EP0132955A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Ophthalmic lens
Assignee: Carl Zeiss Vision Australia Holdings Ltd
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Filing: 1984-06-28
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Granted: —
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Expires: 2004-06-28
Abstract
Abstract An ophthalmic lens which is a multifocal, progressive lens, has a distance viewing zone (10) and an intermediate viewing zone (14) leading to a near zone (12). The shape of a surface of the lens is defined by a final surface function such that there is no change in height at the zone boundaries (16, 18) and at least the first three derivatives of the final surface function are continuous across those boundaries. The surface of the near zone (12) is defined by a function which is the sum of the surface function of the distance zone (10) extended over the entire lens, and a near zone surface function having a factor given by a fourth degree expression in cartesian coordinates.
Inventors
- 👤 Eric F. Barkan
- 👤 David H. Sklar
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 03:12
CPC Classifications
G; G02; G02C; G02C7/00; G02C7/02; G02C7/06; G02C7/061; G02C7/024; Y; Y10; Y10S; Y10S425/00; Y10S425/808
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
208 words
An ophthalmic lens with a lens surface having a near viewing zone (12), a distance viewing zone (10) and an intermediate zone (14) in which there is a gradual change in optical power along an eye path from the distance zone (10) to the near zone (12), characterised in that boundaries (16, 18) defined between the distance zone (10) and the intermediate zone (14), and between the intermediate zone (14) and near zone (12) are projections of algebraic curves on the lens surface; the shape of the surface of the lens is defined by a final surface function such that the surfaces of the zones (10, 12 and 14) are the same height at the boundaries (16, 18) and so that at least the first three derivatives of the final surface function are continuous across the boundaries; and the surface of the near zone (12) is defined by an equation of the form Z T =Z d +Z s where Z T is the final function, Z d is the rotationally symmetric surface function of the distance zone extended over the entire lens, and Z s is a near zone surface function having a factor given by a fourth degree expression in the cartesian coordinates x and y.
Claim 2
Dependent Claim
208 words
An ophthalmic lens with a lens surface having a near viewing zone (12), a distance viewing zone (10) and an intermediate zone (14) in which there is a gradual change in optical power along an eye path from the distance zone (10) to the near zone (12), characterised in that boundaries (16, 18) defined between the distance zone (10) and the intermediate zone (14), and between the intermediate zone (14) and near zone (12) are projections of algebraic curves on the lens surface; the shape of the surface of the lens is defined by a final surface function such that the surfaces of the zones (10, 12 and 14) are the same height at the boundaries (16, 18) and so that at least the first three derivatives of the final surface function are continuous across the boundaries; and the surface of the near zone (12) is defined by an equation of the form Z T =Z d +Z s where Z T is the final function, Z d is the rotationally symmetric surface function of the distance zone extended over the entire lens, and Z s is a near zone surface function having a factor given by a fourth degree expression in the cartesian coordinates x and y.
Claim 3
Dependent Claim
35 words
A lens as claimed in Claim 1, wherein the near zone surface function is given by an expression of the form wherein As, B s , x o , Yo and z o are constants.
Claim 4
Dependent Claim
147 words
A lens as claimed in Claim 1 or Claim 2, wherein the surface function in the intermediate zone (14) is defined by an equation of the form: wherein Z T is the final surface function, Z d is the surface function of the distance zone extended over the entire optical body, and Z is defined by an equation of the form: where n and m are each integers less than 10, where Ai j are a set of constants and where u t and vj are coordinates of a curvilinear coordinate system, raised to the ith and jth power, respectively, u and v being defined such that the cartesian coordinates x and y are given by transformation equations of the form: and where p, q, r and s are each integers less than or equal to 2; and where Xij and Yij are further sets of constants.
Claim 5
Dependent Claim
15 words
A lens as claimed in Claim 3, wherein Z = 0 in the distance zone.
Claim 6
Dependent Claim
27 words
A lens as claimed in Claim 3 or Claim 4, wherein the transformation equations are given by: wherein a, c, v o and v l are constants.
Claim 7
Dependent Claim
65 words
A lens as claimed in Claim 5, wherein the curve u = 0 is the eye path (20); the curve v = 0 is the boundary between the distance zone (10) and the intermediate zone (14); v o and c are parameters which determine a nasal offset of the near zone boundary (18); and the constant, a, determines the curvatures of the boundaries (16, 18).
Claim 8
Dependent Claim
27 words
A lens as claimed in Claim 6, wherein the surface height along the eye path is substantially determined by a function of the fifth degree of v.
Claim 9
Dependent Claim
36 words
A lens as claimed in Claim 6, wherein a is from 0 to 1mm -2 ; c is from -1 to 1; v o is greater than lmm; and v 1 is from -100 to 100mm.
Claim 10
Dependent Claim
41 words
A lens as claimed in any one of Claims 3 to 8, wherein the final surface function is the sum of the function Z d and the function Z which is the product of a preliminary function and an auxiliary function.
Claim 11
Dependent Claim
52 words
A lens as claimed in Claim 9, wherein the preliminary function is selected so that the surfaces of the zones (10, 12, 14) are the same height at the boundaries (16, 18) and so that at least the first three derivatives of the preliminary function are continuous across the boundaries (16, 18).
Claim 12
Dependent Claim
25 words
A lens as claimed in Claim 9 or Claim 10, wherein the auxiliary function is continuous in all derivatives up to and including the third.
Claim 13
Dependent Claim
56 words
A lens as claimed in Claim 9, wherein the auxiliary function is a function S(y) given by an equation of the form: where y is a cartesian coordinate, y c and σ y are constants, whereby astigmatism is reduced in at least a portion of the intermediate zone lying above the line y c - y.
Claim 14
Dependent Claim
75 words
A lens as claimed in Claim 9, wherein the auxiliary function is a function U(u) given by an equation of the form: for all u, where u is a coordinate of a curvilinear coordinate system in which line u * 0 is the eye path, and σ u is a constant, whereby the constant σ u is selected to improve orthoscopy in a portion of the intermediate zone on both sides of the eye path.
Claim 15
Dependent Claim
31 words
A lens as claimed in any one of the preceeding claims, wherein each of the algebraic curves, whose projections on the lens surface define the boundaries (16, 18), is a parabola.
Claim 16
Independent Claim
173 words
A method for making an ophthalmic lens having a distance viewing zone (10), a near viewing zone (12), and an intermediate zone (14) in which there is a gradual change in optical power from the distance zone (10) to the near zone (12), characterised by selecting a base surface function Z d progenitive of prescribed optical properties in the distance zone (10); selecting a deviation function Z representative in value of a deviation from the base surface in the intermediate zone (14), said deviation function having a zero value in the distance zone (10) and having a value in the intermediate zone (14) given by a polynomial function in a two dimensional curvilinear coordinate system (u, v), boundaries of the zones in the coordinate system being defined so that, along the eye path (20), u equals a constant, and so that, along a distance zone boundary (16) and a near zone boundary (18), v equals a constant; and forming a lens surface in the lens responsive to a surface function Z T where
Claim 17
Independent Claim
173 words
A method for making an ophthalmic lens having a distance viewing zone (10), a near viewing zone (12), and an intermediate zone (14) in which there is a gradual change in optical power from the distance zone (10) to the near zone (12), characterised by selecting a base surface function Z d progenitive of prescribed optical properties in the distance zone (10); selecting a deviation function Z representative in value of a deviation from the base surface in the intermediate zone (14), said deviation function having a zero value in the distance zone (10) and having a value in the intermediate zone (14) given by a polynomial function in a two dimensional curvilinear coordinate system (u, v), boundaries of the zones in the coordinate system being defined so that, along the eye path (20), u equals a constant, and so that, along a distance zone boundary (16) and a near zone boundary (18), v equals a constant; and forming a lens surface in the lens responsive to a surface function Z T where
Claim 18
Dependent Claim
73 words
A method as claimed in Claim 16, wherein the value of the deviation function in the intermediate zone (14) is given by a polynomial function as defined by an equation of the form: where n and m are degrees of u and v, respectively; where Aij is a set of constants; and where u i and v3 are the coordinates of the curvilinear coordinate system, raised to the ith and jth power, respectively.
Claim 19
Dependent Claim
20 words
A method as claimed in Claim 16, wherein n and m are each integers less than or equal to 8.
Claim 20
Dependent Claim
66 words
A method as claimed in Claim 16 or Claim 17, wherein u and v are defined such that the cartesian coordinates x and y are given by transformation equations of the form: and where p and q are degrees of u and v defining x, where r and s are degrees of u and v defining y; and where Xij and Yij are sets of constants.
Claim 21
Dependent Claim
22 words
A method as claimed in Claim 18, wherein p, q, r and s are each integers less than or equal to 2.
Claim 22
Dependent Claim
81 words
A method as claimed in Claim 18, comprising evaluating the optical properties of the lens surface formed responsive to the surface function Z T , modifying the shape of the zone boundaries (16, 18), repeating the selection of a base surface function Z d and a deviation function Z to obtain a final surface function having desired astigmatism and orthoscopy characteristics in the intermediate zone (14) and the near zone (12), and forming a lens responsive to that final surface function.
Claim 23
Independent Claim
26 words
A method as claimed in any one of Claims 15 to 20, comprising using the lens to profile a former for further formation of such lenses.
References Cited (Backward Citations)
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