JP3226108B2 - Method of manufacturing progressive lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the shape of the surface of a progressive power lens at a power measuring position.

[0002]

2. Description of the Related Art As a conventional technique, Japanese Patent Publication No. 2-397
As shown at 68, there is an invention in which the curvature ρt in the direction along the main meridian and the curvature ρs in the direction perpendicular to it are different. The main effect of the present invention is to improve the vision (astigmatism and image distortion) of the spectacle wearer. Therefore, when actually worn as spectacles, a good visual field can be provided.

[0003]

However, in the progressive lens of Japanese Patent Publication No. 2-39768, a certain effect (improvement of astigmatism and distortion) can be certainly obtained in a state of wearing as spectacles. When the distance power and near power of the lens are measured with a lens meter, ρt and ρ
It has been found that the astigmatic power occurs due to the difference in curvature of s. This is because the passage of the light beam in the wearing state is different from the passage of the light beam in the measurement state by the lens meter. That is, when the aberration is improved in the wearing state, the aberration occurs in reverse to the measurement by the lens meter.

When an ophthalmologist prescribes a spectacle lens, a patient is given a trial of a lens having a predetermined power, generally called a trial lens, to select an optimum power.
The power of the trial lens is guaranteed by the measurement of the lens meter. Therefore, unless the power of the spectacle lens to be worn is also guaranteed by the lens meter, it cannot be said that the spectacle lens is as prescribed. That is,
The lens of Japanese Patent Publication No. 2-39768 has improved aberrations when placed on the eyes, but is not necessarily a lens as prescribed by an ophthalmologist.

In particular, it is generally known that off-axis aberrations increase as the power measurement position moves away from the optical center. According to the study of the present inventors, it has been found that, in the conventional progressive lens, when the power is measured at a distance of 10 mm or more from the optical center, the off-axis aberration becomes so large that it cannot be ignored. It is for this reason that many progressive lenses set the distance power measurement position within 10 mm from the optical center to assure prescription power. On the other hand, the near dioptric power measurement position is often located at a distance of 10 mm or more from the optical center. However, in a conventional progressive lens, the near dioptric power is not guaranteed, and the addition can only be measured by reference.

[0006]

In order to solve the above problems, a progressive lens according to the present invention comprises a distance center 13 which is the lower end of a distance portion 1 of a main meridian curve 4 and a near distance region of the curve. A progressive power lens whose refractive power changes in accordance with a predetermined rule between the near centers 14 which are the upper ends of the lenses 2 to give an additional power, wherein at least the distance portion 1 and the near portion 2 In part or all of one of the regions, the curvature (ρt) of the main meridian curve 4 in the direction along the curve and the curvature (ρs) in the direction perpendicular to the curve are ρt.
In a progressive-focus lens of ≠ ρs, the surface refractive power Dt in the direction along the main meridian at the distance power measurement position 8 in the distance portion area 1 or the near power measurement position 9 in the near portion area 2. And the surface refractive power Ds in a direction perpendicular to the principal meridian
Are characterized by the following relationship:

[0007]

ΔD = Ds−Dt = a × Pw ² + b × Pw + c where Ds = (n−1) × ρs [unit: diopter] Dt = (n−1) × ρt [unit: diopter] Pw: far Power [unit: diopter] a, b, c: coefficient n: refractive index of lens material.

Further, in a progressive-focus lens in which the refracting surface for providing the addition is the convex refracting surface 11 of the lens, the coefficient a is a positive value.

Also, in a progressive lens wherein the refractive surface for providing the addition is the concave-side refractive surface 12 of the lens,
The coefficient a is a negative value.

[0010]

In the progressive lens according to the present invention, the difference between the curvature ρt in the direction along the principal meridian and the curvature ρs in the direction perpendicular to the principal meridian is set to an appropriate value, thereby guaranteeing the power when measured with a lens meter. It can be so.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic view of a progressive lens according to a first embodiment of the present invention. The symbols in the figure are a distance portion region 1, a near portion region 2, a middle portion region 3, a principal meridian 4, a lens body 5, a boundary line 6 between the distance portion region 1 and the middle portion region 3, and a middle portion region 3. And near vision region 2, distance power measurement position 8, near power measurement position 9, optical center 10, convex-side refraction surface 11, concave-side refraction surface 12 of lens, distance center 13, near vision It is the center 14. For the sake of simplicity, the boundaries 6 and 7 are shown in the drawing, but there is no boundary in an actual lens. The distance between the optical center 10 and the distance measuring position 8 is 15 mm. The lens is made of a material having a refractive index n = 1.50, and has an addition power of 2.00 [diopter: hereinafter referred to as D].
It is.

FIG. 2 is an enlarged view of the portion of the convex refracting surface 11 shown in FIG. Refractive surface curvature ρ
t is the curvature in the direction along the principal meridian 4, and ρs is the curvature in the direction perpendicular to it. Surface power Dt in the direction along the principal meridian and surface power Ds in the direction perpendicular to it
Has the following relationship with the curvatures ρt and ρs. Note that ρt,
The unit of ρs is [1 / m].

[0014]

Ds = (n−1) × ρs [unit: diopter] Dt = (n−1) × ρt [unit: diopter] n: refractive index of the lens material It is not the gist of the present invention to specify the values of Dt and Ds themselves in order to adjust by making an appropriate spherical surface or toric surface or the like. In order to improve the off-axis aberration, only the difference ΔD between Dt and Ds becomes a problem. FIG. 3A shows the relationship between the prescription power Pw of the distance portion and ΔD. When this relationship was analyzed in more detail, it was found that the following relationship was established between Pw and ΔD.

[0015]

ΔD = Ds−Dt = a × Pw ² + b × Pw + c Pw: distance power [unit: diopter] a, b, c: coefficient FIG. 3 (b) shows a near power measurement position 9 in this embodiment. At
It shows the relationship between Pw and ΔD. Pw is not the power of the near portion but the prescription power of the far portion. The near power measurement position 9 is 18 mm away from the optical center 10. Also in this case, the same relationship as described above holds between Pw and ΔD.

Table 1 shows the values of coefficients a, b, and c in this embodiment.

[0017]

[Table 1]

(Embodiment 2) FIGS. 4 (a) and 4 (b) show the relationship between Pw and ΔD of a distance portion and a near portion in a second embodiment of the present invention. In this embodiment, the refractive index of the lens material and the positions of the optical center 10, the distance power measurement position 8, and the near power measurement position 9 are the same as those in the first embodiment, but the addition is 1.00 [D]. ]. Table 2 shows the values of the coefficients a, b, and c in this embodiment.

[0019]

[Table 2]

(Embodiment 3) FIGS. 5A and 5B show the relationship between Pw and ΔD in the third embodiment of the present invention.

The operation is the same as that of the first embodiment except that the addition is 3.00 [D]. Table 3 shows the values of the coefficients in this embodiment.

[0022]

[Table 3]

(Embodiment 4) FIGS. 6A and 6B show the relationship between Pw and ΔD in a fourth embodiment of the present invention. In this embodiment, the distance power measuring position 8 is 10 mm away from the optical center 10 and the near power measuring position 9 is 23 mm away. The addition is 2.00 [D] and the refractive index is 1.50. Table 4 shows the values of the coefficients of the present embodiment.

[0024]

[Table 4]

(Embodiment 5) FIGS. 7A and 7B show the relationship between Pw and ΔD in the fifth embodiment of the present invention. In this embodiment, the distance power measuring position 8 is 20 mm away from the optical center 10, and the near power measuring position 9 is 13 mm away. The addition is 2.00 [D] and the refractive index is 1.50. Table 5 shows the values of the coefficients of the present embodiment.

[0026]

[Table 5]

[0027]

According to the present invention, in a progressive power lens whose power measurement position is located away from the optical center, the power can be accurately measured by a lens meter, and not only the prescribed power can be guaranteed by an ophthalmologist, but also the eye can be guaranteed. It was found that there was an effect of improving the aberration even in the state of being applied.

Further, the following effects can be obtained in manufacturing a lens. A general spectacle prescription specifies a spherical power and an astigmatic power as basic powers of a lens. The lens manufacturer must process these two powers, the spherical power and the astigmatic power, according to the prescription instructions. At this time, if the power measurement position and the optical center are separated,
The off-axis aberration is added to the astigmatic power, and it is difficult to process with an accurate astigmatic power. For example, spherical power −2.00
In the case of [D], astigmatic power -4.00 [D], and astigmatic axis 90 degrees, the power along the main meridian (vertical direction of the lens) is -2.00 [D], which is a relatively weak power. Therefore, the off-axis aberration can be almost ignored, and the power can be guaranteed by the conventional processing. However, in the direction perpendicular to the principal meridian (horizontal direction of the lens), the power is the sum of the spherical power and the astigmatic power. 00 [D]
And off-axis aberrations cannot be ignored. For this reason, in the conventional processing, the concave refractive surface has to be finely adjusted to guarantee the astigmatic power. If the astigmatism axis is fixed at 90 degrees, the power can be guaranteed by the conventional processing method, but since the astigmatism axis changes depending on the spectacle wearer, the concave side is used to cope with all astigmatism axes. It is not possible to adjust the refractive surface. In the present invention, since the off-axis aberration is canceled out by the difference in curvature between the other refracting surfaces (in the embodiment, the convex refracting surface), the power can be guaranteed irrespective of the direction of the astigmatic axis. For this reason, it is possible to manufacture a lens having a number of intensities in which off-axis aberration is a problem, and it is possible to provide spectacle lenses to more people.

In the embodiment of the present invention, the refractive index is 1.50.
Has been described, but the effects of the present invention do not change even if the lenses have different refractive indices. In addition, in the case of a lens having a concave surface on which a refraction surface giving the addition is provided, an effect equivalent to that of the present invention can be obtained by providing a curvature difference on the concave surface side. In this case, the signs of the coefficients a, b, and c are inverted. Further, in the embodiments of the present invention, the description has been made on the assumption that the off-axis aberration is completely removed at the time of measurement with the lens meter, but if the value is corrected to a value within a generally accepted tolerance. , Included in the progressive lens of the present invention.

[Brief description of the drawings]

FIG. 1 is a schematic view of a progressive lens according to the present invention.

FIG. 2 is a diagram illustrating a shape of a refraction surface at a power measurement position.

FIG. 3 is a diagram showing a surface refractive power difference of the first embodiment. (A) Far-sight frequency measurement position (b) Near-sight frequency measurement position

FIG. 4 is a diagram showing a surface refractive power difference of the second embodiment. (A) Far-sight frequency measurement position (b) Near-sight frequency measurement position

FIG. 5 is a diagram showing a surface refractive power difference of the third embodiment. (A) Far-sight frequency measurement position (b) Near-sight frequency measurement position

FIG. 6 is a diagram showing a surface refractive power difference of the fourth embodiment. (A) Far-sight frequency measurement position (b) Near-sight frequency measurement position

FIG. 7 is a diagram showing a surface refractive power difference of the fifth embodiment. (A) Far-sight frequency measurement position (b) Near-sight frequency measurement position

[Explanation of symbols]

 1 ··· Distance section area 2 ··· Near section area 3 ···· Intermediate section 4 ··· Main meridian 5 ··· Lens body 6・ Boundary line between distance section area and middle section area 7 ・ ・ ・ ・ ・ ・ ・ Border line between middle section area and near section area 8 ・ ・ ・ ・ ・ ・ Distance power measurement position 9 ・ ・ ・ ・ ・ ・ ・ Near power measurement Position 10 ··· Optical center 11 ··· Convex side refractive surface 12 ··· Concave side refractive surface 13 ··· Distance center 14 ··· Near center ρt ··· To the main meridian Curvature of refraction surface along direction ρs ...

Claims (1)

(57) [Claims] 1. A distance center (13) which is a lower end of a distance portion area (1) of a main meridian curve (4) and a near distance center (14) which is an upper end of a near area (2) of the curve. A progressive power lens that changes its refractive power in accordance with a predetermined rule to provide an additional power, and is a part of at least one of the distance portion region (1) and the near portion region (2). Alternatively, in all, manufacture of a progressive lens having a curvature (ρt) in a direction along the principal meridian curve (4) and a curvature (ρs) in a direction perpendicular to the curve is ρt ≠ ρs
In the method, the at the near vision diopter measurement position of the far vision diopter measurement position of the distance portion (1) (8) or the near portion region (2) (9), the direction of the surface along said principal meridional The refractive power Dt and the surface refractive power Ds in a direction perpendicular to the principal meridian satisfy the following relationship:
A method of manufacturing a progressive lens , wherein the shape of the lens surface is formed as described above . ΔD = Ds−Dt = a × Pw ² + b × Pw + c where Ds = (n−1) × ρs [unit: diopter] Dt = (n−1) × ρt [unit: diopter] Pw: distance power [unit] : Diopter] a, b, c: coefficient n: refractive index of the lens material, and the coefficient a takes a positive value or a negative value.