Patent Grant
7445333
The present invention relates to a corrective lens, in particular to a spectacle lens having a large front warpage angle.
So-called wrap-around spectacles configured to have a relatively large front warpage angle to protect eyes of a wearer from light, wind, particles, etc., which would enter the eyes from temporal region sides of a head, have become widespread. However, most of the conventional wrap-around spectacles are configured as a non-corrective lens (i.e., glasses having no dioptric power). There are demands to use wrap-around spectacles which can provide proper visual acuity to a person who needs correction of visual acuity.
A spherical lens having a deep base curve (approximately 8 dioptre) formed to fit into a spectacle frame having a large front warpage angle such as wrap-around spectacles has been proposed. However, when such a spherical lens is worn by a wearer, even a visual axis defined when the wearer faces the front can not avoid intersecting with a lens surface obliquely. Therefore, large aberrations are caused when the spherical lens is used to correct visual acuity. Providing a negative power to a spherical lens having a deep base curve can lead to large aberrations even if the spectacle frame to which the spherical lens is to be fitted has no front warpage angle. That is, to design a spherical lens for wrap-around spectacles to attain refractive correction yields problems to be addressed.
In Japanese Patent Provisional Publication No. HEI 5-323185A (hereafter, referred to as JP HEI 5-323185A), a spectacle lens configured to have an extended toric surface on its back surface to attain refractive correction is disclosed. The extended toric surface is configured to have a symmetric property with respect to each of two axes (X-axis and Y-axis) perpendicularly intersecting with respect to each other. For this reason, the degree of freedom of lens design is limited, and thereby optical performance such as an aberration correction function is deteriorated. Since the spectacle lens disclosed in JP HEI 5-323185A is designed such that an inclination angle at a centration point is relatively small and a base curve is relatively shallow, the degree of wraparound becomes small and thereby the degree of covering the temporal region side of a head (i.e., a wrapping property) becomes insufficient. The term “inclination angle at a centration point” means an angle formed between an outward normal line normal to a front surface and an axis passing through a center of rotation of an eye and the centration point.
In Japanese Patent Provisional Publication No. P2000-506628A (hereafter, referred to as JP 2000-506628A), a spectacle lens configured such that off-axis aberrations are corrected by providing an aspherical surface on its front surface, and that off-axis aberrations are corrected by changing the degree of curve of a toric surface or a spherical surface provided on its back surface. However, since both of back and front surfaces of the spectacle lens disclosed in JP 2000-506628A are designed to be symmetric, it is impossible in principle to correct asymmetrical aberrations which increase as the inclination angle at the centration point becomes larger. The spectacle lens is configured to only achieve a balance between aberrations.
The present invention is advantageous in that it provides a spectacle lens which is capable of attaining excellent optical performance even if it is designed to be fitted into a spectacle frame having a large front warpage angle such as wrap-around spectacles.
According to an aspect of the invention, there is provided a spectacle lens having an aspherical surface on its one of front and back surfaces. An outward normal line normal to the front surface at a centration point inclines with respect to an axis passing through the centration point and a center of rotation of an eye. A cross section of the aspherical surface defined by a plane including the outward normal line and the axis is asymmetrical.
With this configuration, it is possible to provided the spectacle lens, having a suitable wrapping property of sufficiently covering a temporal region side of a head, being capable of correcting asymmetrical aberrations which the conventional spectacle lens (e.g., the lenses disclosed in JP HEI 5-323185A or JP 2000-506628A) can not correct, and being capable of having suitable optical performance even in a condition where the spectacle lens is fitted in a frame having a large front warpage angle.
The axis passing through the centration point and a center of rotation of an eye substantially coincides with an visual axis defined when a wearer looks at an infinite distance.
In at least one aspect, when a direction passing through the centration point and the center of rotation of an eye from the centration point to the center of rotation of an eye is defined as a Z-axis, two axes perpendicularly intersecting with the Z-axis are respectively defined as a X-axis and a Y-axis so that a left hand coordinate system is defined at the centration point in such a manner that an orthographic projection of the outward normal line to an X-Y plane facing a minus direction of the X-axis, curvatures of cross-sections of the front and back surfaces defined by a plane which includes the Z-axis and forms an angle θ with respect to the X-axis are respectively defined as C1(h,θ) (dpt) and C2(h,θ) (dpt), where h represents a distance mm from the Z-axis, a thickness of the spectacle lens at the centration point is represented as t (mm), a refractive index of medium of the spectacle lens is represented as n, a prescribed spherical power is represented as SPH (dpt), a prescribed cylindrical power is represented as CYL (dpt), and a cylinder axis measured in a counterclockwise direction with respect to the X-axis is represented as AX (°), cross-section surface power D1(h,θ) of the front surface is defined as:
D1(h,θ)=(n−1)·C1(h,θ) (1),
cross-section surface power D2(h,θ) of the back surface is defined as:
D2(h,θ)=(1−n)·C2(h,θ) (2),
an amount P˜(h,θ) regarding a vertex power is defined as:
P˜(h,θ)=D1(h,θ)/{1−D1(h,θ)·t/1000/n}+D2(h,θ) (3),
a prescribed dioptric power P0(θ) for a lens center and paraxial rays is defined:
P0(θ)=SPH+CYL·sin2(θ−AX) (4), and
an amount ΔP˜(h, θ) regarding an aspheric amount is defined as:
ΔP˜(h, θ)=P˜(h,θ)−P0(θ) (5).
In this configuration, the spectacle lens satisfies a following condition (6) at least in a range of 5<h<20:
ΔP˜(h,0)≠ΔP˜(h,180) (6).
Satisfying the condition (6) means that the aspheric amount for the case of the angle θ=0° is different from that for the case of the angle θ=180°. That is, the condition (6) represents a state where the cross-section of the aspherical surface is asymmetrical in a mathematical expression.
In at least one aspect, an angle formed between the outward normal line and the axis passing through the centration point and the center of rotation of an eye may be larger than or equal to 10°.
With this configuration, a spectacle lens capable of being used for a frame having a large front warpage angle can be provided.
The following aspects of the invention relate to a configuration in regard to the determination of the aspheric amount for achieving correction of asymmetrical aberrations caused when the outward normal line inclines with respect to the axis (passing through the centration point and the center of rotation of an eye) at the centration point.
In at least one aspect, the spectacle lens satisfies following conditions (7) and (8):
P0(0)>0 (7),
ΔP˜(5,180)>ΔP˜(5,0) (8).
The condition (7) means that the spectacle lens is a plus lens. With regard to the spectacle lens having a positive power, it is possible to reduce the asymmetric aberrations by configuring the lens such that, at the height of 5 mm, the aspheric amount at θ=180° is larger than the aspheric amount at θ=0°.
In at least one aspect, the spectacle lens satisfies following conditions (9) and (10):
P0(0)<0 (9),
ΔP˜(5,180)<ΔP˜(5,0) (10).
The condition (9) means that the spectacle lens as a minus lens. With regard to the spectacle lens having a minus power, it is possible to reduce the asymmetric aberrations by configuring the lens such that, at the height of 5 mm, the aspheric amount at θ=0° is larger than the aspheric amount at θ=180°.
In at least one aspect, the spectacle lens satisfies following conditions (7), (11) and (12):
P0(0)>0 (7),
ΔP˜(0,0)<0 (11),
ΔP˜(0,90)≅0 (12).
It is preferable for a plus lens to satisfy the conditions (11) and (12). With this configuration, it is possible to enhance optical performance while reducing the astigmatism for the lens center and paraxial rays.
In at least one aspect, the spectacle lens satisfies following conditions (9), (13) and (12):
P0(0)<0 (9),
ΔP˜(0,0)>0 (13),
ΔP˜(0,90)≅0 (12).
It is preferable for a minus lens to satisfy the conditions (13) and (12). With this configuration, it is possible to enhance optical performance while reducing the astigmatism for the lens center and paraxial rays.
In at least one aspect, the spectacle lens satisfies following conditions (14) and (15):
P0(θ)>0 (14),
D1(0,θ)<Ap·P0(θ)+Bp (15)
where Ap=1.02n−0.51, Bp=13.24n−14.79.
In this case, a following condition (16) may be satisfied when the angle θ is in a range of −90≦θ≦90:
ΔP˜(5,θ)>ΔP˜(10,θ)>ΔP˜(15,θ) (16).
The spectacle lens satisfying the condition (14) has a positive power. The spectacle lens satisfying the condition (15) uses a surface having a base curve which is shallower than a base curve of a spherical surface configured to suitably attain a prescribed spherical power SPH in regard to aberrations in the case where there is no inclination angle. That is, with regard to the spectacle lens having a positive power and a relatively shallow surface, it is possible to enhance the off-axis optical performance by designing the lens such that the aspheric amount (i.e., the amount of departure from a spherical surface shape) becomes smaller as the distance h from the Z-axis increases in a plane including the Z-axis and forming the angle θ with respect to the X-axis.
In at least one aspect, the spectacle lens satisfies following conditions (17) and (18):
P0(θ)<0 (17),
D1(0,θ)<Am·P0(θ)+Bm (18).
where Am=0.62n−0.40, Bm=20.09n−23.46.
In this case, a following condition (19) may be satisfied when the angle θ is in a range of −90≦θ≦90:
ΔP˜(5,θ)<ΔP˜(10,θ)<ΔP˜(15,θ) (19).
Each coefficient Am, Bm, Ap, Bp is obtained by defining four spherical lenses having refractive indexes of 1.5, 1.6, 1.7 and 1.8, obtaining coefficients of a regression line which is obtained when the linear regression is applied to a constant-aberration line of an aberration of 0 of each spherical lens while dividing the dioptric power into a plus dioptre region and a minus dioptre region, and further applying the liner regression to the obtained coefficients using a refractive index n.
The spectacle lens satisfying the condition (17) has a negative power, The spectacle lens satisfying the condition (18) uses a surface having a base curve which is shallower than a base curve of a spherical surface configured to suitably attain a prescribed spherical power SPH in regard to aberrations in the case where there is no inclination angle. That is, with regard to the spectacle lens having a negative power and a relatively shallow surface, it is possible to enhance the off-axis optical performance by designing the lens such that the aspheric amount becomes larger as the distance h from the Z-axis increases in a plane including the Z-axis and forming the angle θ with respect to the X-axis.
In at least one aspects the spectacle lens satisfies following conditions (17) and (20):
P0(θ)< (17),
D1(0,θ)>Am·P0(θ)+Bm (20)
where Am=0.62n−0.40, Bm=20.09n−23.46.
In this case, a following condition (16) may be satisfied when the angle θ is in a range of 90≦θ≦270:
ΔP˜(5,θ)>ΔP˜(10,θ)>ΔP˜(15,θ) (16).
The spectacle lens satisfying the condition (20) uses a surface having a base curve which is deeper than a base curve of a spherical surface configured to suitably attain a prescribed spherical power SPH in regard to aberrations in the case where there is no inclination angle. That is, with regard to the spectacle lens having a negative power and a relatively deep surface, it is possible to enhance the off-axis optical performance by designing the lens such that the aspheric amount becomes smaller as the distance h from the Z-axis increases in a plane including the Z-axis and forming the angle θ with respect to the X-axis.
In at least one aspect, the front surface is formed to be a spherical surface. By forming the front surface to be a spherical surface, it is possible to simplify the manufacturing process of the spectacle lens.
If the front surface of the spectacle lens is formed to be the spherical surface, the above mentioned conditions may be changed to the following conditions.
In at least one aspect, the spectacle lens satisfies following conditions (7) and (21):
P0(0)>0 (7),
D2(5,180)>D2(5,0) (21).
In this case, the condition (8) is changed to the condition (21).
In at least one aspect, the spectacle lens satisfies following conditions (9) and (22):
P0(0)<0 (9),
D2(5,180)<D2(5,0) (22).
In this case, the condition (10) is changed to the condition (22).
The conditions (11), (12) and (13) may be combined into one the following conditions (23) and (24).
In at least one aspect, the spectacle lens satisfies following conditions (7) and (23):
P0(0)>0 (7),
D2(0,0)−CYL·sin2(AX)<D2(0,90)−CYL·cos2(AX) (23).
In at least one aspect, the spectacle lens satisfies following conditions (9) and (24):
P0(0)<0 (9),
D2(0,0)−CYL·sin2(AX)>D2(0,90)−CYL·cos2(AX) (24).
A relationship the left side part of the condition (11)< the left side part of the condition (12) holds. Further, since the front surface is a spherical surface, D1(0,0)=D1(0,90) holds. Therefore, by deleting terms including D1 and SPH in the relationship, the condition (23) can be obtained. Similarly, since a relationship the left side part of the condition (13)> the left side part of the condition (12) and D1(0,0)=D1(0,90) hold, the condition (24) can be obtained.
The conditions (16) and (19) can be changed to conditions (25), and (26), respectively.
In at least one aspect, the spectacle lens satisfies conditions (14) and (15):
P0(θ)>0 (14),
D1(0,θ)<Ap·P0(θ)+Bp (15)
where Ap=1.02n−0.51, Bp=13.24n−14.79.
In this case, condition (25) may be satisfied when the angle θ is in a range of −90≦θ≦90:
D2(5,0)>D2(10,θ)>D2(15,θ) (25).
In at least one aspect, the spectacle lens satisfies following conditions (17) and (18) are satisfied:
P0(θ)<0 (17),
D1(0,θ)<Am·P0(θ)+Bm (18)
where Am=0.62n−0.40, Bm=20.09n−23.46.
In this case, a following condition (26) may be satisfied when the angle θ is in a range of −90≦θ≦90:
D2(5,θ)<D2(10,θ)<D2(15,θ) (26).
In at least one aspect, the spectacle lens satisfies following conditions (17) and (20):
P0(θ)<0 (17),
D1(0,θ)>Am·P0(θ)+Bm (20)
where Am=0.62n−0.40, Bm=20.09n−23.46.
In this case, a following condition (25) may be satisfied when the angle θ is in a range of 90≦θ≦270:
D2(5,θ)>D2(10,θ)>D2(15,θ) (25).
According another aspect of the invention, there is provided Spectacles, which is provided with a frame having a front warpage angle more than or equal to 10°; and the above mentioned spectacle lens.
Hereinafter, an embodiment according to the invention is described with reference to the accompanying drawings.
In the following, left hand coordinate systems are defined at the centration points 12 and 22 for the spectacle lenses 11 and 12, respectively. For the spectacle lens 11, the direction passing through the centration point 12 and a center of rotation 10 from the centration point 12 to the center of rotation 10 is defined as a Z-axis (a plus direction of the Z-axis), an axis which is orthogonal to the Z-axis and is substantially equal to a horizontal direction in a state where the spectacles 100 are worn by a wearer is defined as an X-axis, an axis which is orthogonal to the Z-axis and is substantially equal to a vertical direction in the state where the spectacles 100 are worn by the wearer is defined as a Y-axis. For the spectacle lens 21, the direction passing through the centration point 22 and a center of ration 20 from the centration point 22 to the center of ration 20 is defined as a Z-axis (a plus direction of the Z-axis), an axis which is orthogonal to the Z-axis and is substantially equal to a horizontal direction in a state where the spectacles 100 are worn by a wearer is defined as an X-axis, an axis which is orthogonal to the Z-axis and is substantially equal to a vertical direction in the state where the spectacles 100 are worn by the wearer is defined as a Y-axis. Each left-hand coordinate system is defined so that each of directions of orthographic projections 14 and 24 (which are represented by outline arrows in the coordinate systems, respectively) of the outward normal lines 13 and 23 to the respective X-Y plane is equal to a minus direction of the corresponding X-axis. In other words,
The spectacle lens 11 is configured such that an angle formed between the outward normal line 13 and the Z-axis is larger than or equal to approximately 10°. The spectacle lens 21 is also configured such that an angle formed between the outward normal line 23 and the Z-axis is larger than or equal to approximately 10°. That is, the spectacle lenses 11 and 21 are suitably designed for the frame 50 having a large front warpage angle. In other words, each of the spectacle lenses 11 and 21 has an excellent wrapping property and is suitable for wrap-around spectacles.
Each of the back surfaces 11b and 21b of the spectacle lenses 11 and 21 is formed to be an aspherical surface. Further, the back surface 11b is configured such that a cross-section thereof defined in a plane (i.e., the X-Y plane) including the Z-axis and the outward normal line 13 is asymmetrical. Similarly, the back surface 21b is configured such that a cross-section thereof defined in a plane (i.e., the X-Y plane) including the Z-axis and the outward normal line 23 is asymmetrical. By configuring a cross-section of an aspherical surface to be asymmetrical, it is possible to sufficiently suppress asymmetric aberrations caused depending on an inclination angle at the centration point 12 (22).
For each of the left-hand coordinate systems, the curvatures of the cross-sections of the front and back surfaces defined by a plane which includes the Z-axis and forms an angle θ with respect to the X-axis are defined as C1(h,θ) [dpt: dioptre] and C2(h,θ) [dpt], respectively, where h represents a distance [mm] from the Z-axis. A thickness of a lens at the centration point is represented as t [mm], a refractive index of medium of the spectacle lens is represented as n, a prescribed spherical power is represented as SPH [dpt], a prescribed cylindrical power is represented as CYL [dpt], and a cylinder axis measured in a counterclockwise direction with respect to the X-axis is represented as AX [°].
By the above mentioned definitions, the cross-section surface power D1(h,θ) of the front surface is defined as:
D1(h,θ)=(n−1)·C1(h,θ) (1),
the cross-section surface power D2(h,θ) of the back surface is defined as:
D2(h,θ)=(1−n)·C2(h,θ) (2),
the amount P˜(h,θ) regarding vertex power is defined as:
P˜(h,θ)=D1(h,θ)/{1−D1(h,θ)·t/1000/n}+D2(h,θ) (3),
a prescribed dioptric power for a lens center and paraxial rays is defined:
P0(θ)=SPH+CYL·sin2(θ−AX) (4),
the amount ΔP˜(h, θ) regarding an aspheric amount is defined as:
ΔP˜(h, θ)=P˜(h,θ)−P0(θ) (5).
Since the amount ΔP˜(h, θ) can be regarded as a sum of aspheric amounts of the front and back surfaces, the amount ΔP˜(h, θ) is simply referred to as an aspheric amount hereafter.
Hereafter, eight concrete examples of the spectacle lens according to the embodiment will be described. The following explanations are given principally for the spectacle lens 11 for the right eye.
Table 1 shows the numerical configuration of the spectacle lens 11 according to the first example. In Table 1 (and in the following similar tables), P˜ represents an amount regarding a vertex power, and P0 represents prescribed dioptric power for a lens center and paraxial rays.
As shown in
ΔP˜(h,0)≠ΔP˜(h,180) (6)
That is, the cross-section of the back surface 11b is rotationally asymmetrical. As shown in Table 1, P0(0) is 3.00. Therefore, the spectacle lens 11 satisfies a condition (7).
P0(0)>0 (7)
As shown in
ΔP˜(5,180)>ΔP˜(5,0) (8)
The spectacle lens 11 according to the first example satisfies conditions (11) and (12).
ΔP˜(0,0)<0 (11)
ΔP˜(0,90)≅0 (12)
As described above, the front surface 11a is formed as a spherical surface. Therefore, as shown in
D2(5,180)>D2(5,0) (21)
Since the spectacle lens 11 satisfies the conditions (11) and (12), the spectacle lens 11 according to the first example satisfies a condition (23).
D2(0,0)−CYL·sin2(AX)<D2(0,90)−CYL·cos2(AX) (23)
Table 2 shows the numerical configuration of the spectacle lens 11 according to the second example.
As shown in
P0(0)<0 (9)
As shown in
ΔP˜(5,180)<ΔP˜(5,0) (10)
The spectacle lens 11 according to the second example satisfies conditions (12) and (13).
ΔP˜(0,90)≅0 (12)
ΔP˜(0,0)>0 (13)
As shown in Table 2, the spectacle lens 11 according to the second example satisfies a condition (20).
D1(0,θ)>Am·P0(θ)+Bm (20)
As shown in
ΔP˜(5,θ)>ΔP˜(10,θ)>ΔP˜(15,θ) (16)
As described above, the front surface 11a is formed as a spherical surface. Therefore, as shown in
D2(5,180)<D2(5,0) (22)
Since the spectacle lens 11 satisfies the conditions (12) and (13), the spectacle lens 11 according to the second example satisfies a condition (24).
D2(0,0)−CYL·sin2(AX)>D2(0,90)−CYL·cos2(AX) (24)
As can be seen from
D2(5,θ)>D2(10,θ)>D2(15,θ) (25)
Since the spectacle lens 11 according to the second example further satisfies the condition (20), a base curve, which is deeper than a base curve of a spherical surface configured to suitably attain a prescribed spherical power in regard to aberrations in the case where there is no inclination angle, is employed in the second example. However, by satisfying the condition (16) when the angle θ is in a predetermined range, it is possible to attain suitable off-axis optical performance.
Table 3 shows the numerical configuration of the spectacle lens 11 according to the third example.
As shown in
As described above, the front surface 11a is formed as a spherical surface. Therefore, as shown in
In addition to the above mentioned advantages, the spectacle lens 11 according to the third example is configured to have larger front warpage angle of 20°. Therefore, the spectacle lens according to the third example has a high wrapping property.
Table 4 shows the numerical configuration of the spectacle lens 11 according to the forth example.
As shown in
As can be seen from Table 4, the spectacle lens 11 according to the fourth example satisfies the condition (20). As shown in
As described above, the front surface 11a is formed as a spherical surface. Therefore, as shown in
In addition to the above mentioned advantages, the spectacle lens 11 according to the fourth example is configured to have larger front warpage angle of 20°. Therefore, the spectacle lens according to the fourth example has a high wrapping property.
Since the spectacle lens 11 according to the fourth example satisfies the condition (20), a base curve, which is deeper than a base curve of a spherical surface configured to suitably attain a prescribed spherical power in regard to aberrations in the case where there is no inclination angle, is employed in this example. However, by satisfying the condition (16) when the angle θ is in a predetermined range, it is possible to attain suitable off-axis optical performance.
Table 5 shows the numerical configuration of the spectacle lens 11 according to the fifth example.
As shown in
D1(0,θ)<Ap·P0(θ)+Bp (15)
where Ap=1.02n−0.51, Bp=13.24n−14.79.
As shown in
As described above, the front surface 11a is formed as a spherical surface. Therefore, as shown in
In addition to the above mentioned advantages, the spectacle lens 11 according to the fifth example is configured to have larger front warpage angle of 20°. Therefore, the spectacle lens according to the fifth example has a high wrapping property.
Since the spectacle lens 11 according to the fifth example satisfies the condition (15), a base curve, which is shallower than a base curve of a spherical surface configured to suitably attain a prescribed spherical power in regard to aberrations in the case where there is no inclination angle, is employed in the fifth example. However, by satisfying the condition (16) when the angle θ is in a predetermined range, it is possible to attain suitable off-axis optical performance.
Table 6 shows the numerical configuration of the spectacle lens 11 according to the sixth example.
As shown in
D1(0,θ)<Am·P0(θ)+Bm (18)
where Am=0.62n−0.40, Bm=20.09n−23.46.
As shown in
ΔP˜(5,θ)<ΔP˜(10,θ)<ΔP˜(15,θ) (19)
As described above, the front surface 11a is formed as a spherical surface. Therefore, as shown in
D2(5,θ)<D2(10,θ)<D2(15,θ) (26)
In addition to the above mentioned advantages, the spectacle lens 11 according to the sixth example is configured to have larger front warpage angle of 20°. Therefore, the spectacle lens according to the sixth example has a high wrapping property.
Since the spectacle lens 11 according to the sixth example satisfies the condition (18), a base curve, which is shallower than a base curve of a spherical surface configured to suitably attain a prescribed spherical power in regard to aberrations in the case where there is no inclination angle, is employed in the sixth example. However, by satisfying the condition (19) when the angle θ is in a predetermined range, it is possible to attain suitable off-axis optical performance.
Table 7 shows the numerical configuration of the spectacle lens 11 according to the seventh example. As shown in Table 7, the spectacle lens according to the seventh example has a function of correcting astigmatism.
As shown in
As described above, the front surface 11a is formed as a spherical surface. Therefore, as shown in
In addition to the above mentioned advantages, the spectacle lens 11 according to the seventh example is configured to have larger front warpage angle of 15°. Therefore, the spectacle lens according to the seventh example has a high wrapping property.
Since the spectacle lens 11 according to the seventh example satisfies the condition (15), a base curve, which is shallower than a base curve of a spherical surface configured to suitably attain a prescribed spherical power in regard to aberrations in the case where there is no inclination angle, is employed in the seventh example. However, by satisfying the condition (16) when the angle θ is in a predetermined range, it is possible to attain suitable off-axis optical performance.
Table 8 shows the numerical configuration of the spectacle lens 11 according to the sixth example. As shown in Table 8, the spectacle lens according to the eighth example has a function of correcting astigmatism.
As shown in
In addition to the above mentioned advantages, the spectacle lens 11 according to the eighth example is configured to have larger front warpage angle of 15°. Therefore, the spectacle lens according to the eighth example has a high wrapping property.
In
Although the present invention has been described in considerable detail with reference to certain preferred embodiments thereof; other embodiments are possible.
This application claims priority of Japanese Patent Application No. P2005-159538, filed on May 31, 2005. The entire subject matter of the application is incorporated herein by reference.
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