Decentered noncorrective lens for eyewear

IS 2 196 191 T3

DESCRIPTION

Lenses for off-center non-corrective glasses.

The present invention relates to lenses used in optics, and more specifically to off-center, non-corrective lenses to reduce ooptical distortion.

Introduction

In recent years, important improvements have been made in the field of optics, especially in the field of glasses for people who practice sports and sunglasses as a fashion item. These advances have been incorporated into single lens eyewear, such as the “Blades®” design (Dakley, Inc.), the “M Frame®” line (Dakley, Inc.) and the “Zero®” line, as well. produced by Dakley Inc. All of these designs present a number of functional advantages, such as maximum increase in peripheral light interception, reduction of optic distortion, and improvement in overall wearer comfort, compared to previously existing sports eyewear.

The unitary lens of the “Blades¹® ”incorporates cylindrical geometry, known from, for example, US Patent No. 4,859,048 to Janard. This geometry allows the lens to fit comfortably to the wearer's face and intercept light, wind, dust, etc., directly incident from the front of the wearer (anterior direction) or from the periphery (lateral direction). See also US Patent No.^° 4,867,550 to Jannard (toroidal geometry for lenses).

Although previous unit lens systems provided side-to-side range of vision and good lateral eye protection, the potential for ioptic distortion still existed. In a unitary lens system, for example, the angle of incidence formed by the wearer's eye and the posterior surface of the lens changes as the wearer's line of sight shifts to the lateral direction. This results in uneven refraction between light entering most near the front of the lens and peripheral light entering through the side ends. To correct for this source of prism distortion, U.S. Patent No.^° 4,859,048 shows a narrowing of the lens thickness from the middle portion towards the lateral edges.

Dual lens systems have also been used previously, in which two different lenses are mounted on a front frame. In previous dual lens systems, the right and left lens were approximately coplanar in configuration once the wearer put on the glasses. Thus the wearer's line of sight, when looking straight ahead, generally crosses the rear surface of the lens at a normal surface of the lens in the ioptic zone. One of the disadvantages of this type of lens configuration was that the glasses practically did not provide any side protection without the use of special modifications, such as special temples or side attachments.

Later, dual lens systems appeared, in which the lateral edge of each lens was curved inward from the frontal plane and around the wearer's head in order to provide a warp similar to that obtained with lens systems. unit lenses. While well-warped dual lens systems provided side protection, lens curvature generally introduced measurable prism distortion across the wearer's viewing angle range. This was especially clear on lenses made of a material with a low refractive index. In addition, although it is sometimes desirable to have a high base curvature (eg. g. base 6 or mine) to optimize sag and maintain small eyewear dimensions, such lenses have proven impractical due to the relatively high level of prism distortion.

Therefore, there remains a need for a non-ioptic-prescribed raised base lens for use in dual lens eyewear, which can intercept light primarily throughout the full angular range of vision while, at the same time, minimizes ioptic distortion throughout the entire range. Summary of the invention

In accordance with the present invention, a method is provided for the manufacture of spectacle lenses for use in non-corrective dual lens spectacles, as defined in Claim 1. This spectacle lens is used in combination with a frame. to hold the lens so that it is in the wearer's normal line of sight.

The lens is made up of the lens body, which has a front surface, a rear surface, and a certain thickness between them.

The front surface of the lens forms a portion of the surface in a solid geometric shape. Preferably, the front surface of the lens substantially forms a portion of a first sphere having a first center. The rear surface of the lens substantially forms a portion of the surface in a solid geometric shape, which may be the same or a different one from the one that forms the front surface. Preferably, the rear surface forms substantially a portion of the surface of a second sphere having a second center.

The first and second centers are offset from each other in order to regulate the thickness of the lens. The lens is mounted on the mounting frame in such a way that the line drawn between the first and second centers is generally held in parallel with the wearer's normal line of vision.

The lens is cut from a raw lens. Preferably, the lens is oriented over the wearer's head by the spectacle frame, such that the wearer's normal line of sight crosses the anterior surface of the lens at an angle of (approximately) more than 95^°, preferably within a range of between about 100^° and 120^°, keeping the line of the lens's ioptic center in a generally parallel relationship with the wearer's normal line of sight. The ioptic center line of the lens may or may not pass through the lens.

IS 2 196 191 T3

Other features and advantages of the present invention will be clearly understood from the detailed description of the preferred embodiment of this invention that follows, and when this description is read in conjunction with the accompanying claims and drawings. Brief description of the drawings

Figure 1 is a perspective drawing of glasses incorporating the lenses corrected by narrowing, in accordance with one of the embodiments of the present invention.

Figure 2 is a cross-sectional view taken from the allolargodelaslone 2-2 of Figure 1.

Figure 3 is a schematic horizontal cross-sectional view of an uncorrected lens prior to the present invention for a dual lens eyewear system.

Figure 4 is a schematic horizontal cross-sectional view of a narrowed corrected lens for a dual lens eyewear system.

Figure 5 is a cross-sectional view like Figure 2, showing a narrowing corrected lens, having a greater curvature at the base, in accordance with another embodiment of the present invention.

Figure 6 is a perspective view of a lens blank that fits a portion of the surface of a sphere, showing the profile of the lens to be cut from the lens blank according to one of the preferred embodiments of the present invention.

Figure 7 is a perspective cross-section showing the interior, with the walls tapered in a spherical shape, the raw lens and the lens of Figure 6.

Figure 8 is a horizontal cross-sectional view of a lens constructed in accordance with one of the preferred embodiments of the present invention.

Figure 9 is a top view of the lens of Figure 8, showing the degree of wrapping of the glasses in relation to the wearer.

Figure 10 is a side cross-sectional view from the right side of the lens and wearer shown in Figure 9, showing the tilt of the lens.

Figure 11 schematically illustrates the projection of the lens profile from the desired orientation within the eyeglass frame for the lens blank according to one of the preferred embodiments of the present invention.

Figure 12 is a front view of the lens and lens blank of Figure 6, rotated to project the mechanical central lone on the normal axes of the page.

Detailed description of the preferred embodiment of the present invention

While the preferred embodiment of the present invention will be described below in terms of lenses having "spherical" front and rear surfaces (surfaces that substantially conform to a portion of the surface of a sphere), those skilled in the art You will easily understand that the present invention is also applicable to lenses with other surface geometries. Furthermore, it is understood that the present invention is applicable to lenses with many shapes and orientations in front view once they are worn by the user, not limited to those illustrated herein.

Figures 1 and 2 show spectacles 10, for example spectacles having a first and second lens 12, 14, constructed in accordance with one of the embodiments of the present invention. Although the invention is illustrated in the context of an eyewear design marketed by Dakley under the trade name Eye Jackets^TMThe present invention is solely concerned with the curvature and narrowing of the lens, as well as its orientation with respect to the wearer's head. Therefore, the specific shape of the lens presented in Figure 1 is not important to the present invention. Actually, lenses of many other shapes and configurations can be constructed according to the present invention, as will be seen below.

Also, the mount 16 shown in the Figure is not essential to the present invention. The frame 16 may be attached only to the lower edge or edges of the lenses 12, 14, only to the upper edges or to the entire lens, as is the case in the Figure. Alternatively, the frame 16 may be attached to any other portion of the lenses, as will be readily understood by those skilled in the art. Rimless spectacles can also be constructed in accordance with the present invention, as long as the orientation of the lens relative to the wearer's head is essentially kept in a predetermined relationship with respect to the normal line of vision, such as he said later. However, it is preferable that the lenses 12, 14 are mounted in an annular and orbital fashion, as shown in the Figure.

A pair of temples 20, 22 are hingedly attached to frame 16. Alternatively, temples 20, 22 can be attached directly to lenses 12, 14. The frame can be made of any of a number of metals, amalgam of materials or molded and relatively rigid thermoplastic materials, all of which are well known to those skilled in the art, and can be transparent or of any color, molded. by injection, machine turning or by any other manufacturing technique, all of this being well known in the field of application of the present invention.

The lenses, according to the present invention, can be manufactured by any of the manufacturing processes that are well known in this field.

Typically, high optical quality lenses are cut from a preformed lens blank by injection molding. Since the right and left lenses are preferably mirror images of each other, we will refer only to the right lens in the following. As an alternative, the lens can be directly molded to its final shape and size and eliminate the need to mold it after cutting.

Preferably, the lens or lens blank from which the former is cut is injection molded and formed of a relatively rigid, ooptically suitable material,

ES 2 196 191 T3 such as polycarbonate. Other polymeric lens materials can also be used, such as CR-39, and a number of high index plastics that are well known in the field of application of the present invention. The correction by decentration and narrowing of the present invention can also be applied to glass lenses, although the need for correction in this context is generally more pronounced in materials other than glass.

If the lens is to be shortened from the lens blank, the curvature and taper of a carefully preselected portion of the molded lens blank is transferred to the lens in accordance with one of the preferred manufacturing processes, described below. Preferably, the frame has a slit or other device that helps the molded curvature of the lens to minimize deflection and even to maintain its curved configuration.

Alternatively, the lens or lens blank can be punched or cut from tapered stock sheets, and then bent to obtain the curved configuration in accordance with the present invention. This curved configuration can then be maintained by using a relatively rigid curved frame, or by heating the curved sheet to maintain its curved configuration, following techniques that are well known in the field of thermal molding.

It is best to create the curvature of both lens surfaces on the lens blank by molding and honing, and then cutting the lens shape from the lens blank according to the part of the invention described below.

Figure 2 shows the lens 14 of the present invention, which is characterized in the horizontal plane as having an arcuate shape, extending from the median edge 24 through at least a portion of, and preferably all, the range of vision of the person wearing the glasses to a side edge 26. The length of the lens arc from the mid edge 24 to the lateral edge 26 in a dual lens system will generally be within a range of between about 1 1/2 and 3 1/2, preferably within a range of between about 2 and 3. In one of the preferred embodiments of the present invention, the arc length of the lens is approximately 2 3/8.

Although the outer surfaces of lenses 12, 14 are illustrated as if they were on a common circle 31, the right and left lenses are generally tilted such that the middle edge of each lens will fall outside the circle 31, while the side edges will fall within the circle 31. This tilt of the lenses increases the angle θ (Fig. 2) and also increases the desired optical correction that is achieved by the present invention.

When the spectacles are worn, the lens 14 should extend at least along the normal line of vision 27 of the wearer, preferably especially along the peripheral vision areas of the wearer. As used herein, the user's normal line of vision refers to a line that projects straight ahead of the user's eyes, substantially without any angular deviation in either the vertical or horizontal planes. as illustrated in Figures 9 and 10 by line 130.

The lens 14 has an anterior surface 28, a posterior surface 30 and a thickness that varies from one surface to the other. The thickness of lens 14 in the mid-edge region 24 of a polycarbonate lens is generally within a range of about 1 to 2.5mm, preferably within a range of about 1.5 to 1.8mm. . In one of the preferred embodiments of the present invention, the thickest portion of lens 14 is located at or near the optical center line, and is approximately 1.65mm.

Preferably, the thickness of the lens 14 is progressively decreasing in a smooth, not necessarily linear manner, from a maximum thickness near the middle edge 24 to a comparatively less thickness at the lateral edge 26. The thickness of the lens near the lateral edge 26 is a generally within a range of about 0.635 to 1.52mm, preferably within a range of about 0.762 to 1.27mm. In one of the preferred polycarbonate embodiments of the present invention, the lens has a minimum thickness in the middle of about 1.15mm. The minimum thickness at the lateral edge 26 generally depends on the impact resistance you want to give the lens.

Figure 3 schematically shows the refraction in a lens 41 prior to the present invention, with horizontal cross-sections of the circular inner and outer surfaces and a uniform thickness 44. With such a lens 41, the angle of incidence of the beams from lens 41 to eye 46 changes throughout the entire angular range of vision. For example, we will refer to illuminating effects to one of the beams as the middle light beam 50. This beam hits the lens 41 forming an angle α with the normal at the point of incidence. As anyone knowledgeable in this field knows, the curvature of the light beam at the transmitting surfaces depends in part on the angle of incidence of the light beams. The beam 50 is refracted or bent in the opposite direction to the outer 52 and inner 54 surfaces of the lens, which produces a transmitted beam 56 that is parallel to the incident beam 50. The transmitted beam 50 is laterally displaced relative to the path of the incident beam 50 by a determined distance 58. This displacement constitutes a first source of optical distortion.

Furthermore, the refractive shift is even more pronounced at the lateral edge 60, due to the existence of a greater angle of incidence β. An incident peripheral ray 62 undergoes a greater displacement 64 than a mean incident ray 50 in accordance with Snell's law, as is well known to all who are knowledgeable in optics. The discrepancy between the displacement of the peripheral ray 64 and the displacement of the middle ray 58 gives rise to a

ES 2 196 191 T3 second source of optical distortion. This type of optical distortion can cause significant warping of the image seen through relatively lateral portions of the lens 41.

Figure 5 schematically shows a lens 71 of progressively decreasing thickness to compensate for the greater degree of incidence of the lateral ends 60 of lens 41 (Fig. 3), as described in the context of unitary lens systems. in US Patent No. 4,859,048 to Janard. The progressive reduction in the thickness of the lens produces a smaller thickness 74 at one of the lateral ends 76, compared to the thickness of the lens 78 at a more medial point 80. This smaller thickness 74 somewhat reduces the displacement of the lenses. Peripheral rays 82, in comparison with the displacement of peripheral rays 64 that occurs in the lens 41 not subjected to a progressive reduction of its thickness that appears in the Figure

Four. In other words, the smaller thickness 74 of the lens near the lateral end 76 of the lens undergoing progressive reduction in thickness 71 compensates to some extent for the larger angle of incidence β ', as compared to the thickness 76 and the angle of incidence at the most medial point 80.

The resulting difference between the peripheral ray shift 82 and the medial ray shift 84 in the same lens 71 is not as great as the corresponding difference shown in Figure 3, which reduces the second source of optic distortion. Note that the degree of correction of this second source of optic distortion depends on the relationship between the shape and the degree of progressive reduction in the thickness of the lens from the vortex 85 to each of the lateral extremities 76 and on the shape of the lens. that the angle of incidence changes over the same range.

The lens 71 of Figure 4 is presented as if it were mounted in a frame (not shown in the Figure), such that the normal line of vision of the user 86 passes perpendicular through the lens 71 at the vortex of the lens. or mechanical center 85. In other words, the angle of incidence with the normal of the lens is equal to zero for the normal viewing area of ​​the user. The outer and inner surfaces of lens 71 in the cross-sectional illustration are adapted to deflection, corcles with the same radius represented by center points 87 and 88, respectively. A lone passing through the central points 87 and 88, called the lone of the ooptic center of the lens, is collinear with the lone of normal vision in the orientation that exists when the spectacles are worn. This conventional configuration is defined as a centrally oriented lens for better compression of the description. Circumferentially clockwise or counterclockwise with respect to the normal line of vision 86, the angle of incidence with the normal of the lens increases steadily from zero to the lens vortex 85. A high degree of sag may be desirable for aesthetic design reasons, to protect the eyes laterally from entry of airborne particles, or to intercept peripheral light. Warping can be achieved by using closed horizontal curvature (raised base) lenses, such as small radius spherical lenses, or by mounting each lens in a laterally and backward inclined position compared to centrally oriented dual lenses. This inclination changes the normal line of vision 86 and alters the collinear relationship with the line of the optic center, also changing the optic properties of the lens. As a consequence, dual lens eyewear prior to the present invention had significant "sag" on both sides of the wearer's face, which was achieved at the expense of some degree of prismatic distortion.

The present invention provides a better optical configuration and a method to minimize prism distortion. The present invention can be applied to a very wide range of lens shapes and orientations; however, the invention has special application to dual lens glasses with a high base curvature that have a high degree of sag when worn by the user.

Figures 2 and 5 show eyeglasses incorporating inclined lenses 12 or 14 or 102 or 104, mounted in a laterally rotated position, compared to the mounting of conventional centrally oriented dual lenses. An inclined lens can be conceived as a lens having an orientation relative to the wearer's head that was obtained from conventional dual lens glasses having centrally oriented lenses by bending the frame inward at the wearer's temples to achieve sag. around the head.

As a consequence of the increased warping, the wearer's normal vision line 27 no longer impinges on the lens 14 in a perpendicular manner, as shown in Figure 4. Ensulugar, the angle of incidence θ^° with the normal viewing range of the user 27 it is generally greater than 90^°, and, if you want to obtain a good sag, they can be approximately 95^°, preferably within the range of about 100^° and 135^°, and in an embodiment of the present invention based on 9.5 would be 101.75^°. Lenses with a lower base generally have a greater angle θ in the orientation than the glasses have when the user wears them, and this angle in an embodiment of the present invention that had a base of 6.5 was approximately 113, 4^°. In another embodiment of the present invention that had a base of 4 and a pupillary distance of 2.8 inches, the angle θ was approximately 118.864^° (Note: One inch equals 2.54 cm).

Figure 5 shows the horizontal cross section of glasses 100 according to one of the embodiments of the present invention, with a design similar to that presented in Figure 2, except that the lenses 102 and 104 have a curvature closed masse (raised masse base) and possibly greater sag. When the wearer wears glasses 100, a side edge 106 of lens 104 sags significantly around the wearer's head and is positioned very close to the temples to achieve 5

ES 2 guiding a suitable lateral protection, as it has been said previously.

An anterior (front) surface 108 of the lens in accordance with the present invention generally conforms to a portion of the surface of a regular geometric solid, such as a sphere 110, shown here in horizontal cross section. The center surfaces of the spherical lenses 102 and 104 of the embodiment of the present invention illustrated in the Figure can therefore be characterized by a radius. By industry convention, curvature can also be expressed in terms of a base value, such that the radius (R) in millimeters of the anterior surface of the lens is equal to 530 divided by the base curve, or (1 ) R =⁵b⁰

The present invention provides a method for the construction of dual lens eyeglass systems having relatively high sag, using lens blanks with a base curve of 6 or greater, preferably between about 7-1 / 2 and 10-1 / 2. , better still between about 8 and 9-1 / 2, and, in one embodiment of the present invention, between about 8-3 / 4 and 9. The radius of the corcle that conforms to the anterior surface of an 8-3 / 4 base lens, for example, is approximately 60.57 millimeters. For comparison purposes, the radius of the circle that characterizes the anterior surface of a lens with a base of 3 is approximately 176.66 millimeters.

The embodiment of the present invention shown in Figure 5 can be cut from a lens stock with an 8 3/4 base, approximately 0.0649 inches thick at the lone of the optic center and about 0.053 inches in thickness. a reference point located on the outer circumference located two inches from the lone of the optic center. Alternatively, the lens can be molded directly to its final shape and configuration.

Figure 6 shows a perspective view of a lens blank 122 with a convex outer surface 138, which generally conforms to a portion of a surface of a three-dimensional geometrical shape 124. Persons with knowledge in the field of application of the The present invention is understood that the lens according to the invention can be adapted to a series of geometrical shapes.

Preferably, the outer surface of the lens conformed to a shape with a smooth and continuous surface and a constant horizontal radius (spherical or cylindrical) or a progressive curve (eloptic, toroidal or ovoid) in either the horizontal or vertical plane. The geometrical shape 124 of the embodiment described here of the present invention, however, generally approximates a sphere.

The sphere 124 shown in Figures 6 and 7 is an imaginary three-dimensional solid, a portion of the wall of which is suitable for cutting a slow 20. As is known, a precise cut can often be achieved by producing a

191 T3 10 lens blank 122, from which a lens 120 is finally cut. However, those with knowledge in this field should note from Figures 6 and 7 that the use of a different lens blank is optional and that lens 120 can be directly molded, if desired, to its final shape and configuration.

In Figures 6 and 7 it can also be seen that the lens 120 and / or the lens blank 122 can be positioned in different ways along the sphere 124. For the purposes of the present invention, the lone of the optical center 132 is used as a reference line to orient lens 120 with respect to sphere 124. In the embodiment of the present invention shown here, in which both the outer and inner surfaces adapt to a portion of a sphere, the lone of the optic center is defined as lone 132 that joins the two centers C1 and C2 . The anaologous reference line for non-spheric geometry lenses can be formed in a different way without connecting the two geometrical centers of the sphere, as anyone with knowledge in this field will understand.

Lens 120 is ultimately formed in such a way that it preserves the geometry of a portion of the wall of the sphere, as shown in Figure 7. The location of lens 120 on sphere 124 is selected such that when lens 120 is oriented in the eyeglass frame, the wearer's normal viewing area 130 through the lens will generally remain parallel to the lens. of the optic center 132 of the geometrical configuration from which the lens 120 was obtained. In Figures 6 and 7, the lens 120 is the right lens, and has a significant degree of warping and some degree of tilt. A lens having a different shape or a lesser degree of warping may overlap the lone of the optic center of the imaginary sphere 124, from which the lens was formed. However, whether the line of the optic center of the imaginary sphere 124 crosses the lens 120 or not is irrelevant, as long as the line of vision 130 of the lens 120 is generally kept in parallel with the line of the optic center. in the orientation that the glasses have when the user wears them.

For the purposes of the present invention, "substantially parallel" means that the viewing lone 130 generally does not deviate from the horizontal plane more than about ± 10 ° from the lone parallel to the lone of the optical center when the lens 120 is oriented in the glasses worn by the user. Preferably, the normal viewing line 130 should not deviate more than about ± 10^° from the line of the optical center 132, better still the normal line of vision should not deviate more than approximately ± 5^°, and even better not more than about ± 2^° from the line parallel to the line of the optical center 132. The best that the line of vision 130 is parallel to the line of the optical center in the orientation of the glasses when the user wears them. Typically, an eyeglass frame has a vertical plane of symmetry substantially parallel to line of vision 132. Consequently, the line of optical center 132 will be substantially parallel to the vertical plane of symmetry of the frame.

IS 2 196 191 T3

Variations of the parallel line in the horizontal plane tend to have a more significant negative influence on the lens than variations in the vertical plane. Therefore, the solid angle that forms between the line of vision 130 and the line of the oáptic center 132 in the vertical plane can exceed the values ​​established above in the case of some glasses, as long as the horizontal component of the angle of deviation It is within the deviation intervals with respect to the aforementioned parallel orientation. Preferably, the line of sight 130 should not deviate in the vertical plane by more than about ± 3 ° from the line of optical center in the orientation of the spectacles existing when the wearer is wearing them.

Figure 7 is a cross-section showing the interior of lens 120, lens blank 122, and geometrical shape 124 shown in Figure 6. This cross-section shows that preferred geometrical shape 124 is hollow and has walls of variable thickness, as seen in the horizontal cross-sectional view 134 made in the line of the aoptic center of the geometric shape 124.

The walls with a progressive reduction in the thickness of the geometric shape 124 have their origin in two horizontally deviated spheres, represented by their central points C1 and C2 and by their radii R1 and R2. An outer surface 136 of the preferred lens blank 122 conforms to one sphere (of radius R1), while an inner surface 138 of lens blank 122 conforms to the other sphere (of radius R2). By adjusting the parameters of the two spheres, the nature of the narrowing of the lens blank 122 can also be adjusted.

Specifically, it is better to select the parameters of the two spheres to which the outer surface 136 and inner surface 138 of the raw lens adapt in such a way that a refractive capacity equal to zero is produced in lenses not prescribed by the oculist. . Where CT represents the chosen thickness of the center (maximum wall thickness of the hollow geometrical shape 124), n is a refractive index of the raw lens material, R1 is established from the design chosen for the curvature of the surface exterior 136, and R2 can be determined by the following equation:

CT (2) R2 = Ri - CT + n

CT / n represents the separation of the spherical centers C1 and C2. For example, if a 6 base lens is desired for design reasons, a 3mm center thickness is selected, and if the refractive index of the preferred material (polycarbonate) is 1.586, it can be calculated R2 applying the previous equation:

rq / Ά q

R2 = --3 + - = 87.22-mm 6 1.586

In this example, the radius R1 of the outer surface 136 is equal to 66.333 mm, the radius R2 of the inner surface is equal to 87.22-mm, and the spherical centers C1 and C2 are separated by a distance of 1.892 mm. These parameters describe the curvature of the lens blank 122 of the preferred embodiment of the present invention.

In the case of the preferred embodiment of this invention, the optical center line 132 is the line that passes through both central points (C1 and C2) of the deflection spheres. This line passes through the thickest portion of the walls of the preferred geometrical shape 124 at an optic center 14-, although this may not be the case in other non-spherical embodiments of the present invention. The anoptic center 144 passes through the surface 138 of the lens blank 122 shown in the Figure, although it does not necessarily have to. The optic center 14- does not fall into the lens, although this may not be the case when it comes to larger lenses or lenses in which a lower degree of curvature is intended in the orientation of the glasses when the user he wears them.

Figure 8 shows a horizontal cross-sectional view of the preferred lens 12-, showing in simulation the geometrical shape 124, to which the outer surface 136 and the inner surface 138 conform. The lens blank does not appear in this drawing. In accordance with the present invention, the optic center line 132 associated with the chosen type of narrowing is aligned such that it is parallel to the wearer's normal line of vision 13- when the lens 12- is mounted on the eyepiece frame. glasses.

Furthermore, while the preferred embodiments of the present invention are circular in both horizontal and vertical cross-sectional view, it is possible to make a number of lens configurations in both planes within the scope of this invention. Thus, for example, the outer surface of the lens of the present invention can generally conform to a spherical shape, as shown in Figures 6 and 7. An alternative is to adapt the lens to a right circular cylinder, a truncated cone, an elliptical cylinder, an ellipsoid, a revolution ellipsoid, or any other three-dimensional shape. However, regardless of the particular horizontal or vertical curvature of the outer surface, the inner surface should be chosen such that a smooth narrowing of the lens thickness can be realized at least in the horizontal plane.

Figures 9-12 contribute to the description of the method for choosing the placement on the blank lens, from which the lens on the right side 12- is to be cut, according to one of the preferred embodiments of the present invention. . It is understood that a similar method can be used to construct the left side lens in the case of the dual lens eyewear of the present invention.

As a first step, the overall curvature that is desired for the outer surface 136 of the lens is chosen. In the case of the preferred lens 12-, this choice will determine the base value of the lens blank 122. As already mentioned, a number of other curvatures can be used within the scope of the present invention. You can also preset the thickness of the lens. Specifically, the minimum thickness can be chosen in such a way that the lens can withstand an impact force

ES 2 196 191 T3 preselected.

You can also choose the shape of the lens. For example, an example front view of the shape of lens 120 is shown in Figure 12. Generally, the shape of the lens is of no importance to the optics of the off-center lenses described in this invention.

Likewise, you must choose the orientation you want the camera to have when the user wears the glasses. As previously stated, the orientation chosen can provide a significant degree of sag for lateral protection and interception of peripheral light, as well as for aesthetic design reasons. For example, in the embodiment of the present invention shown in Figures 6-12, a sloping slow 120 is used to obtain the desired degree of sag. Alternatively, the desired warping can be achieved by using a lens with a higher base and a more conventional (not tilted) orientation. Figures 9 and 10 show in a more simple way the relationship between the different orientations and the user's line of sight 130.

The designer of the glasses can also choose a certain degree of inclination (vertical fall), as can be deduced from Figure 10, which schematically shows the vertical orientation of the lens 120 in relation to the wearer's head 126, and with respect to specifically to the normal vision line 130. A downward tilt, as shown in the Figure, is desirable for a number of reasons, such as greater user comfort, as this type of tilt is better suited to the anatomy of the head. As those skilled in the art would readily understand, a lens 120 with a mechanical center located below the horizontal plane that intersects with the lone of the optical center 132 (see Figure 7) tends to have a downward tilt, such as as shown in Figure 10. This occurs because lens 120 has been formed below the equator of the sphere relative to the lone of the optic center. Since the orientation of the lens 120 with respect to the line of the optical center 122 in the imaginary sphere must be the same that exists between the lens 120 and the line parallel to the normal line of vision 130 when the wearer is wearing the glasses, Any lens cut from an area of ​​the sphere below the lones of the ooptic center 132 exhibited some degree of downward tilt.

Figure 11 presents a plane of the horizontal orientation of lens 120 on lens blank 122. The normal viewing area 130, with respect to which the chosen orientation is measured, is kept substantially parallel to the line of optical center 132 .

Once a particular aesthetic pattern, such as that shown in Figure 11, has been chosen and the lens blank 122 has a suitable base curvature to accommodate that pattern, the pattern can be projected onto the surface of the sphere to determine what portion of this is adequate to obtain lens 120. The projection of the shape of the lens on the sphere must be carried out by moving the surface of the sphere until it is positioned in such a way that when cutting the lens from the sphere in that position, the appropriate inclination and drop can be appreciated that are intended in the design chosen without any rotation of the lens 120 out of its orientation, in which the line of the ooptic center of the sphere is generally parallel to the normal line of vision in the orientation of the glasses when the subject wears them.

Although it does not appear in the Figure, it is understood that a similar projection can be made for the chosen vertical orientation, as described in Figure 10, for example. Figure 10 provides reference points for the shape of the upper edge 152 and lower edge 154 of the lens with respect to the viewing line 130. The projection can then be moved up or down until the upper edge 152 and the lower edge are simultaneously aligned with corresponding points on the outer surface 136 of the lens blank, while keeping the viewing line 130 substantially parallel. to the lone of the optical center 132.

The projection of the horizontal and vertical profiles can be carried out simultaneously, locating a single position on the blank lens 122 that corresponds to the desired three-dimensional shape of the lens (including the shape in front view shown in Figure 12), in which the viewing line 130 is parallel to the line of the optical center 132 or to another reference line on the lens blank 122. Of course, it is understood that lines 130 and 132 may be substantially parallel, that is, they may be within the acceptable range of angular deviation that we have established above.

This shape can then be cut from the lens blank 122 or it can be molded directly into the final configuration that the lens will have. The resulting lens 120 not only conforms to the desired shape but also minimizes prism distortion.

Figure 12 shows a lens blank 122 that conforms to a portion of the surface of the sphere of Figures 6 and 7. In Figure 12, the lens blank 122 has been rotated such that its mechaonic center appears at the center of the drawing. The lens 120 shown in the Figure has a middle edge 148, a side edge 144, an upper edge 152, and a lower edge 154. At least a portion of the right-side lens 120 falls into the left (third) quadrant of the lens. raw 122. Preferably, in an embodiment of the present invention in which both the sag and the downward tilt are shown, at least about half of the lens area fell within the third quadrant of the lens blank 122. Preferably, the entire area or a substantial portion of the area of ​​lens 120 would fall below and to the left of the optic center, as shown in the Figure. Lenses that exhibit a similar degree of tilt but less sag can be placed over the lens blank 122 such that 50% or more of the lens area is within the lower right (second) quadrant of the lens blank 122 .

The present invention, therefore, provides

ES 2 196 191 T3 uses a precise method to achieve the correction of the correspondence between the narrowing and the variable angle of incidence from the wearer's eye to the lens surface. By finding a new relationship between the wearer's viewing area and the shape of the narrowing, the present invention allows any of a number of lens designs to be used and minimizes prismatic distortion. For example, an eyewear designer may choose the orientation and curvature they want for the lens in relation to the wearer's viewing area. Orientation and curvature can be chosen from a very wide range of tilts (i.e. vertical lens "holes"), as well as horizontal tilts, base values, and proximity to the wearer's face, including the parameters that give rise to a variable degree of warping. Next, the form of narrowing can be chosen by the method presented in this invention, in such a way that the prism distortion is reduced to the maximum.

While the present invention has been described in terms of certain preferred embodiments, the possibility of various other embodiments will be clear to all skilled in the art in light of what is set forth herein. Therefore, the present invention should not be construed as being limited to the described preferred embodiments, but should be understood on the basis of the claims presented below.