Patent Application
20080013046
The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanied drawings in which:
It will be appreciated that for simplicity and clarity of illustration, elements shown in the drawings have not necessarily been drawn accurately or to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity or several physical components included in one functional block or element. Further, where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements.
In the following description, various aspects of the present invention will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the present invention. However, it will also be apparent to one skilled in the art that the present invention may be practiced without the specific details presented herein. Furthermore, well-known features may be omitted or simplified in order not to obscure the present invention. Similar reference numerals refer to similar elements of the invention.
Reference is made to
Mold surface 102 may include an inner progressive zone 130 having a progressive surface 132 with progressive optical properties and an outer beveled zone 110 having a bevel surface 112. Progressive surface 132 may have a generally concave surface with varying concavity corresponding to desired progressive optical properties. Progressive zone 130 may have a relatively steep region 135 and a relatively shallow region 133.
Bevel surface 142 may be a generally flat surface along a periphery of mold 100 that surrounds progressive zone 130. Bevel surface 142 may have a substantially constant height relative to horizontal axis 115.
According to embodiments of the invention, mold 100 may include a transition zone 120, in between progressive zone 130 and bevel zone 110. Transition zone 120 may have a transition surface 122 that may provide a smooth transition between the variable curvature of progressive surface 132 at its outer boundary, and the generally level bevel surface 112 at its inner boundary. Transition zone 120 may have an inner edge 123 that borders the outer boundary of progressive zone 130 and an outer edge 125 that borders the inner boundary of bevel zone 110.
According to an embodiment of the invention, each of progressive zone 130, bevel zone 110 and transition zone 120 may have a desired symmetry. For example, progressive zone 130, bevel zone 110 and transition zone 120 may be substantially concentric about vertical axis 111. The shape of the concentric progressive zone 130, transition zone 120, and bevel zone 110 may be generally circular, elliptical, or any other suitable shape. The concentric zones may be symmetric relative to vertical axis 111. This mold 100 may provide a more symmetric mold surface 102 than conventional molds provide. Thus, for example, a generally symmetric thin film may be positioned more evenly relative to mold 100 compared to a conventional mold.
As described above, the steepness along different regions of progressive zone 130 may vary, and consequently, the height along the outer boundary of progressive zone 130 may vary. Boundary points 113 and 117 may represent points along the boundary between transition zone 120 and the relatively steep region 135 and the relatively shallow region 133 of progressive zone 130, respectively. For example, in
In some embodiments, bevel surface 112 may include surface indentations, for example, grooves for securing progressive mold 100 during casting.
According to an embodiment of the invention, the height of bevel surface 112, h3, may be substantially constant, for example, relative to horizontal axis 115. Bevel height, h3, may be greater or equal to the height of progressive surface 132 and transition surface 122 at any given point. In some embodiments, the outer boundary points of progressive zone 130, for example, boundary points 113 and 117, may have heights, h1 and h2, respectively, which may be less than the height, h3, of bevel surface 112. In another example, a boundary point 143 may represent a point along the boundary between bevel zone 110 and transition zone 120. In this example, the height of boundary point 143, along the outer edge 125 of transition zone 120, is equal to the height of bevel surface 112, i.e. h3.
Transition zone 120 may include a transition surface 122 of gradual transition between the curved progressive surface 132 and the generally level bevel surface 112. The inner edge 123 of transition surface 122 may provide a smooth surface where transition surface 122 and progressive surface 132 may meet. The outer edge 125 of transition surface 122, may provide a smooth and level surface where transition surface 122 and bevel surface 112 may meet. In one embodiment, the substantially smooth surface of transition zone 120, may contain no sharp edges or protrusions, and may be substantially continuously differentiable.
The height of transition surface 122 may vary gradually from h2 to h3. Since inner edge 123 of transition zone 120 borders the outer boundary of progressive zone 130, for example, at boundary points 113 and 117, which may vary in height as discussed above, the inner edge 123 of transition surface 122 may likewise vary in height. Since the outer edge 125 of transition zone 120 meets the inner boundary of bevel zone 110, for example, at boundary points 143, which as discussed above, may have constant height, h3, the outer edge 125 of transition zone 120 may have constant height. Transition surface 122 may vary in steepness to form a gradual incline between the outer boundary of progressive surface 132 with varying height, from h1 to h2, and the inner boundary of bevel surface 112 with constant height, h3. Transition surface 122 may have any substantially smooth transitional shape, in accordance with embodiments of the invention. In some embodiments, transition surface 122 may have limited, for example, minimal number of points of inflection, where the concavity of the surface changes from convex to concave, for example, along the radial meridian. In some embodiments, transition surface 122 may have one such point on each meridian.
Transition surface 122 may form a substantially gradual incline from progressive zone 130 to bevel zone 110. A substantially gradual incline may prevent mold 100 from having the steep inclines and/or nondifferentiable points of conventional molds, which may form castes of uneven thickness and/or with sharp edges. Since transition zone 120 provides a gradual transition towards flatness, transition zone 120 may be substantially shallower than progressive zone 130. For example, the average curvature along transition surface 122 may be shallower than the average curvature along progressive surface 132.
Transition surface 122 may be designed by interpolation between the outermost curvature of progressive surface 132 and the generally level bevel surface 112. Any suitable interpolation technique may be used, for example, Krigging interpolation.
Thin film 160 may be positioned for casting on mold 100 during a molding process according to some embodiments of the invention. Thin film 160 may be a thin lens having two surfaces, for example, a top surface 162 and a bottom surface 164. Top surface 162 and bottom surface 164 may both be spherical and may have the same curvature at corresponding locations. Thin film 160 may be positioned on progressive mold 100 prior to the casting process. The casting material, for example, a plastic material, may be poured onto thin film 160 and mold 100. Thin film 160 may become engulfed by the casting material, such that there may be no spacing between thin film 160 and the casting material. Thin film 160 may be made of materials such as, plastics, photo chromatic materials, polarized materials or any other suitable material.
Reference is made to
Caste 200 may include a front surface 202 and a back surface 204. Back surface 204 may be substantially spherical. Front surface 202 may correspond to mold surface 102. Front surface 202 of caste 200 may include an imprint of a portion of mold surface 102 of mold 100, for example, the progressive zone 130 and transition zone 120 shown in
Lens 200 may include lens center 250 that may correspond to center point 150 of progressive mold 100. Lens center 250 may be a most protrusive point on the progressive caste zone. Caste center 250 may be the center point of progressive caste region 232 and transient caste region 222. A vertical axis 111 and a horizontal axis 115 may have their origins at caste center 250.
Progressive caste surface 232 may correspond to progressive surface 132 and transition caste surface 222 may correspond to transition surface 122. Each zone of front surface 202 may have substantially similar surface properties to the corresponding zone of mold surface 102 from which they were caste. Transition caste zone 220 may surround progressive caste zone 230. Progressive caste zone 230 and transition caste zone 220 may be generally concentric about vertical axis 111.
Progressive caste surface 232 may be the innermost region of front surface 202. Progressive caste zone 230 may be centered at center point 250. Progressive caste surface 232 may be generally convex and may have variable curvature. Progressive caste zone 230 may include progressive optical properties.
Since the curvature of progressive caste surface 232 may vary, a height along an outer boundary of progressive caste zone 230 may vary. Boundary points 213 and 217 may represent points along the boundary between transition caste zone 220 and progressive caste zone 230. In some embodiments, boundary point 213 may be higher, relative to horizontal axis 115, than boundary point 217.
Transition caste surface 220 may provide a substantially smooth transition from the outer boundary of progressive caste zone to an outer edge 210 of caste 200. In some embodiments, transition caste surface 222 may have limited, for example, minimal number of points of inflection, where the concavity of the surface changes from convex to concave, for example, along the radial meridian. In some embodiments, transition surface 122 may have one such point on each meridian.
Referring briefly back to
The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. It should be appreciated by persons skilled in the art that many modifications, variations, substitutions, changes, and equivalents are possible in light of the above teaching. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
