Method for additively manufacturing an ophthalmic device and manufacturing system configured to carry out such a method

Abstract

The disclosure provides a method for additively manufacturing an ophthalmic device having at least a curved face, thanks to at least one inkjet print head having at least one nozzle, comprising providing a manufacturing file comprising parameters including a plurality of images, at least one image being defined by a network of voxels representative of a distribution of droplets of material for inkjet printing of the curved layer and being used for activating and deactivating the nozzle; wherein the at least one image is planar and determined as a function of curvature geometrical characteristics of the curved layer of the ophthalmic device to manufacture, of geometrical characteristics of a curved supporting surface onto which are deposited the droplets of material to at least partially form the curved layer, and of location parameters of the at least one inkjet print head relative to the curved supporting surface.

Description

[0001] Method for additively manufacturing an ophthalmic device and manufacturing system configured to carry out such a method

[0002] FIELD OF THE DISCLOSURE

[0003] The disclosure relates to a method for additively manufacturing an ophthalmic device and a manufacturing system configured to carry out such a method.

[0004] Such an ophthalmic device is usually to be worn by a wearer.

[0005] The disclosure also relates to a command and control unit including system elements configured to run a computer program in order to implement steps of the additive manufacturing method, and to a manufacturing system comprising such a command and control unit and configured for carrying out steps of such a method.

[0006] The disclosure also relates to a computer program including instructions configured to implement such an additive manufacturing method, when said computer program is run by a computer, and to a client-server communication interface for transferring to a remote computer at least manufacturing data which are determined by a computer program that implements steps of the additive manufacturing method, when said computer program is run in a command and control unit, the remote computer implementing the other steps of such method.

[0007] BACKGROUND ART

[0008] It is known to use an additive manufacturing technology to manufacture an ophthalmic device, such as spectacle lenses.

[0009] Known methods for additively manufacturing of ophthalmic lenses, such as stereolithography and its variants, comprise curing steps and layering steps which are performed successively in a manufacturing system which comprises a curing device, a layering device and a building platform located in relation to a vat filled with a predetermined material.

[0010] For instance, each ophthalmic lens is built layer by layer on the building platform which is movable relative to the vat including a volume of the predetermined material. The building platform is located in a predetermined position, the curing device including an irradiation source performs the curing step of a first layer of material, the layering device performs the layering step at least thanks to a displacement of the building platform so that a novel layer of material having a predetermined thickness can be cured, etc.

[0011] In other words, in such known methods, a curing step is performed on a layer which is for instance liquid for the plurality of ophthalmic lenses to be manufactured on the building platform. The liquid layer is thus hardened and next a layering step is performed for forming a new liquid layer on the previous hardened layer of the plurality of ophthalmic lenses to be manufactured.

[0012] Another method of additive manufacturing may comprise successively depositing droplets of liquid material and curing them in order to form layers of material. This method, usually called 3D-printing, or inkjet printing, generally controls the shape of the layers by controlling the position and volume of the deposited droplets whereas the curing step may be global or continuous during printing.

[0013] Other additive manufacturing methods may also be used.

[0014] In the above methods, a plurality of layers is formed in order to manufacture the ophthalmic device which often comprises at least a curved face, that is to say a face having a determined curvature, which can be simple or complex and in particular spherical and / or toroidal and / or of the freeform type.

[0015] Therefore, the layers may be planar or the layers may have a curved shape.

[0016] In this respect, and in particular in case of inkjet printing where the layers are deposited thank to nozzles on a predetermined substrate, depending on the predetermined shape of the layers and / or the shape of the substrate, distance between the nozzle and the substrate at any given point may not be constant, and a printing accuracy can vary.

[0017] International application WO 2024 / 039797 provides a method for producing an ophthalmic lens with an improved printing accuracy when printing non-flat layers.

[0018] In particular, WO 2024 / 039797 discloses a method for producing a three-dimensional optical structure, in particular an ophthalmic lens, wherein at least one layer is printed on a substrate by depositing droplets of printing ink at predetermined locations, wherein the droplets are ejected by at least one nozzle of a print head along a trajectory towards the predetermined locations, wherein the print head, in particular the at least one nozzle, is controlled such that a volume of at least one, in particular each, droplet is adjusted in dependence of the distance between the nozzle and the corresponding predetermined location, wherein in particular the volume is increased when the distance increases.

[0019] In other words, the droplets comprise a first volume if the distance between the nozzle and the corresponding predetermined location is smaller than or equal to a first threshold distance, while the droplets comprise a second volume if the distance between the nozzle and the corresponding predetermined location is greater than the first threshold distance and preferably smaller than or equal to a second threshold distance, the second volume being greater than the first volume.

[0020] It is also explained in WO 2024 / 039797 that when the distance between the nozzle and the predetermined location at which a droplet which is ejected at this position lands, i.e. is deposited, is very small, external influences are neglectable and the print head may be controlled such that the droplet comprises a first volume, which is preferably the ideal volume for high accuracy printing. In contrast, when the print head has been moved and the nozzle is located at a relatively high distance above the corresponding predetermined location for a droplet ejected at this position, a small droplet would be impacted by external influences and be subject to undesired effects. It is possible that during its flight along the trajectory, it nebulizes, i.e. breaks into a plurality of smaller sub-droplets, causing deviations on the trajectory and shift on deposition location and thus low printing accuracy. This is why the droplet volume is adjusted according to the distance between the nozzle and the location, and by choosing a second larger droplet volume, external influences are greatly reduced and accurate printing is achieved.

[0021] SUMMARY OF THE DISCLOSURE The disclosure is directed to a method for additively manufacturing an ophthalmic device, for instance by inkjet-printing, which is simple and convenient to carry out.

[0022] The disclosure accordingly provides a method for additively manufacturing an ophthalmic device having at least a curved face, thanks to at least one inkjet print head having at least one nozzle, comprising providing a manufacturing file comprising parameters including a plurality of images, at least one image being defined by a network of voxels representative of a distribution of droplets of material for inkjet printing of at least partially a curved layer of the ophthalmic device and being used for activating and deactivating the at least one nozzle of the at least one inkjet print head.

[0023] The at least one image is planar and determined as a function of curvature geometrical characteristics of the curved layer of the ophthalmic device to manufacture.

[0024] The at least one image is planar and determined also as a function of both geometrical characteristics of a curved supporting surface onto which are deposited the droplets of material to at least partially form the curved layer, and location parameters of the at least one inkjet print head relative to the curved supporting surface.

[0025] In the method according to the disclosure, the at least one image used for the inkjet printing of the curved layer thus takes into account the fact that the network of voxels is defined on a planar representation while the deposited layer is curved, in relation to the location of the print head relative to the curved supporting surface.

[0026] Indeed, the planar representation has a smaller area than the area of the curved supporting surface and the area of the curved layer as such, thus implying something like an area difference parameter.

[0027] Thanks to the method according to the disclosure, it is possible to control accurately the inkjet printing of the curved layer of the ophthalmic device to manufacture on the curved supporting surface, by taking into account not only the droplets of material locally but rather in relation with other adjacent droplets of material, either adjacent side by side or adjacent by superposition, along the curved supporting surface.

[0028] Therefore, the method according to the disclosure may allow to provide, thanks to the technology of 3D-inkjet printing, an ophthalmic device having a homogeneous deposition of the droplets of material despite the curved deposition, for instance without accumulation at some locations and without removal at some other locations.

[0029] The at least one image is planar and determined also as a function of slipping parameters representative of a variable, or non-uniform, deposition of the droplets of material to at least partially form the curved layer on the curved supporting surface, the slipping parameters being determined at least as a function of material properties and of the geometrical characteristics of the curved supporting surface.

[0030] In addition, in the method according to the disclosure, the at least one image used for the inkjet printing of the curved layer thus takes into account the fact that the network of voxels is deposited on the curved supporting surface, and that the droplets of material ejected by the nozzle can slip along the curved supporting surface at the moment of contact with the “underlying layer”, or shift after the deposition, due to gravity or slope, and the deposition of material can vary or can be non-uniform compared to a deposition on a planar surface.

[0031] Considering the adjacent voxels on the image or the adjacent droplets of material of the curved layer on the curved supporting surface of the substrate, allows to take into consideration a phenomenon according to which the droplets of material deposited by the nozzle which is located remote to the curved supporting surface are moving and can slip from a determined location to another location, due to at least one of the material properties, the geometrical characteristics of the curved supporting surface and the location of the print head relative to the curved supporting surface.

[0032] It is to be noted that the curved supporting surface can be formed by a substrate on which is deposited the curved layer, or by a previous curved layer of the ophthalmic device already deposited by inkjet printing. The substrate can form a starting optical element of the ophthalmic device, the subsequent deposited curved layer being thus added according to a so-called build-over technology, or the substrate can define a support which is then released from the ophthalmic device.

[0033] The manufacturing file may include geometrical characteristics of a sliced ophthalmic device which are representative of the layers to be built.

[0034] A slice may comprise one or several images, each representative of the voxels distribution to be ejected by the at least one nozzle.

[0035] In the voxels distribution, the voxels may have determined sizes, determined heights, determined widths, and thus determined volumes, the voxels being similar or being different in each image.

[0036] It is to be noted that such an ophthalmic device is usually to be worn by a wearer.

[0037] The ophthalmic device can be for instance a part of a spectacle lens, a smart eyewear, a visor, or a mask, etc.

[0038] Advantageous and convenient features of the manufacturing method are described below.

[0039] The method may comprise a step of generating the manufacturing file.

[0040] The geometrical characteristics of the curved supporting surface may comprise local slopes at determined locations of the curved supporting surface where droplets of material are to be deposited, as defined in the at least one planar image.

[0041] The method may comprise a step of determining corrective parameters based on the curvature geometrical characteristics of the curved layer, the geometrical characteristics of the curved supporting surface and the location parameters of the at least one inkjet print head relative to the curved supporting surface; and / or determining the slipping parameters.

[0042] The material properties may comprise the material properties of the droplets, including resin properties, and / or the material properties of the curved supporting surface, including surface energy.

[0043] The corrective and / or slipping parameters may further be determined as a function of at least one inkjet print parameters, including firing speed of the droplets of material, distances, and / or orientation, between nozzle and determined locations of the curved supporting surface where droplets of material are to be deposited, and contact angle of the droplets of material at said determined locations, for instance depending on the trajectory of the droplets ejected by the inkjet print head.

[0044] The corrective and / or slipping parameters may comprise a determined thickness profile representative of corrective print parameters, including a determined distribution of drop density and / or a determined distribution of drop volume.

[0045] The determined thickness profile may depend on the curvature geometrical characteristics of the curved layer of the ophthalmic device to manufacture, including convexity or concavity.

[0046] The network of voxels defining the at least one planar image may be representative of a first thickness of material, while the curved layer of the ophthalmic device to manufacture and defined by the distribution of droplets of material may be representative of a second thickness of material different to the first thickness.

[0047] At least one of the first thickness and second thickness may be variable.

[0048] The at least one image of the manufacturing file is obtained by combining parameters representative of the curved layer of the ophthalmic device to manufacture, and corrective parameters representative of both the curved supporting surface and the location parameters of the at least one inkjet print head relative to the curved supporting surface.

[0049] In particular, the at least one image of the manufacturing file may be obtained by combining a first image representative of the curved layer of the ophthalmic device to manufacture, and a corrective image including corrective parameters representative of the above corrective parameters and for instance also of the slipping parameters and applied to data of the first image, so that to obtain the network of voxels of the at least one image.

[0050] Determining the above corrective parameters and / or slipping parameters may comprise inkjet printing and / or simulating inkjet printing at least a reference curved layer on a reference curved supporting surface, measuring geometrical characteristics of the reference curved layer obtained by inkjet printing or simulating, comparing measured geometrical characteristics to predetermined geometrical characteristics and deducing corrective and / or slipping parameters representative of the variable or non-uniform deposition of the droplets of material to form the reference curved layer on the reference curved supporting surface.

[0051] The method may further comprise generating and / or providing a database including, for predetermined curved layers made of predetermined materials to be formed on predetermined curved supporting surfaces also made of predetermined materials, associated corrective and / or slipping parameters representative of the variable or non-uniform deposition of the droplets of material to at least partially form the predetermined curved layers on the predetermined curved supporting surface.

[0052] The manufacturing file may comprise further images representative of a distribution of voxels or a distribution of droplets for inkjet printing at least partially further layers or sub-layers of the ophthalmic device and being used for activating and deactivating the at least one nozzle of the at least one inkjet print head, the further layers including at least a filtering layer distinct to the at least one curved layer and having a thickness comprised between 1 pm and 100 pm, so that to act as a levelling layer.

[0053] The manufacturing file may comprise further parameters including curing characteristics.

[0054] The method may comprise a step of curing at least partially the at least one curved layer of the ophthalmic device based on the provided manufacturing file.

[0055] The inkjet printing of the at least one curved layer and the curing of said layer may be performed at least partially alternatively and / or successively.

[0056] The at least one curved layer may comprise several sub-layers of similar or different thicknesses, depending on the determined thickness profile.

[0057] The sub-layers may be at least partially juxtaposed and / or at least partially superimposed. The sub-layers may be inkjet printed at least partially simultaneously and / or at least partially successively.

[0058] The step of inkjet printing the at least one curved layer may be performed with print properties which can be fixed or variable during inkjet printing.

[0059] The print properties may comprise an ink material and / or a drop density and / or a drop volume and / or a drop viscosity and / or a drop ejection speed, equated to the firing speed of droplets.

[0060] The print properties may also comprise a print head resolution corresponding to a radial resolution of the print head which is defined at least as a function of the number and the arrangement of the nozzles.

[0061] The manufacturing file may comprise parameters further including positioning data of the ophthalmic device and / or of the at least one inkjet print head, which are determined depending on the at least one nozzle and / or on the curvature geometrical characteristics of the at least one curved face and / or on the geometrical characteristics of the curved supporting surface.

[0062] The method may comprise a step of positioning the ophthalmic device and / or the at least one inkjet print head based on the manufacturing file.

[0063] The disclosure also provides, according to a second aspect, a command and control unit including system elements configured to run a computer program in order to additively manufacture an ophthalmic device having at least a curved face, thanks to at least one inkjet print head having at least one nozzle, by providing a manufacturing file comprising parameters including a plurality of images, at least one image being defined by a network of voxels representative of a distribution of droplets of material for inkjet printing of at least partially a curved layer of the ophthalmic device and being used for activating and deactivating the at least one nozzle of the at least one inkjet print head; wherein the at least one image is planar and determined as a function of curvature geometrical characteristics of the curved layer of the ophthalmic device to manufacture, of geometrical characteristics of a curved supporting surface onto which are deposited the droplets of material to at least partially form the curved layer, and of location parameters of the at least one inkjet print head relative to the curved supporting surface.

[0064] The disclosure further provides, according to a third aspect, a manufacturing system comprising an inkjet printer comprising at least one inkjet print head having at least one nozzle and a command and control unit, the system being configured for additively manufacturing an ophthalmic device having at least a curved face, by providing to the inkjet printer a manufacturing file comprising parameters including a plurality of images, at least one image being defined by a network of voxels representative of a distribution of droplets of material for inkjet printing of at least partially a curved layer of the ophthalmic device and being used for activating and deactivating the at least one nozzle of the at least one inkjet print head; wherein the at least one image is planar and determined as a function of curvature geometrical characteristics of the curved layer of the ophthalmic device to manufacture, of geometrical characteristics of a curved supporting surface onto which are deposited the droplets of material to at least partially form the curved layer, and of location parameters of the at least one inkjet print head relative to the curved supporting surface.

[0065] The disclosure also provides, according to a fourth aspect, a computer program including instructions configured to cause a manufacturing system and / or a command and control unit to additively manufacture an ophthalmic device having at least a curved face, thanks to at least one inkjet print head having at least one nozzle, by determining a manufacturing file comprising parameters including a plurality of images, at least one image being defined by a network of voxels representative of a distribution of droplets of material for inkjet printing of at least partially a curved layer of the ophthalmic device and being used for activating and deactivating the at least one nozzle of the at least one inkjet print head; wherein the at least one image is planar and determined as a function of curvature geometrical characteristics of the curved layer of the ophthalmic device to manufacture, of geometrical characteristics of a curved supporting surface onto which are deposited the droplets of material to at least partially form the curved layer, and of location parameters of the at least one inkjet print head relative to the curved supporting surface, when said computer program is run by a computer.

[0066] The disclosure further provides, according to a fifth aspect, a clientserver communication interface for transferring to a remote computer at least a manufacturing file for additively manufacturing an ophthalmic device having at least a curved face, the manufacturing file being determined by a computer program when said computer program is run in a command and control unit of the client-server communication interface and comprising parameters including a plurality of images, at least one image being defined by a network of voxels representative of a distribution of droplets of material for inkjet printing of at least partially a curved layer of the ophthalmic device and being used for activating and deactivating the at least one nozzle of the at least one inkjet print head; wherein the at least one image is planar and determined as a function of curvature geometrical characteristics of the curved layer of the ophthalmic device to manufacture, of geometrical characteristics of a curved supporting surface onto which are deposited the droplets of material to at least partially form the curved layer, and of location parameters of the at least one inkjet print head relative to the curved supporting surface, the remote computer being configured to cause a manufacturing system to implement inkjet printing the at least one curved layer of the ophthalmic device.

[0067] BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The description of the disclosure now continues with a detailed description of embodiments given hereinafter by way of non-limiting example and with reference to the appended drawings.

[0069] Figure 1 is a schematic view of a manufacturing system configured to carry out a method for additively manufacturing ophthalmic devices.

[0070] Figure 2 diagrammatically shows a client-server communication interface comprising system parts configured for transferring at least one manufacturing file determined by the method according to the disclosure to a remote data processing system.

[0071] Figure 3 shows another view of the manufacturing system illustrated in Figure 1 . Figure 4 is a schematic view showing some steps for additively manufacturing ophthalmic devices thanks to an inkjet printer of the manufacturing system.

[0072] Figure 5 is another schematic view showing a representation of a planar image obtained from a slicing in Figure 4 for the inkjet printing of a curved layer of the ophthalmic device, in comparison to a representation of the curved layer when deposited on a curved supporting surface.

[0073] Figure 6 is a block diagram showing steps of the method for additively manufacturing an ophthalmic device according to the disclosure.

[0074] Figure 7 is a block diagram showing further steps of the method.

[0075] Figure 8 shows images having different voxels distributions and details thereof.

[0076] DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0077] The disclosure is directed to a method and a manufacturing system for additively manufacturing by inkjet printing an ophthalmic device having at least one curved face and formed by at least one or several curved layers of material.

[0078] Figure 1 illustrates schematically a manufacturing system 1 configured to carry out a method for additively manufacturing ophthalmic devices 5, such as for instance spectacle lenses.

[0079] More generally, the ophthalmic device is usually to be worn by a wearer and can be for instance a part of spectacles or other eyewear’s, such as a part spectacle lens, a smart eyewear, a visor, or a mask, etc.

[0080] The ophthalmic device 5 has for instance a predetermined optical function and is made from at least one predetermined material, such as liquid resin.

[0081] The manufacturing system 1 comprises an additive unit also called additive manufacturing module, which is here formed by an inkjet printer 2 configured for projecting volumes of the predetermined material in the shape of droplets.

[0082] The manufacturing system 1 further comprises system parts generally formed by at least one command and control unit 3 configured to communicate with a data processing system (or control unit) of the inkjet printer 2 and configured to run a computer program having instructions configured to implement at least some steps of the method, when said computer program is run by a computer.

[0083] The inkjet printer 2 comprises one or a plurality of inkjet print heads 6 configured to project the predetermined material, for instance as droplets or in jets of droplets, and at least one curing device 4 including for instance an irradiation source configured for curing the droplets of material previously projected.

[0084] Droplets that are deposited concurrently and that are adjacent and thus in direct contact may merge to form the layer or a part of the layer.

[0085] The inkjet print heads 6 may comprise a plurality of nozzles located in a determined arrangement, for instance along a predetermined length and a predetermined width, so that to define one or a plurality of groups of adjacent nozzles.

[0086] The inkjet printer 2 may comprise a data processing system or a control unit (not shown) configured for controlling at least the inkjet print heads 6 and the curing device 4.

[0087] The command and control unit 3 comprises a microprocessor 7 having a memory 8, in particular a non-volatile memory, allowing it to load and store the computer program, also called software, which when it is executed in the microprocessor 7, allows the implementation of the method according to the disclosure and thus the use of the inkjet printer 2.

[0088] This non-volatile memory 8 is for example of the ROM (“read only memory”) type.

[0089] The command and control unit 3 further comprises a memory 9, in particular a volatile memory, allowing data to be stored during the execution of the software and the implementation of the method.

[0090] This volatile memory 9 is for example of the RAM or EEPROM type (respectively "random access memory" and "electrically erasable programmable read only memory”).

[0091] The command and control unit 3 may be only at least partially integrated into the inkjet printer 2. In other words, the command and control unit 3 may be arranged in part, or in whole, outside the inkjet printer 2. In particular, the command and control unit 3 may comprise one or a plurality of command and control modules located inside and / or outside the inkjet printer 2.

[0092] The inkjet printer 2 is here configured at least for the inkjet printing of the ophthalmic device 5, layer by layer, each layer being formed by a volume of the predetermined material, and for curing the volumes of material in order to polymerize and harden the layers and thus to form the ophthalmic device 5.

[0093] At least one or several of the layers are curved and deposited on a curved supporting surface, either formed by a substrate or by a previous deposited layer.

[0094] In this respect, the command and control unit 3 is also configured to command and control at least some of steps of an additive manufacturing method described below at least in reference to Figures 6 and 7.

[0095] Figure 2 shows a client-server communication interface 10 comprising for instance a so-called supplier-side 11 a and another, so-called client-side 11 b, and these two sides communicating via for instance an internet interface 12.

[0096] The supplier-side 11 a comprises a supplier server 13a linked to a data processing system or a command and control unit 3a of the same type as that in Figure 1 , this server 13a being configured to communicate with the internet interface 12.

[0097] The client-side 11 b also comprises a client server 13b which is configured to communicate with the internet interface 12, and which is linked to a data processing system or a command and control unit 3b of the same type as that of the supplier-side .

[0098] In addition, the command and control unit 3b on the client-side 11 b is linked to an inkjet printer 2b of the same type as that in Figure 1 , and is configured to additively manufacture at least a curved layer of the ophthalmic device on a curved supporting surface.

[0099] For instance, the command and control unit 3a on the client-side 11 b is configured for receiving some parameters including curvature geometrical characteristics of the curved layer of the ophthalmic device, geometrical characteristics of a curved supporting surface onto which are deposited the droplets of material to at least partially form the curved layer, location parameters of the at least one inkjet print head relative to the curved supporting surface, and / or slipping parameters representative of a variable or non-uniform deposition of droplets of material to at least partially form the curved layer on the curved supporting surface.

[0100] For instance, the parameters about the ophthalmic device may include geometrical characteristics, including curvature geometrical characteristics of the curved layer(s) of the ophthalmic device, and / or optical function, which may include a 3D file representative of the ophthalmic device (such as CAD files, STL files or other) and / or images defined by networks of voxels representative of a distribution of droplets of material for inkjet printing the layers of the ophthalmic device and used for activating and deactivating the nozzles of the inkjet print head(s), and / or other ophthalmic properties of an ophthalmic surface of the ophthalmic device 5b intended to be manufactured, and / or at least one information representative of intrinsic parameter of a material of the ophthalmic device.

[0101] For instance, the parameters about the curved supporting surface, about the location of the inkjet print head with regard to the curved supporting surface and / or about slipping issue, may include material properties and / or geometrical characteristics of the curved supporting surface, such as surface energy and / or local slopes including slope value and slope direction from a centre of the curved supporting surface at determined locations of the curved supporting surface, and / or orientation of the local slope with regard to an expected trajectory of the droplets ejected by the inkjet print head.

[0102] For instance, the command and control unit 3a on the client-side 11 b is configured for receiving also some parameters about the inkjet print heads include information representative of the status of each print head, such as a number of nozzles and / or a geometrical arrangement of the nozzles, in addition to the location parameters thereof relative to the curved supporting surface.

[0103] The command and control unit 3b on the client-side 11 b, using the internet interface 12 and both client server 13b and supplier server 13a, sends at least some data received by the command and control unit 3b on the client-side 11 b, to the command and control unit 3a on the supplier-side 11 a for the determination of a manufacturing file representative of operational parameters, including images defined by networks of voxels representative of the distribution of droplets of material for inkjet printing the curved layer of the ophthalmic device 5 on the curved supporting surface, the network of voxels being determined by taking into account the shape of the device to manufacture, the fact that the image is a planar representation having a smaller area than the area of the curved supporting surface and the area of the curved layer as such, and / or also the fact that the droplets of material ejected by the nozzle can slip along the curved supporting surface and the deposition of material can be non-uniform compared to a deposition on a planar surface.

[0104] It is to be noted that the image can be representative of a planar projection of a curved surface, having a smaller or a similar area than the curved surface.

[0105] In other words, a first local area on the image can be different to a first corresponding local area on the curved surface. In particular, the first local area on the image can be lower than the first corresponding local area on the curved surface due to the curvature of the curved surface, and also due to the location of the inkjet print head because the projection of the first corresponding local area on the inkjet print head is also smaller than the first corresponding local area as such and can vary depending on the orientation of the inkjet print head.

[0106] The command and control unit 3a on the supplier-side 11 a executes the computer program that it contains in order to determine the manufacturing file.

[0107] Using the supplier server 13a and the internet interface 12, the command and control unit 3a on the supplier-side 11a sends the manufacturing file to the command and control unit 3b on the client-side 11 b.

[0108] The command and control unit 3b on the client-side 11 b is here configured to execute software for implementing the other steps of the manufacturing method for manufacturing by inkjet printing the ophthalmic device thanks to the inkjet printer 2b. In an alternative embodiment, a step of determining the manufacturing file can be carried out by the command and control unit 3b on the client-side 11 b.

[0109] In another alternative embodiment, the inkjet printer 2b can be located on the supplier-side 11 a so that the command and control unit 3a on the supplierside 11 a is further configured to inkjet print the ophthalmic device.

[0110] Figure 3 illustrates schematically the inkjet printer 2 which carries out the method for additively manufacturing the ophthalmic device 5 formed by curved layers 17 and delimited by an external surface 14.

[0111] The inkjet print heads 6 of the inkjet printer 2 have each a plurality of nozzles 15 from which the predetermined material is projected in jets of droplets 16, or stream, to form the curved layers 17 of the ophthalmic device 5, which are then cured by the curing device 4.

[0112] The curved layers 17 are each deposited on the curved supporting surface which can be formed by an upper face 18a of a support member 18, also called substrate, or by a previous layer 17 already deposited.

[0113] A jet of droplets, or stream, includes droplets which can be considered as being a volume of at least one material devoid of tail or satellite, whether such tail or satellite actually happens.

[0114] Each print head 6 has a predetermined number of nozzle(s) 15 and a predetermined arrangement thereof. The nozzles 15 can be activated or deactivated.

[0115] For instance, each inkjet print head 6 may comprise nozzles 15 arranged in juxtaposed rows thus defining a predetermined length and a predetermined width.

[0116] The command and control unit 3 may also be configured to command and control the inkjet print heads 6 and in particular, a print head resolution corresponding to a radial resolution of the inkjet print heads 6 which is defined at least as a function of the number and the arrangement of the nozzles 15.

[0117] The command and control unit 3 may be configured to command and control activation and / or deactivation of each nozzle 15 and also each nozzle firing frequency if any.

[0118] The nozzle firing frequency can be variable or fixed. The nozzle firing frequency may depend at least on geometrical characteristics of the ophthalmic device 5 to be manufactured and / or on the location, including for instance tilting and radial shifting relative to a manufacturing axis MA, of the inkjet print heads 6, thus determining and varying the location of the inkjet print head relative to the curved supporting surface.

[0119] The inkjet printer 2 is here located on an upper side of the support member 18 and is configured to build successively the superimposed curved layers 17 on the support member 18.

[0120] The first curved layer 17 is thus built over the curved supporting surface defined by the upper face 18a of the support member 18, while the subsequent curved layers 17 are built over the already deposited curved layers 17 so that a subsequent curved layer 17 is deposited onto the curved supporting surface defined by the immediate under curved layer 17.

[0121] The command and control unit 3 may be configured to locate the inkjet print heads 6 at a distance value selected among a plurality of distance values from the support member 18.

[0122] The distance value is comprised between a minimum height according to which the predetermined material is able to forms droplets and a maximum height according to which the droplets of predetermined material are deposited accurately on the support member 18.

[0123] The support member 18 can be able to rotate around a rotation axis corresponding to the manufacturing axis MA and the inkjet print heads 6 and the support member 18 can be able to be inclined one relative to each other and / or the inkjet print heads 6 can be able to be inclined relative to the manufacturing axis MA.

[0124] In this respect, the command and control unit 3 may also be configured to command and control a tilt angle of the inkjet print heads 6 and the support member 18 one relative to each other, and a rotation speed of the support member 18 around the manufacturing axis MA, if any.

[0125] It is to be noted that the variable locations of the inkjet print heads 6 may generate a variable difference of areas between the image and the curved supporting surface and are thus taken into account in the images defined by the networks of voxels representative of the distribution of droplets of material for inkjet printing the curved layer of the ophthalmic device.

[0126] In addition, the command and control unit 3 may be configured to command and control a print resolution of the inkjet print heads 6, which comprises a process resolution corresponding to an angular resolution which is defined at least as a function of nozzles firing frequency, and the print head resolution as defined above.

[0127] As stated above, the inkjet printer 2 is configured to perform inkjet printing of the curved layers 17 thanks to parameters from the manufacturing file, thus defining a so-called sliced ophthalmic device 5, and in particular the plurality of images each representative of the determined networks of voxels.

[0128] To be noted that each layer 17 may correspond to one or several images.

[0129] Figure 4 shows schematically slicing of the ophthalmic device 5 to be manufactured.

[0130] In particular, the ophthalmic device 5 has its external surface 14 which is defined by a first face 14a, also-called front face which is here convex, and a second face 14b, also-called back face which is here concave and opposite to the first face 14a.

[0131] The ophthalmic device 5 is at least partly divided into slices 19 from the second face 14b to the first face 14a.

[0132] In the case the ophthalmic device 5 is entirely built by inkjet printing on the support member 18, the slices 19 form the entire ophthalmic device 5, and the support member 18 is then removed.

[0133] In an alternative, the ophthalmic device 5 is divided into slices 19 for at least a part between the second face 14b to the first face 14a, in particular in the case where only a part of the ophthalmic device 5 is built by inkjet printing. In this respect, the slices 19 are built over the support member 18 which is a part of the ophthalmic device 5. The support member 18 is thus a substrate which forms a starting optical element of the ophthalmic device 5.

[0134] The slices 19 are representative of both the layers 17 which are curved and the images 20 which are planar. In particular, each slice 19 may comprise one or several planar images 20, each representative of the material distribution to be ejected in jets of droplets 16 by the selected nozzles 15 of the inkjet print heads 6 towards the curved supporting surface of the support member 18 and / or towards the curved supporting surface of the previous layers 17 already deposited.

[0135] Indeed, each image 20 is used for activating and deactivating at least some nozzles 15 of the inkjet print heads 6, according to a predetermined trajectory followed by the inkjet print heads 6 so as to form the curved layer.

[0136] To be noted that, as explained above, the trajectory followed by the inkjet print heads is generally not parallel to the curved supporting surface, so that it is important to take into account location parameters of the inkjet print heads relative to the curved supporting surface.

[0137] Figure 5 shows the representation of the planar image 20 obtained from the slicing in Figure 4 for the inkjet printing of the curved layer 17, in comparison with the representation of the curved layer 17 when deposited on the curved supporting surface formed here by the upper face 18a of the support member 18. Of course, the curved supporting surface can be formed by the upper face of the previous deposited curved layer 17.

[0138] Figure 5 shows that the network of voxels defining the planar image 20 is a planar representation having a smallest area than the area of the curved supporting surface and the area of the curved layer 17.

[0139] According to the disclosure, this first feature is taken into consideration when determining the image 20 (as explained below).

[0140] In addition, the network of voxels defining the planar image 20 is representative of a first thickness of material, while the curved layer 17 defined by the distribution of droplets of material is representative of a second thickness of material different to the first thickness.

[0141] The first thickness and the second thickness can be different one to each other.

[0142] One or both of the first thickness and the second thickness may be variable. For instance, the first thickness can be variable and at least partially greater than the second thickness, while the second thickness is constant.

[0143] In alternative, the first thickness can for instance be constant and at least partially smaller than the second thickness, so that to obtain a variable second thickness.

[0144] This second feature is also taken into consideration when determining the image 20 (as also explained below).

[0145] It is to be noted that the planar image 20 can be determined directly or by combining a first image representative of the curved layer 17 and determined without taken into consideration the first feature and / or the second feature discussed above, and a second corrective image including corrective parameters and / or slipping parameters, and applied to data of the first image, so that to obtain the network of voxels of the planar image 20 representative of the distribution of droplets of material for inkjet printing the curved layer 17, taking into consideration the first feature and / or the second feature discussed above.

[0146] It is to be noted also that the images 20 can be determined thanks to at least one mathematical function such as linear, power, polynomial, exponential, logarithmic, sinusoidal, etc., used alone or in combination.

[0147] Each curved layer 17 can thus be defined by one or a plurality of planar images 20, depending on the curvature geometrical characteristics of the curved layer 17, on the corrective parameters determined as a function of the curvature geometrical characteristics of the curved layer, of geometrical characteristics of the curved supporting surface and of location parameters of the inkjet print heads relative to the curved supporting surface; and / or on the slipping parameters determined at least as a function of material properties and of geometrical characteristics of the curved supporting surface, and / or on print properties and / or on the print resolution and / or on the process resolution defined above.

[0148] The print properties may comprise an ink material and / or a drop density and / or a drop volume and / or a drop viscosity and / or a drop ejection speed equated to a firing speed.

[0149] In addition, in the voxels network which defines the planar image 20, the voxels may have determined sizes, determined heights, determined widths, and thus determined volumes, the voxels being similar or being different in each image, reminding that the network of voxels is representative of the distribution of droplets of material.

[0150] Figure 6 is a block diagram showing the main steps of the method 100 for additively manufacturing the ophthalmic device, the method 100 being carried out thanks to the manufacturing system 1 as described above.

[0151] The method 100 comprises a step of generating and / or providing 101 the manufacturing file representative of the operational parameters, including the planar images 20 as described above.

[0152] The manufacturing file may comprise parameters including positioning data of the ophthalmic device 5 and / or of the inkjet print heads 6, including location parameters thereof relative to the curved supporting surface, which are determined depending on the selected nozzles 15; and parameters including curing characteristics.

[0153] It is to be noted that the manufacturing file may comprise several subfiles including one or several of the above-mentioned parameters and data.

[0154] The method 100 may further comprise a step of positioning 102 the ophthalmic device 5, thanks to the support member 18, and / or the inkjet print heads 6, one relative to the other and also in relation to the manufacturing axis MA, based on dedicated parameters in the generated and / or provided manufacturing file.

[0155] The method 100 further comprises a step of inkjet printing 103 at least the curved layers 17 of the ophthalmic device 5 on the support member 18, based on dedicated parameters in the generated and / or provided manufacturing file.

[0156] The step 103 of inkjet printing the curved layers 17 may comprise substeps of inkjet printing, performed at least partially simultaneously and / or at least partially successively, for instance to make sub-layers at least partially juxtaposed and / or at least partially superimposed.

[0157] In other words, the curved layer can be made thanks to several passages of the inkjet print heads, each passage allowing to form a sub-layer which merge with the previous or subsequent sub-layer so as to form the curved layer. In addition, the step 103 of inkjet printing the curved layers 17 may be performed with print properties, similar to each other, or different.

[0158] The print properties can be fixed or variable during inkjet printing.

[0159] The method 100 further comprises a step of curing 104 at least partially the curved layers 17 of the ophthalmic device 5 based on dedicated parameters in the generated and / or provided manufacturing file.

[0160] It is to be noted that the curing step may be done only when the whole curved layer is inkjet printed, or after each sub-layers if any, or after a partial deposition of a sub-layer. Of course, the curing applied to a sub-layer may render this sub-layer integrated to the underneath sub-layers, thus forming a layer as such.

[0161] At least some steps of the method 100 can be performed iteratively. For instance, the position of the support member 18 and / or of the inkjet print heads 6 can change, and / or the curing can be performed after each curved layer 17 built or after several layers or sub-layers, etc.

[0162] Figure 7 describes further steps for generating the manufacturing file according to step 101 .

[0163] In particular, the method may comprise a step 111 of receiving material properties, such as surface energy, geometrical characteristics of the curved supporting surface, such as shape, curvature and / or local slopes at determined locations on the curved supporting surface, and location parameters such as relative position between the inkjet print head and the curved supporting surface.

[0164] The method may comprise a step 112 of receiving geometrical characteristics, including curvature geometrical characteristics, of the curved layer(s), and material properties of the droplet material, including ink or resin properties such as viscosity, for the inkjet printing of the curved layer(s).

[0165] The method may comprise a step 113 of providing and / or determining the inkjet print parameters including firing speed of the droplets of material, trajectory of the print head relative to the curved supporting surface (or plan of print head if the trajectory is planar), distances between nozzle and determined locations of the curved supporting surface where droplets of material are to be deposited, and contact angle of the droplets of material at said determined locations.

[0166] The inkjet print parameters may be determined at least as a function of the data received in steps 111 and 112.

[0167] The method may comprise a step 114 of determining corrective parameters based on the data received in steps 111 to 114, and the slipping parameters representative of a variable or non-uniform deposition of the droplets of material to at least partially form the curved layer on the curved supporting surface.

[0168] In this respect, the corrective parameters and / or the slipping parameters may be determined at least as a function of the material properties and of the geometrical characteristics of the curved supporting surface, and / or as a function of the inkjet print parameters, including at least one amongst the firing speed of the droplets of material, the distances between nozzle and determined locations of the curved supporting surface where droplets of material are to be deposited, and the contact angle of the droplets of material at said determined locations, and / or as a function of the location and orientation of the curved supporting surface with regard to either or both of gravity and intended axis of trajectory of droplets ejected from the inkjet print head.

[0169] Determining the corrective parameters and / or slipping parameters may comprise determining a thickness profile representative of corrective print parameters, including a determined distribution of drop density and / or a determined distribution of drop volume.

[0170] Such determined thickness profile may depend on the curvature geometrical characteristics of the curved layer of the ophthalmic device to manufacture, including convexity or concavity.

[0171] For instance, if the curved layer is convex, the thickness profile may be determined so that to be thinner on edges than on centre of the convex curved layer, due to the slipping of the material towards the edges.

[0172] In contrast, if the curved layer is for instance concave, the thickness profile may be determined so that to be thicker on edges than on centre of the concave curved layer, due to the slipping of the material towards the centre. It is to be noted that the step 114 of determining the corrective parameters and / or slipping parameters may be done by simulations and / or by tests.

[0173] In particular, determining corrective parameters and / or slipping parameters may comprise the step 115 of inkjet printing and / or simulating inkjet printing at least a reference curved layer on a reference curved supporting surface, then measuring geometrical characteristics of the reference curved layer obtained by inkjet printing or simulating, then comparing measured geometrical characteristics to predetermined geometrical characteristics, and then deducing corrective parameters and / or slipping parameters representative of the variable or non-uniform deposition of the droplets of material to form the reference curved layer on the reference curved supporting surface.

[0174] The steps 114 and 115 of determining the corrective parameters and / or slipping parameters may also be carried out thanks to a dedicated database or predetermined table.

[0175] In particular, the method may further comprise a step 116 of generating and / or providing a database including, for predetermined curved layers made of predetermined materials to be formed on predetermined curved supporting surfaces also made of predetermined materials, associated corrective parameters and / or slipping parameters.

[0176] The method may comprise a step 117 of determining the planar image(s) 20 as a function of both the curvature geometrical characteristics of the curved layer 17 to manufacture, the corrective parameters described above, and / or the slipping parameters.

[0177] As stated below, the planar image 20 can be determined directly or by combining a first image representative of the curved layer 17 and determined without taken into consideration the corrective parameters and / or the slipping parameters, and a second corrective image including the corrective parameters and / or the slipping parameters and applied to data of the first image, so that to obtain the network of voxels of the planar image 20 representative of the distribution of droplets of material for inkjet printing the curved layer 17. Figure 8 shows two planar images 20a and 20b having different network of voxels, including image 20a representing a drop volume gradient between a layer’s core 17a and a layer’s edge 17b; and image 20b representing drop density gradient between the layer’s core 17a and the layer’s edge 17b, both being also representative of different thickness profiles.

[0178] In the method according to the disclosure, the at least one planar image used for the inkjet printing of the curved layer thus takes into account the fact that the network of voxels is deposited on a curved supporting surface, and also the fact that part of the material deposited by the droplets of material ejected by the nozzle can slip along the curved supporting surface and the deposition of material can be further non-uniform compared to a deposition on a planar surface.

[0179] In addition, in the method according to the disclosure, the at least one planar image used for the inkjet printing of the curved layer thus takes into account the fact that the network of voxels is defined on a planar representation while the deposited layer is curved, because the planar representation has a smaller area than the area of the curved supporting surface and the area of the curved layer as such, and that such difference in area is inhomogeneous along the curved layer, leading to a variable thickness deposition if not taken into account.

[0180] Thanks to the method according to the disclosure, it is possible to control accurately the inkjet printing of the curved layer of the ophthalmic device to manufacture on the curved supporting surface, by taking into account not only the droplets of material locally but rather in relation with other adjacent droplets of material, either adjacent side by side or adjacent by superposition, along the curved supporting surface.

[0181] Indeed, considering the adjacent voxels on the image or the adjacent droplets of material of the curved layer on the curved supporting surface of the substrate, allows to take into consideration a phenomenon according to which the droplets of material deposited by the nozzle which is located remote to the curved supporting surface are moving and can slip from a determined location to another location, due to at least the material properties and the geometrical characteristics of the curved supporting surface. In an embodiment, the manufacturing file may comprise further images representative of a distribution of voxels or a distribution of droplets for inkjet printing at least partially further layers or sub-layers of the ophthalmic device and being used for activating and deactivating the at least one nozzle of the at least one inkjet print head.

[0182] The further layers may include at least a filtering layer distinct to the at least one curved layer, and having a thickness comprised between 1 pm and 100 pm, so that to act as a levelling layer on the curved layer.

[0183] Therefore, the method according to the disclosure may allow to provide, thanks to the technology of 3D-inkjet printing, an ophthalmic device having a most homogeneous deposition of the droplets of material despite the curved deposition, for instance without accumulation at some locations and without removal at some other locations.

[0184] It should be noted more generally that the disclosure is not limited to the examples described and represented.

Claims

CLAIMS1. Method for additively manufacturing an ophthalmic device (5) having at least a curved face (17), thanks to at least one inkjet print head (6) having at least one nozzle (15), comprising providing (101 ) a manufacturing file comprising parameters including a plurality of images (20), at least one image being defined by a network of voxels representative of a distribution of droplets of material for inkjet printing of at least partially a curved layer of the ophthalmic device and being used for activating and deactivating the at least one nozzle of the at least one inkjet print head; wherein the at least one image is planar and determined as a function of curvature geometrical characteristics of the curved layer of the ophthalmic device to manufacture, of geometrical characteristics of a curved supporting surface onto which are deposited the droplets of material to at least partially form the curved layer, and of location parameters of the at least one inkjet print head relative to the curved supporting surface.

2. Method according to claim 1 , wherein the at least one image is planar and determined also as a function of slipping parameters representative of a variable, or non-uniform, deposition of the droplets of material to at least partially form the curved layer on the curved supporting surface, the slipping parameters being determined at least as a function of material properties and of the geometrical characteristics of the curved supporting surface.

3. Method according to claim 2, wherein the geometrical characteristics of the curved supporting surface comprise local slopes at determined locations of the curved supporting surface where droplets of material are to be deposited, as defined in the at least one planar image (20); and / or wherein the material properties comprise the material properties of the droplets, including resin properties, and / or the material properties of the curved supporting surface, including surface energy.

4. Method according to one of claims 2 and 3, wherein the slipping parameters are further determined as a function of at least one inkjet print parameters, including firing speed of the droplets of material, distances between the at least one nozzle (15) and determined locations of the curved supporting surface where droplets of material are to be deposited, and contact angle of the droplets of material at said determined locations.

5. Method according to any one of claims 1 to 4, comprising determining corrective parameters and / or slipping parameters, comprising a determined thickness profile representative of corrective print parameters, including a determined distribution of drop density and / or a determined distribution of drop volume.

6. Method according to claim 5, wherein the determined thickness profile depends on the curvature geometrical characteristics of the curved layer (17) of the ophthalmic device (5) to manufacture, including convexity or concavity.

7. Method according to any one of claims 1 to 6, wherein the network of voxels defining the at least one planar image (20) is representative of a first thickness of material, while the curved layer (17) of the ophthalmic device (5) to manufacture and defined by the distribution of droplets of material is representative of a second thickness of material different to the first thickness.

8. Method according to claim 7, wherein at least one of the first thickness and second thickness is variable.

9. Method according to any one of claims 1 to 8, wherein the at least one image (20) of the manufacturing file is obtained by combining parameters representative of the curved layer (17) of the ophthalmic device (5) to manufacture, and corrective parameters representative of both the curved supporting surface and the location parameters of the at least one inkjet print head relative to the curved supporting surface.

10. Method according to any one of claims 1 to 9, comprising determining corrective parameters and / or slipping parameters by inkjet printing and / or simulating inkjet printing at least a reference curved layer on a reference curved supporting surface, measuring geometrical characteristics of the reference curved layer obtained by inkjet printing or simulating, comparingmeasured geometrical characteristics to predetermined geometrical characteristics and deducing corrective parameters and / or slipping parameters representative of the variable or non-uniform deposition of the droplets of material to form the reference curved layer on the reference curved supporting surface.

11. Method according to claim 10, comprising generating and / or providing a database including, for predetermined curved layers made of predetermined materials to be formed on predetermined curved supporting surfaces also made of predetermined materials, associated corrective parameters and / or slipping parameters.

12. Method according to any one of claims 1 to 11 , wherein the manufacturing file comprises further images representative of a distribution of voxels or a distribution of droplets for inkjet printing at least partially further layers or sub-layers of the ophthalmic device and being used for activating and deactivating the at least one nozzle of the at least one inkjet print head, the further layers including at least a filtering layer distinct to the at least one curved layer and having a thickness comprised between 1 pm and 100 pm, so that to act as a levelling layer.

13. A command and control unit including system elements configured to run a computer program in order to additively manufacture an ophthalmic device (5) having at least a curved face (17), thanks to at least one inkjet print head (6) having at least one nozzle (15), by providing a manufacturing file comprising parameters including a plurality of images (20), at least one image being defined by a network of voxels representative of a distribution of droplets of material for inkjet printing of at least partially a curved layer of the ophthalmic device and being used for activating and deactivating the at least one nozzle of the at least one inkjet print head; wherein the at least one image is planar and determined as a function of curvature geometrical characteristics of the curved layer of the ophthalmic device to manufacture, of geometrical characteristics of a curved supporting surface onto which are deposited the droplets of material to at least partially form the curved layer, and of location parameters of the at least one inkjet print head relative to the curved supporting surface.

14. A manufacturing system comprising an inkjet printer (2) comprising at least one inkjet print head (6) having at least one nozzle (15) and a command and control unit (3), the system being configured for additively manufacturing an ophthalmic device (5) having at least a curved face (17), by providing to the inkjet printer a manufacturing file comprising parameters including a plurality of images (20), at least one image being defined by a network of voxels representative of a distribution of droplets of material for inkjet printing of at least partially a curved layer of the ophthalmic device and being used for activating and deactivating the at least one nozzle of the at least one inkjet print head; wherein the at least one image is planar and determined as a function of curvature geometrical characteristics of the curved layer of the ophthalmic device to manufacture, of geometrical characteristics of a curved supporting surface onto which are deposited the droplets of material to at least partially form the curved layer, and of location parameters of the at least one inkjet print head relative to the curved supporting surface.

15. A client-server communication interface for transferring to a remote computer at least a manufacturing file for additively manufacturing an ophthalmic device (5) having at least a curved face (17), the manufacturing file being determined by a computer program when said computer program is run in a command and control unit (3a, 3b) of the client-server communication interface (10) and comprising parameters including a plurality of images (20), at least one image being defined by a network of voxels representative of a distribution of droplets of material for inkjet printing of at least partially a curved layer of the ophthalmic device and being used for activating and deactivating the at least one nozzle of the at least one inkjet print head; wherein the at least one image is planar and determined as a function of curvature geometrical characteristics of the curved layer of the ophthalmic device to manufacture, of geometrical characteristics of a curved supporting surface onto which are deposited the droplets of material to at least partially form the curved layer, and of location parameters of the at least one inkjet print head relative to the curved supporting surface, the remote computer being configured to cause a manufacturing system to implement inkjet printing the at least one curved layer of the ophthalmic device.

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