JP4806218B2 - Progressive power lens - Google Patents

Description

The present invention relates to a progressive power lens in which the distance portion vertex power is positive and at least the inner surface is a progressive surface.

Conventionally, progressive-power lenses have been used for the purpose of correcting presbyopia. The progressive power lens preferably has a progressive surface on the inner surface, that is, the surface closer to the eye of the wearer when wearing spectacles, from the viewpoint of ensuring a high degree of freedom in processing and a wide clear vision region. ing. A progressive power lens having such an inner surface as a progressive surface is disclosed in, for example, Patent Document 1 shown below.

International Publication No. 97/19382 Pamphlet

Here, it is generally considered that the spectacle lens should have a meniscus shape. This is because the following problems occur in the case of a spectacle lens having a convex inner surface. For example, when the lens is placed on a flat table (for example, a table) with the convex inner surface down, the vicinity of the center of the lens comes into contact with the flat table. As a result, there is a problem that the vicinity of the center of the lens is easily damaged. In addition, the skin and body hair (for example, wrinkles) of the wearer are likely to adhere to the convex inner surface. Thereby, there also exists a problem that this inner surface will be easily soiled.

Therefore, the progressive-power lens of Patent Document 1 is designed so that the surface refractive power of the outer surface, that is, the object-side surface when wearing spectacles, is larger than the sum of the distance portion vertex refractive power and the addition refractive power. The meniscus shape is realized.

However, when the above design is applied to a progressive addition lens having a positive distance vertex refractive power, a new problem arises that the center thickness is increased and the overall thickness cannot be reduced.

In view of the above circumstances, an object of the present invention is to provide a progressive-power lens having a positive distance-distance apex power, and having a thin center thickness while maintaining a meniscus shape. To do.

The progressive-power lens according to the present invention is a progressive-power lens having a positive distance vertex refractive power and at least an inner surface being a progressive surface, and an axis along the normal line of the outer surface at the prism measurement reference point. Z-axis (however, the direction from the outer surface to the inner surface is positive), the axis perpendicular to the Z-axis passing through the intersection of the inner surface and the Z-axis is Y-axis (however, when wearing, from the lower end of the lens to the upper end of the lens The sag amount and the curvature at an arbitrary height y from the Z-axis of the curve formed by the intersection of the YZ plane and the inner surface are z2 (y) and C2 respectively. (Y), yf is the height from the Z axis to the distance measurement reference point, yn is the height from the Z axis to the near measurement reference point, yt is the height from the Z axis to the upper end of the lens, and Z If the height from the shaft to the lower end of the lens is yu, the following three conditions ,
It meets at the same time,
Furthermore, among the two main curvatures when the inner surface shape is approximated by a toric surface, the minimum curvature C2min is as follows:
It is characterized by satisfying .

Condition (2) is a condition for the progressive power lens having positive distance portion vertex refractive power to have a meniscus shape at least in the distance portion. If the curvature C2 (yf) at the distance measurement reference point does not satisfy the condition (2), that is, if the curvature C2 (yf) takes a negative value, the shape of the inner surface becomes completely convex, which is inappropriate. It is. Condition (3) is a condition for reducing the center thickness of the progressive-power lens. If the curvature C2 (yn) at the near-point measurement reference point does not satisfy the condition (3), that is, if the curvature C2 (yn) takes a positive value, the base curve increases and the lens center thickness decreases. I can't.

Furthermore, the condition (4) indicates the relationship between the sag amounts at the upper and lower ends of the lens and the sag amount on the Z axis. For example, the lens satisfying the condition (4) is designed to have a shape in which only the peripheral portion of the lens comes into contact with the flat table when the lens is placed on the flat table with the inner surface facing down. That is, by satisfying the condition (4), a meniscus progressive power lens suitable for effectively preventing the occurrence of scratches and dirt on the inner surface, particularly the central portion of the inner surface, is provided.

In general, in an inner surface or double-sided progressive addition lens that is not intended for astigmatism correction, a vertical cross section of the inner surface, that is, a cross section in the YZ plane is an approximately gentle curve (hereinafter referred to as a minimum curvature cross section). ). Therefore, the above-mentioned progressive-power lens also defines each condition on the assumption that the vertical cross section of the inner surface is the minimum curvature cross section. However, in the case of a progressive-power lens that also has astigmatism correction, in other words, a progressive-power lens including astigmatism refractive power, the inner surface is designed as a surface having both a progressive characteristic and an astigmatism correction characteristic. That is, the direction of the minimum curvature cross section of the inner surface of such a progressive-power lens changes depending on the direction of the astigmatic axis AX. Therefore, the vertical section is not necessarily the minimum curvature section. Similarly, in a progressive-power lens in which the added vertical component and horizontal component are respectively distributed on the outer surface and the inner surface, the vertical section is not always the minimum curvature section.

Therefore, the condition (5) defines a condition that the minimum curvature should satisfy among the two main curvatures when the inner surface shape is approximated by a toric surface. If the minimum curvature C2min is lower than the lower limit of the condition (5), the lens cannot maintain the meniscus shape, that is, the inner surface may become a convex surface, which is not preferable. Further, if the curvature C2min exceeds the upper limit of the condition (5), it is not preferable because the lens cannot be made sufficiently thin.

Thereby, astigmatism correction characteristics are imparted to the inner surface (Claim 2), or either the vertical component or the horizontal component of the addition power is distributed to the outer surface and the inner surface (Claim 3). A progressive-power lens that is thin while maintaining a meniscus shape is provided.

Several methods for approximating the toric surface are conceivable. For example, the following method can be proposed. First, an equation representing a sag amount of a toric surface having a main cross section in a direction coinciding with the X axis and the Y axis and having the main curvature radius of the main cross section as rx and ry,
f (x, y; rx, ry)
And Also, six parameters representing coordinate transformation are (α, β, γ, Δx, Δy, Δz). However, the first three parameters represent the surface tilt (rotation) amount, and the last three parameters represent the shift amount from the origin. An expression representing the sag of the toric surface as a result of coordinate transformation with respect to the coordinates (x, y) using the above parameters is expressed as follows.
F (x, y; rx, ry, α, β, γ, Δx, Δy, Δz)

Here, assuming that the surface to be approximated is spatially sampled at an arbitrary interval (xi, yi, zi), the square sum of the approximation error is expressed as follows.
Σ {zi-F (xi, yi; rx, ry, α, β, γ, Δx, Δy, Δz)} ²
A combination of parameters for minimizing the sum of squares of the approximation errors is calculated by using a known optimization algorithm such as an attenuation least square method. Thus, approximation on the toric surface is performed.

The progressive-power lens according to the present invention further has the following conditions, where Pf is the distance vertex power in the vertical section, ADD is the add power, and D1 is the surface power of the outer surface.
It is preferable to satisfy.

Condition (1) is a condition for providing a progressive-power lens having a thin center thickness while maintaining a meniscus shape suitable for a spectacle lens. If the base curve, that is, the surface refractive power D1 of the outer surface is below the lower limit of the condition (1), the meniscus shape may not be maintained. Therefore, scratches and dirt are easily attached to the inner surface, which is not preferable. On the other hand, if the base curve D1 exceeds the upper limit of the condition (1), the center thickness is increased, and it is not preferable because the lens cannot be thinned.

As described above, according to the present invention, in the progressive addition lens having positive distance portion vertex refractive power, the center thickness is maintained while maintaining the meniscus shape by setting the specifications of the lens to appropriate values. Can provide a thin progressive addition lens.

6 is a vertical sectional view of a progressive-power lens according to Reference Example 1. FIG. This is the transmission refractive power of the progressive addition lens of Reference Example 1 . This is the sag amount on the inner surface of the progressive-power lens of Reference Example 1 . It is a vertical cross-sectional curvature of the inner surface of the progressive-power lens of Reference Example 1 . 6 is a vertical sectional view of a progressive-power lens of Comparative Example 1. FIG. It is the transmission refractive power of the progressive-power lens of Comparative Example 1. It is a sag amount of the inner surface of the progressive-power lens of Comparative Example 1. 3 is a vertical cross-sectional curvature of the inner surface of the progressive-power lens of Comparative Example 1. 6 is a vertical sectional view of a progressive-power lens according to Reference Example 2. FIG. This is the transmission refractive power of the progressive-power lens of Reference Example 2 . This is the sag amount on the inner surface of the progressive addition lens of Reference Example 2 . It is a vertical cross-sectional curvature of the inner surface of the progressive-power lens of Reference Example 2 . 6 is a vertical sectional view of a progressive-power lens in Comparative Example 2. FIG. This is the transmission refractive power of the progressive addition lens of Comparative Example 2. It is a sag amount of the inner surface of the progressive-power lens of Comparative Example 2. 4 is a vertical cross-sectional curvature of the inner surface of the progressive-power lens of Comparative Example 2. 1 is a vertical sectional view of a progressive-power lens according to Example 1. FIG. 3 is a contour line of the shape of the inner surface of the progressive-power lens of Example 1. FIG. FIG. 3 shows the transmission refractive power of the progressive-power lens of Example 1. FIG. It is the amount of sag on the inner surface of the progressive-power lens of Example 1 . 2 is a vertical sectional curvature of the inner surface of the progressive-power lens of Example 1. FIG. 6 is a vertical sectional view of a progressive-power lens according to Comparative Example 3. FIG. 10 is a contour line of the shape of the inner surface of the progressive-power lens of Comparative Example 3; This is the transmission refractive power of the progressive addition lens of Comparative Example 3. It is a sag amount of the inner surface of the progressive addition lens of Comparative Example 3. 10 is a vertical cross-sectional curvature of the inner surface of the progressive-power lens of Comparative Example 3. 10 is a vertical sectional view of a progressive-power lens according to Reference Example 3. FIG. This is the transmission refractive power of the progressive-power lens of Reference Example 3 . This is the sag amount on the inner surface of the progressive addition lens of Reference Example 3 . 5 is a vertical sectional curvature of the outer surface of the progressive-power lens of Reference Example 3 . It is a vertical cross-sectional curvature of the inner surface of the progressive-power lens of Reference Example 3 . 6 is a vertical sectional view of a progressive-power lens in Comparative Example 4. FIG. This is the transmission refractive power of the progressive addition lens of Comparative Example 4. It is a sag amount of the inner surface of the progressive addition lens of Comparative Example 4. 10 is a vertical cross-sectional curvature of the outer surface of the progressive-power lens of Comparative Example 4. 10 is a vertical sectional curvature of the inner surface of the progressive-power lens of Comparative Example 4. 6 is a vertical sectional view of a progressive-power lens according to Embodiment 2. FIG. 7 is a contour line of the shape of the inner surface of the progressive-power lens of Example 2. FIG. FIG. 6 shows the transmission refractive power of the progressive-power lens of Example 2. FIG. It is the amount of sag on the inner surface of the progressive-power lens of Example 2 . FIG. 4 shows the vertical cross-sectional curvature and sagittal curvature of the outer surface of the progressive-power lens of Example 2. FIG. FIG. 3 shows the vertical cross-sectional curvature and sagittal curvature of the inner surface of the progressive-power lens of Example 2. FIG. 10 is a vertical sectional view of a progressive-power lens according to Comparative Example 5. FIG. 10 is a contour line of the shape of the inner surface of the progressive-power lens of Comparative Example 5; It is the transmission refractive power of the progressive-power lens of Comparative Example 5. It is a sag amount of the inner surface of the progressive-power lens of Comparative Example 5. 7 is a vertical sectional curvature and a sagittal curvature of the outer surface of the progressive-power lens of Comparative Example 5. FIG. 7 is a vertical sectional curvature and a sagittal curvature of an inner surface of a progressive-power lens of Comparative Example 5.

Hereinafter, a progressive-power lens according to an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of a progressive-power lens 10 according to an embodiment of the present invention. As shown in FIG. 1, the progressive addition lens 10 includes an outer surface 1 and an inner surface 2. The progressive addition lens 10 has a positive distance vertex power, and the outer surface 1 is a spherical surface or a progressive surface, and the inner surface 2 is a progressive surface. In FIG. 1, the axis along the normal line of the outer surface 2 at the prism measurement reference point 3 is taken as the Z axis. In addition, an axis that passes through the intersection of the inner surface 2 and the Z axis, is orthogonal to the Z axis, and extends along the vertical direction when wearing spectacles is defined as a Y axis. That is, FIG. 1 is a cross-sectional view of the progressive-power lens 10 on the YZ plane. In the following description, for the sake of convenience, the Z-axis is positive in the direction from the outer surface 1 to the inner surface 2. The Y axis is positive in the direction from the lower end of the lens toward the upper end of the lens when wearing glasses. Reference numeral 4 represents a distance measurement reference point, and reference numeral 5 represents a near measurement reference point.

The progressive-power lens 10 is configured to satisfy the following condition (1).

However, Pf is the distance portion vertex refractive power in the vertical section (cross section in the YZ plane),
ADD gives the addition power,
D1 represents the surface refractive power of the outer surface.

The progressive-power lens 10 configured to satisfy the condition (1) has a meniscus shape as a whole and is designed to have a thin center thickness.

In addition, the progressive-power lens 10 having a meniscus shape as a whole and designed to have a thin center thickness satisfies the following conditions (2) to (4) at the same time.



However, z2 (y) is a curve formed by the intersection of the YZ plane and the inner surface, and is a sag amount at an arbitrary height y from the Z axis.
C2 (y) is the curvature at an arbitrary height y in the curve,
yf is the height from the Z axis to the distance measurement reference point,
yn is the height from the Z-axis to the near-site measurement reference point,
yt is the height from the Z axis to the top of the lens,
yu represents the height from the Z-axis to the lower end of the lens.

Further, when the progressive addition lens 10 has astigmatism refractive power or when the additional vertical and horizontal components are distributed to the outer surface and the inner surface, the vertical section is not necessarily the minimum curvature section. Therefore, in this case, the minimum curvature C2min among the two main curvatures obtained by approximating the inner surface 2 of the progressive addition lens 10 with a toric surface is configured to satisfy the following condition (5).

By satisfying the condition (5), thinning can be achieved while maintaining a meniscus shape even in a progressive-power lens in which the vertical section does not necessarily have the minimum curvature section.

Hereinafter, two specific examples of the above embodiment will be described together with three reference examples and five comparative examples . In addition, the progressive power lenses of all Examples , Reference Examples, and Comparative Examples are common with respect to the specifications shown in Table 1 below. Specifically, Reference Example 1, Reference Example 2, Example 1, and Comparative Examples 1 to 3 are examples of lenses whose outer surface is a spherical surface and whose inner surface is a progressive surface. Reference example 3 and comparative example 4 are examples of lenses in which both surfaces are progressive surfaces. Example 2 and comparative example 5 are examples of lenses in which the outer surface is a progressive surface that distributes the added vertical component, and the inner surface is a progressive surface that distributes the added horizontal component.

(Reference Example 1)
FIG. 1 is a vertical sectional view of a progressive-power lens 10 (hereinafter simply referred to as a lens 10) of Reference Example 1 . FIG. 2 is a graph showing the transmission refractive power of the lens 10 of Reference Example 1 . FIG. 3 is a graph showing the sag amount of the inner surface 2 of the lens 10 of Reference Example 1 . FIG. 4 is a graph showing the vertical sectional curvature of the inner surface 2 of the lens 10 of Reference Example 1 . Table 2 shows specific numerical configurations of the lens 10 of Reference Example 1 calculated based on the graphs shown in FIGS.

As shown in FIGS. 3 and 4, the inner surface 2 of the lens 10 of Reference Example 1 has a shape in which the vicinity of the near-field measurement reference point is convex toward the eye side. However, as shown in Table 2, the outer surface 1 of the lens 10 of Reference Example 1 has a surface refractive power D1 of 4.88D. Therefore, the lens 10 of Reference Example 1 satisfies the condition (1). Similarly, as shown in Table 2, the lens 10 of Reference Example 1 satisfies all the conditions (2) to (4).

As a result, it can be seen that the lens 10 of Reference Example 1 has a meniscus shape as a whole even if a partial region of the inner surface 2 has a convex shape. Further, the amount of projection of the outer surface 1 of the lens 10 of Reference Example 1 (i.e., the difference between the sag on the outer surface vertex and the outer surface uppermost) near 5.07Mm, since the center thickness becomes 5.53Mm, Reference Example 1 Lens 10 It is also derived that it is very thin.

(Comparative Example 1)
5 to 8 are, in order, a vertical sectional view, a transmission refractive power graph, an inner surface sag amount graph, and an inner surface vertical sectional curvature graph regarding the progressive addition lens of Comparative Example 1. FIG. Table 3 shows specific numerical configurations of the progressive-power lens of Comparative Example 1 calculated based on the graphs shown in FIGS.

As shown in Table 3, in the progressive addition lens of Comparative Example 1, the distance portion vertex power Pf, the addition power ADD, and the refractive index of the material are set to be the same as those of the lens 10 of Reference Example 1 . However, following Patent Document 1 described above, the surface refractive power D1 of the outer surface was set to 6.79D.

As shown in Table 3, in the progressive-power lens of Comparative Example 1, the curvature C2 (yn) at the near-point measurement reference point does not satisfy the condition (3). As a result, the protruding amount of the outer surface is 7.20 mm and the center thickness is 5.77 mm. That is, although the progressive addition lens of Comparative Example 1 has a meniscus shape, it is considerably thicker than the lens 10 of Reference Example 1 .

(Reference Example 2)
9 to 12 are a vertical sectional view, a transmission refractive power graph, an inner surface sag amount graph, and an inner surface vertical sectional curvature graph regarding the lens 10 of Reference Example 2 in order. Table 4 shows specific numerical configurations of the lens 10 of Reference Example 2 calculated based on the graphs shown in FIGS.

As shown in FIGS. 11 and 12, the inner surface 2 of the lens 10 of Reference Example 2 has a shape in which the vicinity of the near-field measurement reference point is convex to the eye side, as in Reference Example 1 . However, as shown in Table 4, the outer surface 1 of the lens 10 of Reference Example 2 has a surface refractive power D1 of 7.14D, which satisfies the condition (1). Similarly, as shown in Table 4, the lens 10 of Reference Example 2 also satisfies all the conditions (2) to (4).

As a result, the lens 10 of Reference Example 2 has a meniscus shape as a whole of the lens 10 even if a part of the inner surface 2 has a convex shape. Further, the protrusion amount of the outer surface 1 of the lens 10 of Reference Example 2 is 7.61 mm, and the center thickness is 7.86 mm. That is, the lens 10 of the reference example 2 is also very thin like the lens 10 of the reference example 1 .

(Comparative Example 2)
FIGS. 13 to 16 are a vertical sectional view, a transmission refractive power graph, an inner surface sag amount graph, and an inner surface vertical sectional curvature graph, respectively, regarding the progressive addition lens of Comparative Example 2. FIGS. Specific numerical configurations of the progressive addition lens of Comparative Example 2 calculated based on the graphs shown in FIGS. 14 to 16 are shown in Table 5.

As shown in Table 5, in the progressive addition lens of Comparative Example 2, the distance portion vertex refractive power Pf, the addition refractive power ADD, and the refractive index of the material are set to be the same as those of the lens 10 of Reference Example 2 . However, following Patent Document 1 described above, the surface refractive power D1 of the outer surface was set to 9.39D.

As shown in Table 5, in the progressive-power lens of Comparative Example 2 that is numerically set as described above, the curvature C2 (yn) at the near portion measurement reference point does not satisfy the condition (3). As a result, the protrusion amount of the outer surface is 10.40 mm, and the center thickness is 8.31 mm. That is, the progressive addition lens of Comparative Example 2 has a meniscus shape, but is considerably thicker than the lens 10 of Reference Example 2 .

(Example 1)
The progressive-power lens 10 of Example 1 is a lens having astigmatism correction characteristics on the inner surface 2. FIG. 17 is a vertical sectional view of the lens 10 according to the first embodiment . FIG. 18 is a contour map showing the shape of the inner surface 2 by contour lines spread at intervals of 0.5 mm. In FIG. 18 , the X axis passes through the intersection of the inner surface 2 and the Z axis, and is an axis orthogonal to the Y and Z axes, that is, an axis along the horizontal direction when wearing glasses. The same applies to FIGS. 22, 37, and 43 described later. Table 6 shows the minimum curvature C2min, the maximum curvature C2max, and the direction γ of the minimum curvature section obtained when the inner surface 2 shown in FIG. 18 is approximated by a toric surface. As shown in Table 6, the lens 10 of Example 1 satisfies the condition (5).

FIGS. 19 to 21 sequentially show a graph of transmission refractive power, a graph of the sag amount on the inner surface, and a graph of the vertical cross-sectional curvature of the inner surface regarding the lens 10 of Example 1 . Specific numerical configurations of the lens 10 of Example 1 calculated based on the graphs shown in FIGS. 19 to 21 are shown in Table 7. In Table 7, SPH represents spherical power, CYL represents cylindrical power, and AX represents an astigmatic axis.

20, as shown in FIG. 21, the inner surface 2 of the lens 10 of the first embodiment, similarly as in Reference Example 1, 2, has a shape in which the vicinity of the near reference point is convex to the eye side. As shown in Table 7, the lens 10 of Example 1 also satisfies all the conditions (1) to (4).

Thus, the lens 10 of Example 1 has a meniscus shape as a whole. Further, the protruding amount of the outer surface 1 of the lens 10 of Example 1 is 5.18 mm, and the center thickness is 6.16 mm. That is, the lens 10 of Example 1 is also very thin like the lens 10 of Reference Example 1 and Reference Example 2 .

(Comparative Example 3)
FIG. 22 is a vertical sectional view of the progressive addition lens of Comparative Example 3. FIG. 23 is a contour map showing the inner shape of the progressive addition lens of Comparative Example 3 by contour lines laid out at intervals of 0.5 mm. Table 8 shows the minimum curvature C2min, the maximum curvature C2max, and the direction γ of the minimum curvature section obtained when the inner surface 2 shown in FIG.

As shown in Table 8, in the progressive-power lens of Comparative Example 3, the minimum curvature C2min exceeds the upper limit of the condition (5). As a result, the progressive addition lens of Comparative Example 3 has an outer surface protrusion amount of 8.27 mm and a center thickness of 6.52 mm. That is, the progressive addition lens of Comparative Example 3 has a meniscus shape, but is considerably thicker than the lens 10 of Example 1 .

FIGS. 24 to 26 show, in order, a transmission refractive power graph, an inner surface sag amount graph, and an inner surface vertical sectional curvature graph regarding the progressive addition lens of Comparative Example 3. FIG. Specific numerical configurations of the progressive addition lens of Comparative Example 3 calculated based on the graphs shown in FIGS. 24 to 26 are shown in Table 9.

As shown in Table 9, the progressive addition lens of Comparative Example 3 has spherical refractive power SPH, cylindrical refractive power CYL, astigmatism axis AX, distance portion vertex refractive power Pf, addition refractive power ADD, and material refractive index. It is set to be the same as the lens 10 of the first embodiment . However, following Patent Document 1 described above, the surface refractive power D1 of the outer surface was set to 8.50D. As shown in Table 5, in the progressive-power lens of Comparative Example 3 set numerically as described above, the curvature C2 (yn) at the near portion measurement reference point does not satisfy the condition (3).

(Reference Example 3)
In the progressive-power lens 10 of Reference Example 3 , both the outer surface 1 and the inner surface 2 are progressive surfaces. In Reference Example 3 , half of the addition is given by the surface refractive power of the outer surface 1, and the remaining addition and aberration correction are performed on the progressive surface of the inner surface 2. 27 to 31 are, in order, a vertical sectional view, a transmission refractive power graph, a sag amount graph of the inner surface 2, a vertical sectional curvature graph of the outer surface 1, and a vertical sectional curvature of the inner surface 2 regarding the lens 10 of Reference Example 3 . It is a graph of. Table 10 shows specific numerical configurations of the lens 10 of Reference Example 3 calculated based on the graphs shown in FIGS. 28 to 31.

As shown in FIGS. 29 and 31, the inner surface 2 of the lens 10 of Reference Example 3 also has a shape in which the vicinity of the near-field measurement reference point is convex to the eye side, as in Reference Example 1, Reference Example 2, and Example 1. I am doing. However, as shown in Table 10, the inner surface 2 of the lens 10 of Reference Example 3 satisfies all of the conditions (2) to (4).

As a result, the lens 10 of Reference Example 3 has a meniscus shape as a whole of the lens 10 even if a partial region of the inner surface 2 is convex. Further, the protrusion amount of the outer surface 1 of the lens 10 of Reference Example 3 is 4.88 mm, and the center thickness is 5.22 mm. That is, the lens of the reference example 3 is also very thin like the reference example 1, the reference example 2, and the lens 10 of the example 1 .

(Comparative Example 4)
32 to 36 are, in order, a vertical sectional view, a transmission refractive power graph, an inner surface sag amount graph, an outer surface vertical sectional curvature graph, and an inner surface vertical sectional curvature regarding the progressive addition lens of Comparative Example 4. It is a graph. Table 11 shows specific numerical configurations of the progressive-power lens of Comparative Example 4 calculated based on the graphs shown in FIGS. 33 to 36.

As shown in Table 11, in the progressive addition lens of Comparative Example 4, the distance portion vertex power Pf, the addition power ADD, and the refractive index of the material are set to be the same as those of the lens 10 of Reference Example 3 . However, following Patent Document 1 described above, the distance-part surface refractive power D1 of the outer surface was set to 7.00D.

As shown in Table 11, in the progressive-power lens of Comparative Example 4 set numerically as described above, the curvature C2 (yn) at the near portion measurement reference point does not satisfy the condition (3). As a result, the protrusion amount of the outer surface is 7.30 mm and the center thickness is 5.65 mm. That is, the progressive-power lens of Comparative Example 4 has a meniscus shape, but is considerably thicker than the lens 10 of Reference Example 3 .

(Example 2)
The progressive-power lens 10 of Example 2 has a progressive surface in which the additional vertical component is distributed on the outer surface and the additional horizontal component is distributed on the inner surface. FIG. 37 is a vertical sectional view of the lens 10 according to the second embodiment . FIG. 38 is a contour map that represents the shape of the inner surface 2 by contour lines spread at intervals of 0.5 mm. Table 12 shows the minimum curvature C2min, the maximum curvature C2max, and the direction γ of the minimum curvature section obtained when the inner surface shown in FIG. 38 is approximated by a toric surface. As shown in Table 12, the lens 10 of Example 2 satisfies the condition (5).

39 to 42, the transmission refractive power graph, the inner surface sag amount graph, the outer surface vertical cross section curvature (solid line), and the cross section orthogonal to the cross section in the vicinity of the cross section of the lens 10 of Example 2 are shown in FIGS. A graph of curvature (hereinafter referred to as sagittal curvature) (broken line), a vertical sectional curvature of the inner surface (solid line), and a sagittal curvature (broken line) graph are shown in this order. Specific numerical configurations of the lens 10 of Example 2 calculated based on the graphs shown in FIGS. 39 to 42 are shown in Table 13. Here, C2m is a vertical section curvature, and C2s is a sagittal curvature.

In the lens in which the addition is distributed in the vertical direction and the horizontal direction as in this embodiment, even if there is no astigmatic refractive power, the vertical section is not necessarily the minimum curvature section. As shown in FIG. 40, FIG. 42, and Table 13, the vertical cross section of the inner surface has a shape that is concave on the eye side everywhere, but the sagittal cross section curvature becomes smaller and negative in the near portion. It is a value. However, as shown in Table 12, in this embodiment, C2min satisfies the conditional expression (5) so that a meniscus shape can be obtained as a whole. Therefore, the protrusion amount of the outer surface 1 of the lens of Example 2 is 6.37 mm, and the center thickness is 5.48 mm. That is, the lens 10 of Example 2 is also very thin like the lenses 10 of Reference Example 1, Reference Example 2, Example 1, and Reference Example 3 .

(Comparative Example 5)
FIG. 43 is a vertical sectional view relating to the progressive-power lens of Comparative Example 5. FIG. 44 is a contour map representing the inner surface shape of the progressive addition lens of Comparative Example 5 by contour lines spread at intervals of 0.5 mm. Table 14 shows the minimum curvature C2min, the maximum curvature C2max, and the direction γ of the minimum curvature section obtained when the inner surface 2 shown in FIG. 44 is approximated by a toric surface.

As shown in Table 14, in the progressive-power lens of Comparative Example 5, the minimum curvature C2min exceeds the upper limit of the condition (5). As a result, the progressive-power lens of Comparative Example 5 has an outer surface protrusion amount of 8.49 mm and a center thickness of 5.89 mm. That is, the progressive addition lens of Comparative Example 5 has a meniscus shape, but is considerably thicker than the lens 10 of Example 2 .

45 to 48, the graph of the transmission refractive power, the graph of the sag amount on the inner surface, the vertical sectional curvature (solid line) and the sagittal curvature (dashed line) of the outer surface, the inner surface, regarding the progressive-power lens of Comparative Example 5. The vertical section curvature (solid line) and sagittal curvature (broken line) graphs are sequentially shown. Specific numerical configurations of the progressive-power lens of Comparative Example 5 calculated based on the graphs shown in FIGS. 46 to 48 are shown in Table 15.

As shown in Table 15, in the progressive addition lens of Comparative Example 5, the distance portion vertex refractive power Pf, the addition refractive power ADD, and the refractive index of the material are set to be the same as those of the lens 10 of Example 2 . However, following Patent Document 1 described above, the distance-part surface refractive power D1 of the outer surface was set to 7.50D. As shown in Table 15, the progressive-power lens of Comparative Example 5 set numerically as described above satisfies the condition (3) for both the curvature C2m (yn) and C2s (yn) at the near reference measurement reference point. do not do.

DESCRIPTION OF SYMBOLS 1 Outer surface 2 Inner surface 3 Prism measurement reference point 4 Distance part measurement reference point 5 Near part measurement reference point 10 Progressive refractive power lens

Claims (4)

A progressive power lens having a positive distance vertex refractive power and at least an inner surface being a progressive surface;
The axis along the normal of the outer surface at the prism measurement reference point is the Z axis (where the direction from the outer surface toward the inner surface is positive), and the axis orthogonal to the Z axis passing through the intersection of the inner surface and the Z axis. The Y axis (however, the direction from the lower end of the lens toward the upper end of the lens is positive when worn), and a curve formed by the intersection of the YZ plane and the inner surface at an arbitrary height y from the Z axis. The amount of sag and the curvature are z2 (y) and C2 (y), respectively, the height from the Z axis to the distance measurement reference point is yf, the height from the Z axis to the near measurement point is yn, If the height from the Z axis to the upper end of the lens is yt and the height from the Z axis to the lower end of the lens is yu, the following three conditions are satisfied:
It meets at the same time,
Furthermore, among the two main curvatures when the inner surface shape is approximated by a toric surface, the minimum curvature C2min is as follows:
A progressive-power lens characterized by satisfying   The progressive power lens according to claim 1, wherein the inner surface has an astigmatism correction characteristic.   The progressive addition lens according to claim 1, wherein the addition refractive power is divided into a vertical component and a horizontal component and distributed to each of the outer surface and the inner surface. Assuming that the distance vertex power in the vertical cross section is Pf, the addition power is ADD, and the surface power of the outer surface is D1, the following conditions:
The progressive-power lens according to any one of claims 1 to 3, wherein: