US 7,125,118 B2Granted

Progressive multifocal lens and method of designing the same

AssigneeSeiko Epson Corporation

InventorTadashi Kaga

Life of this patent

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Abstract

To provide a new progressive multifocal lens having eyesight corrective power and astigmatism corrective power in the same refracting interface by forming an eyeball-side refracting interface 2 or an object-side refracting interface 3 into a curved surface denoted by a combined refracting interface 14+15 composed of an original progressive refracting interface 14 set only to exhibit a desired eyesight corrective characteristic and an original toric surface 15 set only to exhibit a desired astigmatism corrective characteristic with a combination expression denoted by combination expression (1) or (2).

Claims8

Dependent claims

A progressive multifocal lens for correcting eyesight comprising:

a progressive refracting interface, said progressive refracting interface is located on a side of an eyeball or on a side of an object,
wherein the progressive refracting interface comprises:
a distance portion,
a near portion with different refractive powers, and
a progressive portion of which refractive power varies progressively therebetween,
wherein the eyeball-side refracting interface or the object-side refracting interface is a combined refracting interface comprising an original progressive refracting interface set only to exhibit a desired eyesight corrective characteristic and an original toric surface set only to exhibit a desired astigmatism corrective characteristic,
wherein, when z-axis is an axis passing through the center of the progressive refracting interface from the object toward the eyeball, x-axis is cylinder axis of the original toric surface, and y-axis is an axis perpendicular to the x-axis and the z-axis, value zpin any point P (xp, yp, zp) in the combined refracting interface is expressed by a first expression (1) or a second expression (2) by using approximate curvature Cp of the original progressive refracting interface, curvature Cx in the x-axis direction, and curvature Cy in the y-axis direction,
wherein the first expression (1) is expressed as
z
p
=
(
c
p
+
c
x
)
⁢
x
2
+
(
c
p
+
c
y
)
⁢
y
2
1
+
1
-
(
(
c
p
+
c
x
)
⁢
x
2
+
(
c
p
+
c
y
)
⁢
y
2
)
2
x
2
+
y
2
(
1
)
and
wherein the second expression (2) is expressed as
z
p
=
(
c
p
+
c
x
)
⁢
x
2
1
+
1
-
(
c
p
+
c
x
)
2
⁢
(
x
2
+
y
2
)
+
⁢
⁢
(
c
p
+
c
y
)
⁢
y
2
1
+
1
-
(
c
p
+
c
y
)
2
⁢
(
x
2
+
y
2
)
.
(
2
)

137 more elements

A method for designing a progressive multifocal lens for correcting eyesight having a progressive refracting interface on a side of an eyeball or on a side of an object, the progressive refracting interface comprising a distance portion, a near portion with different refractive powers, and a progressive portion of which refractive power varies progressively therebetween, the method comprising:

obtaining an original progressive refracting interface only in order that the eyeball-side refracting interface or the object-side refracting interface exhibits an eyesight corrective characteristic;
obtaining an original toric surface only in order that the eyeball-side refracting interface or the object-side refracting interface exhibits a desired astigmatism-corrective-characteristic;
and
obtaining a combined refracting interface as the eyeball-side refracting interface or the object-side refracting interface, the combined refracting interface comprising the original progressive refracting interface set only to exhibit a desired eyesight corrective characteristic and the original toric surface set only to exhibit a desired astigmatism corrective characteristic,
wherein in the obtaining of the combined refracting interface, when z-axis is an axis passing through the center of the progressive refracting interface from the object toward the eyeball, x-axis is the cylinder axis of the original toric surface, and y-axis is an axis perpendicular to the x-axis and the z-axis, value zp in any point P (xp, yp, zp) in the combined refracting interface is obtained by a first expression (1) or a second expression (2) by using an approximate curvature Cp of the original progressive refracting interface, a curvature Cx in the x-axis direction, and a curvature Cy in the y-axis direction,
wherein the first expression (1) is expressed as
z
p
=
(
c
p
+
c
x
)
⁢
x
2
+
(
c
p
+
c
y
)
⁢
y
2
1
+
1
-
(
(
c
p
+
c
x
)
⁢
x
2
+
(
c
p
+
c
y
)
⁢
y
2
)
2
x
2
+
y
2
(
1
)
wherein the second expression (2) is expressed as
z
p
=
(
c
p
+
c
x
)
⁢
x
2
1
+
1
-
(
c
p
+
c
x
)
2
⁢
(
x
2
+
y
2
)
+
⁢
⁢
(
c
p
+
c
y
)
⁢
y
2
1
+
1
-
(
c
p
+
c
y
)
2
⁢
(
x
2
+
y
2
)
.
(
2
)

134 more elements

Dependencies are inferred from the claim text.

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Abstract