JP2002372689A - Progressive multifocal lens and spectacle lens - Google Patents

Abstract

(57) [Problem] To provide a progressive multifocal lens and a spectacle lens capable of improving image distortion and distortion caused by a change in magnification of a distance portion and a near portion of a progressive multifocal lens. SOLUTION: A progressive refraction surface conventionally added to an object side surface is provided on an eyeball side surface. As a result, the surface on the object side can be formed into a spherical surface having a constant base curve, so that it is possible to prevent a change in magnification due to a shape factor, and it is possible to reduce a difference in magnification between the distance portion and the near portion. Further, it is possible to suppress a change in the magnification of the progressive portion. Therefore, it is possible to provide a progressive multifocal lens that can reduce image shaking and distortion due to a difference in magnification and can provide a comfortable visual field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a progressive multifocal lens for correcting eyesight and a spectacle lens using the same.

[0002]

2. Description of the Related Art A progressive multifocal lens is a lens having two visual field portions having different refractive powers and a visual field portion in which the refractive power changes progressively between them. These visual field portions have no boundary and are excellent in appearance, and further, visual fields having different refractive powers can be obtained with one lens. For this reason, it is often used as a spectacle lens having a function of correcting vision, such as presbyopia. FIG.
2 shows a general structure of a conventional progressive multifocal lens often used as an eyeglass lens. This progressive multifocal lens 1 is provided with a far vision portion 11 which is a visual field portion for viewing a distant object at an upper position, and has a field of view having a different refracting power from the distance vision portion 11 for looking at a short distance object. Part is near part 1
2 is provided below the distance portion 11. And
The distance portion 11 and the near portion 12 are smoothly connected by a progressive portion 13 which is a visual field portion having a continuously changing refractive power so as to see an object at an intermediate distance between a long distance and a short distance. .

In a single-plate lens 1 used for spectacles, a refracting surface 2 on the eyeball side and a refracting surface 3 on the object side to be watched.
All the performances required of the spectacle lens by the two surfaces, for example, the vertex power to suit the power of the user, the cylindrical power to correct astigmatism, the addition power to correct presbyopia, and even It is necessary to provide a prism refractive power or the like for correcting the oblique position. For this reason, as shown in FIG. 25, in the conventional progressive multifocal lens 1, progressive refraction giving a refractive power that changes continuously to configure the distance portion 11, the near portion 12, and the progressive portion 13 is performed. The surface 5 is formed on the object-side refractive surface 3, and the eyeball-side refractive surface 2 is used as a refractive surface for correcting astigmatism, as described later.

FIG. 26 shows the astigmatism obtained by the conventional progressive multifocal lens 1. FIG. 27 shows the z coordinate of the progressive refracting surface 5 formed on the object side refracting surface 3 of the conventional progressive multifocal lens 1. Is shown. In addition, on the refraction surface 3,
A plane is defined as xy coordinates, and a direction indicating the thickness of the lens perpendicular to the xy plane is defined as z coordinates. The directions of the x and y coordinates do not need to be particularly defined, but hereinafter, a description will be given with the y-coordinate as the up-down direction and the x-coordinate as the left-right direction when mounted as an eyeglass lens.

[0005] The progressive refraction surface 5 is aspherical so as to continuously change the refracting power. Therefore, the curvature changes depending on each area of the surface. Therefore, as can be seen from FIG. 26, even if the progressive multifocal lens 1 is not for correcting astigmatism and has the spherical surface 2 on the eyeball side, the introduction of the progressive refraction surface 5 on the surface 3 on the object side will cause the x direction. And a curvature difference in the y direction causes astigmatism on the surface. This astigmatism is expressed in units of diopters (D), and areas of predetermined diopters connected by contour lines are astigmatism diagrams shown in FIG.

A user of spectacles without astigmatism (user)
If the astigmatism appearing in the lens is 1.0 diopter or less, preferably 0.5 diopter or less, clear vision can be obtained without much perceived blurring of the image. For this reason,
The astigmatism along the main line of sight (navel meridian) 14 extending from the distance portion to the near portion and slightly bending to the nose side in view of the convergence of the eye is 1.0 diopter or preferably 0. The clear visual field 21 which is 5 diopters or less is arranged. In particular, on this main line of sight 14, the x direction and y
The curvature difference in the direction is almost eliminated so that astigmatism does not occur. Accordingly, since the shape becomes aspherical from the main line of sight 14 toward the periphery of the lens 1, astigmatism appears greatly. Further, if such astigmatism greatly fluctuates, when the user moves his / her line of sight, the image is distorted along the line of sight and causes discomfort. For this reason, the astigmatism is set so that it does not fluctuate so much in the distance portion 11 where the movement of the line of sight is large, and the progressive refraction surface 5 where the astigmatism does not fluctuate much in other regions.
Has been designed. Then, the lens 1 is shaped into a shape that matches the frame of the spectacles to form a spectacle lens 9, which is provided to the user.

The lens 1 shown in FIG. 26 and FIG.
The base curve Pb indicating the basic refractive power of the object-side surface 3 to which the progressive refraction surface 5 is added is 4.00D, and the addition power Pa
Is 2.00 V, and the surface refractive power D2 of the eyeball-side surface 2 is 6.00.
D, the center thickness t of the lens is 3.0 mm, and the lens diameter d is 7
It is a 0.0 mm lens.

FIG. 28 shows a conventional progressive multifocal lens 1 for astigmatism in which a toric surface 6 having a cylindrical refractive power C for correcting astigmatism is formed on the eyeball-side surface 2.
FIG. 29 shows an astigmatism diagram of this lens.
FIG. 30 shows the z coordinate of the toric surface 6. FIG.
Has a cylindrical refractive power C of -2.0.
The other conditions are the same as those of the lens showing astigmatism in FIG. The progressive multifocal lens 1 for astigmatism is used to correct astigmatism along the main gazing line 14.
The astigmatism of 00D is almost uniformly introduced, and the eyeglass lens 9 can be formed by processing the lens along the eyeglass frame in the same manner as described above.

As described above, spectacle lenses whose refractive power continuously changes from a distance portion to a near portion using a progressive refraction surface are commercially available, including correction of astigmatism, and are often used for correcting visual acuity. Have been. A progressive multifocal lens has a large power to be corrected for visual acuity, and if the addition power, which is the difference between the refractive powers of the distance portion and the near portion, is large, the progressive refraction surface becomes more aspherical. Also has a large astigmatism. For this reason, the shape of the progressive refraction surface is improved so that astigmatism is excluded from the area of a lens that is normally used, and abrupt fluctuation of astigmatism is prevented, so that a comfortable field of view can be provided to the user. Image fluctuations and distortions can be improved by suppressing fluctuations in astigmatism. However, in progressive multifocal lenses, image fluctuations and distortions are also caused by differences in refractive power (power) between the distance portion and the near portion. appear. That is, the distance portion 11 has a refractive power such that the focus is far, while the near portion 12 has a different refractive power from that of the distance portion 11 so that the vicinity is focused. Therefore, in the progressive section 13, the magnification gradually changes, which is another main cause of shaking or distortion of the obtained image.

Various proposals have already been made in the design of a progressive refraction surface, and designs that make use of the computational power of a computer are also being actively made, and the astigmatism of the progressive refraction surface is improved to improve the image quality. It is considered that suppressing the fluctuation and the distortion has almost reached the limit. Therefore, an object of the present invention is to provide a progressive multifocal lens capable of improving image distortion and distortion caused by a change in magnification between a distance portion and a near portion of the progressive multifocal lens. The objective of the present invention is to provide a progressive multifocal lens and a spectacle lens that can reduce the image fluctuation and distortion, which are reaching the limit in the design of the progressive refraction surface, and provide a more comfortable visual field to the user. And Also, a progressive multifocal lens that can provide a clear field of view with little shaking or distortion even for a user who has a large difference in power (addition) between the distance portion and the near portion where image shaking or distortion is likely to occur. It aims to provide spectacle lenses.

[0011]

For this reason, the inventors of the present application pay attention to the arrangement of the progressive refraction surface which gives the magnification of the progressive multifocal lens, and bring the progressive refraction surface to the surface on the eyeball side. The difference in magnification between the distance section and the near section can be reduced,
It has been found that image shaking and distortion due to this can be greatly reduced. That is, in the progressive multifocal lens for vision correction comprising a distance portion and a near portion having different refractive powers of the present invention, and a progressive portion whose refractive power changes progressively between them, The progressive multifocal lens is characterized in that a curvature of a progressive refraction surface for forming a distance portion, a near portion, and a progressive portion is added to a surface on the eyeball side of the progressive power lens.

The magnification SM of a lens is generally expressed by the following equation.

SM = Mp × Ms (1)

Here, Mp is called a power factor, and Ms is called a shape factor. As shown in FIG. 1, the distance from the vertex (inner vertex) of the eyeball-side surface of the lens to the eyeball is L, The refractive power of the inner vertex (the inner vertex refractive power) is Po, the thickness of the lens center is t, the refractive index of the lens is n, and the base curve (refractive power) of the object-side surface of the lens is P.
If b is used, it is expressed as follows.

Mp = 1 / (1-L × Po) (2) Ms = 1 / (1- (t × Pb) / n) (3)

In calculating equations (2) and (3), diopter (D) is used for inner vertex power Po and base curve Pb, and meter (m) is used for distance L and thickness t. .

It is the inside vertex refractive power Po that contributes to the correction of visual acuity in the distance portion and the near portion. If the lens has the same inside vertex refractive power Po, the base curve Pb of the object side surface is obtained. By suppressing the fluctuation of the magnification S
It can be seen that the change in M can be suppressed. For example, if the base curve Pb of the convex surface on the object side is kept constant, the variation of the magnification MS due to the shape factor Ms can be eliminated. However, as shown by the dashed line in FIG.
If the progressive refraction surface is provided on the surface on the object side, the base curve Pb on the object side cannot be kept constant, and the fluctuation of the shape factor Ms increases as the addition power increases, resulting in image fluctuation. And distortion increase. Therefore, in the present invention, by bringing the progressive refraction surface to the eyeball-side surface serving as the concave surface of the lens, the fluctuation of the base curve Pb of the object-side surface is suppressed as shown by the solid line in FIG. For example, a spherical progressive multifocal lens with a constant base curve can be provided. Therefore, in the progressive multifocal lens of the present invention, the difference in magnification between the distance portion and the near portion can be kept to a minimum, and the change in magnification in the progressive portion can be suppressed. Can be reduced. Therefore, according to the present invention, it is possible to provide a progressive multifocal lens and a spectacle lens with reduced image distortion / distortion even if the performance due to astigmatism is almost the same as that of a conventional progressive multifocal lens, A more comfortable view can be provided to the user. In particular, in a progressive addition lens having a large addition, it is possible to greatly reduce distortion and distortion.

FIG. 2 shows that the base curve Pd is 5.00 D,
The addition Pa is 3.00D, the spherical refractive power S is 2.00D,
As an example, the magnification obtained with a progressive multifocal lens of the present invention having a refractive index n of 1.662 and a distance L of 15.0 mm is the same as the magnification obtained with a conventional multifocal lens having a progressive refraction surface on the object side. It is shown in comparison. As can be seen from the figure, in the progressive multifocal lens of the present invention, the magnification difference between the distance portion and the near portion can be suppressed to 80% of the conventional magnification difference, and image shaking and distortion are largely prevented. You can see what you can do.

Further, as shown in FIG. 3, this effect becomes more remarkable as the addition Pa increases. FIG.
The base curve Pd is set to 4.00 D for the above lens,
A magnification difference between a distance portion and a near portion of a progressive multifocal lens provided with a progressive refracting surface on the eyeball side surface (concave surface) according to the present invention with a spherical refractive power S of 0.00D is shown as an example. For comparison, the magnification difference between the distance portion and the near portion of the conventional progressive multifocal lens having a progressive refraction surface on the object side surface (convex surface) is also shown. As can be seen from this figure, in the progressive multifocal lens according to the present invention, the conventional progressive multifocal lens from one rank (addition of Pa is about 0.25D) down to two ranks below at high addition is used as the addition Pa. It is possible to make the magnification difference approximately the same as that of the lens, and as a result, it is possible to suppress the fluctuation and distortion of the image obtained by the user to the same degree as that of a conventional lens having an addition one rank lower or two ranks. it can.

In the progressive multifocal lens of the present invention, the curvature (the reciprocal of the radius of curvature) of the progressive refraction surface along the main line of sight is far away in order to impart the curvature of the progressive refraction surface to the surface on the eyeball side. The near portion is smaller than the portion. In the distance portion, the curvature of the progressive refraction surface decreases in at least a part of the region as the distance from the main line of sight increases, and in the near portion, the curvature of the progressive refraction surface in the at least one region decreases. The distance increases from the gaze line.

Also, a progressive multifocal lens having an addition of 0.5 to 3.5 over a wide range from a user with little presbyopia to a user with presbyopia and little adjustment power. As shown in FIG. 3, the progressive multifocal lens of the present invention has a great effect in improving image shaking and distortion within this range, as shown in FIG. Addition in this range, when the object side surface of the progressive multifocal lens of the present invention is a rotationally symmetric surface,
Average surface refractive power D1 on the eyeball side near the main line of sight of the distance portion
And the average surface power D on the eyeball side near the main line of sight of the near portion
2 is expressed as follows.

0.5 ≦ (D1-D2) ≦ 3.5 (4)

Further, as the progressive refracting surface, it is desirable to minimize astigmatism in forming the progressive refracting surface on the main line of sight. It is desirable that the curvature of the progressive refraction surface be equal in two orthogonal directions.

In the progressive multifocal lens of the present invention, since the progressive refracting surface is provided on the surface on the eyeball side, by adding the curvature of the toric surface for correcting astigmatism to the surface on the eyeball side, the surface on the eyeball side is astigmatic. A progressive multifocal lens for correcting astigmatism having correction characteristics can be provided. That is, it is possible to provide a progressive multifocal lens whose surface on the eyeball side is a progressive refraction surface, and which further has a cylindrical refractive power. Then, by employing the progressive multifocal lens having the astigmatism correction characteristic of the present invention as a spectacle lens, a progressive refraction surface is provided on the eyeball side surface, so that the magnification of the distance portion and the near portion is set as described above. The difference can be kept to the minimum necessary, astigmatism can be corrected, and image distortion and shaking are small, so that a user who has astigmatism can be provided with a more comfortable visual field.

The progressive multifocal lens in which the visual acuity correction characteristic and the astigmatism correction characteristic are added to the surface on the eyeball side is a progressive refraction surface (hereinafter referred to as a refracting surface) only for the purpose of exhibiting the desired visual acuity correction characteristic on the eyeball side surface. Is a first step of calculating the curvature of the original progressive refraction surface, and a second step of calculating the curvature of the toric surface (hereinafter referred to as the original toric surface) solely for the purpose of the eyeball-side surface exhibiting the desired astigmatic correction characteristics.
And a third step of obtaining the eyeball-side surface of the progressive multifocal lens by combining the curvature of the original progressive refraction surface and the curvature of the original toric surface. it can. By bringing the progressive refraction surface composed of the original progressive refraction surface and the original toric surface to the eyeball-side surface, a function of correcting astigmatism using the toric surface and a progressive refraction surface other than the correction of astigmatism were used. A progressive multifocal lens having both a visual acuity correcting function and less fluctuation and distortion can be realized.

In the above-described third step, z for forming an original toric surface having astigmatic correction characteristics is used.
It is also possible to configure a progressive refraction surface having astigmatism correction characteristics by adding the z-coordinate value constituting the original progressive refraction surface having vision correction characteristics to the coordinate values. However, according to the results examined by the inventor of the present application, in order to obtain a performance (astigmatism characteristic) of correcting astigmatism equivalent to that of a conventional progressive power lens for correcting astigmatism on the object side and the toric surface on the eyeball side in the related art. For this purpose, it is desirable to form the progressive refraction surface using a synthesis formula as shown in the following expression (5). That is, in the third step, the value Z at an arbitrary point P (X, Y, Z) on the eyeball-side surface of the progressive multifocal lens is converted into the approximate curvature Cp of the original progressive refractive surface and the x-direction of the original toric surface. By using the curvature Cx and the curvature Cy in the y direction according to the following equation (5), the lens has a capability of correcting astigmatism and a capability of correcting visual acuity equivalent to that of a conventional progressive multifocal lens. It is possible to provide a progressive multifocal lens for correcting astigmatism, which has small fluctuations and improved shaking and distortion.

[0027]

(Equation 1) ... (5)

Here, in the spectacle wearing state, the axis passing through the center of the progressive refraction surface from the object side to the eyeball side is the z-axis, the axis extending from below to the top is orthogonal to the z-axis, and the axis orthogonal to the z-axis is z-axis. When the axis orthogonal to the axis is the x axis, X and Y are
The coordinates of arbitrary points of the x- and y-coordinates of the eyeball-side surface are indicated, and Z indicates the vertical z-coordinate of the eyeball-side surface. Also, the curvature Cp is calculated at an arbitrary point p on the original progressive surface.
(X, Y, Z) is an approximate curvature, and the curvature Cx is the curvature in the x direction of the toric surface for correcting astigmatism, and the curvature Cy is y.
The curvature in the direction. In this example, the approximate curvature C
The average curvature in the radial direction is adopted as p, and includes an arbitrary point p (X, Y, Z) on the original refracting surface and passes along the z axis (passing through the lens center or the inner vertex (0, 0, 0)). In a vertical xy plane, a point p ′ (−
The reciprocal of the radius of a circle passing through three points of (X, -Y, Z) and the inner vertex (0, 0, 0) is used. However, when the point p on the original progressive refractive surface is located at the inner vertex, the radial average curvature Cp is not defined and Z =
It is set to 0.

In the present invention, the characteristics of the original progressive refraction surface and the original toric surface can be added to the eyeball-side surface by employing such a synthetic formula (5). Accordingly, a progressive multifocal lens having a progressive refracting surface for vision correction on the eyeball side and a progressive multifocal lens having a progressive refracting surface having both characteristics for vision correction and correcting astigmatism on the eyeball side are provided. It is possible to realize a wide range of spectacle lenses that can cover a range from a user who does not have astigmatism to a user who needs correction of astigmatism. For this reason, it becomes possible to provide a series of spectacle lenses using a progressive multifocal lens with less shaking and distortion to all users.

Also, a progressive multifocal lens having a progressive refraction surface on the eyeball side can be made thinner by adding a prism in the direction of the base 270 degrees. Also, the vertex power Ps of the distance portion and the addition power (addition power)
By setting Pa and the refractive power (base curve) Pb of the object-side surface of the progressive multifocal lens so as to satisfy the following expression, the progressive refraction toward the eyeball of the present invention as a meniscus lens suitable for a spectacle lens. A progressive multifocal lens having a surface can be provided.

Pb> Ps + Pa (6)

[0032]

[Example 1]

FIG. 4 shows a progressive multifocal lens 10 of the present invention in which a progressive refracting surface 5 is provided on the eyeball-side surface 2. The progressive multifocal lens 10 of this example is provided with a far vision portion 11 which is a visual field portion for viewing a distant object at an upper portion and a lower portion at a lower portion, similarly to the conventional progressive multifocal lens shown in FIG. A field of view having a different refractive power from the distance portion 11 is provided as a near portion 12 in order to see an object at a distance. Further, the distance portion 11 and the near portion 12 have a continuous refractive power. It is a progressive multifocal lens smoothly connected by a changing progressive portion 13. The progressive multifocal lens 10 of the present example includes a distance portion 1
1, a progressive refractive surface 5 which is an aspheric surface is provided on the eyeball-side surface 2 to constitute the near portion 12 and the progressive portion 13. Therefore, the object-side surface 3 can be formed into a spherical surface having a constant base curve Pd. Therefore, in the above,
As described using the expressions (1) to (3), the distance portion 11
And the magnification difference between the near portion 12 and the progressive portion 13
In, the rate at which the magnification changes can be reduced. Therefore, compared with a conventional progressive power lens having a progressive refraction surface provided on the object side surface, it is possible to greatly reduce image fluctuation and distortion caused by a magnification difference.

FIGS. 5 and 6 show astigmatism diagrams of the progressive multifocal lens 10 of the present invention in which a progressive refraction surface is provided on the eyeball-side surface 2 and the eyeball-side surface 2, ie, the progressive refraction surface 5. The z coordinate is shown. The progressive multifocal lens 10 of the present example can obtain astigmatism of the same degree as that of the conventional progressive multifocal lens having the progressive refracting surface provided on the object-side surface 3 described above with reference to FIGS. It is designed to be. In the progressive multifocal lens 10 of the present example shown in FIGS. 5 and 6, the surface 3 on the object side is a spherical surface, and the base curve Pb indicating its refractive power is constant at 4.00D. As for the eyeball-side surface 2, the average surface refractive power of the distance portion 11 is 6.00D, and the near portion 1 is
The average surface refractive power of No. 2 is 4.00 D, and the addition power Pa is set to 2.00 D. Further, the spherical refractive power S of the distance portion 11 is -2.00D, and the center thickness t of the lens is 3.0.
0 mm and the lens diameter d is 70.0 mm. Under such conditions, the progressive refraction surface 5 as shown in FIG. 4 can be provided on the eyeball-side surface 2, and as a result, the progressive multifocal lens 10 having astigmatism as shown in FIG. Obtainable. The astigmatism of the progressive multifocal lens 10 of this example shown in FIG. 5 is almost the same as the astigmatism of the conventional progressive multifocal lens shown in FIG. It can be seen that even if is provided, a progressive multifocal lens 10 having the same performance as that of a conventional progressive multifocal lens having a progressive refracting surface on the object-side surface 3 can be realized with respect to astigmatism.

Therefore, the progressive multifocal lens 10 of this embodiment is
The astigmatism is a progressive multifocal lens which has the same performance as the conventional one, has a sufficient clear vision area, and has little image distortion and fluctuation caused by fluctuation of astigmatism. Furthermore, when comparing the magnification difference between the distance portion 11 and the near portion 12,
In the progressive multifocal lens 10 of this example, the magnification of the distance portion 11 is 0.976, the magnification of the near portion 12 is 1.007, and the difference is 0.031. In contrast, the conventional lens 1 shown in FIG.
In, the magnification of the distance portion is 0.976, the magnification of the near portion is 1.011, and the difference is 0.035. Therefore, in the progressive multifocal lens 10 of this example, it can be seen that the difference in magnification between near and far can be improved by about 12 to 13% as compared with the related art. By reducing the magnification difference in this manner, in the progressive multifocal lens 10 of the present example, it is possible to further improve the image fluctuation and distortion caused in the progressive multifocal lens due to the magnification difference as compared with the related art. Will be possible. For this reason, by processing the progressive multifocal lens 10 of this example in accordance with the eyeglass frame in accordance with the eyeglass frame, it is possible to provide a spectacle lens 9 which is bright and has greatly improved shaking and distortion.

The progressive refraction surface 5 provided on the eyeball-side surface 2 of this embodiment will be further described. FIG. 7 shows a change in the radius of curvature of the progressive refraction surface 5 along the main gazing line 14. In the z-coordinate of this figure, the direction of the object to be watched is set to be negative, and the direction of the eyeball is set to be positive. Progressive refraction surface 5 along main line of sight 14
Let r1 be the radius of curvature of the upper distance portion 11 and r2 be the radius of curvature of the near portion 12, of the curvature radius of the refractive power of the distance portion 11 in the progressive multifocal lens for spectacles. Is smaller than the value of the refractive power of the near portion 12, that is, it is set to be negative when the value of the refractive power of the near portion 12 is subtracted from the value of the refractive power of the distance portion 11. The radius of curvature r1 of the progressive multifocal lens 10 of this example is the radius of curvature r
It becomes smaller than 2. Therefore, when expressed by curvatures C1 and C2, which are the reciprocals of the respective radii of curvature r1 and r2, the curvature C1 of the distance portion 11 and the curvature C2 of the near portion 12 need to satisfy the following relationship.

C1> C2 (7)

The radius of curvature of the distance portion 11 in the direction 15 perpendicular to the main gazing line 14 is, as shown in FIG. 8A, a progressive portion continuous with the near portion 12 having a large radius of curvature. 13
In order to construct the above, there is provided an area which becomes larger as the distance from the main gazing line 14 increases. On the other hand, the curvature of the near portion 12 in the direction 16 perpendicular to the main line of sight 14 constitutes the progressive portion 13 continuous with the far portion 11 having a small radius of curvature as shown in FIG. In addition, there is provided an area which becomes smaller as the distance from the main gazing line 14 increases. That is, the distance portion 11
In the direction 15 orthogonal to the main gaze line 14, the radius of curvature near the main gaze line 14 is r3, and the radius of curvature is 5 to 3 from the main gaze line 14.
Assuming that the radius of curvature of the region separated by about 5 mm is r4, the radius of curvature r3 is equal to or smaller than r4. When this is represented by curvatures C3 and C4, which are the reciprocals of the radii of curvature r3 and r4, the curvature C3 in the region far from the main gazing line 14 is different from the curvature C3 near the main gazing line 14 in the distance portion 11.
Satisfies the following relationship.

C3 ≧ C4 (8)

It is of course possible to secure a wide clear vision area in the distance portion 11 by using the eyeball side surface 2 constituting the distance portion 11 as a spherical surface, and to concentrate the progressive portion 13 in the vicinity of the near portion 12. In this case, in the distance portion 11, the curvature C3 and the curvature C4 are equal. On the other hand, the main sight line 14 of the near portion 12
In a direction 16 perpendicular to the above, if the curvature in the vicinity of the main gazing line 14 is r5 and the curvature of a region separated from the main gazing line 14 by about 5 to 35 mm is r6, the curvature r5 is equal to or larger than r6. Therefore, when expressed by curvatures C5 and C6, which are the reciprocals of the radii of curvature r5 and r6, in the near portion 12, the curvature C5 near the main fixation line 14 is different from the main fixation line 1
The curvature C6 in a region away from the region 4 satisfies the following relationship.

C5 ≦ C6 (9)

Also in the near portion 12, a wide clear vision area is secured in the near portion 12 by using the eyeball-side surface 2 as a spherical surface.
Can be concentrated near the distance portion 11. In this case, the curvature C5 and the curvature C6 are equal in the near portion 12. Note that the change in the radius of curvature of the above equations (8) and (9) toward the horizontal side with respect to the main gazing line 14 has been described using the curvatures in the directions 15 and 16 orthogonal to the main gazing line as an example. There is no strict limitation on the direction,
It is sufficient that the average curvature satisfies the above equations (8) and (9) as the distance from the main gazing line 14 increases.

When the user wears the spectacle lens 9 of this embodiment, the eyeball often moves along the main line of sight 14.
For this reason, in the progressive multifocal lens 10 which does not require the correction of astigmatism, it is desirable that the main gaze line 14 is constituted by a set of navel points in order to prevent image distortion and shaking. Therefore, the following relationship is established among the above-mentioned curvatures C1, C2, C3 and C5.

C1 = C3 C2 = C5 (10)

At this time, the distance portion 1 along the main line of sight 14
The average surface refractive power D1 of the eyeball-side surface 2 and the average surface refractive power D2 of the eyeball-side surface 2 of the near portion 12 are expressed by the following equations.

D1 = (n−1) × C1 D2 = (n−1) × C2 (11) where n is the refractive index of the lens material constituting the progressive multifocal lens 10 of the present example. .

In the progressive multifocal lens 10 of this embodiment, since the object-side surface 3 is formed of a spherical surface, the addition power Pd is determined by the average surface refracting power D1 of the distance portion 11 and the average surface refraction of the near portion 12. Force D
It can be represented by the difference of two. Further, since the curvature C1 of the distance portion 11 is larger than the curvature C2 of the near portion 12 as shown in the equation (7), the distance portion 11 on the eyeball-side surface 2 is formed.
Is larger than the average surface refractive power D2 of the near portion 12. As described above with reference to FIG. 3, by using the progressive multifocal lens 10 of the present invention, the addition power for a user who has little adjustment power is 3.5.
From the diopter progressive multifocal lens, it is possible to reduce the magnification difference between the distance portion 11 and the near portion 12 within a wide range of the 0.5 diopter progressive multifocal lens in which presbyopia hardly advances. Thus, it is possible to provide the user with a comfortable field of view by suppressing the image shake and distortion. For example,
Even a wearer with no accommodation at all can see up to about 30 cm from infinity at 3.50 diopters. When this range of addition is shown using the average surface refractive powers D1 and D2 of the distance portion 11 and the near portion 12, the following expression (4) is obtained as described above.

0.5 ≦ (D1-D2) ≦ 3.5 (4)

When a toric surface is added to the eyeball-side surface 2 for correcting astigmatism, the main gazing line 14 does not become a set of navel points as shown in the next embodiment, and astigmatism is corrected. To do so, a substantially constant astigmatism is added along the main line of sight 14.

Further, as disclosed in Japanese Patent Publication No. 2-39768, the directionality of the refracting power along the main sight line 14 is reduced due to the thinning of the spectacle lens and the standardization. If it occurs, it is desirable to generate astigmatism due to the curvature difference in a direction to cancel the astigmatism due to the refractive power. Therefore, in such a case, it is desirable to provide a difference between the curvatures C1 and C2 along the main line of sight 14 and the curvatures C3 and C5 in the direction orthogonal thereto. In the progressive multifocal lens 10 in which the progressive refracting surface 5 is provided on the eyeball-side surface 2 of the present example, the refractive power Pt along the main gazing line 14 is closer to the outer periphery of the lens, and the refractive power Ps is in the direction perpendicular to the lens. More generally, a positive frequency is obtained. Accordingly, in such a case, in order to cancel the astigmatism due to the refractive powers Pt and Ps, the curvature C1 along the main gazing line 14 as shown in the following equation (12).
And C2 are desirably slightly larger than the curvatures C3 and C5 in the orthogonal direction.

C1> C3 C2> C5 (12)

As shown in FIG. 9A, in the progressive multifocal lens 10 of this embodiment, since the surface 2 on the eyeball side is the progressive refraction surface 5, the distance portion 11 is closer to the near portion 12. Lens becomes thicker. Therefore, in order to make the progressive multifocal lens 10 thinner and lighter, it is desirable to add a prism in the direction of 270 degrees at the base, which is not intended for vision correction. This allows
As shown in FIG. 9B, a very thin progressive multifocal lens 1
0 can be realized. In addition, the direction of the prism base indicates the direction in which the light beam perpendicularly incident on the eyeball-side surface 2 of the lens deflects due to the prism effect, as a counterclockwise angle with respect to the horizontal as viewed from the object-side surface 3. . Also,
The prism amount added at this time can select an optimum value for the user from 0.25 to 3.00 prism diopters.

In the progressive multifocal lens 10 of this embodiment, the object-side surface 3 suitable for a spectacle lens is a convex surface and the eyeball-side surface 2 is a concave surface. Refractive power (vertex power) Ps and addition power (addition power) P
a and the refractive power (base curve) Pb of the object-side surface 2 of the progressive multifocal lens must be set so as to satisfy the following expression (6).

Pb> Ps + Pa (6)

By selecting the vertex refracting power Ps, the addition Pa, and the base curve Pb so as to satisfy the equation (6), the progressive multifocal lens 10 having a meniscus shape can be obtained. Can provide lenses. [Example 2]

FIG. 10 shows a progressive multifocal lens 10 of the present invention in which the surface 2 on the eyeball side is provided with the characteristics of a progressive refraction surface 5 and a toric surface 6. In the following, in order to distinguish from the progressive refraction surface of the present example having both the visual acuity correction characteristic and the astigmatism correction characteristic formed on the eyeball-side surface 2, the eyeball-side surface has a desired visual acuity correction characteristic. A progressive refraction surface set only for exhibiting characteristics (characteristics other than astigmatism correction characteristics) is called an original progressive refraction surface, and is set only for a surface on the eyeball side to exhibit desired astigmatism correction characteristics. The resulting toric surface is called an original toric surface.

The progressive multifocal lens 10 of this example is designed and manufactured by the procedure shown in the flowchart of FIG. First, in step ST1, an original progressive refraction surface is obtained by parameters suitable for situations such as the degree of presbyopia of the user and how to use glasses, and the result is stored as coordinates or curvature. Before and after this,
In step ST2, an original toric surface for correcting the user's astigmatism is obtained, and the result is stored as a curvature. Of course, it is also possible to store the coordinates. Then, in step ST3, using the results of steps ST1 and ST2, the coordinates of the eyeball-side surface having the visual acuity correction characteristics and the astigmatic correction characteristics are obtained.
In this example, in step ST3, the z-coordinate value Z of the eyeball-side surface 2 is obtained using the following synthesis formula (5) as described above.

[0058]

(Equation 2) ... (5)

By using this synthetic formula (5), a progressive multifocal lens having a function of correcting astigmatism for correcting visual acuity, similarly to the conventional progressive multifocal lens shown in FIG. That can be provided.

FIG. 11 shows a progressive multifocal lens according to the present invention, which corresponds to a conventional progressive multifocal lens having a progressive refractive surface on the object side surface 3 and a toric surface on the eyeball side surface 2 shown in FIG. An astigmatism diagram of the lens 10 is shown. FIG.
2 shows the value of the z coordinate of the progressive multifocal lens 10 of this example. By combining the original progressive refractive surface 5 shown in FIG. 6 and the original toric surface 6 shown in FIG. 30 using the above equation (5), a value Z of the z coordinate as shown in FIG. 12 is provided. The eyeball-side surface 2 can be synthesized.
The progressive multifocal lens 10 of this example is formed by using the eyeball-side surface 2 and the spherical object-side surface 3 and has substantially the same astigmatism characteristics as shown in FIG. Thus, a progressive multifocal lens for correcting astigmatism can be obtained. Therefore, according to the present invention, a progressive lens having a visual acuity correcting capability and an astigmatic correction capability equivalent to that of a conventional progressive multifocal lens in which a progressive refractive surface is provided on the object side surface 3 and a toric surface is provided on the eyeball side surface 2. The multifocal lens 10 can be obtained.

As described above, in this embodiment, the curvature of the toric surface for correcting astigmatism can be added to the surface on the eyeball side in addition to the curvature of the progressive refractive surface for correcting vision, and the surface on the eyeball side also has astigmatic correction characteristics. In other words, it can have a cylindrical refractive power. Therefore, since a progressive refraction surface having a visual acuity correction capability and an astigmatism correction capability can be prepared on the eyeball side, the magnification difference between the distance portion 11 and the near portion 12 can be reduced in addition to the visual acuity correction capability and the astigmatism correction capability. The progressive multifocal lens 10 in which the fluctuation and the distortion of the lens are improved can be provided. As shown in FIG. 14, the magnification difference of the progressive multifocal lens 10 of the present example is improved by 12 to 13% in both the 90-degree direction and the 180-degree direction as compared with the conventional lens, as shown in FIG. According to the present invention, it can be seen that shaking and distortion can be reduced even in a progressive multifocal lens for correcting astigmatism. Therefore, by processing the progressive multifocal lens 10 of the present example along the eyeglass frame, it is possible to correct eyesight and astigmatism, and to provide the eyeglass lens 9 with very little image sway and distortion. . For this reason, the spectacle lens 9 of the present invention can provide a comfortable visual field even for a user having astigmatism.

In the progressive multifocal lens 10 shown in FIGS. 11 and 12, the base curve Pb indicating the refractive power of the object-side surface 3 is constant at 4.00D. In the eyeball-side surface 2, the progressive refraction surface 5 before combining the toric surface has an average surface refractive power of the distance portion 11 of 6.00 as in the first embodiment.
D, the average surface refractive power of the near portion 12 is set to 4.00D, and the addition power Pa is set to 2.00D. On the other hand, the astigmatic axis is 90 degrees, the spherical refractive power S is -2.00D, A toric surface having a cylindrical refractive power C of -2.00D is synthesized.
The center thickness t of the lens is 3.0 mm, and the lens diameter d is 70.0 mm.

In FIG. 15, instead of using the above-described synthesis formula (5), the value of the z coordinate of the original toric surface shown in FIG. 30 is added to the value of the z coordinate of the original progressive refractive surface shown in FIG. 1 shows a lens 19 provided with a progressive refracting surface forming an eyeball-side surface 2. FIG. 16 shows an astigmatism diagram of the lens 19, and FIG. 17 shows the z coordinate of the eyeball-side surface 2 of the lens 19. By adding the value of the z coordinate of the original toric surface to the value of the z coordinate of the original progressive refractive surface, it is also possible to form a progressive refractive surface having vision correction characteristics and astigmatic correction characteristics.
However, as can be seen from FIG. 16, when the above-described synthesis formula (5) is not used, it is difficult to obtain astigmatism equivalent to that of the conventional progressive power multifocal lens for correcting astigmatism shown in FIG. It can be seen that it is difficult to obtain exactly the same correction of visual acuity and the ability to correct astigmatism exactly as with a progressive multifocal lens for correcting astigmatism.

This state also appears in the change of astigmatism along the main line of sight 14 of each progressive multifocal lens shown in FIG. In FIG. 18, the absolute value of astigmatism along the main line of sight 14 of the conventional progressive power multifocal lens 1 for correcting astigmatism shown in FIG. The absolute value of astigmatism along the main line of sight 14 of the progressive power multifocal lens 10 for correcting astigmatism shown in FIG. As can be seen from the figure, in the progressive multifocal lens 10 of the present example in which the eyeball-side surface 2 is synthesized using the synthetic formula (5), almost the entire area of the main gazing line is the same as that of the conventional progressive multifocal lens 1. 2D without compromising the ability to correct vision for correcting astigmatism
Is assured very stably. On the other hand, in the progressive refraction surface of the lens 19 in FIG. 16 in which the coordinates of the original toric surface are simply added to the coordinates of the original progressive refraction surface, as shown by a black square broken line 33 in FIG. Although 2D astigmatism for the purpose of correcting astigmatism is obtained along the line, it is difficult to secure stable astigmatism as compared with the lens 10 using the synthetic formula (5). In particular, fluctuation of astigmatism is large in the peripheral portion of the lens 19, and it is difficult to secure astigmatism for correcting astigmatism. Further, since the fluctuation of astigmatism is relatively large, the image is more likely to sway or be distorted when the eyeball is moved along the main gazing line as compared with the progressive multifocal lens 10 manufactured using the synthetic formula (5). Thus, by combining the original progressive refraction surface and the original toric surface using the combination formula (5), it can be seen that a progressive multifocal lens that is more comfortable and has a field of view with less fluctuation can be provided.

In the above description, the vertical direction of the lens (AX
The case where a prescription in which the spherical refractive power of the toric surface is set to IS (90 degrees IS) is applied (that is, a case in which the cylindrical refractive power of the toric surface is set in the lateral direction of the lens) is shown as an example. Of course, the invention is not limited to this. That is, the direction of the xy axis can be set to an appropriate direction that is limited to the above-described direction, and the above-described processing can be performed in the coordinate system. For example, even when a prescription in which the spherical refractive power of the toric surface is set in the left-right direction of the lens is applied, the directions of the x-axis and the y-axis of the xy coordinate are set to 90 degrees to the left with respect to the example shown above. Expression (5) of the present embodiment simply by performing the operation of rotating
Can be applied. Furthermore, even when a prescription in which the spherical refractive power of the toric surface is set in an arbitrary direction (including an oblique direction) of the lens is applied, xy
Equation (5) of the present embodiment can be obtained by simply performing an operation of rotating the x-axis and y-axis directions of the coordinates to the left by α degrees (α is an arbitrary angle of 0 to 360 degrees) with respect to the above examples. The synthesis method used can be applied.

In such a case, first, as described above, the step of determining a progressive refraction surface (original progressive refraction surface) having no astigmatic correction ability as shown in the first embodiment is performed. In the subsequent calculation of equation (5), it is necessary to use the same coordinate system for expressing the original progressive refractive surface and the coordinate system for expressing the toric surface. Therefore, in determining the original progressive refractive surface that does not have astigmatic correction ability, the coordinate system that matches the expression of the toric surface, that is, the direction in which the spherical refractive power of the toric surface is set, is added to the left in the above example. It is desirable to be able to represent an original progressive surface having no astigmatic correction ability using a coordinate system rotated by α degrees from the viewpoint of simplifying the calculation. [Other Examples]

FIGS. 19 to 24 show a progressive multifocal lens 1 for correcting astigmatism using the synthetic formula (5) of the present invention under other conditions.
An example in which 0 is formed is shown. FIG. 19 shows the astigmatism of the progressive multifocal lens 10 of the present invention, which is formed by combining the original progressive refractive surface 5 and the original toric surface 6 that are closest to the spherical surface by the combining formula (5). . The progressive multifocal lens 10 of this example has a spherical refractive power S of 0.00
D, the cylindrical refractive power C is -0.25D, the astigmatic axis is 45 degrees, and the addition Pa is 0.50D. FIG. 20 shows the astigmatism of the conventional progressive multifocal lens 1 designed under the same conditions. Is shown. As can be seen by comparing FIGS. 19 and 20, by using the synthetic formula (5), the progressive multifocal lens 10 having astigmatism almost equivalent to that of the conventional progressive multifocal lens 1 is obtained. In addition, it is possible to obtain a progressive multifocal lens having the same performance as that of the related art with respect to the ability of correcting vision and correcting astigmatism. Further, in the progressive multifocal lens 10 of this example, the surface 2 on the eyeball side is provided with a curvature exhibiting the functions of the progressive refraction surface 5 and the toric surface 6, so that the surface 3 on the object side has a constant base curve. Can be spherical. Therefore, similarly to the above-described embodiment, the magnification difference between the distance portion and the near portion can be reduced, and the magnification variation of the progressive portion can be reduced, so that the user is provided with a comfortable field of view with less image shaking and distortion. be able to.

Also in this example, the astigmatism of the lens 19 forming the eyeball-side surface 2 by simply adding the z-coordinate values of the original progressive refractive surface and the original toric surface is shown in FIG.
It is shown in FIG. The state of astigmatism shown in FIG.
9 and FIG. 20, it can be seen that a lens having the same performance as the conventional progressive multifocal lens 1 in astigmatism can be provided by using the synthetic formula (5). Therefore, since the present invention can reduce the image shaking and distortion, it is possible to provide a progressive multifocal lens that can be more comfortably mounted as a spectacle lens than conventional progressive multifocal lenses.

FIG. 22 shows the astigmatism of the progressive multifocal lens 10 of the present invention formed by combining the original progressive-refractive surface 5 and the original toric surface 6 that are farthest from the spherical surface by the combining formula (5). Is an example of the progressive multifocal lens of the present invention in which the fluctuation of the z coordinate of the synthesized eyeball-side surface 2 is largest. Progressive multifocal lens 10 of this example
Has a spherical refractive power S of 0.00D and a cylindrical refractive power C of -6.
FIG. 23 shows the astigmatism of the conventional progressive power multifocal lens 1 designed under the same conditions as 00D, the astigmatic axis of 45 degrees, and the addition Pa at 3.50D. As can be seen by comparing FIG. 22 and FIG. 23, by using the synthetic formula (5), the progressive multifocal lens 10 having astigmatism almost equivalent to that of the conventional progressive multifocal lens 1 also in this example.
Can be obtained. As described above, the synthetic formula (5) of the present invention indicates that the progressive refractive surface 5 having an addition Pa of 0.5 to 3.5 D and the toric surface 6 having a cylindrical refractive power C of 0.25 to 6.00 D This is effective for synthesizing surfaces in the range. Therefore, by using the synthetic formula (5) of the present invention, it is possible to provide a progressive multifocal lens for correcting astigmatism, in which a progressive refracting surface is provided on the eyeball-side surface 2 and image shaking and distortion are greatly improved. Can be.

Also in this example, FIG. 24 shows the astigmatism of the lens 19 in which the surface 2 on the eyeball side is formed by adding the z coordinate of the progressive refraction surface and the toric surface. As can be seen from this drawing, also in this example, the inner progressive surface with further improved astigmatism is obtained by using the synthetic formula (5) by comparing the lens with the z-coordinate of the original progressive refractive surface and the original toric surface. A multifocal lens can be obtained.

It should be noted that the preferred embodiments described in this specification are illustrative and not restrictive. The scope of the invention is indicated by the appended claims, and all modifications that come within the spirit and scope of the invention are intended to be covered by the claims.

[0072]

As described above, in the progressive multifocal lens of the present invention, by setting the progressive refracting surface to the eyeball side surface, the object side surface must be made aspherical. It is open so that the surface on the object side can be constituted by a spherical surface having a constant base curve. Therefore, it is possible to prevent the magnification MS from fluctuating due to the shape factor Ms caused by the object-side surface, so that it is possible to reduce the magnification difference between the distance portion and the near portion. For this reason, in recent years, in the situation where the design technology of the progressive refraction surface has advanced and the astigmatism appearing in the progressive multifocal lens has been improved, the image fluctuation and the distortion have been suppressed to the limit, the present invention has further improved the distance. It is possible to provide a progressive multifocal lens capable of improving image shaking and distortion caused by a difference in magnification between the utility portion and the near portion. In particular, in a progressive addition lens having a large difference in refractive power between the distance portion and the near portion having a large addition, by using the progressive addition lens of the present invention, it is possible to greatly improve image shaking and distortion. it can. Therefore, according to the present invention, it is possible to provide a comfortable field of view for a user of a progressive addition lens having a large addition and suffering from image shaking and distortion.

Further, in the present invention, there is provided a synthetic formula capable of exhibiting a predetermined performance by synthesizing a progressive refractive surface and a toric surface for correcting astigmatism on the surface on the eyeball side. Also, in a progressive multifocal lens for correcting astigmatism, a progressive refracting surface can be provided on the surface on the eyeball side to improve image shaking and distortion. Therefore, according to the present invention, it is possible to realize a progressive multifocal lens capable of providing a user with a comfortable field of view with suppressed shaking and distortion regardless of the presence or absence of astigmatism correction. By using the synthetic formula of the present invention, the progressive multifocal lens of the present invention can be applied to lenses of any conventional progressive surface design, and the effects of the present invention such as improvement of shaking and distortion can be obtained. Can be. Therefore, it is possible to replace the series of progressive multifocal lenses that have been provided with a progressive refraction surface on the object side as a series with a progressive refraction surface on the eyeball side, and to market them all. It is possible to provide a comfortable and bright field of view to the users.

Further, in the progressive multifocal lens of the present invention, since a progressive refraction surface and a toric surface can be set on the surface on the eyeball side, the surface on the object side can be used for any purpose. As described above, it is possible to provide a spectacle lens with a high fashionability while preventing the image from fluctuating or distorting by forming the convex surface on the object side as a fashionable spherical surface having a constant base curve. Further, in order to improve the astigmatism of the entire lens, the convex surface on the object side may be an aspherical surface which is rotationally symmetric. JP-A-2-2898
No. 18 adopts an aspherical convex surface whose curvature increases substantially from the symmetry axis toward the outer periphery of the lens at least in the vicinity of the symmetry axis of the rotation axis as the object-side convex surface. It is disclosed that the thickness can be reduced, and that astigmatism can be improved. Such a convex surface of the rotationally symmetric aspherical surface can be adopted as the convex surface of the progressive multifocal lens of the present invention. Furthermore, the convex surface on the object side is not limited to a spherical surface or an aspherical surface symmetrical with respect to the rotational axis, but an aspherical surface for further improving the optical performance of the lens such as astigmatism, according to the personality of the user. It is also possible to provide a fashionable aspheric surface with a convex surface on the object side. As described above, according to the present invention, it is also possible to provide a convex surface with an aspheric surface for giving fashionability to the optical performance as a progressive multifocal lens. Therefore,
By processing the progressive multifocal lens of the present invention into a spectacle lens, it is also possible to provide a spectacle lens that adds a fashionable personality claim to the optical performance as a progressive multifocal lens, and furthermore, a spectacle lens The use of the object side surface can be expanded in various ways.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an outline of a progressive multifocal lens of the present invention.

FIG. 2 is a table showing examples of a magnification of a distance portion, a magnification of a near portion, and a magnification difference between a distance portion and a near portion of a progressive multifocal lens of the present invention, in comparison with a conventional progressive multifocal lens. FIG.

FIG. 3 is a diagram showing an example of a magnification difference between a distance portion and a near portion for each addition of the progressive multifocal lens of the present invention in a table, as compared with a conventional progressive multifocal lens.

4A and 4B are diagrams showing an outline of a progressive multifocal lens according to Example 1 of the present invention, wherein FIG. 4A is a front view and FIG. 4B is a cross-sectional view taken along a main gazing line.

FIG. 5 is a diagram showing astigmatism of the progressive multifocal lens shown in FIG. 4;

FIG. 6 is a view showing the z of the eyeball-side surface of the progressive multifocal lens shown in FIG.
It is a figure showing a coordinate.

7 is a diagram showing a radius of curvature (reciprocal of curvature) of a surface on the eyeball side along a main gazing line of the progressive multifocal lens shown in FIG. 4;

8 is a diagram showing a radius of curvature of a surface on the eyeball side in a direction orthogonal to the main gazing line of the progressive multifocal lens shown in FIG. 4, and FIG.
FIG. 8A shows the radius of curvature of the distance portion, and FIG. 8B shows the radius of curvature of the near portion.

9A and 9B are diagrams illustrating a state in which a prism having a basis of 270 degrees is applied to the progressive multifocal lens illustrated in FIG. 4; FIG. 9A illustrates a cross section of a progressive multifocal lens in which no prism is provided; (B) shows a cross section of a progressive multifocal lens in which a prism is provided.

10A and 10B are diagrams illustrating an outline of a progressive multifocal lens according to Embodiment 2 of the present invention. FIG. 10A is a front view, and FIG.
(B) is a cross-sectional view along the main gazing line.

11 is a diagram showing astigmatism of the progressive multifocal lens shown in FIG.

12 is a diagram showing z coordinates of a surface on the eyeball side of the progressive multifocal lens shown in FIG.

FIG. 13 is a flowchart illustrating a method for manufacturing a progressive power multifocal lens having a visual acuity correcting ability and an astigmatism correcting ability according to the present invention.

FIG. 14 is a table showing an example of a magnification difference between a distance portion and a near portion of a progressive multifocal lens having a visual acuity correcting ability and an astigmatism correcting ability according to the present invention, in comparison with a conventional progressive multifocal lens. FIG.

15A and 15B are diagrams showing an outline of a lens obtained by adding an original progressive refractive surface and an original toric surface in Embodiment 2 of the present invention. FIG. 15A is a front view, and FIG.
FIG. 3 is a cross-sectional view taken along a main gazing line.

16 is a diagram showing astigmatism of the lens shown in FIG.

17 is a diagram showing z coordinates of a surface on the eyeball side of the lens shown in FIG.

18 is a graph showing changes in astigmatism along the main line of sight of the progressive multifocal lens according to Embodiment 2 of the present invention shown in FIG. 10 by using the conventional progressive multifocal lens shown in FIG. 28 and the lens shown in FIG. It is a graph shown with it.

FIG. 19 is a diagram showing astigmatism of a progressive multifocal lens according to a different embodiment of the present invention.

20 is a diagram showing astigmatism of a conventional progressive multifocal lens corresponding to the progressive multifocal lens shown in FIG.

FIG. 21 is a diagram illustrating astigmatism of a progressive multifocal lens formed without using a combining equation corresponding to FIG. 19;

FIG. 22 is a diagram showing astigmatism of a progressive multifocal lens according to still another embodiment of the present invention.

FIG. 23 is a diagram illustrating astigmatism of a conventional progressive multifocal lens corresponding to the progressive multifocal lens shown in FIG. 22;

FIG. 24 is a diagram illustrating astigmatism of a progressive multifocal lens formed without using a combining equation corresponding to FIG. 22;

25 (a) is a front view, and FIG. 25 (b) is a cross-sectional view taken along a main gazing line.

26 is a diagram showing astigmatism of the progressive multifocal lens shown in FIG. 25.

FIG. 27 is a diagram showing az coordinate of a progressive refraction surface on the object side of the progressive multifocal lens shown in FIG.

28A and 28B are diagrams showing an outline of a conventional progressive multifocal lens for correcting astigmatism; FIG. 28A is a front view, and FIG.
FIG. 3 is a cross-sectional view taken along a main gazing line.

29 is a diagram showing astigmatism of the progressive multifocal lens shown in FIG. 28.

30 is a diagram showing z coordinates of a toric surface on the eyeball side of the progressive multifocal lens shown in FIG. 28.

Claims (9)

[Claims] 1. A progressive multifocal lens for vision correction comprising a distance portion and a near portion having different refractive powers, and a progressive portion having a refractive power progressively changing between them. A progressive multifocal lens, wherein a curvature of a progressive refraction surface for forming the distance portion, the near portion, and the progressive portion is added to an eyeball side surface of the multifocal lens. 2. The progressive multifocal lens according to claim 1, wherein an object-side surface of the progressive multifocal lens is a spherical surface. 3. The progressive multifocal lens according to claim 1, wherein an object-side surface of the progressive multifocal lens is a rotationally symmetric aspherical surface. 4. The distance vision system according to claim 1, wherein an object-side surface of the progressive multifocal lens is a rotationally symmetric surface, and has a main gazing line extending from the distance portion to a near portion. Surface refractive power D of the eyeball-side surface near the main gaze line of the portion
A progressive multifocal lens, characterized in that the following relationship exists between 1 and an average surface refractive power D2 of the eyeball-side surface near the main gazing line of the near portion. 0.5 ≦ (D1-D2) ≦ 3.5 (A) 5. The device according to claim 1, further comprising a main line of sight extending from the distance portion to the near portion, wherein a curvature of the progressive refraction surface along the main line of sight is compared with the distance portion. A progressive multifocal lens wherein the near portion is smaller. 6. The method according to claim 1, further comprising a main line of sight extending from the distance portion to the near portion, wherein a curvature of the progressive refractive surface for forming the distance portion is at least one part. A progressive multifocal lens, wherein the distance from the main line of sight decreases in a region. 7. The device according to claim 1, further comprising a main line of sight extending from the distance portion to the near portion, wherein a curvature of the progressive refractive surface for constituting the near portion has at least one part. A progressive multifocal lens, wherein the distance from the main line of sight increases in a region. 8. The method according to claim 1, further comprising a main line of sight extending from the distance portion to the near portion, wherein the curvature of the progressive refractive surface for forming the main line of sight is at least one part. A progressive multifocal lens characterized in that, in a region, curvatures in two orthogonal directions are equal. 9. An eyeglass lens obtained by subjecting the progressive multifocal lens according to claim 1 to a lens shape according to the shape of an eyeglass frame.