Method for calculating finished lenses

Abstract

The present invention relates to a finished lens having a predetermined shape, the finished lens comprising a front face, a back face, and a periphery corresponding to the shape, including a prescription portion on the lens that, together with the front face, satisfies the prescription data of a wearer and a peripheral portion on the lens, the prescription portion being defined by a thickness curve and the peripheral portion extending from the thickness curve toward the outer edge of the lens, the thickness curve corresponding to a thickness value less than or equal to a predetermined thickness requirement.

Description

[0001] The present invention relates to a method for calculating a finished lens and a related system and lens.

[0002] The optical lens involved in the method has a concave surface, a convex surface, and an outer periphery, wherein the thickness of the outer periphery is within a preset range.

[0003] Optical lenses are usually made from semi-finished lens blanks. Semi-finished lens blanks generally have two opposing major surfaces, at least one of which is unfinished. The unfinished surface is typically the surface corresponding to the rear surface of the optical lens that is oriented toward the wearer's eye during use. The unfinished surface of the semi-finished lens blank is machined according to the wearer's prescription to provide the desired rear surface of the optical lens. Prior to machining of the rear surface, the diameter of the blank is typically reduced by cutting into a shape (e.g., a circle or an oval), a cutting process known as cribbing.

[0004] An optical lens having a finished rear surface and a finished front surface is often referred to as an uncut optical lens or a finished lens. The finished lens is then edged according to the shape of the frame to which the optical lens is to be mounted, so as to obtain an edged or cut lens.

[0005] refer to Figure 1A , Figure 1B and Figure 3 By machining the unfinished rear surface of the semi-finished lens blank so that it meets a specific preset prescription, there may be problems with the thickness of the outer periphery 2 of the finished lens. In fact, the thickness may be too thin, and may even be zero or negative, which means that once the finished lens has been machined, its outer periphery 2 is no longer circular, but has a concavity 3, resulting in the formation of local sharp edges 4 at the outer periphery of the finished lens.

[0006] A disadvantage of a sharp edge 4 is that it is susceptible to cracking or chipping, resulting in either or both contamination of subsequent cleaning or coating steps of the manufacturing process and an unusable finished lens.

[0007] Furthermore, the sharp edges 4 may damage the polishing tool during the polishing step of the manufacturing process.

[0008] Furthermore, the sharp edge 4 makes the finished lens more difficult to handle manually or by machine and may cause injury to the person who will handle the finished lens.

[0009] Finally, finished lenses with sharp edges 4 are more likely to exhibit coating defects (eg, portions of the anti-reflective coating not being properly applied to the finished lens) and be rejected as having an unacceptable appearance.

[0010] In practice, it makes sense to suppress such sharp edges 4 for the following reasons:

[0011] - Avoid damage to some tools, such as polishing tools, by the sharp parts of the finished lens.

[0012] - allows automation of the manufacturing process by reducing the diversity of shapes of finished lenses to be processed,

[0013] - Facilitate the processing of finished lenses,

[0014] - Reduce edge brittleness,

[0015] - Improve the aesthetics of the finished lens to be delivered.

[0016] The known solution involves a method that tends to remove the sharp edges of the finished lens by knowing the shape of the frame on which the optical lens is intended to be mounted. The finished lens has a thickness within a preset range, a central useful area that meets a specific preset ophthalmic prescription (which defines a machined surface and has a useful periphery that coincides with the periphery of the specific preset frame), and an outer transition area that connects the useful periphery of the central useful area to the outer periphery.

[0017] More generally, during the lens manufacturing process, marks of lens handling clips may appear in useful portions of the lens, as well as varnish drops may appear in useful portions of the lens.

[0018] Furthermore, lenses may be rejected because of defects that occur only in non-useful portions of the lens that will ultimately be edged.

[0019] There is a need to optimize appearance control rejection and varnish coating processes during lens manufacturing.

[0020] Furthermore, the method according to the invention allows to avoid the presence of sharp edges in the finished lens, independently of the shape of the frame on which the optical lens is intended to be mounted, while guaranteeing that the finished lens, after edge trimming, has the shape of the mastered geometry.

[0021] A first object of the present invention is a computer-implemented method for calculating a finished lens having a predetermined shape, the finished lens comprising a front face, a back face, and a periphery corresponding to said shape, the computer-implemented method comprising the following steps:

[0022] - providing a lens blank having a convex front face and a concave rear face,

[0023] - In the absence of frame shape data in which the lens is to be mounted, determining a first curvature profile of a back surface to be machined on the back of the lens blank, and determining a prescription portion on the lens that together with the front face satisfies the wearer's prescription data and a peripheral portion on the lens by determining a thickness curve corresponding to a thickness value less than or equal to a predetermined thickness requirement, the prescription portion being defined by the thickness curve and the peripheral portion extending from the thickness curve toward the outer edge of the lens.

[0024] The principle of this method according to the invention is to determine the thickness curve in the finished lens and then select a suitable thickness curve to determine the prescription part and the peripheral non-useful part of the lens without using the shape of the frame intended to receive the useful part of the optical lens, which prescription part surrounds the useful part of the optical lens intended to be mounted on the frame.

[0025] The term "useful portion" refers to the portion of the lens that will be machined into the optical lens and will have the final suitable shape to be mounted on the frame.

[0026] According to a possible characteristic of the invention, the method further comprises a step of optimizing the orientation of the finished lens during the varnish application step.

[0027] According to a possible feature of the invention, varnish basket orientation markings are defined in a peripheral portion of the lens.

[0028] The second object of the present invention is a finished lens having a predetermined shape, the finished lens comprising a front face, a back face, and a periphery corresponding to the shape, including a prescription portion on the lens that together with the front face satisfies the wearer's prescription data and a peripheral portion on the lens, the prescription portion being defined by a thickness curve and the peripheral portion extending from the thickness curve toward the outer edge of the lens, the thickness curve corresponding to a thickness value less than or equal to a predetermined thickness requirement.

[0029] A third object of the present invention is a computer-implemented method for calculating a finished lens having a predetermined shape, the finished lens comprising a front face, a back face, and a periphery corresponding to said shape, the computer-implemented method comprising the following steps:

[0030] - providing a lens blank having a convex front face and a concave rear face,

[0031] - provide a minimum edge thickness for the finished lens,

[0032] - determining a first curvature profile of the rear surface to be machined on the rear face of the lens blank,

[0033] - in the absence of frame shape data in which the lens is to be mounted, determining a prescription portion on the lens that satisfies the wearer's prescription data together with the front face and a peripheral portion on the lens by determining a thickness curve corresponding to a thickness value less than or equal to a predetermined thickness requirement, the prescription portion being bounded by the thickness curve and the peripheral portion extending from the thickness curve toward the outer edge of the lens,

[0034] - if the rear surface of the rear face of the lens blank is manufactured using the first curvature profile at the peripheral portion, determining whether the thickness of the outer edge of the peripheral portion of the lens blank machined later using the first curvature profile at the peripheral portion is less than the minimum edge thickness,

[0035] - If the thickness of the outer edge of the peripheral portion is less than the minimum edge thickness, determining a new curvature profile of the peripheral portion of the rear surface to be machined, wherein the thickness in the peripheral portion is greater than or equal to the minimum edge thickness in order to avoid sharp edges.

[0036] The principle of the method according to the invention is to determine the thickness curve in the finished lens, then to select a suitable thickness curve around the useful portion of the optical lens intended to be mounted on a frame, and finally to determine the optimized curvature profile of the back surface to be machined at the peripheral portion positioned around the prescription portion defined by said thickness curve, if the algorithm detects the presence of a potential sharp edge.

[0037] The selection of this thickness profile is carried out without using data on the shape of the frame intended to receive the useful portion of the optical lens.

[0038] The method according to the invention presents the advantage of manufacturing an optical lens without any sharp edges and without exact knowledge of the frame in which the finished lens is intended to be mounted or without using this frame information.

[0039] According to a possible characteristic of the invention, the predetermined thickness requirement corresponds to the edge thickness of the lens cutout provided during the ordering of the finished lens.

[0040] According to a possible characteristic of the invention, the thickness profile is a constant thickness profile.

[0041] According to a possible feature of the invention, a local or global safety margin is applied to the thickness curve in order to define a thickness curve delimiting the prescription portion and the peripheral portion of the lens.

[0042] According to a possible characteristic of the invention, the minimum edge thickness is preferably greater than or equal to 0.4 mm. By this thickness value, we can estimate that the outer edge of the lens is no longer sharp.

[0043] According to a possible feature of the invention, the predetermined shape of the optical lens is selected from an elliptical shape, a circular shape or an optimized shape. These types of shapes are intended to facilitate, for example, the lens handling or coating process to avoid coating defects on the lens.

[0044] According to a possible characteristic of the invention, the determination of the new curvature profile of the peripheral portion of the rear surface to be machined is weighted to take into account a manufacturing requirements function.

[0045] According to a possible characteristic of the invention, the step of determining a new curvature profile of the peripheral portion of the rear surface to be machined is based on an interpolation method of well-distributed points.

[0046] According to a possible feature of the invention, the step of determining a new curvature profile of the peripheral portion of the rear surface to be machined comprises the following steps:

[0047] - sampling a first set of points which lies inside the selected thickness curve,

[0048] - sampling a second set of points that are different from the first points and are located on the outer edge,

[0049] - changing the height of the second point so that the thickness corresponding to the second point is greater than or equal to the minimum predetermined thickness,

[0050] - Compute a back surface consisting of the sample points when interpolating points outside the thickness curve and the sample points on the initial surface when inside or on the selected thickness curve.

[0051] According to a possible characteristic of the invention, the method comprises a step of optimizing the position and / or orientation and / or size of a sharp edge zone identified at a peripheral portion of the rear surface of the rear face of the lens, wherein the curvature profile must be modified.

[0052] According to a possible feature of the invention, the method comprises the following steps:

[0053] - Determine the diameter D of the finished lens after trimming cribb ,

[0054] - determining an optimal position of the trimming diameter in order to minimize the overlapping area between said trimming diameter and a predetermined thickness curve and / or to minimize the curvature in a peripheral portion of the rear surface.

[0055] Another object of the invention is a method for manufacturing an optical lens comprising a step of edging the finished lens determined by using the method described above.

[0056] According to a possible characteristic of the invention, the method further comprises a step of engraving manufacturing marks in the peripheral portion of the lens.

[0057] According to a possible characteristic of the invention, the method further comprises a step of optimizing the lens appearance control step.

[0058] According to a possible characteristic of the invention, during the cosmetic control step, the location of cosmetic defects in the lens is determined and if defects are detected in a peripheral portion of the lens, the lens is not rejected as having cosmetic defects.

[0059] Another object of the invention is a computer program product comprising a program code for executing the steps of the above method when the computer program product runs on a data processing device.

[0060] Another object of the invention is a computer-readable medium carrying one or more sequences of instructions of a computer program product.

[0061] Another object of the present invention is a finished lens having a predetermined shape, the finished lens comprising a front face, a back face, and a periphery corresponding to said shape, comprising a prescription portion on the lens that, together with the front face, satisfies the prescription data of the wearer and a peripheral portion on the lens, the prescription portion being delimited by a thickness curve and the peripheral portion extending from the thickness curve towards the outer edge of the lens, the thickness curve corresponding to a thickness value less than or equal to a predetermined thickness requirement. Such a finished lens can preferably be obtained by the computer-implemented method according to the present invention.

[0062] As will be apparent from the following discussion, unless otherwise specifically stated, it should be appreciated that throughout this specification, discussions using terms such as "compute", "determine", "generate", etc. refer to the actions and / or processes of a computer or computing system or similar electronic computing device that manipulate data represented as physical (e.g., electronic) quantities within the computing system's registers and / or memories and / or convert them into other data similarly represented as physical quantities within the computing system's memories, registers, or other such information storage, transmission, or display devices.

[0063] Embodiments of the present invention may include an apparatus for performing the operations described herein. This apparatus may be specially constructed for the desired purpose, or it may include a general purpose computer or a digital signal processor ("DSP") selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a computer-readable storage medium, such as, but not limited to, any type of disk, including a floppy disk, an optical disk, a CD-ROM, a magneto-optical disk, a read-only memory (ROM), a random access memory (RAM), an electronically programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic card or an optical card, or any other type of medium suitable for storing electronic instructions and capable of being coupled to a computer system bus.

[0064] The process and display proposed herein are not originally relevant to any specific computer or other equipment. Various general purpose systems can be used together with the program according to the teaching herein, or it can prove to be very convenient to build more special equipment to perform desired methods. In addition, embodiments of the present invention are not described with reference to any specific programming language. It will be appreciated that various programming languages ​​can be used to implement the teaching of the present invention described herein.

[0065] Hereinafter, we will describe in detail an embodiment of the method according to the present invention by referring to the following drawings:

[0066] - Figure 1A and Figure 1B The front view and stereogram of the finished lens with sharp edges are shown respectively.

[0067] - Figure 2A and Figure 2B The front view and stereogram of the finished lens with non-sharp edges are shown respectively.

[0068] - Figure 3 is a front view of a finished lens having sharp edges and showing a central area which delimits the periphery of the useful portion of the optical lens intended to be mounted on a frame,

[0069] - Figure 4 is a front view of the finished lens, showing the equal thickness distribution of the lens,

[0070] - Figure 5A and Figure 5B are front views of finished lenses, respectively showing examples of selected isopycnic curves and said selected isopycnic curves comprising a useful portion of the optical lens intended to be mounted on a frame,

[0071] - Fig. 6A , Figure 6B , Figure 6C and Fig.6D are four front views of a finished lens illustrating the four steps of an embodiment of an interpolation method included in the method according to the invention,

[0072] - Figure 7 is a simplified diagram giving the thickness of the finished lens versus the diameter sector of the lens, showing the sharp edges,

[0073] - Figure 8 yes Figure 7 A simplified diagram after correction showing the outer edge of the finished lens with minimum thickness.

[0074] refer to Figure 2A , Figure 2B , Figure 7 and Figure 8 The method according to the present invention aims to provide a finished lens 1 having a predetermined shape, whose outer edge 15 is not sharp but has a minimum edge thickness. Such a finished lens 1 has a rear face (or concave face) and a front face (or convex face), and its thickness decreases from the central area to the outer edge 15. The predetermined shape of the finished lens (1) can be selected from an elliptical shape, a circular shape and any optimized shape.

[0075] The finished lens 1 must integrally comprise a useful portion 5 intended to be mounted on a predetermined frame.

[0076] According to the method of the present invention, the method comprises the following steps:

[0077] Obtain prescription data of S1 wearers,

[0078] Provide S2 lens blanks with convex front face and concave rear face,

[0079] Select S5 to select the thickness curve corresponding to the thickness value less than or equal to the predetermined thickness requirement. This curve defines:

[0080] the outer periphery of the prescription portion 13 of the rear surface to be machined on the rear face of the finished lens 1 which, together with the front surface of the front face of the lens blank, meets the prescription data of the wearer, and

[0081] A peripheral portion 14 extending from the thickness curve towards the outer edge 15 of the finished lens 1 on the rear surface to be machined on the rear side of the lens blank

[0082] Furthermore, in one embodiment, the method comprises the following steps:

[0083] Provide S3 minimum edge thickness for the finished lens 1,

[0084] determining S4 a first curvature profile of the rear surface to be machined on the rear face of the lens blank,

[0085] If the rear surface of the lens blank is manufactured to have a first curvature profile at the peripheral portion 14, determine S6 whether the thickness of the outer edge 15 of the peripheral portion 14 is less than a minimum edge thickness

[0086] If the thickness of the outer edge 15 of the peripheral portion 14 is less than the minimum edge thickness and the outer edge 15 is therefore sharp, an optimized curvature profile of the peripheral portion 14 of the rear surface to be machined is determined, wherein the thickness in the peripheral portion 14 is greater than or equal to the minimum edge thickness in order to obtain an outer edge 15 with a minimum thickness and preferably no longer sharp.

[0087] In step S3, a minimum edge thickness Te is provided min . Minimum edge thickness Te min is the minimum edge thickness required at the outer edge 15 of the finished lens 1 produced from the lens blank. Minimum edge thickness Te min The value of is preferably chosen to avoid any sharp edges at the outer edge 15 of the finished lens 1 and to provide a finished lens with a predetermined shape.

[0088] Preferably, the minimum edge thickness Te min Greater than or equal to 0.4mm.

[0089] In step S5, a thickness curve 12 corresponding to a thickness value less than or equal to the predetermined thickness requirement Tr is determined, and a prescription portion 13 and a peripheral portion 14 are defined in the rear surface of the rear face of the lens.

[0090] In one embodiment of the present invention, the predetermined thickness requirement Tr may be a value of the outer edge thickness of the lens cut product. This data may be provided during the ordering of the optical lens.

[0091] Preferably, the predetermined thickness requirement Tr is greater than or equal to 0.8 mm.

[0092] In order to define the thickness curve 12 , the method according to the invention comprises a thickness determination step in which the thickness of the lens 1 whose back surface is to be machined at several points is determined.

[0093] The thickness is defined by the front and back surfaces and the distance between the faces at a given point on these surfaces.

[0094] The thickness value may be determined by any known method in any convenient coordinate system by any known laboratory management system.

[0095] In one embodiment of the present invention, in a first sub-step, a map of the mean thickness curves 7, 8, 9 of the finished lens 1 is created. In practice, by knowing the geometry of the finished lens 1, in particular the back surface to be machined later, the map of the mean thickness curves 7, 8, 9 of the lens 1 can be created. Figure 4 The thickness distribution of the lens is shown in FIG. The maximum thickness of the finished lens 1 is located in the central area 10 of the lens 1 , while the thinnest thickness of the lens 1 is located in the peripheral area 11 , and the thickness decreases from the central area 10 to the peripheral edge 11 .

[0096] In the second substep, select the thickness corresponding to the given Figure 5A The constant thickness curve 12 is shown.

[0097] In one embodiment, the constant thickness curve 12 is selected to correspond to a value less than or equal to a predetermined thickness requirement Tr corresponding to the minimum thickness required on the edge of the lens cutout.

[0098] In another embodiment, the selected iso-thickness curve 12 is defined based on adjustable values ​​that depend on the type of frame that is intended to receive the cut lens.

[0099] refer to Figure 5B This suitable constant thickness curve 12 defines: a prescription portion 13 which must include the useful portion 5 of the optical lens 1 intended to be mounted on a predetermined frame; and a peripheral portion 14 extending towards the outer edge 15 of the finished lens 1 .

[0100] exist Figure 5B In the example shown, a suitable constant thickness curve 12 is chosen to surround the useful portion 5 of the optical lens 1 by maintaining a minimum distance from said useful portion 5 .

[0101] The inventors have determined that when using a thickness curve based on the desired thickness on the edge of a cut lens or the type of frame data, the useful portion 5 of the lens is always included in the prescription portion 13 of the finished lens 1 .

[0102] According to the present invention, the prescription portion 13 and the peripheral portion 14 of the rear surface of the rear face of the finished lens are defined without using the useful portion data 5 and / or the frame shape data defining the spectacle frame contour. This means that, without the frame shape data in which the cut finished lens 1 is to be mounted, two different portions are determined.

[0103] In an embodiment not shown, a safety margin can be provided for the thickness curve 12. In this case, the thickness curve 12 selected to define the outer perimeter of the prescription portion 14 is locally or globally modified to include in its contour points where the thickness is less than the thickness requirement Tr. The advantage is to ensure that the useful portion 5 of the cut lens is not deformed in the frame contour.

[0104] In the next step, when the rear surface of the lens blank is manufactured to have a first curvature profile, the algorithm determines whether the thickness of the outer edge 15 of the peripheral portion 14 is less than the minimum edge thickness Temin .

[0105] If the algorithm detects that the outer edge 15 of the peripheral portion 14 is less than the minimum edge thickness Te min and therefore too thin and therefore sharp (e.g. Figure 7 ), the algorithm performs a step of determining the optimal curvature profile of the peripheral portion 14 of the rear surface to be machined. In this step, the thickness in the peripheral portion 14 is modified to be greater than or equal to the minimum edge thickness Te min , so as to obtain an outer edge 15 having a minimum predetermined thickness, such as Figure 8 as shown in the example.

[0106] This minimum thickness may be, for example, 0.4 mm.

[0107] exist Figure 8 In the simplified diagram of FIG. 1 , the algorithm calculates a new machining profile or optimized curvature profile of the rear surface of the rear face of the finished lens 1 (as shown by curve 18) replacing the initial profile shown by dashed line 17. In this way, the outer edge 15 has a minimum thickness and is no longer sharp. The initial profile embodied by curve 17 shows a sharp outer edge 15 delimiting a recess 3, and the new machining profile allows compensating this recess 3 by expanding the diameter of the finished lens 1 so as to provide the lens with a predetermined shape, for example a circular shape. Thus, the initially sharp outer edge 15 is displaced to increase the optical lens size, thus explaining the Figure 7 and Figure 8 The difference in position between the outer edges is 15.

[0108] In order to determine the optimal curvature profile of the peripheral portion 14 of the rear surface to be machined (where the thickness of the peripheral portion 14 should be greater than or equal to the minimum edge thickness Te min ), several surface optimization or adjustment methods can be used in a given situation.

[0109] The method may be any known interpolation method.

[0110] In one embodiment, the interpolation method uses a first set of points inside the thickness curve 12 where the minimum edge thickness Te min ) and a second set of points at the outer edge of the peripheral portion of the finished lens (where the minimum edge thickness Te is not met min to optimize the thickness at the second point) to provide an optimized curvature profile of the peripheral portion 14 of the rear surface to be machined.

[0111] In one example, a method of determining an optimized curvature profile for a peripheral portion of a rear surface to be machined comprises the following steps:

[0112] - Sampling a first set of points 20 which are located inside the selected constant thickness curve 12 and define a thickness greater than or equal to the minimum edge thickness Te min parts, such as Fig. 6A As shown,

[0113] In such Fig. 6A In an alternative shown, the first set of points is defined not only in the edge of the constant thickness curve, but also in all surfaces whose outer periphery is the constant thickness curve 12 .

[0114] - Sampling a second set of points 21 which are different from the first points 20 and do not satisfy the minimum edge thickness Te min and distributed on the outer edge 15 of the peripheral portion 14, such as Figure 6B As shown,

[0115] - Optimize the height of the second point 21 so that the thickness corresponding to the second point 21 is greater than or equal to the minimum thickness Te min ,

[0116] - Calculating the optimized curvature profile of the peripheral portion of the back surface, which is composed of the sampling points when interpolating points outside the isopycnic line 12 and the sampling points on the initial back surface when located inside or on the selected isopycnic line 12.

[0117] In one example, the second set of points can be Figure 6B Evenly distributed as shown.

[0118] In another embodiment, the method provides a step of sampling a third set of points 22 describing a profile having a predetermined diameter greater than the diameter of the finished lens 1 in order to link the interpolated back surface to the initial back surface (e.g. Figure 6C ), and provides a step for calculating the interpolation of these points 22 (as shown Fig.6D shown).

[0119] In another embodiment, the determination of the optimized curvature profile of the rear surface of the rear face of the finished lens 1 may be weighted to take into account a manufacturing requirement function due to the minimum edge thickness. The manufacturing requirement function may define manufacturing constraints related to the manufacturing process used and / or the associated cutting tools having an authorized maximum curvature that can be provided to the surface.

[0120] Furthermore, one or several cutting steps may be provided during the machining of the rear face of the lens 1 in order to define an optimized curvature profile of the rear face of the lens.

[0121] The method may further comprise the step of optimizing a zone at the peripheral portion of the rear face of the lens, wherein the curvature profile has to be modified when a sharp edge is identified, referred to as the sharp edge zone.

[0122] Such optimization may comprise at least optimizing the position and / or orientation and / or size of the sharp edge area at the peripheral portion of the rear face of the lens 1 .

[0123] Optimizing the sharp edge area of ​​the peripheral portion 14 comprises the following sub-steps:

[0124] - Determine the diameter D of the finished lens after trimming cribb ,

[0125] - determining an optimal position of the trimming diameter in order to minimize the overlapping area between said trimming diameter and a predetermined thickness curve and / or to minimize the curvature in a peripheral portion of the rear surface.

[0126] The trimmed diameter D can be determined by any known method. cribb .

[0127] The predetermined thickness curve may preferably be greater than or equal to 0.4 mm.

[0128] In order to determine the best position of the trimming diameter, the trimming diameter D can be optimized. cribb The position and / or size compared to a predetermined thickness curve.

[0129] In one embodiment, the trimmed diameter D cribb The optimal position of is defined by an iterative solution in an appropriate coordinate system.

[0130] In another embodiment, the method comprises the step of optimizing the orientation of the finished lens in the varnish basket during the varnish application step based on the definition of the peripheral portion and the prescription portion defined by the selected thickness curve 12 .

[0131] Optimizing the orientation of the finished lenses in the varnish basket consists of the following sub-steps:

[0132] - Positioning the handling device of the varnish basket, for example a clip element, so as to place it in the peripheral portion 14 .

[0133] - Determining the optimal position of the lens so as to maximize the distance between the thickness curve 12 and the processing means.

[0134] The optimal position may be determined by any known method.

[0135] To determine the optimal position, the orientation of the lens may be optimized to move the treatment device away from the thickness curve 12 .

[0136] When the optimal position is defined, visible markings for the varnish basket orientation can be defined and engraved in the peripheral portion of the lens to guide the operator during loading the basket.

[0137] In another embodiment, the location of the drop can be further optimized for placement in the peripheral portion of the lens.

[0138] Another embodiment relates to a method for manufacturing an optical lens, the method comprising the step of edging a finished lens determined by using the above method.

[0139] In addition, the manufacturing method may include the step of engraving manufacturing marks in the peripheral portion of the lens. These engraved marks may be helpful during the manufacturing process or to assist the eye care professional in providing him / her with information about the lens. However, since these marks will be cut away from the lens during edging of the lens, they are not intended to be used by the wearer.

[0140] In another embodiment, the manufacturing method may include the step of optimizing the appearance control of the lens.

[0141] During the appearance control step, the location of the appearance defects in the lens is determined and if the defect is detected in the peripheral portion of the lens as defined by the method according to the invention, the lens will not be rejected as having an appearance defect because this peripheral portion will be suppressed during edging of the lens to be mounted in the frame.

Claims

1. A computer-implemented method for calculating a finished lens (1) having a predetermined shape, the finished lens comprising a front face, a back face, and a periphery (2) corresponding to the shape, the computer-implemented method comprising the following steps: - providing a lens blank having a convex front face and a concave rear face, - in the absence of frame shape data in which the lens is to be mounted, determining a prescription portion (13) on the lens that satisfies the wearer's prescription data together with the front face and a peripheral portion (14) on the lens by determining a first curvature profile of a rear surface to be machined on the rear face of the lens blank and by determining an isothickness curve (12) corresponding to a thickness value less than or equal to a predetermined thickness requirement, wherein the prescription portion (13) is defined by the isothickness curve (12) and the peripheral portion (14) extends from the isothickness curve (12) toward an outer edge (15) of the lens (1), The method further comprises the following steps: - providing a minimum edge thickness to the finished lens (1), - determining a first curvature profile of the rear surface to be machined on the rear face of the lens blank, - determining whether the thickness of the outer edge (15) of the peripheral portion (14) of the lens blank to be machined laterally with the first curvature profile at the peripheral portion (14) is less than the minimum edge thickness, - if the thickness of the outer edge (15) of the peripheral portion (14) is less than the minimum edge thickness, determining a new curvature profile of the peripheral portion (14) of the rear surface to be machined, wherein the thickness in the peripheral portion (14) is greater than or equal to the minimum edge thickness in order to avoid sharp edges, The finished lens (1) comprises a prescription portion (13) defined by an isopycth curve (12) corresponding to a thickness value less than or equal to a predetermined thickness requirement and a peripheral portion (14) extending from the isopycth curve (12) towards an outer edge (15) of the lens.

2. The method according to claim 1, wherein: The minimum edge thickness is greater than or equal to 0.4 mm.

3. The method according to any one of claims 1 to 2, wherein: The predetermined thickness requirement corresponds to the edge thickness of the lens cutout provided during the ordering of the finished lens.

4. The method according to any one of claims 1 to 2, wherein: A local or global safety margin is applied to the isopach curve (12) in order to define an isopach curve (12) that delimits a prescription portion (13) and a peripheral portion (14) of the lens (1).

5. The method according to any one of claims 1 to 2, wherein: The step of determining a new curvature profile of the peripheral portion (14) of the rear surface to be machined is based on an interpolation method using a first set of points inside the constant thickness curve (12) and a second set of points at the outer edge of the peripheral portion of the finished lens.

6. The method according to any one of claims 1 to 2, further comprising the following steps: Optimizing the position and / or size of the sharp edge area at the peripheral portion (14) of the rear surface of the rear face of the lens, wherein the curvature profile must be modified, Determine the diameter D of the finished lens (1) after trimming cribb , An optimum position of the trimming diameter is determined so as to minimize an overlap area between the trimming diameter and a predetermined thickness curve and / or to minimize a curvature in the peripheral portion (14) of the rear surface.

7. The method according to any one of claims 1 to 2, comprising a step of optimizing the orientation of the finished lens (1) in the varnish basket during the varnish coating step, comprising the following sub-steps: determining the position of the handling device of the varnish basket so as to place the handling device in the peripheral portion (14), The optimal position of the lens is determined so as to maximize the distance between the isopach curve (12) and the processing device.

8. A method for manufacturing an optical lens, comprising the step of engraving manufacturing marks in a peripheral portion (14) of the finished lens (1) determined by using the method according to any one of claims 1 to 7.

9. The method according to claim 8, further comprising the step of optimizing the appearance control step, wherein The location of the cosmetic defect in the lens is determined, and if a defect is detected in the peripheral portion (14) of the finished lens (1), the finished lens (1) is not rejected as having a cosmetic defect. 10 . A computer program product comprising a program code for executing the steps of the method according to claim 1 , when the computer program product is run on a data processing device.

11. A computer-readable medium carrying one or more instruction sequences of the computer program product of claim 10.

12. A finished lens having a predetermined lens shape based on the computer-implemented method according to claim 1, the finished lens comprising a front face, a back face, and a periphery (2) corresponding to the shape, comprising a prescription portion (13) on the lens that satisfies the prescription data of the wearer together with the front face and a peripheral portion (14) on the lens, the prescription portion (13) being defined by an isopyctric curve (12) and the peripheral portion (14) extending from the isopyctric curve (12) toward an outer edge (15) of the lens (1), wherein the thickness in the peripheral portion (14) is greater than or equal to the minimum edge thickness Te required at the outer edge (15) min , the isothickness curve (12) corresponds to a thickness value less than or equal to a predetermined thickness requirement, and wherein the minimum edge thickness Te is selected min The value of is used to avoid any sharp edges at the outer edge (15) of the finished lens (1) and to provide the finished lens (1) with a predetermined shape.

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