Patent Application
20200033634
The present invention relates to lenses, and in particular to a method for designing a plurality of lenses, a process for producing the same, lenses obtained by means of such design or process, and a computer for performing such design or assisting in the production process.
A lens is usually obtained either by a molding process or by machining it from a so called blank. As known in the art, a blank is a unit or physical body made of a material suitable for lenses and obtained for instance by means of a molding process. The lens is obtained from the blank by means of a machine, which removes material from the blank until a lens is obtained having surfaces with desired optical properties. Both surfaces of the lens can be obtained by removing material from the blank, or only one lens surface in case the other lens surface coincides with one of the blank surfaces.
It is usual to obtain one single lens from one single blank by following a process including steps like:
Step A) Receiving prescription data for a wearer (also indicated as RX);
Step B) Generating, on the basis of the prescription data, lens surface data in the form of (typically) a point-by-point file representing a model for the physical lens surface(s) to be obtained from the blank; the step of generating is substantially a step of processing, in which also very complex functions are processed in view of constraints represented by the prescription to obtain the surface(s) matching the prescription data;
Step C) Programming a CNC (Computer Numeric Control) machine on the basis of the point-by-point model data;
Step D) Machining the semi-finished lens. In particular, machining includes running the (correspondingly programmed) CNC machine to physically generate the surface from the semi-finished lens. Subject to machining tolerances, programming errors, etc., the physical surface is as much as possible close to the point-by-point surface previously obtained by processing.
Step E) The machining is followed by other conventional steps, like for instance polishing (i.e. rendering the surface smoother), placing protective layers, etc.
A large number of different ways exist for performing the above, aimed at matching the prescription data or at optimizing different parameters like for instance wearer's preferences or other design parameters.
Conventional methods for obtaining lenses are described for instance in U.S. Pat. No. 7,980,920 or in “Freeform lenses”, parts 1 to 3, by Paul Bullock, Hoya, and more in particular part 2 retrievable at:
https://s3-eu-west-1.amazonaws.com/rbi-communities/wp-content/uploads/importedimages/freeform-lenses-part-2.pdf
Despite all possible differences, one common point to known prior art methods lies in that one single semi-finished lens (one single blank) is used for producing one single final lens. This concept has been typically considered not only simple, but also appropriate, effective, and necessary for producing lenses, and as such widely followed.
Despite the above common practice, the inventors have recognized a need for improving prior art techniques especially when wanting to obtain a plurality of lenses.
It is conceivable to obtain two lenses from a single blank, for instance by generating the surface(s) of each lens and programming the CNC machine to remove material from one single blank in order to obtain the physical surfaces of the two lenses. The two lenses can then be separated from each other. Such solution could be conveniently achieved by using a method as above described, for instance by obtaining data for right and left lens surfaces, programming the CNC machine on the basis of the left and right desired lens surfaces, and producing the final lenses by removing material from the single blank in correspondence of the areas or volumes of the blank from which the two lenses are derived. The inventor has however recognized that such solution is not easy to obtain in practice, or at least not effective and efficient, also when using advanced tooling machines, and surely not viable when wanting to use less advanced tooling machines.
One of the objects of invention is thus to improve existing techniques for obtaining lenses, in particular when wanting to obtain a plurality of lenses preferably from a single lens blank.
Further aspects of the invention are as follows.
said lens surface data comprises data representing at least one surface for each of said at least two lens units,
said junction surface data comprises data representing at least one junction surface joining respective surfaces of said at least two lens units, and
the integrated surface data represents a physical surface that is to be obtained by machining one single semi-finished lens.
wherein the first set surface data and the second set surface data are arranged along a longitudinal direction of the semi-finished lens.
wherein the first set surface data and the second set surface data are arranges along a longitudinal direction of the blank.
The present invention will now be described in conjunction with specific embodiments by making reference to the drawings. It is however noted that these specific embodiments as well as the illustrative figures serve to provide the skilled person with a better understanding of the invention but are not intended to restrict in any way the scope of the invention which is defined by the independent claims.
With reference to
At step S20, the method foresees generating, on the basis of the lens specification information, integrated surface data comprising lens surface data and junction surface data. The lens surface data comprises data representing at least one surface for each of the at least two lens units. The junction surface data comprises data representing at least one junction surface joining respective surfaces of the at least two lens units.
The integrated surface data represents a physical surface that is to be obtained by machining one single semi-finished lens (also SFL, in short). In other words, the integrated surface data is a model of (thus, it represents) the physical surface that is to be generated by means of a tooling machine. Since the integrated surface comprises also the junction surface, it follows that the machine will process the semi-finished lens also in correspondence of such junction surface. In other words, the machine will remove material, as necessary, from the SFL also in correspondence of the junction surface. This is different from another conceivable (see above introduction to the invention) technique according to which each of the lenses is modeled without modeling the surface joining the same, wherein each of the lenses is obtained by removing material from the SFL without any consideration of the junction surface. It is noted that using one single SFL for producing multiple advantages is advantageous in many ways, e.g. stocking of less blanks is needed, material of each blank can be best used, number of different types of blanks can be reduced. By semi-finished lens it is herein meant a physical body from which one or more lenses can be obtained. Herein, semi-finished lens is also interchangeably used as blank. In this sense, the blank may (but not necessarily) have one surface already finished, or may have both surfaces that need to be processed in order to obtain the final lens.
The generating step S20 can be a single step for obtaining lens surface data and junction surface data together, e.g. it may be a single processing operation or routine; or it may comprise multiple steps or processing routines for obtaining lens surface data and junction surface data, which are then combined together into the integrated surface data.
As said, step S20 generates the integrated surface data on the basis of the lens specification information. This should however be understood as that the lens specification information may influence only the generation of the lens surface data, i.e. the junction surface is not necessarily influenced by the lens specification information. Nevertheless, the junction surface data may be generated in a certain way depending on the surface data obtained as a result of the processing, as also later explained in certain examples of optimization. In other words, the lens specification information need not necessarily define constraints that must be met by the junction surface. At the same time, it is possible to impose constraints on the junction surface, like for instance minimum length of such surface (i.e. minimum distance between two lens surfaces), certain degree of curvature, certain gradient of curvature, etc. The constrains for the junction surface may be included in the lens specification information, such that the integrated surface is calculated on such basis.
The data included in the integrated surface data (as well in the lens surface data and/or junction surface data) can be in the form of a set of points describing a surface (e.g. in rectangular or polar coordinates), or parameters of a function describing such surface(s), or a function or combinations of functions describing such surface(s).
Step S20 of generating the integrated surface data includes generating such data using any free form method, or in general any (also very complex) mathematical modelling suitable for describing lens surfaces and a suitable junction surface joining the two lens surfaces. Also, calculating the surface data may comprise calculating for each of said at least two lens units data representing at least one respective surface on the basis of specification information for the respective lens unit (when noting that the specification may be given for one lens, and derived for the other(s); also, the lens specification may be absent for one lens, if this is not supposed to exhibit any specific property). Importantly, it is not required to generate or model both surfaces of each of the plurality of lenses. In fact, in case one surface of the lens is directly found on the SFL, then that surface does not need to be modeled since it does not need to be machined from the lens: for instance, if one surface of the SFL is provided with the addition power specified by the lens specification, the corresponding surface of the lenses do not need to be modeled, being that coincident with the surface of the SFL (or, in alternative, that model may be made coincident with the known surface, or parts thereof, of the SFL). Evidently, this may apply to any of the inner or outer surfaces of one or more of the plurality of lenses. Reference is made for instance to
By the way, for inner surface of a lens it is here meant the surface of the lens facing the eyeball; for outer surface of the lens it is here meant the surface of the lens facing the object, and thus the inner and outer surfaces are opposing each other. Also, inner surface and outer surface are herein also interchangeable with backward (eyeball side) surface and, respectively, forward (object side) surface.
A semi-finished lens is an optical body obtained typically by molding, and typically by mass-production in a factory, and is available in a range of sizes and/or parameters. For instance, the SFL may be a block of material suitable for obtaining lenses and having a cylindrical shape or any other solid shape. The SFL may also have one surface exhibiting certain properties, e.g. exhibiting addition power on a given surface, and/or a given spherical power, etc. The SFL is also called semi-finished lens blank or simply blank.
Reference will now be made to
One technical advantage of such design lies in that it is easier for the tooling machine to work the SFL. In fact, the machine can operate its tool(s) as if only one single surface (corresponding to 500I) is to be machined/obtained, rather than commanding the tool towards two areas 50L and 50R separated from each other. In the latter case, for instance, the tool would need to work on the right side lens, then move away from the SFL (e.g. detaching the tool from the SFL), and finally work on the left side lens (the order could be different of course). Thus, the junction surface is a surface, or contains at least an area along which the tooling does not need to be detached when processing the blank to obtain the surface When using the integrated surface 500I, instead, the machine can more freely decide how to machine the SFL, such that its operation is optimized. In other words, it can be said that the integrated surface 500I represents a model for right lens surface, left side surface, and gap or junction surface; this is in contrast to having two separate surfaces separately modelling left and right lenses. That is, and preferably, the tool needs not necessarily to detach from the SFL when machining areas 50L and 50R, since, in view of the integrated surface 500I, the tool can machine the SFL as if it was a single surface instead that different surfaces.
It is noted that the surface 57L can be made coincident with 50L, e.g. by resizing the junction surface to include all (left sided) areas except 50L, or by making surface 50L as close as possible to area 55, or both. Similar considerations apply to the right side.
Once the machine has worked the SFL to obtain a surface corresponding to 500I, the two lenses can be detached from the obtained surface, in order to obtain lenses 52L and 52R. The obtained lenses can then undergo further processing including polishing.
However, it may be advantageous performing other operations including polishing before cutting out lenses 52L and 52R from the machined integrated surface. One advantage lies in fact that it would be sufficient to polish (or perform other operations) on one workpiece only (the physical integrated surface corresponding to 500I) rather than on two workpieces 52L and 52R. This would make such operation quicker, since for instance only one mounting operation instead of two would be required.
The junction surface may comprise a continuous surface. Such surface may continuously join the lens surfaces, in the sense that it continuously extends from one lens surface to at least another lens surface.
Optionally, the continuous surface is a surface for which at least a first partial derivative exists in at least some of its points, and wherein preferably said at least first partial derivative is different than zero. By partial derivative, it is meant a derivative according to one variable, the variable being represented by any one of the coordinates chosen as reference (e.g. x, y, or z for a rectangular coordinate system; similarly for a polar coordinate system). Further preferably, the junction surface can be differentiable in all its points, or in a large part of its points, e.g. in at least 50% of its points. In fact, it has been noted that by requesting the junction surface to be differentiable, the smoothness of the junction surface increases, rendering the machining operations easier and more efficient to carry out. By increasing the number of points on which the derivative is possible, and preferably different than zero, the machining is simplified and made possible with a wider range of cutting and/or polishing machines.
Optionally, the continuous surface is a surface for which at least a second order partial derivative exists in at least some of its points, and wherein preferably said at least second partial derivative is different than zero. Optionally, the second order derivative exists, and is preferably different than zero, in all the points of the junction surface. Optionally, the surface is differentiable along more than one or in all variables/reference axes; or in a large part of its points, e.g. in at least 50% of its points. The more the points and/or axes along which the second derivate exist, and preferably different than zero, the more convenient is to use and control existing machines to produce multiple lenses from one blank. In fact, by having a second order derivative, it has been found that a very wide range of machining tolls (virtually all those presently used) can easily process the SFL, and a very wide range of polishing machines (virtually all those presently used) can work on the SFL to easily produce and finish a plurality of finished lenses.
In the optional steps from S410 to S430, the SFL is machined in order to produce a physical surface corresponding to the integrated surface data. The production step is independent from the design step(s). In fact, it is conceivable that the design is made first to produce design data including the integrated surface data. Such data can be sent to another party, which may independently produce such lenses. In an example, the design can be made by an optic design lab, and the production by an optic production lab. Both of them may be within the same facility, or remote to each other.
The method of the present embodiment and its variant may optionally comprise a step (not illustrated in the figures) of selecting a semi-finished lens amongst a solid shaped semi finished lens unit, a semi finished lens unit having the inner surface exhibiting given inner properties, and a semi finished lens unit having the outer surface exhibiting given outer properties. More in general, the SFL can be optionally selected on the basis of the lens specification information. In fact, depending on the specification, leading e.g. to certain curvatures, a bigger or smaller SFL may be selected, or depending on the surface of the lens an SFL may be selected showing the required properties. Alternatively or in addition, the SFL may be selected depending on certain requirements of the machines to be used.
Optionally, the step of generating the lens surface data as above illustrated may comprise an optimization processing of the data representing at least one surface of each of said at least two lens units on the basis of the semi-finished lens unit, in particular (i.e. optionally) so that the at least two lens units fit within the single semi-finished lens unit. As exemplified in
Optionally, in fact, the above described optimization processing includes at least one amongst rotating and translating the model representations of at least one of the lens units over the other and/or over the semi-finished lens unit so that the at least two lens units fit in the semi-finished lens unit. For instance, in
Optionally, the above described step of generating the lens surface data comprises an optimization processing including an alignment processing of data representing at least one surface of said at least two lens units so that each of said at least one surface is aligned to a respective surface of the semi-finished lens. The alignment may be explained as that a plane representative of the lens is parallel to a plane representative of the SFL. The plane representative of the lens may be a plan orthogonal to the lens in the z direction, and passing along a representative point of the lens in the z direction; the representative point can be the middle point in the z direction of the lens. The representative plane of the SFL can be a plane passing through center line of the SFL, a plane coincident with an outer plane surface of the SFL, or tangent to an outer surface of the SFL, etc.
Optionally, the above described step of generating may comprise generating the junction surface data on the basis of the optimization processing. It can be said that once the two surfaces of the two lenses have been placed, then the joining surface can be calculated. In this example, in fact, first the lens surfaces are calculated (in the form of surface data) in view of the optimization, and then the junction surface is calculated to join the surfaces as above described. In case certain properties are wished for the junction surface, e.g. a certain order of derivatives (see above), the calculation may comprise a series of iterations, i.e. (re)calculating the lens surface data and the junction surface data a plurality of times until all requirements are met. The method can also foresee a (re)selection of the SFL, in combination with the optimization and with the optimization iterations, so as to maximize usage of the SFL volume, or having sufficient distance between lens surfaces, etc.
With reference to
In step S430, the at least two lenses are machined from a single semi-finished lens unit on the basis of the integrated surface data generated in step S420. Any type of machining can be used. For instance, non-rotation type machining can be used wherein the SFL (representing the workpiece for the machine) is not rotated, and a relative movement between tool and SFL ensures removing the material (e.g. the tool is moved along the SFL in order to remove material therefrom; the tool may or may not be rotating, and the trajectory may be of any type). Also, as a further example, also rotation type machining can be used. For instance the SFL (workpiece) is turned, while the working tool WT operates moves to remove material (following e.g. any trajectory). In this example, the tool may or may not turn, depending on the used machining. The type of machines used can be a 3-axis, 4-axis, 5-axis (or any axis) CNC machine, preferably with synchronized axis. Machining includes milling, lathing, etc. Machining the SFL includes also finishing the SFL, for instance polishing the SFL by any known polishing machine.
Thanks to the integrated surface, a very wide range of existing machines can be used to machine the SFL in order to easily obtain the plurality of lenses. For instance, a 3-axis machine can be used, which otherwise without the integrated surface would not be able to accurately machine the SFL. Furthermore, even if a 5-axis could be considered suitable for producing the plurality of lenses without the integrated surface, with the latter it would be able to more efficiently produce the same. Significantly, the use of integrated surface allows the use of virtually all existing polishing machines, which could otherwise not be suitable to polish two lenses obtained from an SFL when having for instance a non-machined gap between them. Importantly, as previously noted, the higher order derivatives on the joining surface significantly facilitates the operations especially of the polishing machines. One advantage of polishing the two lenses together, i.e. in the state of the entire surface corresponding to the integrated surface data, is that it is not necessary to block and execute a polishing operation for each lens; this can be done for the entire surface in one blocking and polishing operation (by blocking, it is meant the operation wherein a workpiece to be polished is blocked by a jig tool suitable for holding the workpiece while the same undergoes polishing).
It is also noted that step S430 is not limited to a working process by removal of material, but also includes processes based on addition of material like 3D printing.
The machining step S430 may be based on programming data, in turn based on the integrated surface data, or coincident with the integrated surface data, see also what has been mentioned above.
As anticipated, the step production method of this embodiment may comprise a step of polishing the at least two lenses obtained by machining. In particular, the step of polishing may be part of the step of machining in one example, or may be separated in another example.
Optionally, the method of the present embodiment comprises a step of separating from the single semi-finished lens unit the at least two lens units obtained by polishing. Preferably, this is done after polishing the lenses when they are still hold together by the joining surface.
According to a third embodiment, it is provided a computer program for designing lens units, the computer program comprising instructions suitable to execute, when the program is executed on a computer, any of the steps described in correspondence of the first embodiment and/or its variants.
A fourth embodiment provides a computer program for controlling the production of at least two lens units from a single semi-finished lens unit, the computer program comprising instructions configured to execute, when the program is executed on a computer, any of the steps of the second embodiment and its variants above described. For the computer, the same considerations made above apply here.
According to a fifth embodiment, lens units are provided that are obtained or obtainable from a single semi-finished lens by a design method according to the above embodiments (and variants) or above process(es) and variants. In fact, it is noted that multiple lenses obtained from a single SFL according to the herein described methods and processes result in high accuracy and higher degree of polishing (and thus transparency) since the machines can more easily and efficiently work, thus leading to an improved plurality of lenses obtained from a single SFL.
According to a sixth embodiment, it is provided a system for the production of at least two lens units from a single semi-finished lens unit, the system comprising a computing entity suitable for performing any of the above method(s) or process(es) and corresponding variants, and a machine suitable for machining the at least two lenses from a single semi-finished lens unit on the basis of integrated surface data as above described. The computer entity comprised in such system can one as described in above third and/or fourth embodiments.
A seventh embodiment will now be illustrated with reference to the flow chart of
In step S1410, lens specification information are obtained.
In step S1420, a first set of lens units is selected, the first set comprising a first plurality of lens units from the plurality of lens units. Thus, the plurality of lens units according to this embodiment is three or more, and the first set comprises at least two lens units.
In step S1430, first set surface data is generated (S1430) on the basis of the lens specification information, for the first set of lens units. The first set surface data comprises data describing at least one surface of each of the lens units of the first set. In other words, starting from the lens specification information, a model for at least one surface for each of the lenses of the first set is calculated. The result of the modelling is represented by the data, the data being in any of the forms previously illustrated. The surface data thus represents the surface that is to be obtained by machining from a single SFL.
In step S1440, at least the first set of lens units is obtained from one single SFL on the basis of the first subset surface data. To be more exact, lens units are physically obtained, the obtained lens units corresponding to the models of the first set of lens units. The step S1440 of obtaining comprises any machining step, including any finishing step like polishing, see also above discussions.
Optionally, the process may include a step (not illustrated) of selecting a second set of lens units comprising a second plurality of lens units from the plurality of lens units. Then, in an optional additional step, a second set surface data is generated on the basis of the lens specification information, for the second set of lens units. The second set surface data comprises data describing at least one surface of each of the lens units of the second set. The first set surface data and the second set surface data are preferably arranged along a longitudinal direction of the semi-finished lens (more in general, they are arranged along one axis of the SFL).
The (first, second, etc.) subset surface data represents a physical surface that is to be obtained by machining one single semi-finished lens. When more subset surface data relating to different sets are combined, the resulting data also represents a physical surface that is to be obtained by machining one single semi-finished lens. Also, the subset surface data may include a junction surface; in such case, also the junction surface will be physically obtained, as also described in the above embodiments.
As mentioned, the first subset data may model only one of the two surfaces of each of the lens. With reference to
Optionally, the first set surface data further comprises data describing a junction surface joining respective surfaces of said lens comprised in said first set of lenses. Though not shown in
Optionally, the second set surface data further comprises data describing a junction surface joining respective surfaces of said lens comprised in said second set of lenses. In particular, two or more sets of lenses may each comprise a joining surface. Integrated surface data may be generated for each set, or integrated surface data may comprise data corresponding to two or more sets.
According to the present embodiment, obtaining may comprise machining all lenses of the first set (e.g. S1), and machining all lenses of the second set (e.g. S2) after the lenses of the first set have been obtained.
Also, for obtaining any machining is intended, including by removal of material or addition of material. Also, machining comprises finishing, like for instance polishing as a way to give transparency to the previously processed material.
According to an eight embodiment, it is provided a computer program for controlling a computing entity capable of obtaining lens units, the computer program comprising instructions that, when executed by the computing entity, cause the computing entity to perform a steps of obtaining lens specification information for said plurality of lens units. The instructions further cause obtaining a first set of lens units comprising a first plurality of lens units from the plurality of lens units, and generating, on the basis of the lens specification information, for said first set of lens units, first set surface data comprising data describing at least one surface of each of the lens units of the first set. Furthermore, the instructions cause obtaining the at least first set of lens units from said one semi-finished lens unit on the basis of said first subset surface data. The instructions causing the obtaining include controlling a tooling machine in order to obtain the lenses.
Optionally, the computer program comprises instructions causing the computing entity to perform the steps of obtaining a second set of lens units comprising a second plurality of lens units from the plurality of lens units, and generating, on the basis of the lens specification information, for the second set of lens units, second set surface data comprising data describing at least one surface of each of the lens units of said second set. The first set surface data and the second set surface data are arranged along a longitudinal direction of the blank, e.g. along axis z depicted in
Optionally, the computer program comprises instructions for obtaining comprise machining all lenses of the first set, and machining all lenses of the second set after the lenses of the first set have been obtained.
According to a ninth embodiment, lens units are provided that are obtained or obtainable from a single semi-finished lens by a design method according to the above seventh and eight embodiments (and variants) or above process(es) and variants.
According to a further embodiment, a system is provided for the production of a plurality of lens units from a single semi-finished lens unit, the system comprising a computing entity suitable for executing a computer program according to the eight embodiment (and its variants), and a machine suitable for machining the plurality of lenses from a single semi-finished lens unit on the basis of surface data as described above (e.g. of the first and/or any other set of lenses; with or without respective junction surfaces; any variants thereof).
Examples will now be described for facilitating the functioning of the invention and its embodiments. For instance,
Moreover,
In step S1130, an output surface data file is obtained, for instance in a rectangular coordinates and in a “rectangular shape”. The output surface data file may thus comprise the integrated surface data above described. Next to step S1130, there are provided an example for an integrated surface with two lenses, and an example for four lenses with corresponding junction surfaces.
In step S1140, a SFL (or blank, in the figure also BLK) is selected. For instance, a flat blank is selected; as an alternative, a meniscus like blank may be selected, for instance having one or both curved surfaces having respectively different curvatures. Next to step S1140, it is provided an illustration of two lenses obtained by machining both opposite surfaces of the blank, and (see right sided picture) a case wherein only one side of the blank is machined. In fact, in the latter illustration, one side of the lenses coincides with the outer side of the blank, such that it is not necessary to remove material therefrom in order to complete the lenses.
In step S1150, an optimization process may be carried out, for instance to optimize the regular lens shape data; and/or to optimize the alignment of lenses relative to the blank. The alignment process may be a calculation for the 3-dimensional lens shape in order to achieve a specific alignment within the blank. The pictures next to block S1150 show for instance the case where plus lenses are optimized in the sense that they are aligned to the convex surface of the blank; the right picture shows the case wherein minus lenses are aligned to the concave surface of the blank.
In step S1160, the integrated surface may be generated. Preferably, the integrated surface comprises a continuous junction surface, i.e. a model for a continuous gap between the lens surfaces. Also the junction surface is thus a surface to be machined. In the example of step S1160, the integrated surface is generated after the optimization processing, though this is not strictly necessary as above described.
The data thereby obtained can be given to a CNC machine, or translated into a programming file suitable for a certain CNC machine. As a consequence, the machine can process the blank in order to produce a physical surface corresponding to the calculated model. Once the material has been removed from the blank, the obtained physical integrated surface can be easily polished. With a smooth junction (e.g. differentiable) several types of polishing machines can be used. In particular, also a 3-axis polishing machine can be conveniently used. When the junction surface is a second order differentiable surface (in at least a part of its points), then polishing can be very accurately and efficiently executed also by means of an unsophisticated polishing machine.
The right and left lenses can be separated from each other once polishing in completed (though they can be separated after the material has been removed, and before polishing—in such case the advantage is still given in that a wide range of material removing machines can be efficiently used).
It is noted that the lens surface data can be seen as data referring to surfaces that need to exhibit optical properties. The junction surface is a surface that does not necessarily need to exhibit optical properties. In fact, it is mainly calculated so as to give a certain degree of continuity and preferably differentiability to the area joining the optical surfaces.
In case of a continuous junction surfaces, it is possible to perform mirror processing also with a wider range of (material removing) machines. Without a continuous junction surface, mirror processing is difficult even with 5-axis machines (the difficulty being higher with larger areas of discontinuity within the junction surface) or not at all possible with less sophisticated machines. Moreover, the degree of continuity and differentiability advantageously render polishing possible and effective with a very wide range of machines, virtually those presently known.
It will be apparent to those skilled in the art that various modifications and variations can be made in the entities, methods, systems, computer programs and signals (carrying instructions for executing the program) of the invention as well as in the construction of this invention without departing from the scope or spirit of the invention. The invention has been described in relation to particular embodiments and examples which are intended in all aspects to be illustrative rather than restrictive. Those skilled in the art will appreciate that many different combinations of hardware, software and firmware will be suitable for practicing the present invention, which scope and spirit is defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 16191389.2 | Sep 2016 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/036401 | 9/29/2017 | WO | 00 |
