Patent Publication Number: US-2021187863-A1

Title: Method for manufacturing an ophthalmic lens, support and manufacturing system

Description:
TECHNICAL FIELD OF THE INVENTION 
     The invention relates to the manufacturing of ophthalmic lenses. More precisely the invention relates to a method for manufacturing an ophthalmic lens, a support designed to sustain the ophthalmic lens being manufactured and a manufacturing system. 
     BACKGROUND INFORMATION AND PRIOR ART 
     Using an additive manufacturing technology to manufacture an ophthalmic lens is of interest because the obtained ophthalmic lens is directly shaped to fit the frame that shall carry the ophthalmic lens and/or the obtained ophthalmic lens complies with the wearer&#39;s optical prescription. 
     The additive manufacturing process needs to be precisely performed; in particular a new layer needs to be positioned very accurately on the already polymerised layer to correctly manufacture the ophthalmic lens. This delicate process leads to manufacture the ophthalmic lens on a support which will maintain the ophthalmic lens during the whole additive manufacturing process. 
     Document WO2015092017 describes a method to print a three-dimensional structure, such as an ophthalmic lens, by superposing layers of different materials. The whole printing structure lies on a support and some layers may be removed during the process to get the final three-dimensional structure. 
     The final three-dimensional structure is not ready for use as the useful surface presents some optical defects due to the contact with the support and other layers. Some heavy post-processing steps on the final structure, such as polishing, are thus necessary. 
     SUMMARY OF THE INVENTION 
     In this context, the invention provides a method for manufacturing an ophthalmic lens using an additive manufacturing technology in order to directly obtain an ophthalmic lens ready for use, without any post-processing treatment. The invention consists in a method for manufacturing an ophthalmic lens using an additive manufacturing technology, said ophthalmic lens having at least one useful optical surface and a peripheral region surrounding at least in part said useful optical surface, the method comprising the steps of:
         providing a support,   manufacturing a part of the ophthalmic lens comprising a portion of said peripheral region and being in contact with the support by said portion of the peripheral region so that the support bears the part of the ophthalmic lens being manufactured while said useful optical surface is free from any contact with the support.       

     Thanks to the invention, the ophthalmic lens being manufactured is borne by the support contacting the peripheral region. This peripheral region corresponds to a non-useful optical part and the useful optical surface of the ophthalmic lens is manufactured being free from any contact with the support. Thus, this optical surface is manufactured with the correct optical characteristics and is free from any optical defects. Post-processing treatments needed to modify the optical surface of the ophthalmic lens are thus not necessary and the ophthalmic lens can be directly used in a frame. This does not exclude however the possibility to add any type of coating on the ophthalmic lens. 
     Other advantageous features of the invention are the following ones:
         said support has a shape complementary to the portion of the peripheral region of the ophthalmic lens;   said support sustains said part of the ophthalmic lens;   said part of the ophthalmic lens lies on a bearing surface of said support, the vertical line going through the centre of gravity of said part of the ophthalmic lens intersecting said bearing surface of the support;   the geometry or the orientation of the support is arranged before the step of manufacturing the ophthalmic lens in order to prevent said part of the ophthalmic lens from collapsing or being deformed while being manufactured;   the orientation of the support is continuously varied during the step of manufacturing the ophthalmic lens in order to prevent said part of the ophthalmic lens from collapsing or being deformed while being manufactured;   said support upholds said part of the ophthalmic lens;   the ophthalmic lens further comprises a discontinuous linking portion between said part of the ophthalmic lens and said support;   the ophthalmic lens directly obtained from the manufacturing comprises two opposite faces and an edge extending between the two faces, the peripheral region comprising a portion of at least one of the two faces;   the ophthalmic lens is configured to be mounted in a rim of a frame, said rim having an inner face, wherein the ophthalmic lens directly obtained from the manufacturing comprises two opposite faces and an edge extending between the two faces, said edge substantially matching the inner face of the rim.       

     The invention also provides a support designed to bear a part of an ophthalmic lens being manufactured by an additive manufacturing technology, the ophthalmic lens having at least one useful optical surface and a peripheral region surrounding at least in part said useful optical surface, the support being configured so that when the support bears the part of the ophthalmic lens being manufactured by a portion of the peripheral region, the useful optical surface is free from any contact with the support. 
     The support has shape and dimensions determined by features of the useful optical surface of the ophthalmic lens to be manufactured. The support is manufactured using said additive manufacturing technology. 
     The invention also describes a manufacturing system comprising:
         a support designed to bear a part of an ophthalmic lens being manufactured by an additive manufacturing technology, the ophthalmic lens having at least one useful optical surface and a peripheral region surrounding at least in part said useful optical surface; and   a device suitable for manufacturing said part of the ophthalmic lens using said additive manufacturing technology,   whereby said support is in contact with a portion of the peripheral region of the part of the ophthalmic lens being manufactured while said useful optical surface is free from any contact with the support.       

     DETAILED DESCRIPTION OF EXAMPLE(S) 
     The following description, given with regard to the appended drawings, which are given by way of non-limiting examples, will allow what the invention consists of and how it can be carried out to be understood. 
     In the appended drawings: 
       FIG. 1  shows an exemplary manufacturing system adapted to manufacture an ophthalmic lens according to the invention; 
       FIGS. 2 a , 2 b , 2 c  and 2 d    schematically show a concave ophthalmic lens at different manufacturing stages according to a first exemplary embodiment of the invention; 
       FIG. 3  schematically shows a front view of a concave ophthalmic lens on a support according to the first exemplary embodiment of the invention; 
       FIG. 4  schematically shows a front view of a convex ophthalmic lens on a support according to a second exemplary embodiment of the invention; 
       FIG. 5  schematically shows a side view of a convex ophthalmic lens on a support according to the second exemplary embodiment of the invention; 
       FIG. 6  schematically shows a front view of multiple concave ophthalmic lenses on a support according to a fourth exemplary embodiment of the invention; 
       FIG. 7  schematically shows a side view of a convex ophthalmic lens on a support according to a third exemplary embodiment of the invention; 
       FIG. 8  schematically shows a front view of a concave ophthalmic lens on a support according to a fifth exemplary embodiment of the invention; and 
       FIGS. 9 a  and 9 b    schematically show a front view of a plurality of ophthalmic lenses at two different manufacturing stages according to a sixth embodiment of the invention. 
    
    
       FIG. 1  shows a manufacturing system  1  adapted to manufacture an ophthalmic lens. 
     The manufacturing system  1  comprises a device  3  and a support  5 . The device  3  is suitable for manufacturing a part  7  of the ophthalmic lens using an additive manufacturing technology. The expression “additive manufacturing technology” refers to processes that manufacture solid objects by juxtaposing volume elements or voxels. In the case of the present invention, the part  7  of the ophthalmic lens is thus manufactured volume element by volume element, layer by layer. The additive manufacturing technology may be in practice stereolithography (SLA) or polymer jetting or continuous liquid interface production (CLIP) technology. 
     The device  3  comprises a control unit (not shown on  FIG. 1 ). This control unit includes a microprocessor and a memory. The memory stores instructions that allow the manufacturing system  1  to implement a method for manufacturing the ophthalmic lens as described below when these instructions are executed by the microprocessor. 
     The part  7  of the ophthalmic lens comprises at least one useful optical surface and a peripheral region surrounding at least in part said useful optical surface. The part  7  of the ophthalmic lens comprises two opposite faces and an edge extending between the two faces. The peripheral region of the part  7  of the ophthalmic lens comprises at least a portion of the edge and a portion of at least one of the two faces. The peripheral region is a non-useful optical part. The expression “useful optical surface” is understood to mean the surface of the ophthalmic lens adapted to modify the propagation and the transmission of an optical beam going through said ophthalmic lens. The useful optical surface is thus the portion of the ophthalmic lens adapted to the wearer&#39;s optical prescription. Said differently, the useful optical surface is the portion of the ophthalmic lens that may be crossed by the wearer&#39;s gaze direction when the ophthalmic lens is worn by the wearer. 
     The memory comprised in the device  3  also stores elements for defining the ophthalmic lens to be manufactured, especially features defining the useful optical surface. 
     The support  5  shown in  FIG. 1  is designed to sustain the part  7  of the ophthalmic lens being manufactured. The word “bear” is understood to mean maintaining the part  7  of the ophthalmic lens in a certain position thanks to the support  5 . The word “bear” is in no way intended to limit the contact region between the part  7  of the ophthalmic lens and the support  5  to a contact from the bottom of said part  7  of the ophthalmic lens. The support  5  may thus bear the part  7  of the ophthalmic lens from the top of said part  7 , as further described below. 
     In these examples described here, the support  5  is manufactured by the additive manufacturing technology. The support  5  is configured and dimensioned so that when the support bears the part  7  of the ophthalmic lens being manufactured, the useful optical surface is free from any contact with said support  5 . 
     The shape and dimensions of the support  5  are determined considering the features of the useful optical surface of the ophthalmic lens being manufactured. These features include the shape of the manufactured ophthalmic lens (concave or convex) and/or the optical prescription and/or the shape and dimensions of a frame in which the ophthalmic lens will be mounted. 
     The manufacturing system  1  shown in  FIG. 1  and described previously is suitable to execute a method for manufacturing an ophthalmic lens using the additive manufacturing technology. 
     This method comprises a step of providing the support  5  (for instance by producing the support  5  by additive manufacturing) as described previously. The method also comprises a step of manufacturing the part  7  of the ophthalmic lens, using the additive manufacturing technology. During the step of manufacturing, a portion of the peripheral region of the part  7  of the ophthalmic lens is in contact with the support  5  so that the support  5  bears the part  7  of the ophthalmic lens being manufactured. During the step of manufacturing, the useful optical surface is free from any contact with the support  5 . 
       FIGS. 2 a , 2 b  and 2 c    schematically show a concave ophthalmic lens at different manufacturing stages according to a first exemplary embodiment of the manufacturing method just mentioned. This first embodiment corresponds to the manufacturing of the ophthalmic lens from the bottom to the top of the ophthalmic lens. 
       FIG. 2 a    represents a first part  21  of the ophthalmic lens manufactured on the support  5  by the additive manufacturing technology at a first stage of the step of manufacturing.  FIG. 2 b    shows a second part  23  of the ophthalmic lens manufactured at a second stage of the step of manufacturing. The second part  23  is obtained from the first part  21  by adding layers by additive manufacturing on the first part  21 .  FIG. 2 c    shows a final concave ophthalmic lens  25  obtained by adding layers on the second part  23 . 
     The centre of gravity G of the current part (i.e. the first part  21 , the second part  23  or the third part  25 ) of the ophthalmic lens being manufactured is represented in  FIGS. 2 a , 2 b  and 2 c   .The vertical line L going through the centre of gravity G of said current part (i.e. the first part  21 , the second part  23  or the third part  25 ) is also identified in  FIGS. 2 a , 2 b    and  2   c.    
     As shown in  FIGS. 2 a , 2 b  and 2 c   , the support  5  bears the concerned part (i.e. the first part  21 , the second part  23  or the third part  25 ) of the ophthalmic lens. Said concerned part (i.e. the first part  21 , the second part  23  or the third part  25 ) of the ophthalmic lens thus lies on a bearing surface of the support  5 . The bearing surface is defined as the contact surface between the concerned part (i.e. the first part  21 , the second part  23  or the third part  25 ) of the ophthalmic lens and the support  5 . The vertical line L going through the centre of gravity G crosses said bearing surface. 
     The support  5  is arranged according to the ophthalmic lens to be manufactured. As an example, the support  5  is arranged before the step of manufacturing, depending on the predetermined geometry of the ophthalmic lens to be manufactured. The support  5  is thus arranged in shape and orientation to prevent the concerned part (i.e. the first part  21 , the second part  23  or the third part  25 ) of the ophthalmic lens from collapsing or being deformed while being manufactured. 
     In the example just described, the support is in a fixed position during the manufacturing process. According to a possible variation, the support  5  may be tilted by a tilt angle α.  FIG. 2 d    schematically shows the second stage of manufacturing for which the support has been tilted to prevent the final concave ophthalmic lens from collapsing. The second part  23  is represented with the remaining part  24  to manufacture to obtain the final concave ophthalmic lens  25 . 
     The tilt angle α is determined according to the predetermined geometry of the ophthalmic lens. The centre of gravity G of the part  23  of the ophthalmic lens and the vertical line L going through the centre of gravity G of said part  7  are also identified in  FIG. 2 d   . The tilt angle α is defined as the angle between the vertical line L going through the centre of gravity G of the part  23  of the ophthalmic lens and a direction perpendicular to the plane defined by the bearing surface. Said tilt angle α may be fixed during said step of manufacturing. Said tilt angle a corresponds to the optimal angle to prevent the concerned part (i.e. the first part  21 , the second part  23  or the third part  25 ) of the ophthalmic lens from collapsing or being deformed while being manufactured. As an example, in  FIGS. 2 a , 2 b  and 2 c   , the tilt angle a is substantially at 0°. 
     As an alternative, the shape and the orientation of the support  5  are continuously varied during the step of manufacturing. As an example, the tilt angle α is continuously modified during the step of manufacturing in order to prevent the part of the ophthalmic lens from collapsing or being deformed at each stage of manufacturing. 
     As another alternative, the support  5  lies in a resin bath while said part  7  of the ophthalmic lens is manufactured in order to reduce the impact of the gravity. This may for instance be the case when the part  7  of the ophthalmic lens is formed by hardening a resin. The part  7  of the ophthalmic lens is thus plunged into said resin bath. A layer of the resin is polymerised in an upper surface of the resin bath. The support  5  is moved down to polymerise another layer and so on until the ophthalmic lens is completely formed. 
       FIG. 3  shows a front view of a concave ophthalmic lens on a support according to this first exemplary embodiment. The final concave ophthalmic lens  25  comprises a peripheral region  31  and a useful optical surface  33 . The peripheral region  31  surrounds the useful optical surface  33 . The peripheral region  31  is considered as a non-useful optical surface. The support  5  sustains the final concave ophthalmic lens  25  contacting the peripheral region  31 . 
     As an example, the part  7  of the ophthalmic lens may contact the support  5  via a frangible portion (not shown in  FIG. 3 ) possibly made by additive manufacturing. The frangible portion secures the part  7  of the ophthalmic lens to the support  5  and eases later separation of the ophthalmic lens from the support  5 . 
       FIG. 4  schematically shows a front view of a convex ophthalmic lens on the support according to a second exemplary embodiment of the proposed manufacturing method. 
     As shown in  FIG. 4 , a final convex ophthalmic lens  45  comprises the peripheral region  31  and the useful optical surface  33 . As described previously for the concave ophthalmic lens, the support  5  sustains the final convex ophthalmic lens  45 , contacting the peripheral region  31 . However, in this case, the support  5  fits closely the peripheral region  31  of the ophthalmic lens. The support  5  has a shape which is complementary to the portion of the peripheral region  31 . 
       FIG. 5  schematically shows a side view of the final convex ophthalmic lens on the support according to the second exemplary embodiment. As shown in  FIG. 5 , the final convex ophthalmic lens is sustained by the support  5  by imbedding itself in the support  5 . The support  5  is contacting the final convex ophthalmic lens only via the peripheral region  31 . The useful optical surface  33  is free from any contact with the support  5 . 
     As an alternative, the contact between the part  7  of the ophthalmic lens via the peripheral region  31  and the support  5  is discontinuous. The ophthalmic lens further comprises a discontinuous linking portion between said part  7  of the ophthalmic lens and said support  5 . This continuous linking is adapted to easily remove the manufactured ophthalmic lens from the support. 
       FIG. 7  schematically shows a side view of a convex ophthalmic lens on a support according to a third exemplary embodiment of the invention. According to this embodiment, the stability of the ophthalmic lens being manufactured is realised thanks to a lattice framework  60 , as shown in  FIG. 7 . The lattice framework  60  maintains the part  7  of the ophthalmic lens being manufactured by being fixed on the peripheral region  31 . The useful optical surface  33  is free from any contact with the lattice framework  60 . The lattice framework  60  is adapted to prevent the part  7  of the ophthalmic lens from collapsing or being deformed while being manufactured. 
     The centre of gravity G of the part  7  of the ophthalmic lens is identified in  FIG. 7 . The vertical line L going through the centre of gravity G of said part  7  is also identified. The vertical line L intersects said bearing surface in order to prevent the part  7  of the ophthalmic lens from collapsing or being deformed while being manufactured. 
     In the present example, the support  5  is adapted to sustain a plurality of ophthalmic lenses while being manufactured. Only one support  5  sustains the plurality of ophthalmic lenses. As an alternative, the support  5  may be formed by an assembly of several individual supports, each part  7  of the plurality of the ophthalmic lenses being sustained by its own individual support. 
       FIG. 6  schematically shows a front view of multiple concave ophthalmic lenses sustained on the support  5  according to a fourth exemplary embodiment of the invention. The plurality of parts  7  of the ophthalmic lenses comprises the peripheral region  31  and the useful optical surface  33 . The support  5  is contacting the plurality of parts  7  of the ophthalmic lenses only via the peripheral region  31 . 
     The lattice framework  60  maintains the plurality of parts  7  of the ophthalmic lenses. 
       FIG. 8  schematically shows a front view of a concave ophthalmic lens on a support according to a fifth exemplary embodiment of the invention. This fifth embodiment corresponds to the manufacturing of the ophthalmic lens from the top to the bottom of the ophthalmic lens. As described in the previous embodiments, the final concave ophthalmic lens  25  also comprises the peripheral region  31  and the useful optical surface  33 . The support  5  upholds the final concave ophthalmic lens  25  contacting the peripheral region  31 . According to this embodiment, the support  5  is adapted to prevent the part  7  of the ophthalmic lens from falling down or being deformed while being manufactured. 
       FIGS. 9 a  and 9 b    schematically show a front view of a plurality of ophthalmic lenses at two different manufacturing stages according to a sixth embodiment of the invention. According to this sixth embodiment, the support  5  sticks to a tray  90 . The tray  90  is controlled by the control unit previously mentioned. The tray  90  is made of a durable material, such as metal. 
     According to this embodiment, the ophthalmic lens is manufactured from the top to the bottom. The support  5  and the part  7  of the ophthalmic lens are simultaneously manufactured by additive manufacturing. 
       FIG. 9 a    represents two first parts  91 ,  91 ′ of two ophthalmic lenses manufactured with the support  5  by the additive manufacturing technology at a first stage of the step of manufacturing. The two first parts  91 ,  91 ′ of the ophthalmic lenses comprise the peripheral region  31 ,  31 ′ and the useful optical surface  33 ,  33 ′. The support  5  is formed with an assembly of two individual supports  50 ,  51 . 
     The individual support  50  upholds the part  91  of the ophthalmic lens and the individual support  51  upholds the part  91 ′ of the ophthalmic lens. The support  5  is contacting the two first parts  91 ,  91 ′ of the ophthalmic lenses only via the peripheral region  31 ,  31 ′.  FIG. 9 b    shows the plurality of the ophthalmic lenses manufactured at a final stage of the step of manufacturing. The final ophthalmic lenses  95 ,  95 ′ are obtained from the first parts  91 ,  91 ′ by adding layers by additive manufacturing below the first parts  91 ,  91 ′. The final ophthalmic lens  95 ″ is completely manufactured after the manufacturing of the final ophthalmic lenses  95 ,  95 ′. The support  5  is adapted to uphold more than two ophthalmic lenses as shown in 
       FIG. 9 b   . The support  5  is formed by an assembly of several individual supports  50 ,  51 ,  52 . Each of the plurality of ophthalmic lenses is upheld by its own individual support  50 ,  51 ,  52 . Each individual support  50 ,  51 ,  52  contacts with each other, allowing the manufacturing of the plurality of the ophthalmic lenses in any direction. The plurality of ophthalmic lenses is manufactured at once. 
     The final ophthalmic lens is directly obtained from the proposed manufacturing method. The final ophthalmic lens comprises two opposite faces and an edge extending between the two faces. The peripheral region of the final ophthalmic lens comprises at least a portion of the edge and a portion of at least one of the two faces. 
     In practice, the final ophthalmic lens is configured to be mounted in a rim of a frame. The rim has an inner face. In this case, the edge of the ophthalmic lens, extending between the two faces, substantially matches the inner face of the rim.