HK1100300B - Decentered noncorrective lens for eyewear - Google Patents

Description

Eccentric non-corrective lens for goggles

The present application is a divisional application of the chinese patent application No.02127847.4 entitled "filed on 1996, 12/4/o by the applicant of oxdeli limited.

Technical Field

The present invention relates generally to lenses for use in eyewear (eyewear), and more particularly to decentered non-corrective lenses for reducing optical distortion.

Background

In recent years a wide variety of improvements have been made in the field of goggles, particularly for use intended in fast sports or as popular sunglasses. These improvements have been embodied in eyewear having a single lens, for exampleDesign (Oakley Limited liability company), "M frameworkSeries (Oakley Limited liability company), andthe series is also produced by Oakley, Inc. These eyewear designs can provide a variety of functional benefits, such as maximizing peripheral light capture, reducing optical distortion, and improving wearer comfort levels, as compared to the original rapid motion eyewear.

The unitary lens of the goggle has incorporated cylindrical geometry such as disclosed in U.S. patent No.4,859,048 to Jannard. This geometry allows the lens to closely conform to the wearer's face and intercept light, wind, dust, etc. directly from the front (forward) and periphery (lateral) of the wearer. See also U.S. Pat. No.4,867,550 to Jannard (of toroidal lenses)Geometric shape).

Although early single lens systems were able to provide full side-to-side viewing range and good lateral eye protection, the potential for optical distortion still exists. For example, in a single lens system, the angle of incidence from the wearer's eye to the rear surface of the lens varies as the line of sight rotates in the lateral direction. This results in a fundamentally different refraction between light entering closer to the front of the lens and peripheral light entering at both lateral ends. For analysis of sources of prismatic distortion, U.S. Pat. No.4,859,048 discloses a means of chamfering the thickness of the lens from the central portion to the lateral edges.

Prior art eyewear also employs a dual lens system in which two separate lenses are mounted along the front frame. In this early two-lens goggle system, each of the left and right lenses was substantially coplanar when worn. Thus, when looking straight ahead, the wearer's line of sight passes through the lens back surface in the optical zone, typically on a normal to the lens surface. One of the disadvantages of this lens configuration is that the glasses do not substantially provide lateral eye protection without the use of special modifications such as vertically elongated temples (earstem) or side attachments.

Since then dual lens systems have been developed in which the lateral edge of each lens curves backwards from the front plane around the side of the wearer's head so as to provide a lateral shield similar to that achieved by high shield (wrap) single lens systems. Dual-lens eyewear with significant obscuration, while capable of providing lateral eye protection, the curvature of the lenses often results in a measurable prismatic distortion through the wearer's viewing angle range. This is particularly evident in lenses constructed of low refractive index materials. Furthermore, high base curve (e.g., base curve of 6 or higher) is sometimes desirable for optimizing occlusion while maintaining a low profile, but such lenses have not been practical in the past due to their higher level of prismatic distortion.

Thus, the need remains for a non-prescription fitted lens as a high baseline for use in a dual lens goggle that is capable of blocking light substantially throughout the entire viewing angle range while minimizing optical distortion.

Disclosure of Invention

According to one aspect of the invention, an ophthalmic lens for use in a dual lens goggle for non-correction is provided. The ophthalmic lens is utilized in combination with a frame to support the lens in the optical path of the wearer's normal line of sight.

The lens includes a lens body having an anterior surface, a posterior surface, and a thickness therebetween.

The front surface of the lens conforms to a partial surface of a solid geometry. Preferably, the anterior surface of the lens substantially conforms to the surface of the portion of the first sphere having the first center. The posterior surface of the lens substantially conforms to a portion of the surface of a solid geometry, which may be the same or different than the geometry conforming to the anterior surface. Finally, the rear surface is made to substantially coincide with a portion of the surface of a second sphere having a second center.

The first and second centers are offset from each other to taper (taper) the thickness of the lens. The lens is mounted in the frame such that a line drawn through the first and second centers remains generally parallel to the wearer's normal line of sight.

The lens may be cut from a lens blank or directly formed into its final configuration, such as by injection molding or other processes known in the art. The lens is preferably positioned on the wearer's head by the eyeglass frame such that the wearer's normal line of sight passes through the front surface of the lens at an angle greater than about 95 (and preferably in the range of about 100 to 120) while maintaining the optical centerline of the lens in generally parallel relationship with the wearer's normal line of sight. The optical centerline of the lens may or may not pass through the lens.

The method for making lens of the present invention is also disclosed.

Further features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments, taken in conjunction with the appended claims and the accompanying drawings.

Drawings

FIG. 1 is a perspective view of eyewear fitted with a pointed corrective lens made in accordance with an embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a schematic horizontal cross-sectional view of a prior art non-variable cross-section lens for a two-lens eyewear system;

FIG. 4 is a schematic horizontal cross-sectional view of a variable cross-section (taper) lens for a dual lens goggle system;

FIG. 5 is a cross-sectional view similar to FIG. 2 showing a steeply tapered corrective lens having a greater base curve according to another embodiment of the present invention;

FIG. 6 is a perspective view of a lens blank conforming to a portion of the surface of a ball showing the profile of a lens intended to be cut from the blank in accordance with a preferred embodiment of the present invention;

FIG. 7 is a perspective cross-sectional view of the variable cross-sectional wall spherical shape of the depression of FIG. 6, a lens blank and a lens;

FIG. 8 is a horizontal cross-sectional view of a lens constructed in accordance with a preferred embodiment of the invention;

FIG. 9 is a top plan view of the lens of FIG. 8 showing the height shading associated with the wearer;

FIG. 10 is a right side elevational section of the lens and wearer of FIG. 9 showing the lens tilted;

FIG. 11 is a perspective view of a lens blank from a desired orientation in a goggle frame, schematically illustrating the projection of the shape of the lens, in accordance with a preferred embodiment of the present invention;

fig. 12 is a front elevational view of the lens and lens blank of fig. 6 rotated to project the mechanical centerline of the blank normal to the plane of the drawing.

Detailed Description

Although the preferred embodiments of the present invention will be discussed below with respect to lenses having "spherical" front and back surfaces (i.e., those surfaces that substantially conform to a portion of the surface of a sphere), those of ordinary skill in the art will appreciate that the present invention is also applicable to lenses having different surface geometries.

Referring to fig. 1 and 2, eyewear 10 (e.g., sunglasses) is shown with first and second lenses 12, 14 constructed in accordance with an embodiment of the invention. Although the present invention is represented in the context as having Eye sockets^TMThe eyeglass design is designated by Oakley under the name, however the invention relates only to the bending, bevelling and orientation of the lens on the wearer's head. Thus, the lens shape disclosed in fig. 1 is not critical to the invention. Rather, many other shapes and configurations of lenses that can be constructed in connection with the present invention will become apparent based on the disclosure herein.

Likewise, the particular mounting frame 16 shown in the figures is not essential to the invention. The frame 16 may be associated with only the lower edges of the lenses 12 and 14, only the upper edges of the lenses, or the entire lens as shown. Alternatively, the frame 16 may incorporate other portions of the lenses, as will be apparent to those skilled in the art. Rimless eyewear may also be constructed in accordance with the present invention so long as the lenses remain substantially in a predetermined relationship with the normal line of sight in the direction of the wearer's head, as will be discussed below. Preferably, however, each of the lenses 12, 14 is mounted in an annular track as shown.

A pair of temples 20 and 22 are pivotally secured to the frame 16. Alternatively, the temples 20 and 22 may be secured directly to the lenses 12 and 14. The frame may comprise any of a variety of metals, composites, or relatively strong moldable thermoplastic materials, as are known in the art, and may be transparent or any of a variety of colors. Injection molding, machining, and other structural processes are well known in the art.

Lenses according to the invention may be manufactured by any of a variety of processes known in the art.

Typically, high optical quality lenses are cut from a preformed injection molded lens blank. Since the left and right mirrors are preferably specularly reflective images of each other, only the right mirror will be discussed generally below. Alternatively, the lens can be directly molded to its final shape and size, eliminating the need for a post mold cutting step.

The lens or a blank from which the lens is cut is preferably injection molded and is constructed of a relatively strong and optically acceptable material, such as polycarbonate. Other polymeric lens materials may be used such as CR-39 and various high index plastics known in the art. The eccentric chamfer correction of the present invention may also be applied to glass lenses, although the need for correction in this respect is generally more pronounced in non-glass materials.

If the lens is to be cut from a lens blank, then the molded lens blank is transferred to the lens according to the preferred manufacturing process described below by careful pre-selected partial beveling and bending. It is desirable to provide the frame with slots or other fastening means to cooperate with the molded curves of the lens to minimize deviations from the molded curves, and even to improve the curves while remaining molded.

Alternatively, the lens or lens blank may be molded or otherwise cut from a generally flat, beveled sheet stock and then bent into a curved shape in accordance with the present invention. This curved shape may then be maintained by using a relatively strong curved frame, or by heating the curved sheet to maintain its curved shape, as is well known in the thermoforming art.

Most preferably, the curvature of the two surfaces of the lens is produced during the process of molding and polishing the lens blank, and the shape of the lens is cut from the blank according to the invention described below.

Referring to FIG. 2, the lens 14 of the invention is characterized in that it has a generally arcuate shape in a horizontal plane extending from the central edge 24 to the lateral edge 26, at least partially and preferably substantially all the way through the viewing range of the wearerIn inches toIn the range of inches and preferably in the range of about 2 inches to about 3 inches. In a preferred embodiment, the arc length of the lens is aboutIn inches.

The outer surfaces of the lenses 12 and 14, while appearing to be shown as lying on a common circle 31, will typically be tilted so that the central edge of each lens will fall outside the circle 31 and the lateral edges will fall inside the circle 31. By tilting the lens in this manner, the angle θ (FIG. 2) can be increased and the optical correction that the present invention objectively requires can be improved.

When worn, the lens 14 should extend at least across the wearer's normal line of sight 27, and preferably substantially across the wearer's peripheral vision zone. As used herein, the wearer's normal line of sight shall refer to a line cast straight ahead by the wearer's eye, with substantially no angular deviation in either the vertical or horizontal plane, as represented by line 130 in FIGS. 9 and 10.

The lens 14 is provided with an anterior surface 28 and a posterior surface 30 and the thickness therebetween varies. For polycarbonate lenses, the thickness of lens 14 in the region of its central edge 24 is typically in the range of about 1mm to about 2.5mm, and preferably in the range of about 1.5mm to about 1.8 mm. In the preferred embodiment, the thickest portion of the optic 14 is at or near the optical centerline and is about 1.65 mm.

The thickness of the lens 14 is preferably smoothly tapered, however, not necessarily linearly, and tapers from a maximum thickness proximate the central edge 24 to a lesser thickness at the lateral edges 26. The thickness of the lens near the lateral edge 26 is typically in the range of about 0.635mm to 1.52mm, and preferably in the range of about 0.762mm to 1.27 mm. In a preferred embodiment of polycarbonate, the lens has a minimum thickness of about 1.15mm in the medial region. The minimum thickness at the lateral edge 26 is generally determined by the desired impact strength of the lens.

Figure 3 schematically illustrates the refraction of a prior art lens 41 having a uniform thickness 44 with a horizontal cross section of rounded inside and outside surfaces. With such a lens 41, the incident angle of the light from the lens 41 to the eye 46 varies over the angular range of the line of sight. Such as a ray represented for ease of description as a central ray 50, strikes the lens 41 at an angle alpha to the normal. As is well known in the art, the curvature of light on a transmissive surface depends, in part, on the angle of incidence of the light rays. The light ray 50 will refract or bend in opposite directions on each of the outer surface 52 and the inner surface 54 of the lens 41, with the result that the transmitted light ray 56 is parallel to the incident light ray 50. The transmitted ray 56 is laterally displaced a distance 58 relative to the optical path of the incident ray 50. This displacement represents a source of primary optical distortion.

Furthermore, since the light is incident at a greater angle β at the lateral end 60, the refractive shift is even more pronounced there. As will be readily understood by those of ordinary skill in the optical arts, peripheral incident ray 62 undergoes a greater displacement than central incident ray 50 according to snell's law of refraction. The deviation between this peripheral ray displacement 64 and the centered ray displacement 58 will cause secondary optical distortion. This second order distortion may cause substantial distortion of the image seen through the more lateral portion of lens 41.

FIG. 4 schematically illustrates a lens 71 having a tapered thickness to compensate for a greater angle of incidence at the lateral end 60 (FIG. 3) of the lens 41 as disclosed in the context of the single lens system of U.S. Pat. No.4,859,048 to Jannard. the taper produces a lens thickness 74 at the lateral end 76 that is less than the lens thickness 78 at the more central point 80. this less thickness 74 reduces the amount by which its peripheral ray displacement 82 is relative to the peripheral ray displacement 64 through the non-tapered lens 41 of FIG. 3. in other words, the less lens thickness 74 of the tapered lens 71 near its lateral end 76 compensates somewhat for the greater angle of incidence β 'relative to the thickness 78 and the angle of incidence α' at the more central point 80.

The difference between the peripheral ray displacement 82 and the central ray displacement 84 obtained on the same lens 71 is not as large as the corresponding difference in fig. 3, thus reducing its quadratic optical distortion. It should be noted that the degree of secondary distortion correction depends on the manner of cross-section from the apex 85 to each lateral end 76, the degree, and the relationship between the manner of varying the angle of incidence over the same range.

The lens 71 in fig. 4 is shown as if it were mounted in a frame (not shown) such that the wearer's normal line of sight 86 is perpendicular through the lens 71 at the lens vertex or mechanical center 85. In other words, the angle of incidence to the lens normal is zero for the wearer's normal line of sight. In this cross-sectional view, the outer and inner surfaces of the lens 71 conform to offset, equal radius circles, represented by their center points 87 and 88, respectively. The straight line drawn through center points 87 and 88 is referred to herein as the optical centerline of the lens, which is collinear with the normal line of sight in the as worn orientation. For ease of description, this conventional shape shall be defined as a centrally oriented lens. Rotating the normal line of sight 86 circumferentially clockwise or counterclockwise, the angle of incidence to the lens normal will increase progressively in a fixed manner from zero at the lens vertex 85. A high degree of shading may be desirable for aesthetic design reasons, to protect the eyes laterally from flying debris, or to block ambient light. Shading can be achieved by using a tight horizontal curvature (high base) lens (e.g., a spherical lens with a small radius) or by mounting each lens in a position such that it is tilted back in the lateral direction as well as with respect to the centrally oriented dual lens. This tilt changes the collinear relationship of the normal line of sight 86 to the optical centerline and changes the optical effect of the lens. As a result, prior art dual lens eyewear having substantial "shadowing" effects near both sides of the wearer's face are often associated with some degree of prismatic distortion.

An improved optical structure and method are provided in accordance with the present invention to minimize prism distortion. While the invention is applicable to a wide variety of lens shapes and orientations, the invention has particular application to eyewear that employs a high base curve and exhibits high shading when in a worn orientation.

Referring to fig. 2 and 5, eyewear is shown which includes inclined lenses 12 and 14 or 102 and 104 mounted in a laterally rotated position relative to a conventional centrally oriented dual lens mount. The tilted lenses can be envisaged to have a certain directionality with respect to the wearer's head, which can be reached starting from a conventional double-lens goggle with a centrally oriented lens by bending the frame inwards at the temples to hide near the sides of the head.

As a result of the increased obscuration, the wearer's normal line of sight is no longer perpendicular to the lens 14 as shown in figure 4. Instead, the angle of incidence θ ° of the wearer's line of sight 27 is typically greater than 90 °, and in order to achieve good shadowing, it may be greater than about 95 °, preferably in the range of about 100 ° to 135 °, and in one embodiment of a baseline 9.5 about 101.75 °. Low base curve lenses generally exhibit greater theta angles in the as-worn orientation, and theta angles of about 113.4 deg. in a base curve 6.5 embodiment. In an embodiment with a baseline of 4 having a pupil distance of 2.8 inches, the angle theta is about 119.864 deg..

Fig. 5 shows a horizontal cross-section of an eyeglass (eyeglass)100 according to an embodiment of the invention, which is similar in style to that shown in fig. 2, except with lenses 102 and 104 that are flush curved (higher base line) and possibly have greater obscuration. When the eyeglass 100 is worn, the lateral edge 106 of the lens 104 largely conceals and is in close proximity to the wearer's temple to provide significant lateral eye protection, as already discussed.

The anterior surface 108 of the lens of the invention will generally conform to a portion of the surface of a regular geometric body, such as a sphere 110, as represented herein in horizontal cross-section. The front surfaces of the spherical lenses 102 and 104 of the illustrated embodiment are thus characterized by their radii. As is customary in the industry, the curve may also be expressed in terms of the baseline curve, such that the radius (R) of the anterior lens surface in millimeters is equal to 530 divided by the baseline curve (base curve), or

The present invention provides the ability to construct dual lens eyeglass systems with higher obscuration using lens blanks having base curves of 6 or greater, preferably about 6Andpreferably between about 8 and about 8In one embodiment, aboutAnd 9. E.g. with a base lineThe radius of the circle to which the anterior surface of the lens conforms is about 60.57 mm. For comparison, the circle used to characterize the anterior surface of the lens with base line 3 has a radius of about 176.66 mm.

The embodiment of the invention shown in FIG. 5 can be represented by a baselineIs cut, the lens blank having a thickness of about 1.65mm (0.0649 inches) at the optical centerline and about 1.35mm (0.053 inches) at a reference point 50.8mm (2 inches) along the periphery of the lens from the optical centerline. Alternatively, the lens may be directly molded into its final shape and configuration.

Fig. 6 is a perspective view of a lens blank 122 having a convex outer surface 136 that generally conforms to a portion of the surface of the three-dimensional geometry 124. Those skilled in the art will appreciate that lenses according to the invention may conform to any of a variety of geometries.

It is desirable to have the outer surface of the lens conform to a shape with a smooth continuous surface, with a constant horizontal radius (spherical or cylindrical), or with a gradual curve in either the horizontal or vertical plane (elliptical, toric or oval). However, the geometry 124 of the preferred embodiment described herein is generally close to a sphere.

The ball 124 shown in fig. 6 and 7 is an imaginary three-dimensional solid having a portion of its wall adapted to cut the lens 120 therefrom. As is well known in the art, precision lens cutting is often accomplished by producing a lens blank 122 from which a lens 120 is ultimately cut. It should be clear to those skilled in the art from the examples of fig. 6 and 7, however, that the use of a separate lens blank is not necessary and that the lens 120 can be directly molded into its final shape and configuration, if desired.

As can also be seen in fig. 6 and 7, the lens 120 and/or lens blank 122 can be positioned at any one of a number of positions along the spherical surface 124. For the purposes of the present invention, the optical centerline 132 acts as a reference line for the orientation of the lens 120 relative to the sphere 124. In the embodiment shown, where both the outer and inner surfaces coincide with a portion of a sphere, the optical centerline is then defined as the straight line 132 connecting the two centers C1 and C2. For non-aspherical lens geometries, similar reference lines may be formed in a manner other than connecting the geometric centers of the two spheres, as will be clear to those skilled in the art.

The lens 120 is ultimately formed in such a way that it retains the geometry of a portion of the outer wall of the ball shown in fig. 7. The position of the lens 120 on the ball 124 is selected such that when the lens 120 is positioned on the eyeglass frame, the wearer's normal line of sight 130 through the lens will generally be maintained parallel to the optical centerline 132 from which the geometry of the lens 120 is derived. In the example of fig. 6 and 7, the lens 120 is a right lens, with significant obscuration and some degree of tilt. Lenses having different shapes, or less degrees of obscuration, may be lapped (overlap) on the optical centerline 132 of the imaginary sphere 124 from which the lens is formed. It is not important, however, whether the optical centerline of the imaginary sphere 124 passes through the lens 120, so long as the line of sight 130 in the lens 120 is generally maintained parallel to the optical centerline 132 in the as-worn orientation.

For purposes of the present invention, "substantially parallel" shall mean that the line of sight 130 generally does not deviate more than about + -15 deg. from being parallel to the optical centerline 132 in a horizontal plane when the lens 120 is oriented in the as-worn position, preferably the line of sight 130 should not deviate more than about + -10 deg. from being parallel to the optical centerline 132, more preferably the line of sight 130 should deviate not more than about + -5 deg. and most preferably the line of sight 130 should deviate not more than about + -2 deg. from being parallel to the optical centerline 132.

Deviations from parallelism in the horizontal plane generally have a greater detrimental effect on the lens than deviations from parallelism in the vertical plane. Thus, the solid angle between the line of sight 130 and the optical centerline 132 in the vertical plane may be outside the ranges set forth above for some eyewear as long as the horizontal component of the deviation angle is within the above-noted deviation from the parallel direction. Preferably, the line of sight 130 is offset from the optical centerline in the vertical plane by no more than about + -10 deg., and more preferably no more than + -3 deg., in the as-worn orientation.

Fig. 7 is a cross-sectional view of the lens 120, lens blank 122, and geometry 124 of fig. 6. This view shows that the optimal geometry 124 is a hollow body with a varying thickness outer wall, as shown by the horizontal cross-section 134 on the optical centerline of the geometry 124.

The tapered outer wall of the preferred geometry 124 is obtained from two horizontally offset spheres represented by their center points C1, C2 and radii R1, R2. The outer surface 136 of the preferred lens blank 122 conforms to one sphere of radius R1 while its inner surface 138 conforms to another sphere of radius R2. By adjusting the parameters describing the two balls, the nature of the beveling of the lens blank 122 can also be adjusted.

Specifically, the parameters for the two spheres with which the outer surface 136 and the inner surface 138 of the lens blank conform are preferably selected so that they produce zero refractive power, or alternatively, non-prescription ophthalmic lenses. In this case, CT represents the selected center thickness (maximum thickness of the outer wall of the hollow geometry 124), n is the refractive index of the lens blank, R1 is set by design as the curvature of the outer surface 136, and R2 can be determined according to the following formula:

CT/n represents the separation of the two sphere centers C1 and C2. For example, where a lens with a base curve of 6 is desired from a design choice, the center thickness is chosen to be 3mm, the refractive index of the best material (polycarbonate) is 1.586, and R2 can be determined as follows:

for this example, the radius R1 of the outer surface 136 is equal to 88.333mm, the radius R2 of the inner surface 138 is equal to 87.225mm, and the two spherical centers C1 and C2 are 1.892mm apart. These parameters describe the curvature of the lens blank 122 as a preferred embodiment.

In the preferred embodiment, the optical centerline 132 is a straight line passing through the two offset sphere center points C1 and C2. This happens to pass through the thickest portion of the outer wall at the optical center 140 of the optimal geometry 124, although this is not true for alternative aspheric embodiments. The optical centerline 140 happens to pass through the surface 136 of the lens blank 122 as shown, although this is not required. The optical center 140 does not happen to be located above the lens 120, although this is possible for larger lenses or lenses that want to show less obscuration when positioned as worn.

Fig. 8 illustrates a horizontal cross-section of the preferred lens 120 and shows in phantom the geometry 124 to which the outer surface 136 and the inner surface 138 conform. The lens blank 122 has been omitted from this figure. In accordance with the present invention, the optical centerline 132 associated with the selected bevel is adjusted to be parallel to the wearer's normal line of sight 130 when the lens 120 is mounted on the eyeglass frame.

Thus, for example, the outer surface of the inventive lens generally conforms to a spherical shape, as shown in FIGS. 6 and 7, alternatively, the lens may conform to a right circular cylinder, a truncated cone, an ellipsoid of revolution, or any of a number of other three-dimensional shapes.

Fig. 9-12 will help describe the method of cutting the right lens 120 from the lens blank 122 at a selected location thereon according to the preferred embodiment of the invention. It should be understood that a similar method would be used to construct the left lens in the preferred embodiment of the dual lens goggle.

As a first step, a desired total curvature of the outer lens surface 136 may be selected. For the preferred lens 120, this choice determines the baseline value of the lens blank 122. Other bends may also be utilized in connection with the present invention, as noted elsewhere herein. The selection of the lens thickness may also be preselected. Specifically, the minimum thickness can be selected so that the lens withstands a preselected impact force.

The desired lens shape may also be selected. For example, fig. 12 shows an example of the front elevational shape of the lens 120. The particular shape selected is generally independent of the optical characteristics of the decentered lens disclosed herein.

The desired as-worn orientation for the lens should also be selected in relation to the normal line of sight 130 of the wearer 126. As previously indicated, the optimal wearing direction may provide significant lateral shading for lateral protection and shielding from ambient light, as well as aesthetic reasons. Such as the embodiment shown in fig. 6-12, use is made of a tilted lens 120 to achieve the occlusion. Alternatively, shading can also be achieved by using higher base lenses and a more general (non-tilted) orientation. Fig. 9 and 10 more clearly show how the orientation is relative to the wearer's line of sight 130.

The designer of the eyewear may also select a tilt or vertical tilt, as can be appreciated from fig. 10, which schematically illustrates the vertical orientation of the lens 120 with respect to the head of the wearer 126, and particularly with respect to the normal line of sight 130 thereof. The downward slope as shown is desirable for a number of reasons, including improved accommodation for the common cephalic anatomy. As will be clear to those skilled in the art, the optic 120 (see fig. 7), having a mechanical center point falling below the horizontal plane intersecting the optical centerline 132, will tend to have a downward slope as shown in fig. 10. This is because the lens 120 will be formed below the great circle of the sphere about the optical centerline. Since the orientation of the lens 120 in an imaginary sphere with respect to the optical centerline 132 should be the same as the orientation between the lens 120 and the normal line of sight 130 being parallel under wearing conditions, any lens cut from such a sphere below the optical centerline 132 will exhibit a corresponding downward slope.

Referring now to fig. 11, a horizontal orientation of the lens 120 is shown mapped to the lens blank 122. The selected orientation is measured relative to a normal line of sight 130, the normal line of sight 130 being maintained substantially parallel to the optical centerline 132.

Once the aesthetic design is determined as shown in fig. 11, and the formed lens blank 122 has a suitable base curve for fitting in the aesthetic design, the aesthetic design can be "projected" onto the surface of a ball to reveal the portion of the ball suitable for use as lens 120. The projection of the lens shape to the ball will move near the surface of the ball until it is positioned so that the lens cut from the ball in this position exhibits the appropriate masking and tilt for the aesthetic design, and the lens 120 does not have any rotation from its original orientation (in which the optical centerline of the ball is generally parallel to the normal line of sight in the as-worn orientation).

Although not shown, it is understood that similar projections may be made for the option of vertical orientation, such as depicted in FIG. 10. Fig. 10 provides reference points in the form of an upper lens edge 152 and a lower lens edge 154 relative to the line of sight 130. This projection can then be moved up or down until both its upper edge 152 and lower edge 154 are simultaneously aligned with corresponding points on the lens blank outer surface 136, while maintaining the line of sight 130 substantially parallel to the optical centerline 132.

The projection of both the horizontal and vertical sections may be performed simultaneously to define a unique position on the lens blank 122 corresponding to the desired three-dimensional shape of the lens, including the front elevational shape shown in fig. 12, where the line of sight 130 is parallel to the optical centerline 132 or other reference line of the lens blank 122.

This shape can then be cut from the blank 122 or directly molded in accordance with the final configuration of the lens. The resulting lens 120 not only conforms to the desired shape, but also minimizes prism distortion.

Fig. 12 shows a lens blank 122 which is shown to conform to a portion of the surface of the ball of fig. 6 and 7. In fig. 12, the lens blank 122 has been rotated so that the mechanical center of the blank is shown at the center of the figure. The lens 120 is shown having a central edge 148, lateral edges 144, an upper edge 152, and a lower edge 154. At least a portion of the right lens 120 is located in the lower left (third) quadrant of the lens blank 122. In embodiments of the invention that exhibit shading and downward tilt, at least about half of the lens area falls within the third quadrant of the lens blank 122. Preferably, all or substantially all of the area of the optic 120 is located to the left and below the represented optical centerline, as shown. Lenses exhibiting similar tilt but smaller obscurations may be positioned on the lens blank 122 such that as much as 50% or more of the lens area is in the lower right (second) quadrant of the lens blank 122.

The present invention thus provides an accurate method of ensuring proper conformity between the bevel and the variable angle of incidence from the wearer's eye to the lens surface. By taking into account a new relationship between the wearer's line of sight and the form of beveling, the present invention allows the use of any of a variety of lens designs while minimizing prismatic distortion. For example, the designer may select the desired orientation and curvature for the lens relative to the wearer's line of sight. Such directions and curvatures can be selected from a wide range of tilt (i.e., vertical tilt of the lens), horizontal tilt, baseline values, and proximity to the wearer's face, including some parameters that cause high shadowing. The form of the bevel may then also be selected by the method of the present invention so that prism distortion is minimized.

While the invention has been described with respect to certain preferred embodiments, other embodiments will become apparent to those skilled in the art from consideration of the specification. Accordingly, the present invention is not intended to be limited by the preferred embodiments listed, but is to be defined only by reference to the appended claims.

Claims (27)

1. An oriented, non-prescription fitted dual lens for optical correction of eyeglasses, comprising:

a non-glass left lens body and a non-glass right lens body, said left lens body having a left mechanical center and said right lens body having a right mechanical center;

a frame for supporting the right lens in a path of normal line of sight for the right eye of the wearer and the left lens in a path of normal line of sight for the left eye of the wearer, each lens exhibiting an amount of shading and an amount of tilt in a wearing orientation relative to the left and right normal line of sight of the wearer;

determining a lens thickness between two surfaces of each of the left and right lenses at the front and back surfaces on each of the left and right lens bodies;

the front and rear surfaces of the right lens each conform to a partial surface of a front right sphere and a rear right sphere, respectively, the front right sphere having a first center and the rear right sphere having a second center, such that the thickness of the right lens is tapered in horizontal and vertical planes;

the front and rear surfaces of the left lens conform to respective partial surfaces of a front and rear levee, the front levee having a third center and the rear levee having a fourth center, such that the thickness of the left lens is tapered in horizontal and vertical planes;

each of said first, second, third and fourth centers being offset from one another;

a right optical centerline extending through the first and second centers of the right lens;

the left optical centerline extends through the third and fourth centers of the left lens;

wherein the right mechanical center is horizontally and vertically offset from the right optical center line by a vertical distance corresponding to an amount of tilt exhibited by the right lens in the worn orientation and by a horizontal distance corresponding to an amount of shading exhibited by the right lens in the worn orientation, and the left mechanical center is horizontally and vertically offset from the left optical center line by a vertical distance corresponding to an amount of tilt exhibited by the left lens in the worn orientation and by a horizontal distance corresponding to an amount of shading exhibited by the left lens in the worn orientation, thereby forming eyewear that is optically corrected for prism errors that would otherwise be caused by the tilt and shading.

2. The eyewear of claim 1, wherein each of said front right ball and said front left ball has a base curve that is greater than base line 6.

3. The eyewear of claim 2, wherein each of said front right ball and said front left ball has a base curve that is greater than base curve 8.

4. The eyewear of claim 2, wherein each of said front right ball and said front left ball has a base curve in the range of 7.5 to 10.5.

5. The eyewear of claim 4, wherein, in the wearing orientation, a horizontal component of the normal line of sight of each of the wearer's eyes deviates from a horizontal component of the corresponding optical centerline by no more than ± 10 degrees of parallelism.

6. The eyewear of claim 5, wherein, in the wearing orientation, a horizontal component of the normal line of sight of each of the wearer's eyes deviates from a horizontal component of the corresponding optical centerline by no more than ± 5 degrees of parallelism.

7. The eyewear of claim 6, wherein the horizontal component of the normal line of sight of each eye of the wearer is parallel to the horizontal component of the respective optical centerline in the as-worn orientation.

8. The eyewear of claim 4, wherein, in the wearing orientation, a vertical component of a normal line of sight of each eye of the wearer in a vertical plane deviates from a vertical component of the respective optical centerline by no more than ± 10 degrees from parallelism.

9. The eyewear of claim 8, wherein, in the wearing orientation, a vertical component of the normal line of sight of each eye of the wearer is within ± 3 degrees from being parallel to a vertical component of the respective optical centerline.

10. The eyewear of claim 1, wherein the wearer's normal line of sight of each eye intersects the rear surface of the respective lens at an angle in the range of 100 degrees to 135 degrees.

11. The eyewear of claim 1, wherein the normal line of sight of each of the wearer's eyes intersects the rear surface of the lens at an angle of more than 95 degrees.

12. The eyewear of claim 1, wherein each of said left and right lenses comprises polycarbonate.

13. The eyewear of claim 1, wherein each of the left and right lenses is cut from a lens blank.

14. The eyeglasses of claim 1, wherein the maximum horizontal arc length of each of the left and right lenses is 1¹/₂Inch to 3¹/₂In inches.

15. The eyewear of claim 14, wherein the maximum horizontal arc length of each of the left and right lenses is in the range of 2 inches to 3 inches.

16. The eyewear of claim 1, wherein the left and right lenses are tilted such that a middle edge of each of the left and right lenses falls outside a circle defined by the left and right lenses in a non-tilted state and a side edge of each of the left and right lenses falls within the circle.

17. The eyewear of claim 1, wherein the medial edge of each of said left and right lenses has a thickness in the range of 1mm to 2.5 mm.

18. The eyewear of claim 17, wherein the medial edge of each of said left and right lenses has a thickness in the range of 1.5mm to 1.8 mm.

19. The eyeglasses of claim 1, wherein the radius of the front right sphere and the radius of the front left sphere are each about 60.57 mm.

20. The eyewear of claim 1, wherein said eyewear has a vertical plane of symmetry substantially parallel to the wearer's left and right normal lines of sight.

21. The eyewear of claim 1, wherein the right optical centerline intersects the right lens at a point horizontally and vertically offset from the normal line of sight of the wearer's right eye, and the left optical centerline intersects the left lens at a point horizontally and vertically offset from the normal line of sight of the wearer's left eye.

22. The eyewear of claim 21, wherein the right optical centerline is parallel to a normal line of sight for the right eye of the wearer and the left optical centerline is parallel to a normal line of sight for the left eye of the wearer.

23. A pair of dual lens optically corrected eyeglasses comprising:

a first non-glass lens and a second non-glass lens;

a dual lens frame for supporting first and second lenses in a wearing orientation in front of a wearer's first normal line of sight and a wearer's second normal line of sight, respectively, the first normal line of sight corresponding to one eye of the user and the second normal line of sight corresponding to the other eye of the user, each lens exhibiting a obscuration and a downward tilt in the wearing orientation such that the wearer's first and second normal lines of sight intersect rear surfaces of the first and second lenses in horizontal and vertical planes, respectively, at a non-normal angle;

each lens having a posterior surface and an anterior surface, the posterior surface having a posterior center of curvature and the anterior surface having an independent respective anterior center of curvature, and each lens having a thickness between the anterior and posterior surfaces, each lens further having an independent respective optical centerline passing through the respective anterior and posterior centers of curvature;

the thickness of each lens is vertically tapered on each side of a horizontal plane including the respective optical centerline and horizontally tapered on at least one side of a vertical plane including the respective optical centerline for optically correcting each lens in a wear orientation,

wherein the mechanical center of each lens is spaced below horizontal by a distance corresponding to the downward tilt of each lens in the as-worn orientation, thereby minimizing prism shifting due to each lens being mounted at said downward tilt.

24. The eyewear of claim 23, wherein each lens has a base curve in the range of 7.5 to 10.5.

25. The eyewear of claim 24, wherein each lens has a base curve in the range of 8 to 9.5.

26. The eyewear of claim 24, wherein each lens is oriented such that the respective straight-ahead normal line of sight intersects the lens at an angle greater than 95 degrees in the as-worn orientation.

27. The eyewear of claim 26, wherein each normal line of sight intersects the respective lens at an angle in the range of 100 degrees to 135 degrees.