WO2003050596A1

WO2003050596A1 - A wrap-around spectacle lens

Info

Publication number: WO2003050596A1
Application number: PCT/IT2001/000527
Authority: WO
Inventors: Vittorio Tabacchi
Original assignee: Safilo Societa' Azionaria Fabbrica Italiana Lavorazione Occhiali S.P.A
Priority date: 2001-10-18
Filing date: 2001-10-18
Publication date: 2003-06-19
Also published as: AU2002214252A1

Abstract

A wrap-around lens (2) for spectacles (1, 100, 200, 300) is described and is defined by a first surface and a second surface (3a, 3b) which are spaced apart and disposed opposite one another, the first surface (3a) having a continuous geometrical curve (S, S', S'') as its cross-section in a longitudinal plane (X, Y). The continuous geometrical curve (S, S', S'') comprises at least a first part (5) and a second part (6, 7) which are contiguous and each of which includes an arc of a circle, and the tangent to the geometrical curve at the point of connection of the first part to the second part is continuous.

Description

A wrap-around spectacle lens Technical field

The present invention relates to a wrap-around spectacle lens according to the preamble to the main claim. Technological background

Within the technical field referred to, there is a known need to provide spectacles which ensure protection not only of the front portion of the user's eye, but also of the side region, following the curvature of the head. These so-called wrap-around spectacles are used frequently in various sports disciplines and in any activity in which improved eye protection is required, or as sunglasses.

Known spectacles with wrap-around lenses are usually produced by fitting a pair of lateral protection pieces onto the front portion of the spectacles, thus giving rise to an abrupt change of curvature or discontinuity in the spectacles in the region of the connection between the lateral lenses and the central lens. This leads to distorted vision by the user in the regions of discontinuity, as well as to a displeasing appearance .

To prevent these problems, spectacles comprising a single wrap-around lens the cross-section of which in a longitudinal plane is given by an arc of an ellipse have been proposed, for example, by United States patent No. 5825455. Moreover, wrap- around spectacles in which the single lens has a cross-section given by a polynomial curve are known from United States patent No. 5604547. By virtue of these particular geometrical shapes, it is possible to produce spectacles which permit a good wrap-around relative to the user's face without requiring the fitting of lateral lenses, but their design and production are complex.

Moreover, in spectacles the lenses of which confor to a quite specific mathematical function, the lens cannot be modified locally, since a modification of a detail in any region of the lens requires modifications throughout the lens, given that each point of the lens conforms to the same function.

Not least, in these spectacles, the optical region in which vision is not distorted, according to the standards in force, is not particularly extensive. Description of the invention

The problem underlying the present invention is that of providing improved wrap-around spectacles which are designed structurally and functionally to overcome the limitations explained above with reference to the prior art mentioned.

This problem is solved by the present invention by means of wrap-around spectacles formed in accordance with the appended claims .

Brief description of the drawings The characteristics and the advantages of the invention will become clearer from the detailed description of some embodiments thereof which are described by way of non-limiting example, with reference to the appended drawings, in which:

- Figure 1 is a perspective view of spectacles comprising a wrap-around lens formed in accordance with the invention,

- Figure 2 is a perspective view of a second embodiment of the spectacles of Figure 1,

- Figure 3 is a perspective view of a third embodiment of the spectacles of Figure 1, - Figure 4 is a perspective view of a fourth embodiment of the spectacles of Figure 1,

- Figure 5 is a schematic view of a wrap-lens of Figure 1, in partial longitudinal section,

- Figure 6 is a partial perspective view of a first embodiment of the wrap-around lens of Figure 1,

Figure- 7 is a partial perspective view of a second embodiment of the wrap-around lens of Figure 1,

- Figure 8 is a partial perspective view of a third embodiment of the wrap-around lens of Figure 1, Figure 9 is a partial perspective view of a fourth embodiment of the wrap-around lens of Figure 1,

Figures 10a to 10c are a perspective view, a front elevational view, and a side elevational view, respectively, of a fifth embodiment of the wrap-around lens of Figure 1,

Figure 11 is a partially-sectioned view of a further embodiment of the wrap-around lens of Figure 1, and - Figures 12a-12d are further partially-sectioned views of embodiments of the wrap-around lens of Figure 1. Preferred embodiments of the invention

With reference initially to Figure 1, spectacles, generally indicated 1, comprise a wrap-around lens 2 formed in accordance with the present invention.

The term "spectacles" defines herein sunglasses and protective and/or sports masks or glasses, that is, everything which involves the use of one or more lenses for protecting the user's eyes.

The spectacles 1 comprise a single wrap-around lens 2 suitable for protecting both of the user's eyes and preferably made of plastics material, for example, polycarbonate, nylon or equivalent materials, and a frame 11 including two arms, both indicated 12.

The spectacles, indicated 100 in Figure 2, may also be of the "rimless" type, that is, without frames, in which the arms 12 are connected directly to the wrap-around lens 2, in known manner, by means of a pair of shoulders 13.

The lens 2 is produced by injection moulding and is defined by a first principal surface 3a and a second principal surface 3b disposed opposite one another and each covering the user's forward and lateral fields of view when the spectacles are worn. The first and second surfaces 3a, 3b are spaced apart by a distance d equal to the thickness of the lens 2, this thickness being variable according to the design of the lens to ensure the correct optical characteristics. The first surface 3a, which is farthest from the user's face when the spectacles 1 are worn, has a longitudinal section given by a geometrical curve S shown in Figure 5.

This section is taken in a plane (X, Y) substantially parallel to a straight line joining the user's eyes.

According to a particular characteristic of the invention, the curve S is continuous with a continuous derivative at every internal point (that is, with the exclusion of the opposite end points of the curve S, indicated Si and S₂, respectively) , that is, the tangent at any point thereof has no discontinuity. The curve S is also symmetrical with respect to an axis indicated Q in the drawings.

The geometrical curve S comprises a first, central part 5 which has a uniform curvature of radius Ri with its centre Ci lying on the axis Q, and from the two opposite ends 5a, 5b of which a second part 6 and a third part 7, each comprising an arc of a circle of radius R₂, extend in a reflectively symmetrical manner with respect to the axis Q. A further, fourth part and a further, fifth part 8, 9, each comprising an arc of a circle of radius R₃, extend from the free ends 6a, 7a of the second and third parts 6, 7, respectively, in a reflectively symmetrical manner with respect to the axis Q.

The expression "arc of a circle" also includes straight sections since a straight line can be defined as a circle of infinite radius. In particular, in the embodiment of Figure

5, R₃ = ∞ and the fourth and fifth parts are parallel to the axis Q.

For an optimal construction of the lens 2, the values of the radii of curvature listed above are preferably within the following ranges: 70 mm ≤ R_x ≤ 150 mm, 8 mm < R₂ ≤ 30 mm and R₃ = oo.

It is pointed out that the tangent to the curve S is continuous not only at the internal points of the individual parts 5, 6, 7, 8, 9 but also, in particular, at the connecting points between them, by virtue of the appropriate selection of the radii Ri, R₂, R₃ and of the lengths of the parts.

In a further embodiment, shown in Figure 12a, the longitudinal section of the surface 3a, given by the curve indicated S', comprises only the first, central part 5 and the second and third parts 6, 7.

The shape along an axis Z perpendicular to the plane (X, Y) , that is, the three-dimensional shape of the surface 3a, is obtained as described by way of example below. Figures 6 to 9 show four embodiments of the three- dimensional shape of the first surface 3a of the lens 2. The lens 2 shown is thus formed to the desired shape before being fitted in the frame 11. Each drawing shows only half of the first surface 3a, since the plane (X, Y) is a plane of symmetry for the lens 2. Figures lOa-lOc show a fifth embodiment of the three-dimensional shape of the surface 3a as a whole, in which the plane (X, Y) is not a plane of symmetry of the lens 2.

In the first embodiment of the lens 2 , shown in Figure 6, the surface 3a comprises a section of a surface of revolution obtained by rotating the geometrical curve S about an axis A lying in the plane (X, Y) and perpendicular to the axis of symmetry Q. In the preferred embodiment of Figure 6, the axis of rotation A also passes through the centre Ci. The first surface 3a therefore comprises a first portion 15 corresponding to the first part 5 and constituted substantially by a section of a spherical surface, a second portion and a third portion 16, 17 corresponding to the second and third parts 6, 7 and each constituted substantially by a section of a toroidal surface and, finally, a fourth portion and a fifth portion 18, 19 corresponding to the fourth and fifth parts 8, 9 and each constituted substantially by a flat surface. If R₃ ≠∞, then each of the fourth and fifth portions 18, 19 is constituted by a section of a toroidal surface. In detail, the sphere of whose surface the first portion 15 is a section has a radius equal to Ri, and the torus of whose surface the second and third portions 16, 17 are sections is generated by the rotation of a circle of radius R₂ about the

A further embodiment, not shown, provides for the axis A to be translated from the centre of the circle of radius Ri within the plane (X, Y) . In this case, a surface 3a similar to that shown in the embodiment of Figure 6 is obtained, except that the first portion 15 is not a section of a spherical surface, but of a toroidal surface, the torus having a maximum radius equal to the length of the section of the axis Q delimited by the axis A and by the curve S, and the radius of the generator circle is equal to Ri. Moreover, if the fourth and fifth parts 8, 9 were not parallel to the axis Q, the surfaces 18, 19 would be sections of a conical surface

(R₃ = oo) or of a toroidal surface (R₃ ≠ ∞) .

In a second embodiment of the surface 3a shown in Figure

7, in which details similar to those of the previous embodiment are indicated by the same reference numerals, the surface 3a is obtained by a translation of the geometrical curve S along the axis Z. In this case, the first, second and third portions 15', 16', 17' corresponding to the first, second and third parts 5, 6, 7 of the curve S are constituted substantially by sections of cylindrical surfaces of radii Ri and R₂, respectively. The fourth and fifth portions 18, 19 are again flat surfaces (or are also sections of cylindrical surfaces of radius R₃, if R₃ ≠ ∞) •

In a third embodiment of the surface 3a shown in Figure

8, the three-dimensional shape of the surface 3a is obtained by defining a circle of radius R lying in a plane perpendicular to the plane (X, Y) , parallel to a plane (X, Z) , and extending through the free end Si and/or S₂ of the fourth or fifth part 8, 9. An arc 20, contiguous with the fourth part 8 in the preferred embodiment, is then identified in this circle. The surface 3a is then defined by translation of the arc 20 along the entire geometrical curve S lying in the plane (X, Y) without any variation of the inclination of the arc 20 to the plane (X, Y) . If R = R_x is selected, the first portion 15 is constituted by a section of a substantially spherical surface with a sphere radius of R_x, and the second and third portions 16'' and 17'' are constituted by sections of a toroidal surface in which the toroid concerned has a variable generator-circle radius. The fourth and fifth portions 18' and 19' are sections of a substantially cylindrical surface of radius Ri (moreover, if R = R₃ ≠ oo, then the fourth and fifth portions are also sections of a spherical surface) . The variable radius of the generator circle of the variable toroidal surface 16'', 17'' is preferably between 8 mm and 30 mm. In a fourth embodiment of the surface 3a, shown in Figure 9, the first, central portion 15, and the fourth and fifth portions 18', 19' are substantially similar to those of the preceding preferred embodiment of Figure 8, but the way in which the connection is made between these three surface portions is different; in particular, the second and third surfaces 16''' and 17''' are sections of a toroidal surface in which the torus has a constant generator-circle radius equal to R₂.

In the fifth embodiment of Figure 10, the surface 3a is no longer formed so as to be reflectively symmetrical with respect to the plane (X, Y) , but at least a portion of it is inclined to that plane. The inclination at a point of the surface 3a is quantified by an angle γ between the straight line tangential to the surface 3a at the point of interest of the curve S or S', for example, at the point of intersection between the axis Q and the curve S or S^τ, and a straight line perpendicular to the plane (X, Y) and extending through the same point. The expression "inclination of a portion of the surface 3a" is intended to define below the inclination of the plurality of its points. The angle γ, which is equal to 0 in the four embodiments of Figures 6-9, is preferably such that 0° < γ < 25°. In particular, this geometrical shape can be achieved by rotating the curve S about an axis perpendicular to the axis Q but not lying in the plane (X, Y) . Alternatively, the first portion 15'' of the surface 3a is given by a section of a spherical or toroidal surface of radius R_v and centre C_v not belonging to the plane (X, Y) . Again, the first portion is given by a section of a cylindrical surface (R = ∞) having an axis which is not perpendicular to the axis Q. The remaining portions are connected to the first portion in an appropriate manner, for example, for a first, front portion which is a section of a cylindrical surface with γ ≠ 0, and fourth and fifth lateral portions which are sections of cylindrical surfaces with γ = 0, the second and third • portions of the surface 3a are sections of a conical surface.

The three-dimensional shape of the surface 3a having as its longitudinal section the curve S' shown in Figure 12a is the same as that described above in the five preferred embodiments, naturally with modifications (that is, the absence of the fourth and fifth surface portions corresponding to the fourth and fifth parts of the curve) .

In a further embodiment, the surface 3a has a section in the longitudinal plane (X, Y) given by the curve S'' shown in Figure 11. The curve S' ' is continuous, with a continuous derivative at each of its internal points and is symmetrical with respect to the axis Q. It comprises, in addition to the first, second, third, fourth and fifth parts 5, 6, 7, 8, 9, a further, sixth part and a further, seventh part 21, 22 extending from the fourth and fifth parts 8 and 9 in a reflectively symmetrical manner with respect to the axis Q. Each of the sixth and seventh parts 21, 22 comprises an arc of a circle of radius R. In the preferred embodiment of Figure 11, R₄ = ∞ and R₃ ≠ ∞; in particular, the radius R₃ preselected for an optimal embodiment of the lens 2 is such that 110 mm < R₃ < 150 mm. Moreover, an angle α which is preferably such that -10° < α < 40° and, in particular, -3° < α

< 10°, is defined between the axis Q of the curve S'' and the straight part 21 and/or 22.

The three-dimensional shape of the lens 3a, based on the curved section S'', is obtained in a manner similar to that described by way of example above for the curve S. In detail, if the curve S'' is rotated about the axis A extending through Ci, the surface 3a described in the embodiment of Figure 6 also comprises a sixth portion and a seventh portion which correspond to the sixth and seventh parts 21, 22 of the curve S'' and each of which is constituted by a section of a flat surface (R₄ = oo and α = 0) , of a conical surface (R₄ = oo and α ≠ 0) , or of a toroidal surface (R₄ ≠ ∞) .

If the curve S"' is translated along the axis Z, the surface 3a obtained as described in the embodiment of Figure 7 also comprises a sixth portion and a seventh portion each constituted by a section of a cylindrical surface (R₄ ≠ ∞) or of a flat surface (R₄ = oo) .

Moreover, with the use of the three-dimensional shape shown in Figures 8 and 9, the surface 3a is obtained by defining the arc 20 of the circle of radius R contiguous with the end of the sixth or seventh part 21, 22 and by performing a translation thereof along the curve S''. In this case, each of the sixth and seventh portions of the surface 3a is constituted by a section of a spherical surface (R = R₄) , of a toroidal surface (R ≠ R₄) , or of a cylindrical surface (R = oo) . Numerous further three-dimensional shapes of the geometrical curve S, S' or S'' for obtaining the first surface 3a of the lens 2 can be produced, always with the use of the teaching provided. In particular, continuous surfaces having continuous derivatives at every internal point can be obtained on the basis of the curves S, S' and S'' by appropriate connection of portions of spherical, toric or toroidal, cylindrical, conical, and flat surface sections.

The surface 3b is preferably formed in similar manner to the surface 3a and therefore also has a section given by a continuous geometrical curve having a continuous derivative at each of its points.

The spacing and the radii of curvature of the two surfaces 3a, 3b are determined in an appropriate manner to achieve the largest possible optically correct region, that is, the largest possible region free of optical distortions.

The wrap-around spectacles 1, 100 according to the invention are therefore produced by defining, as the sections of the first and of the second surfaces 3a, 3b of the lens 2, two curves, preferably having the same shape, and selected from S, S' and S'', that is by selecting two or more of the radii of curvature Ri, R₂, R₃, R₄, and the length of two or more of the parts 5, 6, 8, 21, according to the preselected curve, for each surface 3a, 3b. In particular, the central part 5 and the second and third parts 6 and 7 of each surface 3a, 3b have dimensions such that the lens 2 has an optically correct region which also extends into the region corresponding to the second radius of curvature R₂ or into a portion thereof. On the basis of the same optically correct region, lenses of different appearance and shape are produced by varying the lengths of the parts 6, 8, 21 and/or the radius R₃ and/or R₄.

Figures 12a-12d show four embodiments of a surface 3a (of which only the longitudinal section is shown) which have the same optical regions, in particular Ri and R₂ are the same for all four embodiments, but different wrap-around and lateral protection. In particular, the angle α determines the extent to which the lens is wrapped around the user's face, and the protection is given by the lengths of the side portions, in particular, of the fourth and sixth parts 8, 21 which define the length of the part of the user's profile which is covered by the lens 2.

The three-dimensional shape of the lens is therefore selected as described above, again according to the appearance to be given to the wrap-around spectacles 1, 100 and according to their optical properties.

The lens 2 is then cut appropriately and connected to a lens-holder rim lie of the frame 11, or directly to the arms 12. The spectacles, indicated 200 in the embodiment of Figure 3, may also comprise a pair of wrap-around lenses 2, each of which covers the user's right or left eye and which are fitted in a frame 11' comprising a bridge 14 joining two lens-holder rims 14a, 14b, in which the two lenses 2 are fitted. In this case, each lens 2 is formed on the basis of a part of the curve S, S' or S'' but in any case with the use of the teaching to form it by means of circle arc portions having a continuous derivative at the connecting points.

In a further embodiment, shown in Figure 4, the spectacles 300 are of the "rimless" type with two lenses, in which each lens 2 is connected to the arm 12 by means of a shoulder 13 and the two lenses are joined together by means of a bridge 14' fixed directly to the lenses 2.

The invention thus solves the problem posed, achieving many advantages over known solutions . A first advantage is that the geometry of the two surfaces of the wrap-around spectacle lens achieves considerable simplicity of processing in all of the stages of the production of the lens, from the production of the mould to the cutting of the lens to the desired shape. A further advantage provided by the wrap-around spectacles according to the invention is the considerable extent of the optically correct region which, if the radii of curvature are selected appropriately, extends over a larger area than in known spectacles . Not least, the geometry of the lens enables wrap-around spectacles of very varied form and shape to be produced easily since it is possible to modify the geometry of the side regions considerably without varying the optically correct central region of more complex design.

Claims

1. A wrap-around lens (2) for spectacles (1, 100, 200, 300), the lens (2) being defined by a first surface and a second surface (3a, 3b) which are spaced apart and arranged opposite one another, the first surface (3a) having a continuous geometrical curve (S, S', S'') as its cross-section in a longitudinal plane (X, Y) , characterized in that the continuous geometrical curve (S, S', S'') comprises at least a first part (5) and a second part (6; 7) which are contiguous and each of which includes an arc of a circle, and in that the tangent to the geometrical curve (S, S', S'') at the point of connection of the first part (5) to the second part (6; 7) is continuous .

2. A wrap-around lens (2) according to Claim 1, in which the longitudinal plane (X, Y) is substantially parallel to a straight line joining a user's eyes when the spectacles (1, 100, 200, 300) are worn.

3. A wrap-around lens (2) according to Claim 1 or Claim 2, in which the geometrical curve (S, S', S'') is reflectively symmetrical with respect to a median axis (Q) of the first part (5) and comprises a third part (7), the second part (6) and the third part (7) extending from the first part (5) in a reflectively symmetrical manner with respect to the axis of symmetry (Q) .

4. A wrap-around lens (2) according to Claim 3, in which the geometrical curve (S, S', S'') also comprises a fourth part (8) and a fifth part (9) extending from the second part (6) and from the third part (7) , respectively, in a reflectively symmetrical manner with respect to the axis of symmetry (Q) .

5. A wrap-around lens (2) according to Claim 1 or Claim 2 in which the geometrical curve (S, S', S'') also comprises a fourth part (8; 9) extending from the second part (6; 7) .

6. A wrap-around lens (2) according to Claim 4 or Claim 5 in which the fourth part (8; 9) is an arc of a circle.

7. A wrap-around lens (2) according to Claim 4 or Claim 6 in which the geometrical curve (S, S', S'') also comprises a sixth part (21) and a seventh part (22) extending from the fourth part (8) and from the fifth part (9), respectively, in a reflectively symmetrical manner with respect to the axis of symmetry (Q) .

8. A wrap-around lens (2) according to Claim 5 or Claim 6 in which the geometrical curve (S, S', S'') also comprises a sixth part (21; 22) extending from the fourth part (8; 9) .

9. A wrap-around lens (2) according to Claim 7 or Claim 8 in which the sixth part (21; 22) is an arc of a circle.

10. A wrap-around lens (2) according to one or more of Claims 4 to 9 in which the tangent to the geometrical curve at the point of connection of the second part (6; 7) to the fourth part (8; 9) is continuous.

11. A wrap-around lens (2) according to one or more of Claims 7 to 10 in which the tangent to the geometrical curve at the point of connection of the fourth part (8; 9) to the sixth part (21; 22) is continuous.

12. A wrap-around lens (2) according to one or more of the preceding claims in which the radius of curvature (Ri) of the first part (5) is between 70 mm and 150 mm.

13. A wrap-around lens (2) according to one or more of the preceding claims in which the radius of curvature (R₂) of the second part (6; 7) is between 8 mm and 30 mm.

14. A wrap-around lens (2) according to one or more of Claims 4 to 13 in which the radius of curvature (R₃) of the fourth part (8; 9) is between 70 mm and 150 mm.

15. A wrap-around lens (2) according to one or more of Claims 4 to 13 in which the fourth part (8; 9) is straight.

16. A wrap-around lens (2) according to Claim 15 in which the fourth part (8; 9) and the axis of symmetry (Q) extend along intersecting axes inclined to one another at an angle (α) of between -10° and 40°.

17. A wrap-around lens (2) according to one or more of Claims 7 to 16 in which the sixth part (21; 22) is straight.

18. A wrap-around lens (2) according to Claim 17 in which the sixth part (21; 22) and the axis of symmetry (Q) extend along intersecting axes inclined to one another by an angle (α) of between -10° and 40°.

19. A wrap-around lens (2) according to one or more of the preceding claims in which the second surface (3b) has, as its cross-section in the longitudinal plane (X, Y) , a second continuous geometrical curve formed in the same manner as the continuous geometrical curve (S, S', S'') according to Claims 1 to 18.

20. A wrap-around lens (2) according to one or more of the preceding claims in which the first surface (3a) comprises a first portion (15; 15'; 15'') including the first part (5) of the geometrical curve (S, S', S'') and constituted by a section of a substantially spherical, cylindrical, or toroidal surface.

21. A wrap-around lens (2) according to one or more of the preceding claims in which the first surface (3a) comprises a second portion (16; 17; 16'; 17'; 16"; 17"; 16'"; 17'") including the second part (6; 7) of the geometrical curve (S, S', S") and constituted by a section of a substantially toroidal, cylindrical or conical surface.

22. A wrap-around lens (2) according to one or more of Claims 4 to 21 in which the first surface (3a) comprises a fourth portion (18, 19; 18'; 19') including the fourth part (8; 9) of the geometrical curve (S, S") and constituted by a section of a substantially cylindrical, flat, toroidal, conical, or spherical surface.

23. A wrap-around lens (2) according to one or more of Claims 7 to 22 in which the first surface (3a) comprises a sixth portion, including the sixth part (21; 22) of the geometrical curve (S") and constituted by a section of a substantially cylindrical, flat, toroidal, conical, or spherical surface.

24. A wrap-around lens (2) according to one or more of Claims 20 to 23 in which the toroidal surface is generated by the rotation of a circle of constant radius.

25. A wrap-around lens (2) according to one or more of Claims 20 to 23 in which the toroidal surface is generated by the rotation of a circle of variable radius.

26. A wrap-around lens (2) according to Claim 25 in which the variable radius is between 8 mm and 30 mm.

27. A wrap-around lens (2) according to one or more of the preceding claims in which the first surface (3a) comprises a section of a surface of revolution obtained by rotating the geometrical curve (S, S', S") about an axis (A) lying in the longitudinal plane (X, Y) .

28. A wrap-around lens (2) according to one or more of Claims 1 to 26 in which the first surface (3a) comprises a section of a surface obtained by translating the geometrical curve (S, S', S") along an axis (Z) perpendicular to the longitudinal plane (X, Y) .

29. A wrap-around lens (2) according to one or more of Claims 1 to 26 in which the first surface (3a) comprises a section of a surface obtained by defining an arc (20) of a circle perpendicular to the longitudinal plane (X, Y) , the arc (20) being contiguous with the second part (6; 7), with the fourth part (8; 9), or with the sixth part (21; 22), and by translating the arc (20) of the circle along the entire geometrical curve (S, S', S").

30. A wrap-around lens (2) according to one or more of the preceding claims in which the longitudinal plane (X, Y) is a median plane of symmetry for the wrap-around lens.

31. A wrap-around lens (2) according to one or more of Claims

1 to 29 in which the angle (γ ) formed between a tangent to the first surface (3a) and/or to the second surface (3b) at a preselected point of the geometrical curve (S, S', S") and an axis perpendicular to the longitudinal plane (X, Y) extending through the preselected point is between 0° and 25°.

32. A wrap-around lens (2) according to Claim 31 in which the preselected point is the point of intersection of the axis of symmetry (Q) with the geometrical curve (S, S', S").

33. A wrap-around lens (2) according to one or more of the preceding claims in which the second surface (3b) is formed in a similar manner to the first surface (3a) , in accordance with one or more of Claims 20 to 32.

34. A wrap-around lens (2) according to one or more of the preceding claims in which the first surface (3a) and the second surface (3b) are continuous with continuous derivatives at each of their internal points.

35. Spectacles (1, 100) comprising the wrap-around lens (2), according to one or more of Claims 1 to 34, extending to protect the user's right eye and left eye.

36. Spectacles (1) according to Claim 35, comprising a frame (11) including two arms (12) and two shoulders (13) articulated to the arms (12) and connected to a lens-holder rim (lie) .

37. Spectacles (100) according to Claim 35, comprising two shoulders (13) connected directly to the wrap-around lens (2) .

38. Spectacles (200, 300) comprising a first and a second of the wrap-around lenses (2) according to one or more of Claims 1 to 34, extending to protect the user's right eye and the user's left eye, respectively.

39. Spectacles (200) according to Claim 38, comprising a frame (11') including two arms (12) and two shoulders (13) articulated to the arms (12) and connected to two lens-holder rims (14a, 14b) .

40. Spectacles (300) according to Claim 38, comprising a bridge (14') and two shoulders (13) connected directly to the two wrap-around lenses (2) .