lens according to claim 1, wherein the progressive-focus lens is separated from a position of mm. 3. The radius of curvature of the longitudinal section increases in the vicinity of the near center of the near portion along the transverse curve and further away from the main meridian curve, and then becomes substantially constant. Progressive focus lens described. 4. The position at which the radius of curvature of the longitudinal section of the refracting surface along the transverse curve changes from an increase to a constant value in the near portion from the main meridian curve when the radius of the progressive-focus lens is W. The progressive-focus lens according to claim 3, wherein the progressive-focus lens is present in a region separated by W / 4 to 3W / 4 in the vertical direction.