EP2305422B1 - Method and device for machining an ophthalmic lens in order to insert said lens in a spectacle frame - Google Patents

Description

TECHNICAL FIELD TO WHICH THE INVENTION REFERS

The present invention relates to a method of machining an ophthalmic lens for mounting in a spectacle frame, according to a predetermined contour.

This method is particularly suitable for trimming ophthalmic lenses whose contour has a complex shape, including negative curvature zones.

TECHNOLOGICAL BACKGROUND

The contours of certain ophthalmic lenses, in particular ophthalmic lenses intended to be mounted in a frame of the surrounding type (fixing to pierced lenses), have complex shapes comprising, for example, zones curved towards the center of the lens, called negative curvature.

These negative curvature zones generally correspond to decorative details of the contour of the lens and need to be machined by a tool of diameter less than the diameter of the grinding wheel commonly used to cut the lens.

There are dedicated machines of the three-axis milling machine type in which a milling drill can be moved freely in a plane perpendicular to its milling axis. This solution is however expensive since it requires the purchase of a specific tool for the trimming of this type of lens. In addition, such a dedicated tool is difficult to implement and its use requires a time of adaptation for the operator.

Another solution proposed in the document US7338350 to cut off such lenses is to use a small diameter cutter (typically the piercing tool). Such a tool equips some clipping devices, in addition to the large diameter grinding wheel commonly used to cut the lenses, to drill the mounting holes of the type of lens without surround. The contour of the lens is then integrally machined with the drill bit. The strawberry has a very small diameter, it can reach all areas of negative curvatures, even those with a very small radius of curvature.

However, the surface state of the edge of the lens thus cut off is unsatisfactory from an aesthetic point of view. In addition, the machining operation by the cutter is very long and causes premature wear of this tool.

OBJECT OF THE INVENTION

An object of the present invention is to overcome the drawbacks of the aforementioned state of the art, by providing a new method of trimming an ophthalmic lens that makes it possible to easily and quickly process lenses whose contour has areas of negative curvature

• analyser au moins une partie dudit contour, pour déterminer, en fonction dudit premier diamètre, une première région de ce contour adaptée à être usinée, sans rognage dudit contour prédéterminé, avec ledit premier outil, ,
• usiner au moins une partie de ladite première région de ce contour prédéterminé avec ledit premier outil,
• usiner au moins une partie du reste du contour avec ledit autre outil.

For this purpose, a method of machining an ophthalmic lens for mounting in an eyeglass frame, according to a predetermined contour, by means of at least two distinct tools, including a first tool, is proposed according to the invention. rotatable about a first axis, having a first cutting envelope, of revolution about this axis, having a first diameter, and at least one other rotary tool about an axis, having another revolution cutting envelope around this axis having another diameter less than said first diameter, said method comprising the following steps:

• analyzing at least a portion of said contour, to determine, according to said first diameter, a first region of this contour adapted to be machined, without trimming said predetermined contour, with said first tool,,
• machining at least a portion of said first region of said predetermined contour with said first tool,
• machining at least a portion of the remainder of the contour with said other tool.

The lens can thus be machined in an outline having areas of negative curvature with the tools of a trimming / milling device. The use of these tools is easy and fast. According to a first embodiment, it is possible in particular to machine all of the first region with the first tool and the rest of the contour with the other tool.

This method can be implemented according to various advantageous and nonlimiting embodiments that can be combined with one another.

• analyser au moins une partie dudit contour pour déterminer, en fonction dudit deuxième diamètre, une deuxième région de ce contour, hors de la première région, adaptée à être usinée avec ledit deuxième outil, sans rognage dudit contour,
• usiner au moins une partie de la deuxième région avec ledit deuxième outil,
• le reste du contour formant une troisième région usinée avec un troisième outil rotatif autour d'un troisième axe, ayant une troisième enveloppe de coupe de révolution autour de ce troisième axe, présentant un troisième diamètre inférieur audit deuxième diamètre.

According to a first advantageous characteristic of the invention, said at least one other tool comprises a second rotary tool around a second axis, having a second cutting envelope, of revolution about this second axis, having a second diameter smaller than said first axis. diameter, the method comprising the following steps:

• analyzing at least a portion of said contour to determine, as a function of said second diameter, a second region of this contour, outside the first region, adapted to be machined with said second tool, without trimming said contour,
• machining at least a portion of the second region with said second tool,
• the remainder of the contour forming a third machined region with a third rotary tool about a third axis, having a third envelope of cutting revolution around this third axis, having a third diameter less than said second diameter.

• déterminer, en fonction dudit deuxième diamètre, une deuxième région de ce contour, hors de la première région, adaptée à être usinée avec ledit deuxième outil sans rognage dudit contour,,
• déterminer, en fonction dudit troisième diamètre, une troisième région de ce contour hors de la première et de la deuxième région, adaptée à être usinée avec ledit troisième outil sans rognage dudit contour"
  chacune des deuxième et troisième régions étant formées d'un ensemble de sous-régions séparées les unes des autres par une sous-région ou une région de l'une des première, deuxième et troisième régions,
• déterminer les sous-régions de ladite deuxième région encadrant une sous-région de la troisième région,
• usiner la deuxième région, à l'exclusion desdites sous-régions de ladite deuxième région encadrant une sous-région de la troisième région, avec ledit deuxième outil,
• usiner ladite troisième région et lesdites sous-régions de ladite deuxième région encadrant une sous-région de la troisième région, avec ledit troisième outil.

According to another advantageous characteristic, said at least one other tool comprising a second rotary tool about a second axis, having a second cutting envelope, of revolution about this second axis, having a second diameter smaller than said first diameter, and a third rotary tool around a third axis, having a third cutting envelope, of revolution about this third axis, having a third diameter smaller than said second diameter, the method further comprises the following steps:

• determining, according to said second diameter, a second region of this contour, outside the first region, adapted to be machined with said second tool without trimming said contour,
• determining, according to said third diameter, a third region of this contour out of the first and second regions, adapted to be machined with said third tool without trimming said contour "
  each of the second and third regions being formed of a set of subregions separated from each other by a subregion or a region of one of the first, second and third regions,
• determine the subregions of said second region surrounding a subregion of the third region,
• machining the second region, excluding said subregions of said second region flanking a subregion of the third region, with said second tool,
• machining said third region and said subregions of said second region flanking a subregion of the third region, with said third tool.

• on détermine la longueur de chaque sous-région de la première région séparant deux sous-régions de la deuxième région et la comparer à une première valeur de longueur seuil,
• on usine chaque sous-région de la première région dont la longueur est inférieure à ladite première valeur de longueur seuil avec ledit deuxième outil.

According to another advantageous characteristic of the method according to the invention, each of the first and second regions being formed of a set of subregions separated from each other by a subregion or a region of one of the first, second and third regions,

• determining the length of each subregion of the first region separating two subregions of the second region and comparing it to a first value of the threshold length,
• each subregion of the first region is machined whose length is less than said first threshold length value with said second tool.

• on détermine la longueur de chaque sous-région de la première région séparant deux sous-régions de la troisième région et on la compare à une deuxième valeur de longueur seuil,
• on usine chaque sous-région de la première région dont la longueur est inférieure à ladite deuxième valeur de longueur seuil avec ledit troisième outil.

According to another advantageous characteristic of the method according to the invention, each of the first and third regions being formed of a set subregions separated from one another by a subregion of one of the first, second and third regions:

• determining the length of each subregion of the first region separating two subregions of the third region and comparing it with a second threshold length value,
• each subregion of the first region is machined whose length is less than said second threshold length value with said third tool.

• on détermine la longueur de chaque sous-région de la deuxième région séparant deux sous-régions de la troisième région et on la compare à une troisième valeur de longueur seuil,
• on usine chaque sous-région de la deuxième région dont la longueur est inférieure à ladite troisième valeur de longueur seuil avec ledit troisième outil.

According to another advantageous characteristic of the method according to the invention, each second and third region being formed of a set of subregions separated from each other by a subregion of one of the first, second and third regions,

• determining the length of each subregion of the second region separating two subregions of the third region and comparing it with a third value of the threshold length,
• each subregion of the second region is milled whose length is less than said third threshold length value with said third tool.

• déterminer la quantité de matière à usiner de la lentille pour chaque partie du contour à usiner avec ledit deuxième outil et la comparer à une valeur seuil de quantité de matière,
• pour chacune de ces parties du contour à usiner avec ledit deuxième outil, si la quantité de matière déterminée est supérieure à ladite valeur seuil de quantité de matière, on usine cette partie du contour selon un contour légèrement plus grand que le contour prédéterminé avec ledit troisième outil puis on usine cette partie du contour selon le contour prédéterminé avec ledit deuxième outil,
• pour chaque partie du contour à usiner avec ledit deuxième outil pour laquelle la quantité de matière à usiner est inférieure à la valeur seuil de quantité de matière, on usine ladite partie selon le contour prédéterminé avec ledit deuxième outil.

According to another advantageous characteristic of the method according to the invention, it further comprises the following steps:

• determining the amount of material to be machined of the lens for each part of the contour to be machined with said second tool and comparing it to a threshold value of quantity of material,
• for each of these parts of the contour to be machined with said second tool, if the determined quantity of material is greater than said material quantity threshold value, this part of the contour is machined to a slightly larger contour than the predetermined contour with said third tool then this part of the contour is machined according to the predetermined contour with said second tool,
• for each part of the contour to be machined with said second tool for which the quantity of material to be machined is less than the material quantity threshold value, said part is machined according to the predetermined contour with said second tool.

• on détermine la fraction de la longueur du contour prédéterminé à usiner avec ledit deuxième outil,
• si cette fraction est supérieure à une première fraction seuil, on usine la totalité du contour prédéterminé avec ledit deuxième outil.

According to another advantageous characteristic of the method according to the invention, it further comprises the following steps:

• the fraction of the length of the predetermined contour to be machined with said second tool is determined,
• if this fraction is greater than a first threshold fraction, the entire predetermined contour is machined with said second tool.

• on détermine la fraction de la longueur du contour prédéterminé à usiner avec ledit troisième outil,
• si cette fraction est supérieure à une deuxième fraction seuil, on usine la totalité du contour prédéterminé avec ledit troisième outil.

According to another advantageous characteristic of the process according to the invention, it further comprises the following steps:

• the fraction of the length of the predetermined contour to be machined with said third tool is determined,
• if this fraction is greater than a second threshold fraction, the entire predetermined contour is machined with said third tool.

• on détermine l'épaisseur de la lentille ophtalmique le long de chaque partie du contour prédéterminé à usiner avec ledit deuxième outil,
• si cette épaisseur est supérieure à une épaisseur seuil, on usine la partie correspondante du contour prédéterminé avec le troisième outil.

According to another advantageous characteristic of the method according to the invention, it further comprises the following steps:

• the thickness of the ophthalmic lens is determined along each part of the predetermined contour to be machined with said second tool,
• if this thickness is greater than a threshold thickness, the corresponding part of the predetermined contour is machined with the third tool.

• on usine d'abord les parties du contour prédéterminé à usiner avec le premier outil,
• on usine ensuite les autres parties du contour prédéterminé.

According to another advantageous characteristic of the method according to the invention, it further comprises the following steps:

• the parts of the predetermined contour to be machined with the first tool are first machined,
• the other parts of the predetermined contour are then machined.

• on usine tour à tour chaque partie du contour prédéterminé à usiner avec le deuxième outil selon le contour prédéterminé pour cette partie avant d'usiner une autre partie du contour prédéterminé à usiner avec le deuxième outil.

According to another advantageous characteristic of the method according to the invention, it further comprises the following steps:

• each part of the predetermined contour to be machined with the second tool is circumferentially machined according to the predetermined contour for that part before machining another part of the predetermined contour to be machined with the second tool.

• on positionne initialement le troisième outil un peu en retrait d'une première extrémité de cette partie, à une cote légèrement plus grande que celle du contour prédéterminé, de manière à rejoindre le contour prédéterminé à ladite première extrémité de cette partie, puis
• on usine ladite partie selon le contour prédéterminé,
• enfin, on amène le troisième outil jusqu'à une position au delà de la deuxième extrémité de cette partie, à une cote légèrement plus grande que celle du contour prédéterminé.

According to another advantageous characteristic of the method according to the invention, it further comprises the following steps, for machining each part of the predetermined contour to be machined with the third tool,

• the third tool is initially positioned a little behind a first end of this part, at a slightly greater height than that of the predetermined contour, so as to join the predetermined contour at said first end of this part, then
• said part is machined to the predetermined contour,
• finally, the third tool is brought to a position beyond the second end of this portion, at a slightly greater elevation than that of the predetermined contour.

• on détermine, pour chaque point du contour, une position de ladite première enveloppe de coupe, lorsque ledit premier outil est tangent à au moins une partie du contour prédéterminé en ce point, et on détermine les points du contour, appelés points additionnels rognés, qui se trouvent à l'intérieur de ladite première enveloppe de coupe dudit premier outil,
• on détermine une première grandeur représentative de l'importance du rognage, par exemple fonction du nombre des points additionnels rognés ou de la distance entre chacun de ces points additionnels rognés et ladite première enveloppe de coupe,
• on compare cette première grandeur représentative à une première valeur seuil prédéterminée,
• on attribue ledit point considéré du contour à ladite première région du contour en fonction du résultat de cette comparaison.

According to another advantageous characteristic of the method according to the invention, it further comprises the following steps, for determining said first region of this contour,

• determining, for each point of the contour, a position of said first cutting envelope, when said first tool is tangent to at least a part of the predetermined contour at this point, and the contour points, called trimmed additional points, which are within said first cutting envelope of said first tool are determined,
• determining a first magnitude representative of the amount of trimming, for example as a function of the number of additional cropped points or the distance between each of these cropped additional points and said first cutting envelope,
• this first representative quantity is compared with a first predetermined threshold value,
• the said contour point of the contour is assigned to the said first region of the contour as a function of the result of this comparison.

• on détermine, pour chaque point du contour en dehors de la première région, une position de ladite deuxième enveloppe de coupe lorsque ledit deuxième outil est tangent à au moins une partie dudit contour prédéterminé en ce point, et on détermine les points du contour, appelés points additionnels rognés, qui se trouvent à l'intérieur de ladite deuxième enveloppe de coupe dudit deuxième outil,
• on détermine une deuxième grandeur représentative de l'importance du rognage, par exemple fonction du nombre des points additionnels rognés ou de la distance entre chacun de ces points additionnels rognés et ladite deuxième enveloppe de coupe,
• on compare cette deuxième grandeur représentative à une deuxième valeur seuil prédéterminée,
• on attribue ledit point considéré du contour à ladite deuxième région du contour en fonction du résultat de cette comparaison.

According to another advantageous characteristic of the method according to the invention, it further comprises the following steps, for determining said second region of this contour,

• determining, for each point of the contour outside the first region, a position of said second sectional envelope when said second tool is tangent to at least a part of said predetermined contour at this point, and the points of the contour, called additional cut points, which are inside said second cutting envelope of said second tool,
• determining a second magnitude representative of the amount of trimming, for example as a function of the number of additional cropped points or the distance between each of these cropped additional points and said second cutting envelope,
• this second representative quantity is compared with a second predetermined threshold value,
• the said contour point of the contour is attributed to the said second region of the contour as a function of the result of this comparison.

• on recherche les positions de ladite première enveloppe de coupe dans lesquelles cette première enveloppe de coupe est tangente audit contour en un couple de points et dans lesquelles une première zone inaccessible du contour située entre les deux points de ce couple et recouverte par ladite première enveloppe de coupe n'est pas atteinte par cette première enveloppe de coupe,
• on définit la première région comme comportant au moins une partie du contour mais excluant les points desdites premières zones inaccessibles.

According to another advantageous characteristic of the method according to the invention, as a variant, for determining said first region of the contour,

• the positions of said first cutting envelope are sought in which this first cutting envelope is tangent to said contour in a pair of points and in which a first inaccessible zone of the contour located between the two points of this pair and covered by said first envelope of cut is not reached by this first cutting envelope,
• the first region is defined as having at least part of the contour but excluding the points of said first inaccessible areas.

• on recherche les positions de ladite deuxième enveloppe de coupe dans lesquelles cette deuxième enveloppe de coupe est tangente audit contour en un couple de points et dans lesquelles une deuxième zone inaccessible du contour située entre les deux points de ce couple et recouverte par ladite deuxième enveloppe de coupe n'est pas atteinte par cette deuxième enveloppe de coupe,
• on définit la deuxième région comme comportant au moins une partie du contour mais excluant ladite première région ainsi que les points desdites deuxièmes zones inaccessibles.

Then, to determine said second region of the contour,

• the positions of said second cutting envelope are sought in which this second cutting envelope is tangent to said contour in a pair of points and in which a second inaccessible zone of the contour situated between the two points of this pair and covered by said second envelope of cutting is not achieved by this second cutting envelope,
• defining the second region as comprising at least a part of the contour but excluding said first region and the points of said second inaccessible zones.

• on détermine, pour chaque point du contour, le rayon de courbure local du contour en ce point,
• on compare ce rayon de courbure avec ledit premier diamètre de ladite première enveloppe de coupe dudit premier outil,
• on attribue le point considéré du contour à ladite première région du contour en fonction du résultat de cette comparaison.

In another variant, for determining said first region of the contour,

• for each point of the contour, the local radius of curvature of the contour is determined at this point,
• this radius of curvature is compared with said first diameter of said first cutting envelope of said first tool,
• the considered point of the contour is assigned to said first region of the contour as a function of the result of this comparison.

• on détermine, pour chaque point du contour en dehors de la première région, le rayon de courbure local du contour en ce point,
• on compare ce rayon de courbure avec ledit deuxième diamètre dudit deuxième outil,
• on attribue le point considéré du contour à ladite deuxième région du contour en fonction du résultat de cette comparaison.

Then, to determine said second region of the contour:

• for each point of the contour outside the first region, the local radius of curvature of the contour is determined at this point,
• this radius of curvature is compared with said second diameter of said second tool,
• the considered point of the contour is assigned to said second region of the contour as a function of the result of this comparison.

• au moins deux outils distincts comprenant un premier outil rotatif autour d'un premier axe, ayant une enveloppe de coupe de révolution autour de ce premier axe présentant un premier diamètre et un autre outil rotatif autour d'un axe, ayant une autre enveloppe de coupe de révolution autour de cet axe présentant un autre diamètre inférieur audit premier diamètre,
• des moyens de traitement électroniques adaptés à analyser au moins une partie dudit contour, pour déterminer, en fonction dudit premier diamètre, une première région de ce contour adaptée à être usinée, sans rognage dudit contour prédéterminé, avec ledit premier outil.

The invention also relates to a device for machining an ophthalmic lens for mounting in an eyeglass frame, according to a predetermined contour, comprising

• at least two separate tools comprising a first rotary tool about a first axis, having a revolution cutting envelope around this first axis having a first diameter and another rotary tool about an axis, having another cutting envelope of revolution about this axis having another diameter less than said first diameter,
• electronic processing means adapted to analyze at least a portion of said contour, to determine, according to said first diameter, a first region of this contour adapted to be machined, without trimming said predetermined contour, with said first tool.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The description which follows, with reference to the accompanying drawings, given by way of non-limiting example, will make it clear what the invention consists of and how it can be achieved.

• les figures 1 à 5 sont des vues schématiques de différentes lentilles ophtalmiques dont les différents contours sont usinés au moyen du procédé selon l'invention ;
• la figure 6 est une vue schématique en perspective d'un dispositif de détourage utilisé pour mettre en oeuvre le procédé selon l'invention ;
• les figures 7 et 8 sont des vues schématiques du contour de la figure 2 discrétisé par un algorithme d'analyse des contours et d'une enveloppe d'un outil d'usinage, illustrant deux méthodes d'analyse de ce contour.

In the accompanying drawings:

• the Figures 1 to 5 are schematic views of different ophthalmic lenses whose different contours are machined using the method according to the invention;
• the figure 6 is a schematic perspective view of a trimming device used to implement the method according to the invention;
• the figures 7 and 8 are schematic views of the outline of the figure 2 discretized by an algorithm for analyzing the contours and envelope of a machining tool, illustrating two methods for analyzing this contour.

The Figures 1 to 5 show lenses 1, 2, 3, 4, 5 ophthalmic, whose respective contours 10, 20, 30, 40, 50, here considered in projection in a general mean plane of the lens concerned, each respectively comprise a complex region 11, 21, 31, 41, 51, delimited respectively by the points C and D, E and F, G and J, O and R, K and N.

Each complex region 11, 21, 31, 41, 51 comprises one or more zones of negative curvatures 11, 21, 34, 43A, 43B, 53A, 53B. These zones of negative curvature are delimited respectively by the points C and D, E and F, G and H, I and J, O and P, Q and R, K and L, M and N on the Figures 1 to 5 .

To cut off one of these lenses, it is placed in a machining device 200 known in itself, such as that described in the document W02008 / 043910 .

• une bascule 204 qui est montée pivotante autour d'un axe de bascule A1, en pratique un axe horizontal, sur un châssis 203, et qui comporte des moyens de support de la lentille 1, 2, 3, 4, 5 permettant une mise en rotation motorisée de cette lentille autour d'un axe de blocage A2 sensiblement perpendiculaire au plan moyen de la lentille et parallèle à l'axe A1;
• un train de meules de grand diamètre, comportant notamment une grande meule 220, montées sur le châssis 203 pour tourner, par entrainement motorisé, autour d'un axe de meule A3 parallèle à l'axe de bascule A1 ;
• un module de finition 235 qui embarque plusieurs outils de finition, dont une meulette 231 et une fraise de perçage 230 montées rotatives autour d'axes A5, A6 parallèles aux axes de bascule A1, de blocage A2 et de meule A3, et qui est monté à pivotement autour de l'axe de meule A3 pour la commande de la position de ses outils de finition par rapport à la lentille.

Such a device, as illustrated on the figure 6 , includes:

• a flip-flop 204 which is pivotally mounted about a flip-flop axis A1, in practice a horizontal axis, on a frame 203, and which comprises means for supporting the lens 1, 2, 3, 4, 5 enabling motorized rotation of this lens around a blocking axis A2 substantially perpendicular to the average plane of the lens and parallel to the axis A1;
• a set of large-diameter grinding wheels, including in particular a large grinding wheel 220, mounted on the frame 203 for rotating, by motorized drive, around a grinding wheel axis A3 parallel to the flip-flop axis A1;
• a finishing module 235 which embeds a number of finishing tools, including a grinder 231 and a drilling cutter 230 rotatably mounted about axes A5, A6 parallel to the flip-flop A1, block A2 and grinding wheel A3, and is pivotally mounted around the wheel axis A3 for controlling the position of its finishing tools with respect to the lens.

The grinding wheel 220 is a conventional grinding wheel, which comprises a cutting surface defining, in its rotation, around the axis A3, a cutting envelope of revolution about this axis A3, having a diameter greater than or equal to 80 millimeters, for example equal to to 155 millimeters.

The grinder 231 is a wheel of smaller diameter than the grinding wheel 220, which comprises a cutting surface defining, in its rotation about the axis A5, a revolution cutting envelope about this axis A5, preferably having a smaller diameter. at 80 millimeters, for example equal to 11 millimeters.

The cutter 230 comprises a cutting edge defining, in its rotation about the axis A6, a cutting envelope of revolution about this axis A6, which has a diameter less than 10 millimeters and preferably less than 5 millimeters, for example equal at 1.4 millimeters.

This grinding device 200 is controlled by an electronic and computer device 100. The electronic and computer device 100 comprises means for acquiring and displaying data, typically comprising a keyboard 101 and a screen 102 adapted to the display of a device. graphic interface, control means capable of controlling the different degrees of freedom of the grinding device 200 and an operating system associated with a software application adapted to control these different components.

The electronic and computer device 100 has a memory in which is inserted the shape of the contour 10, 20, 30, 40, 50 desired for the lens 1,2,3,4,5.

Here, the term "desired contour" or "predetermined contour" is understood to mean a target of radius dimension of the lens that is predetermined as a function of the frame in which the lens is intended to be mounted and as a function of the optical reference of the lens and of the lens. geometric-morphological characteristics of the future carrier. As shown on the figure 1 , the contour 10 is defined by a radius dimension setpoint, which typically consists of a function giving the distance L (Alpha) of each point 13 of this contour 10 with respect to a center 14 of this contour 10 as a function of a Alpha angle measured between a reference direction X and the line connecting the considered point 13 of the contour 10 and said center 14.

The contour 10, 20, 30, 40, 50 of the lens to be cut out comprising, as represented on the Figures 1 to 5 , complex regions, the machining of the lens is realized using at least two separate tools, chosen here from the tools available to the grinding device 200.

Before starting the machining of said lens, the electronic and computer device 100 determines which regions of the desired contour of the lens will be machined by which tool, depending on the geometric characteristics of this desired contour and as a function of the diameters of the section envelopes. tools available. In fact, it is assumed that the first diameter of the first tool is too large to respect the geometry of the desired contour in its negative curvature zones having a too pronounced concavity.

For this, the electronic and computer device 100 executes a desired contour analysis algorithm 10, 20, 30, 40, 50, in order to determine a first region 12, 22, 32, 42A, 42B, 52 of the contour comprising the points of this contour for which the use of a first rotary tool, in this case the grinding wheel 220 of large diameter, to cut the lens, is possible without damaging the shape of the desired lens contour. More precisely, it is a matter of isolating the points of the desired contour at which the machining of the lens with the large grinding wheel 220 to reach the desired lens radius dimension at the point in question is achieved without cutting other parts of the lens 1, 2, 3, 4, 5 located within the desired contour 10, 20, 30, 40, 50.

Here, a cut-off portion of the contour of the lens is understood to mean a part of the contour corresponding to an interval of values of the angle Alpha, for which the setpoint of the radius dimension can not be respected because of the fact that the machining a point of said first region to the desired radius dimension setpoint would result in machining of the lens, in this range of values of the angle Alpha, to a radius of less than the target.

For this, according to a first embodiment, the analysis algorithm discretizes the contour 10, 20, 30, 40, 50 considered in a set 301 of points in projection in a mean plane of this contour, as represented on the figure 7 in the case of contour 20 of the figure 2 . For example, the analysis algorithm models the contour 20 considered by a set 301 of points of this contour 20 located all a degree of angle around a center 302 of this contour. The set 301 of points then comprises 360 points. The center 302 of the contour 20 is for example the center of a rectangle 300 called "boxing" in which said contour 20 is included and each side of which is tangent to said contour 20.

For each point 303 of the set 301 of points modeling the contour 20 of the lens 2, the algorithm calculates the position of the first cutting envelope 220A of the grinding wheel 220 when the grinding wheel 220 is tangent to at least one part of the contour 20 at this point 303. This position of the first cutting envelope 220A of the grinding wheel 220 corresponds to the position of the grinding wheel 220 when it is in position to machine the lens 2 according to the desired contour 20 at this point 303.

This determination of the position of the first cutting envelope 220A of the grinding wheel 220 corresponds to the determination of the position of at least one circular arc whose diameter is that of the grinding wheel 220, corresponding to the edge of the grinding wheel 220 when it is tangent to the contour 20 at the point 303 considered.

The grinding wheel 220 is then situated on the side of this arc of circle opposite to the side where the center 302 of the contour 20 is located.

The algorithm then searches for the points of the contour 301 located inside this first cutting envelope 220A, that is to say located on the side of the arc corresponding to the grinding wheel 220, if exists. These points correspond to the additional points trimmed by the grinding wheel 220 when it is machining the lens 2 at the point 303 considered of the contour 20. Said additional cropped points belong to said trimmed portion of the contour.

For this, the analysis algorithm calculates the distance between each point of the contour located inside the first cutting envelope and said first cutting envelope. If this distance is greater than a predetermined distance threshold, the analysis algorithm retains the point considered to be located inside said envelope. If this distance is less than said predetermined distance threshold, the analysis algorithm determines that the point considered is not an additional point trimmed. This distance threshold is for example between 0 and 0.2 millimeters.

The analysis algorithm then determines a first magnitude representative of the amount of trimming at this point 303, compares this first magnitude with a first predetermined threshold value and assigns said considered point 303 to said first region 12, 22, 32, 42A , 42B, 52 depending on the result of this comparison.

For example, this first magnitude representative of the importance of trimming is a function of the number of additional points trimmed at the point considered. It is for example equal to the number of additional points trimmed.

If this number of trimmed additional points is less than a first predetermined threshold number, the considered point 303 of the contour 20 is assigned to the first region 22 of this contour adapted to be machined, without trimming of said predetermined contour, with the grinding wheel 220. Said first threshold number is example of between 1 and 10. This first threshold number is determined as a function of the total number of points of the set 301 of points or as a function of the interval between each successive point of this set 301.

This is the case, for example, of the additional point 303 represented on the figure 7 , for which there is no additional point trimmed by the grinding wheel 220, and points of the subset of points 304 corresponding to the portion 22 of the contour 20.

Alternatively, this first magnitude representative of the amount of trimming is a function of the distance between each of these trimmed additional points and said first cutting envelope 220A, called the trimmed width of the lens. The analysis algorithm then determines the trimmed width of the lens 2 at these trimmed additional points.

If this cropped width is smaller for all the additional points trimmed to a first predetermined threshold width, the considered point 303 of the contour 20 is assigned to said first region. This first threshold width is for example between 0.5 and 2 millimeters.

In the case of lenses 1, 2, 3, 5 represented on the Figures 1 to 3 and 5 this first region corresponds to the portions 12, 22, 32, 52 of the contour 10, 20, 30, 50 which lies outside the complex region 11, 21, 31, 51. In the case of the lens 4 shown in FIG. figure 4 this first region corresponds to the portion 42A of the contour 40 which lies outside the complex region 41 and to the portion 42B of the contour 40 located in the middle of the complex region 41.

According to the method according to the invention, the electronic and computer device 100 of the grinding device 200 then controls the machining of at least a portion of said first region 12, 22, 32, 42A, 42B, 52 of the contour 10, 20, 30, 40, 50 with said grinding wheel 220 and machining at least a portion of the remainder of the contour with another rotary tool about an axis, having another revolution cutting envelope about this axis having a another diameter less than the diameter of said grinding wheel. This other rotary tool is here the grinder 231 or the mill 230.

For example, according to a first embodiment of the invention, the electronic and computer device 100 of the grinding device 200 controls the machining of the entire first region 12 of the contour 10 of the lens 1 with the large grinding wheel 220 and machining the remainder of the contour 11 with the grinder 231. In the same way, the electronic and computer device 100 of the grinding device 200 controls the machining of the entire first region 22 of the contour 20 of the lens 2 with the large grinding wheel 220 and the machining of the rest of the contour 21 with the mill 230.

According to a second embodiment, the analysis algorithm determines a second region of this contour 10, 20, 30, 40, 50, out of the first region, adapted to be machined with a second rotary tool around a second axis, having a second revolution cutting envelope around this second axis having a second diameter about this axis less than said first diameter. This second tool can be in the example detailed here the grinder 231 or the mill 230.

For this, in the case for example of the contour of the figure 2 for each point of the set of points 301 not belonging to the first region, the analysis algorithm performs the same steps as those described above: the algorithm calculates the position of the second cutting envelope of the second tool (Here the grinder 231 or the mill 230) when it is tangent to at least a portion of the contour at the point considered, which corresponds to the position of the second tool for machining the lens 2 according to the desired contour 20 at this point. For this, it determines the position, in the average plane of the contour, of at least one circular arc whose diameter is that of said second tool, when it is tangent to the contour 20 at the point in question.

The algorithm then searches for the points of the contour that is inside said second sectional envelope, that is to say located on the side of the arc corresponding to the second tool, if there are any. These points correspond to the additional points trimmed by the second tool when it is machining the lens 2 at the considered point of the contour 20.

As before, the analysis algorithm then determines a second magnitude representative of the amount of trimming at this point, compares this second magnitude with a second predetermined threshold value and assigns said considered point to said second region according to the result of this comparison.

For example, this second magnitude representative of the importance of trimming is a function of the number of additional points trimmed at the point considered. It is for example equal to the number of these additional points trimmed.

If the number of trimmed additional points is smaller than a second predetermined threshold number the considered point of the contour 20 is assigned to the second region of that contour adapted to be machined, without trimming of said predetermined contour, with the second tool. Typically, the second threshold number is between 1.5 percent and 3 percent of the total number of points in the set of points modeling the contour of the lens.

Alternatively, this second magnitude representative of the importance trimming is a function of the distance between each of these trimmed additional points and said second cutting envelope, called the trimmed width of the lens. The analysis algorithm then determines the trimmed width of the lens 2 at these trimmed additional points.

If this cropped width is smaller for all the additional points trimmed to a second predetermined threshold width, the considered point of the contour 20 is assigned to the second region.

It is considered in the following description that the second tool is the grinder 231.

Then the analysis algorithm determines that the second region of the contour 10 represented on the figure 1 is the complex region 11, that the second region of the contour 20 represented on the figure 2 is empty, that the second region of the contour 30 shown on the figure 3 comprises the portions 33A, 33B of the complex region 31, that the second region of the contour 40 shown on the figure 4 comprises the parts 43A, 43B of the complex region 41, and that the second region of the contour 50 shown on the figure 5 comprises part 54 of the complex region 51.

The electronic and computer device 100 then controls the machining of at least a portion of the second region 11, 33A, 33B, 43A, 43B, 54 of the contour 10, 30, 40, 50 with the grinder 231.

The remainder of the contour 20, 30, 40, 50 forms a third region 21, 34, adapted to be machined with a third rotary tool about a third axis, having a third revolution cutting envelope around this third axis having a third third diameter less than said second diameter. This third tool here is the strawberry 230.

Alternatively, the second tool may be a first cutter and the third tool is then for example a second cutter of smaller diameter than the first.

The diameter of this third tool 230 is chosen small enough to be able to machine the smallest details of the contour 10, 20, 30, 40, 50.

Alternatively, the analysis algorithm can determine said third region of the contour 10, 20, 30, 40, 50 by applying the same steps as previously described in the case of the first and second tools, using the third envelope of cut of this third tool.

The analysis algorithm can also implement other methods for determining the first and second regions, as an alternative to the two embodiments that have just been described.

For example, the analysis algorithm searches for the positions of said first cutting envelope in which this first cutting envelope is tangent to said contour in a pair of points and in which a first inaccessible zone of the contour situated between the two points of this torque and covered by said first cutting envelope is not reached by this first cutting envelope.

This variant is illustrated by the figure 8 . In this figure, the contour 20 of the lens 2 of the figure 2 , modeled by the set 301 of points.

Alternatively, the analysis algorithm can also use the non-discretized contour of the lens.

In this example, the analysis algorithm finds a position of the first cutting envelope 220A in which it is tangent to a pair of two points 306, 307 of the set of points 301.

The contour zone 20 comprising the points 305 between the two points 306, 307, which corresponds to the complex region 21 of the contour 20, is covered by the first envelope 220A of the grinding wheel 220 and is not reached by this first envelope. 220A: the zone of the points 305 is inaccessible to this grinding wheel 220 and the contour radius setpoint at these points 305 can not be reached by means of the grinding wheel 220.

The analysis algorithm then defines the first region 12, 22, 32, 42A, 42B, 52 as comprising at least part of the contour but excluding the points of said first inaccessible zones.

Here, the first region 22 is defined as comprising the whole of the contour 20, excluding the inaccessible zone of the points 305, which corresponds to the complex region 21.

Then, in the same way, to determine said second region 11, 33A, 33B, 43A, 43B, 54 of the contour, the analysis algorithm searches for the positions of said second cutting envelope in which this second cutting envelope is tangent. audit contour in a pair of points and in which a second inaccessible zone of the contour located between the two points of this pair and covered by said second cutting envelope is not reached by this second cutting envelope.

The analysis algorithm defines the second region 11, 33A, 33B, 43A, 43B, 54 as comprising at least part of the contour 10, 20, 30, 40, 50 but excluding said first region 12, 22, 32, 42A , 42B, 52 as well as the points of said second inaccessible areas.

The analysis algorithm can then either assign the points of the contour belonging neither to the first region 12, 22, 32, 42A, 42B, 52 nor to the second region 11, 33A, 33B, 43A, 43B, 54 in the third region, or determine the third region in realization the same steps as those described above, for the third envelope of the third tool, here the cutter.

• l'algorithme d'analyse détermine, pour chaque point du contour, le rayon de courbure local du contour en ce point,
• il compare ce rayon de courbure avec ledit premier diamètre de ladite première enveloppe de coupe dudit premier outil,
• il attribue le point considéré du contour à ladite première région 12, 22, 32, 42A, 42B, 52 du contour en fonction du résultat de cette comparaison.

According to another method, for determining said first region 12, 22, 32, 42A, 42B, 52 of the contour,

• the analysis algorithm determines, for each point of the contour, the local radius of curvature of the contour at this point,
• it compares this radius of curvature with said first diameter of said first cutting envelope of said first tool,
• it assigns the considered point of the contour to said first region 12, 22, 32, 42A, 42B, 52 of the contour according to the result of this comparison.

The analysis algorithm compares for example, for each point of the contour 10, 20, 30, 40, 50, the radius of curvature of the contour at this point with the product of the first diameter of said first cutting envelope 220A of said first tool here, the grinding wheel 220, by a first factor preferably between 0.5 and 1.5, for example equal to 1.

The first diameter of the first tool being equal to twice the radius of curvature of this tool, this amounts to comparing the radius of curvature of the contour at this point and the radius of curvature of the first tool multiplied by a factor of between 1 and 3, by example equal to 2.

If the radius of curvature of the contour at the point considered is greater than the first diameter multiplied by said first factor, the point considered is assigned by the analysis algorithm to said first region 12, 22, 32, 42A, 42B, 52.

• l'algorithme d'analyse détermine, pour chaque point du contour en dehors de la première région 12, 22, 32, 42A, 42B, 52, le rayon de courbure local du contour en ce point,
• il compare ce rayon de courbure avec ledit deuxième diamètre dudit deuxième outil,
• il attribue le point considéré du contour à ladite deuxième région 11, 33A, 33B, 43A, 43B, 54 du contour en fonction du résultat de cette comparaison.

Then, to determine said second region 11, 33A, 33B, 43A, 43B, 54 of the contour:

• the analysis algorithm determines, for each point of the contour outside the first region 12, 22, 32, 42A, 42B, 52, the local radius of curvature of the contour at this point,
• it compares this radius of curvature with said second diameter of said second tool,
• it assigns the considered point of the contour to said second region 11, 33A, 33B, 43A, 43B, 54 of the contour as a function of the result of this comparison.

For example, if the point considered previously is not assigned to said first region 12, 22, 32, 42A, 42B, 52, the analysis algorithm compares the radius of curvature of the contour at this point to the second diameter of the second envelope of the second tool, here the grinder 231, to determine if this point belongs to said second region 11, 33A, 33B, 43A, 43B, 54.

For this, the analysis algorithm compares for example, for each point of the contour 10, 20, 30, 40, 50 not belonging to the first region 12, 22, 32, 42A, 42B, 52, the radius of curvature of the contour at this point with the product of the second diameter of said second cutting envelope of said second tool by a second factor preferably between 0.5 and 1.5, for example equal to 1.

The second diameter of the tool being equal to twice the radius of curvature of the second tool, it is the same as before to compare the radius of curvature of the contour at this point and the radius of curvature of the second tool multiplied by a factor between 1 and 3, for example equal to 2.

If the radius of curvature of the contour at the point considered is greater than the second diameter multiplied by said second factor, the point considered is assigned by the analysis algorithm to said second region 11, 33A, 33B, 43A, 43B, 54.

As before, the analysis algorithm can then either assign the points of the contour belonging neither to the first region 12, 22, 32, 42A, 42B, 52, nor to the second region 11, 33A, 33B, 43A, 43B, 54 to the third region, or to determine the third region in realization the same steps as those described above, for the third envelope of the third tool, here the mill 230. The analysis algorithm then compares the radius of curvature of the contour at the point considered with the diameter of the third cutting envelope of the third tool multiplied by a third factor preferably between 0.5 and 1.5, for example equal to 1.

Each first 12, 22, 32, 42A, 42B, 52, second 11, 33A, 33B, 43A, 43B, 54 and third 21, 34, 53A, 53B region is continuous or formed of a set of subregions separated by each other by a subregion or region of the other two regions.

Thus, in the most general case, for example in the case of contours 30, 50 represented on the Figures 3 and 5 , the contour 30, 50 desired is divided, at the end of these steps of the algorithm, into a plurality of sub-regions to be machined each by the corresponding tool.

According to a third embodiment of the invention, the electronic and computer device 100 controls the machining of each subregion or region of the first, second and third regions with respectively the first, second and third tools, corresponding here to the grinding wheel. 220, the grinder 231 and the strawberry 230.

According to a fourth embodiment, the analysis algorithm determines the subregions of the second region flanking a subregion of the third region.

The electronic and computer device 100 then controls the machining of the second region, excluding said subregions of said second region flanking a subregion of the third region, with said grinder 231, and the machining of said third region. region and said subregions of said second region flanking a subregion of the third region, with the mill 230.

In the case of the contour 30 shown on the figure 3 the subregions 33A, 33B of the second region frame the third region 34.

The electronic and computer device 100 then controls the machining of the first region 32 by the grinding wheel 220 and the machining of all the two subregions 33A, 33B of the second region and the third region 34 by the milling cutter 230. In this way, two changes of tools are avoided during the machining of the complex region 31 of the contour 30. The machining of the whole of the lens contour 3 is thus faster.

According to a fifth embodiment, the analysis algorithm determines the length of each subregion of the first region separating two subregions of the second region and compares it with a first threshold length value.

The electronic and computer device 100 of the grinding device 200 then controls the machining of each subregion of the first region whose length is less than said first threshold length value with the grinder 231. This first threshold length value is example between 2 and 10 millimeters, for example equal to 5 millimeters.

In the case of the contour 40 represented on the figure 4 the first region has two subregions 42A, 42B, one of which 42B is flanked by two subregions of the second region. The subregion 42B here has a length of a few millimeters smaller than the first threshold length value of 5 millimeters.

The electronic and computer device 100 of the grinding device 200 thus controls the machining of the entire complex region 11 comprising the two subregions 43A and 43B of the second region and the subregion 42B of the first region by the grinder. Only the portion 42A of the first region is machined by the grinding wheel 220.

Similarly, according to a sixth embodiment, the analysis algorithm determines the length of each subregion of the first region separating two subregions of the third region and compares it with a second threshold length value.

The electronic and computer device 100 of the grinding device 200 then controls the machining of each subregion of the first region whose length is less than the said second threshold length value with the mill 230. This second threshold length value is example between 2 and 10 millimeters, for example equal to 5 millimeters.

According to a seventh embodiment, the analysis algorithm determines the length of each subregion of the second region separating two subregions of the third region and compares it with a third value of threshold length.

The electronic and computer device 100 of the grinding device 200 then controls the machining of each subregion of the second region whose length is less than said third length threshold value with the mill 230.

This third threshold length value is for example between 2 and 10 millimeters, for example equal to 5 millimeters.

In the case of the contour 50 represented on the figure 5 the third region comprises two subregions 53A, 53B, which surround the second region 54. The second region 54 here has a length of a few millimeters smaller than the third threshold length value of 5 millimeters.

The electronic and computer device 100 of the grinding device 200 therefore controls the machining of the first region 52 by the grinding wheel 220 and the machining of the entire complex region 51 comprising the two subregions 53A and 53B of the third region and the second region 54 by the strawberry 230.

According to an eighth embodiment of the invention, the analysis algorithm determines the amount of material to be machined of the lens 1, 2, 3, 4, 5 for each part of the contour 10, 20, 30, 40, 50 to be machined with the grinder 231 and compares it with a threshold value of quantity of material.

The amount of material to be machined corresponds to the area between the raw edge of the lens 1, 2, 3, 4, 5 before machining and the desired contour 10, 20, 30, 40, 50 for the cut-out lens, multiplied by 1 average thickness of the lens 1,2,3,4,5.

For each of these parts of the contour 10, 20, 30, 40, 50 to be machined with said grinder, if the quantity of determined material is greater than said value threshold quantity of material, the electronic and computer device 100 controls the machining of this portion of the contour 10, 20, 30, 40, 50 with the mill 230.

The grinder 231 is poorly adapted to the removal of a large amount of material, and its use for this purpose is long and tedious. The use of the cutter 230 makes it possible to accelerate the contouring of the contour 10, 20, 30, 40, 50.

As a variant, for each of these parts of the contour 10, 20, 30, 40, 50 to be machined with the grinder 231, if the quantity of material determined is greater than the said threshold value of quantity of material, the electronic and computer device 100 the machining of this portion of the contour 10, 20, 30, 40, 50 in a slightly larger outline than this contour 10, 20, 30, 40, 50 predetermined with the milling cutter 230 and the machining of this part of the contour according to the contour 10, 20, 30, 40, 50 predetermined with the grinder 231.

Thus, the amount of material to be machined with the grinder is reduced since part of this amount of material has been previously removed by cutting with the bur. In addition, the surface state of the slice of the lens 1, 2, 3, 4, 5 thus obtained is improved.

Each portion of the contour 10, 20, 30, 40, 50 to be machined with the grinder 231 for which the quantity of material to be machined is less than the material quantity threshold value is machined according to the contour 10, 20, 30, 40, 50 predetermined with the grinder 231.

According to a ninth embodiment of the invention, the analysis algorithm determines the fraction of the length of the contour 10, 20, 30, 40, 50 predetermined to be machined with the millstone, and if this fraction is greater than a first threshold fraction, the entire predetermined contour 10, 20, 30, 40, 50 is machined with the grinder 231.

This first threshold fraction is between 75 percent and 100 percent, for example equal to 80 percent.

Thus tool changes during machining are limited and it is faster.

According to a tenth embodiment of the invention, the analysis algorithm determines the fraction of the length of the contour 10, 20, 30, 40, 50 predetermined to be machined with the cutter 230, and if this fraction is greater than one second threshold fraction, the entire contour 10, 20, 30, 40, 50 predetermined with this mill is machined.

This third threshold fraction is between 75 percent and 100 percent, for example equal to 80 percent.

Thus tool changes during machining are limited and it is faster.

According to an eleventh embodiment of the invention, the analysis algorithm determines the thickness of the ophthalmic lens 1, 2, 3, 4, 5 along each part of the contour 10, 20, 30, 40, 50 predetermined to be machined with the grinder 231.

This determination is made according to the contour 10, 20, 30, 40, 50 and the geometric and optical characteristics of the lens 1, 2, 3, 4, 5.

If the determined thickness is greater than a threshold thickness, the corresponding portion of the predetermined contour 10, 20, 30, 40, 50 is machined with the milling cutter 230.

Whatever the embodiment of the invention, in practice, the electronic and computer device 100 preferably controls first the machining of the parts of the contour 10, 20, 30, 40, 50 to be machined with the grinding wheel 220, then machining the other parts of the contour.

In addition, the electronic and computer device 100 preferably controls, in turn, the complete machining of each portion of the contour 10, 30, 40, 50 to be machined with the grinder 231 along said contour before controlling the machining of another part of the contour 10, 30, 40, 50 predetermined to be machined with the grinder 231.

Indeed, the machining of each portion of the contour 10, 30, 40, 50 to be machined with the grinder 231 is preferably made in several successive passes along said portion, machining only said portion, by a movement of and-comes from the grinder 231. The passes are calculated according to the maximum thickness of the lens 1, 2, 3, 4, 5 at this part of the contour. The larger the lens 1, 2, 3, 4, 5, the smaller the passes, so that each pass removes an equivalent volume of material.

In addition, in order to improve the appearance of the junction points between the parts of the contour 20, 30, 40, 50 to be machined with the cutter and the other parts, the electronic and computer device 100 preferably controls the initial positioning of the milling a little recessed from a first end of the portion of the contour to be machined with the milling cutter, to a slightly larger dimension than that of the predetermined contour, so as to join the contour 20, 30, 40, 50 at the first end of this part.

The electronic and computer device 100 then controls the machining of this portion along the contour 20, 30, 40, 50.

At the second end of this part of the contour, the device Electronic and computer 100 controls the movement of the cutter 230 to a position beyond this second end, to a slightly larger dimension than that of the contour 20, 30, 40, 50.

Thus, the connection between the parts of the contour of the lens 2, 3, 4, 5 machined by the cutter 230 and the other parts is more discreet.

According to yet another advantageous aspect, in order to limit the use of tools other than grinding wheel 220, the analysis algorithm can slightly modify the predetermined contour 10, 20, 30, 40, 50 so as to optimize the length of the tool. first region. For this, the analysis algorithm determines the points of the contour 10, 20, 30, 40, 50 located at each end of the subregions of the first region 12, 22, 32; 42A, 42B, 52 and determines the position of the grinding wheel 220 when it is machining each of these end points.

The analysis algorithm then replaces a third predetermined number of points of the second region located near each end point of the first region by points of the arc delimiting the edge of said grinding wheel 220 when factory the corresponding endpoint. The points of the arc that replace the points of the contour 10, 20, 30, 40, 50 are equal in number to said third number of points replaced and are spaced a regular interval.

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant consistent with his mind.

In particular, the various embodiments described can be combined with each other.

The first rotary tool considered may also be another rotary tool, for example the grinder or the milling cutter.

The second and third rotary tools are then, for example, mills of appropriate diameters.

In addition, it can be envisaged that only part of the contour of the lens is likely to have negative curvature zones. For example, the negative curvature zones may be located on the upper or lower portion of the contour, relative to a line connecting the location of the nasal bridge of the frame on which the lens is intended to be mounted to the location of the branch of this mount.

Alternatively, the negative curvature zones may be located on the left or right portion of the contour, with respect to a mediator of the segment connecting the location of the nasal bridge of the frame to the location of the branch of this mount.

We can then consider that only the corresponding portion of the lens contour is analyzed before machining the lens.

Claims (19)

1. A method of machining an ophthalmic lens (1, 2, 3, 4, 5) to have a predetermined outline (10, 20, 30, 40, 50) for mounting the lens in an eyeglass frame, the machining being performed by at least two distinct tools, including a first tool (220) that is mounted to rotate about a first axis (A3) and that has a first axisymmetric cutting envelope presenting a first diameter about that axis (A3), and at least one other tool (230; 231) that is mounted to rotate about an axis (A5; A6), and that has another axisymmetric cutting envelope presenting another diameter about that axis (A5; A6), said other diameter being less than said first diameter, said method comprising the following steps:

   • analyzing at least a portion of said outline (10, 20, 30, 40, 50) in order to determine, as a function of said first diameter, a first region (12, 22, 32, 42A, 42B, 52) of the outline (10, 20, 30, 40, 50) that is suitable for being machined with said first tool (220) without paring away said predetermined outline (10, 20, 30, 40, 50);

   • using said first tool (220) to machine at least a portion of said first region (12, 22, 32, 42A, 42B, 52) of the predetermined outline (10, 20, 30, 40, 50); and

   • using said other tool (230; 231) to machine at least a portion of the remainder of the outline (10, 20, 30, 40, 50).
2. A method according to claim 1, wherein said at least one other tool comprises a second tool (231) that is mounted to rotate about a second axis (A5) and that has a second axisymmetric cutting envelope presenting a second diameter about that second axis (A5), said second diameter being less than said first diameter, the method further comprising the following steps:

   • analyzing at least a portion of said outline (10, 20, 30, 40, 50) in order to determine, as a function of said second diameter, a second region (11, 33A, 33B, 43A, 43B, 54) of the outline (10, 20, 30, 40, 50), outside the first region (12, 22, 32, 42A, 42B, 52) that is suitable for being machined with said second tool (231) without paring away said outline;

   • using said second tool to machine at least a portion of the second region (11, 33A, 33B, 43A, 43B, 54); and

   • using a third tool (230) to machine the remainder of the outline (10, 20, 30, 40, 50) forming a third region (21, 34, 53A, 53B) said third tool (230) being mounted to rotate about a third axis (A6), and having a third axisymmetric cutting envelope presenting a third diameter about that third axis, said third diameter being less than said second diameter.
3. A method according to claim 1 or claim 2, wherein said at least one other tool comprising a second tool (231) that is mounted to rotate about a second axis (A5) and that has a second axisymmetric cutting envelope presenting a second diameter about that second axis (A5), said second diameter about said axis being less than said first diameter, and a third tool (230) that is mounted to rotate about a third axis (A6) and that has a third axisymmetric cutting envelope presenting a third diameter about the third axis (A6) said third diameter being less than said second diameter, the method further comprises the following steps:

   • determining, as a function of said second diameter, a second region (11, 33A, 33B, 43A, 43B, 54) of the outline (10, 20, 30, 40, 50), that is outside the first region (12, 22, 32, 42A, 42B, 52), and that is suitable for being machined with said second tool (231) without paring away said outline;

   • determining, as a function of said third diameter, a third region (21, 34, 53A, 53B) of the outline (10, 20, 30, 40, 50), that is outside the first and second regions (11, 33A, 33B, 43A, 43B, 54), and that is suitable for being machined with said third tool (230) without paring away said outline;

   • each of the second and third regions (33A, 33B, 43A, 43B, 54 and 34, 53A, 53B) being formed by a set of sub-regions separated from one another by a sub-region or a region of one of the first, second, and third regions (32, 42A, 42B, 52; 33A, 33B, 43A, 43B, 54; and 34, 53A, 53B);

   • determining the sub-regions of said second region (33A, 33B, 43A, 43B, 54) on either side of a sub-region of the third region (34, 53A, 53B);

   • using said second tool to machine the second region (33A, 33B, 43A, 43B, 54), with the exception of said sub-regions of said second region (33A, 33B, 43A, 43B, 54) on either side of a sub-region of the third region (34, 53A, 53B); and

   • using said third tool (230) to machine said third region (34, 53A, 53B) and said sub-regions of said second region (33A, 33B, 43A, 43B, 54) on either side of a sub-region of the third region (34, 53A, 53B).
4. A method according to claim 2 or claim 3, wherein both the first region (42A, 42B) and the second region (43A, 43B) are formed by a respective set of sub-regions separated from one another by a sub-region or a region of one of the first, second, and third regions (42A, 42B and 43A, 43B), the method including:

   • determining the length of each sub-region of the first region (42A, 42B) separating two sub-regions of the second region (43A, 43B) and comparing it with a first length threshold value; and

   • using said second tool to machine each sub-region of the first region (42A, 42B) that is of a length that is less than said first length threshold value.
5. A method according to any one of claims 2 to 4, wherein both the first region (22, 32, 52) and the third region (21, 34, 53A, 53B) are formed by a respective set of sub-regions separated from one another by a sub-region or a region of one of the first, second, and third regions (22, 32, 52; 33A, 33B, 43A, 43B, 54; and 21, 34, 53A, 53B), the method including:

   • determining the length of each sub-region of the first region (22, 32, 52) separating two sub-regions of the third region (21, 34, 53A, 53B) and comparing it with a second length threshold value; and

   • using said third tool (230) to machine each sub-region of the first region (32, 52) that is of a length that is less than said second length threshold value.
6. A method according to any one of claims 2 to 5, wherein both the first (54) and the third region (53A, 53B) are formed by a respective set of sub-regions separated from one another by a sub-region of one of the first, second, and third regions (52; 54; and 53A, 53B);

   • determining the length of each sub-region of the second region (54) separating two sub-regions of the third region (53A, 53B) and comparing it with a third length threshold value; and

   • using said third tool (230) to machine each sub-region of the second region (54) of length that is less than said third length threshold value.
7. A method according to any one of claims 2 to 6, further comprising the following steps:

   • determining the quantity of material that is to be machined on the lens (1, 3, 4, 5) for each portion of the outline (10, 30, 40, 50) that is to be machined with said second tool (231) and comparing it with a quantity of material threshold value;

   • for each of the outline portions (10, 30, 40, 50) that is to be machined with said second tool, if the quantity of material determined is greater than said quantity of material threshold value, using said third tool (230) to machine said outline portion (10, 30, 40, 50) along an outline (10, 30, 40, 50) that is slightly outside the predetermined outline (10, 30, 40, 50), then using said second tool (231) to machine said outline portion (10, 30, 40, 50) along the predetermined outline (10, 30, 40, 50); and

   • for each outline portion (10, 30, 40, 50) that is to be machined with said second tool for which the quantity of material to be machined is less than the quantity of material threshold value, using said second tool (231) to machine said portion along the predetermined outline (10, 30, 40, 50).
8. A method according to any one of claims 2 to 7, including:

   • determining the fraction of the length of the predetermined outline (10, 30, 40, 50) that is to be machined with said second tool (231); and

   • if said fraction is greater than a first fraction threshold, using said second tool to machine the totality of the predetermined outline (10, 30, 40, 50).
9. A method according to any one of claims 2 to 8, including:

   • determining the fraction of the length of the predetermined outline (20, 30, 40, 50) that is to be machined with said third tool (230); and

   • if said fraction is greater than a second fraction threshold, using said third tool to machine all of the predetermined outline (20, 30, 40, 50).
10. A method according to any one of claims 2 to 9, including:

    • determining the thickness of the ophthalmic lens (1, 3, 4, 5) along each predetermined outline portion (10, 30, 40, 50) that is to be machined with said second tool (231); and

    • if said thickness is greater than a threshold thickness, using said third tool (230) to machine the corresponding portion of the predetermined outline (10, 30, 40, 50).
11. A method according to any one of claims 2 to 10, wherein, in order to machine each predetermined outline portion (20 30, 40, 50) that is to be machined with the third tool (230), the method includes:

    • initially positioning the third tool slightly set back from a first end of said portion, at a position that is slightly outside the predetermined outline (20, 30, 40, 50), in such a manner as to join the predetermined outline (20, 30, 40, 50) to said first end of said portion; then

    • machining said portion along the predetermined outline (20, 30, 40, 50); and then

    • bringing the third tool (230) into a position beyond the second end of said portion, to a position that is slightly outside the predetermined outline (20, 30, 40, 50).
12. A method according to any one of claims 1 to 11, wherein, in order to determine said first region (12, 22, 32, 42A, 42B, 52) of the outline (10, 20, 30, 40, 50) the method includes:

    • determining, for each point of the outline (10, 20, 30, 40, 50), a position of said first cutting envelope (220A) when the first tool (220) is tangential to at least a portion of the predetermined outline (10, 20, 30, 40, 50) at this point, and determining points of the outline (10, 20, 30, 40, 50), referred to as pared away additional points, that are located inside said first cutting envelope (220A) of said first tool (220);

    • determining a representative first magnitude that is representative of the extent of the paring away;

    • comparing said representative first magnitude to a first predetermined value threshold; and

    • allocating said point under consideration of the outline (10, 20, 30, 40, 50) to said first region (12, 22, 32, 42A, 42B, 52) of the outline (10, 20, 30, 40, 50) as a function of the result of said comparison.
13. A method according to any one of claims 1 to 11, wherein, in order to determine said first region (12, 22, 32, 42A, 42B, 52) of the outline (10, 20, 30, 40, 50) the method includes:

    • seeking positions of said first cutting envelope in which said first cutting envelope is tangential to said outline (10, 20, 30, 40, 50) at a pair of points and in which a first inaccessible zone of the outline situated between the two points of said pair and covered by said first cutting envelope is not reached by said first cutting envelope; and

    • defining the first region (12, 22, 32, 42A, 42B, 52) as comprising at least a portion of the outline (10, 20, 30, 40, 50) but excluding the points of said first inaccessible zones.
14. A method according to any one of claims 1 to 11, wherein, in order to determine said first region (12, 22, 32, 42A, 42B, 52) of the outline (10, 20, 30, 40, 50) the method includes:

    • determining, for each point of the outline (10, 20, 30, 40, 50), the local radius of curvature of the outline (10, 20, 30, 40, 50) at said point;

    • comparing said radius of curvature with said first diameter of said first cutting envelope of said first tool; and

    • allocating said point under consideration of the outline (10, 20, 30, 40, 50) to said first region (12, 22, 32, 42A, 42B, 52) of the outline (10, 20, 30, 40, 50) as a function of the result of said comparison.
15. A method according to any one of claims 2 to 14, wherein, in order to determine said first region (11, 33A, 33B, 43A, 43B, 54) of the outline (10, 20, 30, 40, 50) the method includes:

    • determining, for each point of the outline (10, 20, 30, 40, 50) outside the first region (12, 22, 32, 42A, 42B, 52), a position of said second cutting envelope when the second tool (231) is tangential to at least a portion of said predetermined outline (10, 20, 30, 40, 50) at that point, and determining points of the outline (10, 20, 30, 40, 50), referred to as pared away additional points, that are located inside said second cutting envelope of said second tool;

    • determining a second representative magnitude of the extent of the paring away;

    • comparing said representative second magnitude to a second predetermined value threshold; and

    • allocating said point under consideration of the outline (10, 20, 30, 40, 50) to said second region (11, 33A, 33B, 43A, 43B, 54) of the outline (10, 20, 30, 40, 50) as a function of the result of said comparison.
16. A method according to any one of claims 2 to 14, wherein, in order to determine said second region (11, 33A, 33B, 43A, 43B, 54) of the outline (10, 20, 30, 40, 50) the method includes:

    • seeking positions of said second cutting envelope in which said second cutting envelope is tangential to said outline (10, 20, 30, 40, 50) at a pair of points and in which a second inaccessible zone of the outline situated between the two points of said pair and covered by said second cutting envelope is not reached by said second cutting envelope; and

    • defining the second region (11, 33A, 33B, 43A, 43B, 54) as comprising at least a portion of the outline (10, 20, 30, 40, 50) but excluding said first region and also the points of said second inaccessible zones.
17. A method according to any one of claims 2 to 14, wherein, in order to determine said second region (11, 33A, 33B, 43A, 43B, 54) of the outline (10, 20, 30, 40, 50) the method includes:

    • determining, for each point of the outline (10, 20, 30, 40, 50) outside the first region (12, 22, 32, 42A, 42B, 52), the local radius of curvature of the outline (10, 20, 30, 40, 50) at said point;

    • comparing said radius of curvature with said second diameter of said second tool (231); and

    • allocating the point under consideration of the outline (10, 20, 30, 40, 50) to said second region (11, 33A, 33B, 43A, 43B, 54) of the outline (10, 20, 30, 40, 50) as a function of the result of said comparison.
18. A method according to any one of claims 1 to 17, including:

    • firstly, using the first tool (220) to machine the predetermined outline portions (10, 20, 30, 40, 50); and

    • then, machining the other predetermined outline portions (10, 20, 30, 40, 50).
19. A device for machining an ophthalmic lens (1, 2, 3, 4, 5) to have a predetermined outline (10, 20, 30, 40, 50) for mounting the lens in an eyeglass frame, the device comprising:

    • at least two distinct tools, including a first tool (220) that is mounted to rotate about a first axis (A3) and that has an axisymmetric cutting envelope presenting a first diameter about that first axis (A3), and another tool (230; 231) that is mounted to rotate about an axis (A5; A6), and presenting another diameter that is less than said first diameter about said axis (A5 A6);
    the device being characterized in that it further comprises:

    • electronic processor means that are adapted to analyze at least a portion of said outline as a function of said first diameter in order to determine a first region (12, 22, 32, 42A, 42B, 52) of the outline (10, 20, 30, 40, 50) that is suitable for being machined with said first tool (220) without paring away said predetermined outline (10, 20, 30, 40, 50).

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