Patent Application
20250180923
Various aspects of this disclosure generally relate to the field of calculation modules and methods to select a semi-finished lens blank destined to manufacture a lens intended to be mounted in a frame of an eyewear.
The
The lens L1 or L2 and the frame F, more precisely the rims R1 or R2 receiving the lens must be adapted together. This adaptation must allow the lens L1 or L2 to be removably attached to the frame F. Generally, the user chooses the frame F according to aesthetic considerations and the lenses must be adapted to the parameters of the frame F.
When a user gets a new eyewear, during the consumer journey, the selection of a frame F is a key step. After that, the determination of the parameters of the lenses is usually driven by the user's optical needs, or simple base-curve matching between the frame F and the lenses L1 and L2. Base-curve matching is a method on which the base-curve of the lens is chosen as a base-curve close to the base of the frame F. However, the Eye Care Professional ECP has to evaluate the aesthetics of the final eyeglass by choosing the best possible combination of several input parameters to order the lenses. These combinations are numerous and will lead to different aesthetic solutions. Evaluating the absolute aesthetics of each combination can be difficult without a deep knowledge.
There is a need for a calculation module and method for adapting the parameters of the lens, more precisely to select a semi-finished lens blank destined to manufacture the lens intended to be mounted in a preselectionned frame F.
The following presents a simplified summary in order to provide a basic understanding of various aspects of this disclosure. This summary is not an extensive overview of all contemplated aspects and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. The sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.
One aspect of this disclosure is a calculation module comprising a memory and a processor. The calculation module is configured to select an adapted semi-finished lens blank among a plurality of semi-finished lens blanks for manufacturing an ophthalmic lens to be mounted in a frame of an eyewear. The eyewear is intended to be worn by a user. The calculation module is configured to determine a geometrical parameter value of the ophthalmic lens to be manufactured from a test semi-finished lens blank of the plurality, the geometrical parameter value of the ophthalmic lens depending on a base-curve of the test semi-finished lens blank, a refractive index of the test semi-finished lens blank, a prescription of the user and/or a characteristic parameter value of the frame. The calculation module can also be configured to select the adapted semi-finished lens blank based on the geometrical parameter value of the ophthalmic lens.
The adapted semi-finished lens blank is one of the plurality allowing the geometrical parameter value of the ophthalmic lens to be within a range of geometrical parameter values.
Another aspect of this disclosure is a computer implemented method, for selecting an adapted semi-finished lens blank among a plurality of semi-finished lens blanks for manufacturing an ophthalmic lens to be mounted in a frame of an eyewear. The eyewear is intended to be worn by a user. The computer implemented method comprises a step of determining a geometrical parameter value of the ophthalmic lens to be manufactured from a test semi-finished lens blank of the plurality, the geometrical parameter value of the ophthalmic lens depending on a base-curve of the test semi-finished lens blank, a refractive index of the test semi-finished lens blank, a prescription of the user and/or a characteristic parameter value of the frame. The computer implemented method can also comprise a step of selecting the adapted semi-finished lens blank based on the geometrical parameter value of the ophthalmic lens.
The adapted semi-finished lens blank is one of the plurality allowing the geometrical parameter value of the ophthalmic lens to be within a predetermined range of the geometrical parameter values.
For a more complete understanding of the description provided herein and the advantages thereof, reference is now made to the brief descriptions below, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.
The detailed description set forth below in connection with the appended drawings is intended as a description of various possible embodiments and is not intended to represent the only embodiments in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.
The lenses or ophthalmic lenses L1 and L2 comprise a front face and a rear face. The rear face of the lens is the face of the lens facing the user when the user is wearing the eyewear comprising the lens. The front face is the face of the lens opposite to the rear face.
The front face is also known as the “object side” face of the lens and the rear face is also known as the “eye side” face of the lens.
Conventionally, lenses are manufactured on request in accordance with specifications intrinsic to individual users (for example the prescription of the users, measured by an ophthalmologist or an eye care professional). However, lenses are commonly manufactured by using a limited number of semi-finished lens blanks. A semi-finished lens blank has a front face and a rear face. Generally, the physical parameters of the lenses (for example the thickness) depend on the prescription of the lens. Therefore, the prescription of the lens is generally taken into account while determining these physical parameters.
The front face of a semi-finished lens blank is usually intended to be the final front face of the final lens and the other face is machined so as the optical system of the final lens fits the user's ophthalmic prescriptions. Some minor machining of the front face may occur, but without modifying its curvature.
Therefore, the expressions “the base-curve of the lens”, or “the base-curve of the semi-finished lens blank” on which the lens is manufactured can be indistinctly used, indeed both of these base-curves are identical.
Semi-finished lens blanks are usually obtained by injection moulding or by casting into moulds.
In this disclosure and according to ISO Standard 13666: 1998(E/F) (Ophthalmic optics-Spectacle lenses-Vocabulary), the curvature of the front face of the lenses or the semi-finished lens blanks is called a “base-curve”.
If the curvature of the front face of the semi-finished lens blank is not constant, as it is for example the case with a free-form shape of the front face, the curvature can be determined as the curvature at a reference point of the front face or an average curvature that is averaged over the whole front face.
Often, the base-curves are given for a nominal refractive index of 1.53, even if the material on which the ophthalmic lens is made of has another refractive index. In this divulgation all the base-curves will be given for a nominal refractive index of 1.53 whatever the exact refractive index of the material of the lens is. Therefore, when modifying the base-curve of the lens, only the curvature of the front face is modified and not the material. Similarly, a modification of the material of the lens will not be considered as a modification of the base-curve of the lens.
When the base-curve of a lens decreases, the lens becomes flatter. In contrast, when the base-curve of a lens increases, the lens becomes stepper or rounder. The expressions “decreasing the base-curve of the lens” and “flattering the lens” and the expressions “increasing the base-curve of the lens” and “steppering or rounding the lens” are interchangeable.
Manufacturers typically produce pluralities or series of semi-finished lens blanks, each plurality having its own “base-curve series”. This “base-curve series” is a system of semi-finished lens blanks with the front face increasing incrementally in curvature (e.g., +0.50 D, +2.00 D, +4.00 D, and so on).
Generally, the material or at least the refractive index of the same plurality is identical. Generally the material or at least the refractive index of two different pluralities are different.
Generally, each of the base-curve series comprises a limited number of discrete base-curves. Sometimes, each plurality does not have the same number of semi-finished lens blanks. Furthermore, all the pluralities do not have semi-finished lens blanks with the same base-curve. Therefore, when changing from a semi-finished lens blank of a first plurality to a semi-finished lens blank of a second plurality, a semi-finished lens blank with the same base-curve is sometimes not available. In this case, the semi-finished lens blank of the second plurality with the base-curve the closest to the base-curve of the semi-finished lens blank of the first plurality is selected.
The common trend is to limit the number of semi-finished lens blanks of a plurality to minimize the number of moulds, the stocking costs and inventory requirements. A standard plurality comprises less than twenty semi-finished lens blanks, for example less than ten, and preferably five to eight semi-finished lens blanks.
Each semi-finished lens blank in a plurality is conventionally used for producing a range of prescription.
The front face of a semi-finished lens blank serves as the starting point from which the optical face of the back face will be calculated and the final lens be manufactured according to a user prescription (or focal power).
The front face of the semi-finished lens blanks of a plurality may have a spherical shape, an aspherical shape, a progressive addition shape.
As an example, progressive addition lenses (PAL) may be manufactured thanks to semi-finished lens blanks with a front face of spherical or aspherical shape and the progressive addition face is obtained by machining the rear face of the semi-finished lens blank. Progressive addition lenses can also be manufactured using semi-finished lens blanks with a front face with progressive addition shape and the rear face of the semi-finished lens blank is machined so as to form a rear face with spherical or toric shape. It is also possible to manufacture PAL thanks to semi-finished lens blanks with a front face having a first progressive addition shape and to machine the rear face of the semi-finished lens blank to obtain a rear face with a second progressive addition shape and provide “dual add” PAL.
The
Examples of processors 202-b include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on a chip (SoC), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware for example ASICs (Application-Specific Integrated Circuits) configured to perform the various functionality described throughout this disclosure.
The memory 202-a is computer-readable media. By way of example, and not limitation, such computer-readable media may include a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by the controller 102.
The memory 202-a can be configured to store a computer program comprising instructions which, when the program is executed by the processor 202-b, cause the calculation module 202 to carry out a method for selecting a semi-finished lens blank usable to manufacture the lens (L1 or L2) adapted to the frame F of the eyewear EY. The lens L1 or L2 is also adapted to a prescription of the user. The lens L1 or L2 is adapted to the frame F of the eyewear EY when a geometrical parameter value of the eyewear EY, more precisely of the lens L1 or L2 is within a range of geometrical parameter values.
The system 201 can also comprise a measurement device 203 to determine points of a border of the right rim R1 of the frame F, and/or points of a border of the left rim R2 of the frame F. This measurement device 203 is for example a 3D scanner or a measuring arm.
Using these points of the border of the right rim R1 or the border of the left rim R2, the base of the frame F can be determined. The base of the frame F can be defined as the base-curve for which the corresponding sphere best approximates the shape of the right rim R1 or the left rim R2.
The geometrical parameter can represent an aesthetic score of the assembly comprising the lenses and the frame. This geometrical parameter value of the lens (L1 or L2) can be directly determined or measured from a part of the eyeglass EY, for example from the physical features of the lens (L1 or L2) or the frame F. These features can be the lens surfaces, the lens edges, the lens bevel, the frame face, the frame groove, etc.
The method for selecting a semi-finished lens blank can also comprise the determination of different parameters used for the edging and/or for the mounting of the lens L1 or L2 in the frame F.
The semi-finished lens blank can be selected among at least one plurality of semi-finished lens blanks. For each of the semi-finished lens blanks of one of the pluralities, the base-curve of the semi-finished lens blank is different from the base-curve of the other semi-finished lens blanks. Each plurality forms one of the previously introduced “base-curve series”.
As presented previously, the material or at least the refractive index of the same plurality is generally identical. Generally, the material or at least the refractive index of two different pluralities are different.
The semi-finished lens blanks of the plurality can be organized in an incremental or decremental order of the value of the base-curve. This organization either incrementally or decrementally allows an easier implementation of the method.
The different pluralities can be organized by incremental or decremental order of their refractive index. This organization either incremental or decremental allows an easier implementation of the method.
In a first embodiment presented in
When the geometrical parameter value of the lens L1 or L2 is within the range of the geometrical parameter values the method also comprises a step of selecting 302 the adapted semi-finished lens blank as the first test semi-finished lens blank.
The test semi-finished lens blank can be chosen among the plurality as the semi-finished lens blank with the base-curve the highest one but inferior to the base of the frame F.
Generally, the plurality used in the step of determining 301 the geometrical parameter value of the lens L1 or L2 is the plurality with a material, used to realize semi-finished lens blanks, with the refractive index having the lowest value. For a given geometry, selecting a plurality having the material with the lowest value of refractive index allows the semi-finished lens blanks to be cheaper.
When the geometrical parameter value of the lens L1 or L2 is outside the range of the geometrical parameter values the method also comprises:
Advantageously the step of selecting 303 the second test semi-finished lens blank selects a semi-finished lens blank of the first plurality of semi-finished lens blank allowing, after the potential manufacturing of the lens using the second test semi-finished lens blank, the geometrical parameter value of the lens L1 or L2 to be within the range of the geometrical parameter values.
In the first embodiment, the step of selecting 303 the second test semi-finished lens blank is realized until one of these conditions is reached:
The difference threshold can be for example 2, 3 or 4 dioptres. Advantageously the difference threshold is 3 dioptres. This difference threshold of 3 dioptres allows a more aesthetic integration of the lens in the frame F.
As presented in the
As presented in the
The base-curve of the test semi-finished lens blank of the second plurality is generally close or equal to the base-curve of the second test semi-finished lens blank of the first plurality. In this divulgation “close” means inferior to 2 dioptres, for example 1 dioptre advantageously 0.5 dioptre.
The method can directly output the test semi-finished lens blank of the second plurality as the adapted semi-finished lens blank.
Otherwise and as presented in
When the first condition is reached, the method comprises a step of selecting 306 the semi-finished lens blank allowing the geometrical parameter value of the lens L1 or L2 to be within the range of the geometrical parameter values.
When the second condition is reached, the method comprises a step of selecting 307 the semi-finished lens blank allowing the geometrical parameter value of the lens L1 or L2 to be the closest to the range of the geometrical parameter values.
As described above the geometrical parameter can represent an aesthetic score of the assembly comprising the lenses and the frame. This geometrical parameter value of the lens (L1 or L2) can be directly determined or measured from a part of the eyeglass EY, for example from the physical features of the lens (L1 or L2) or the frame F. The geometric parameter of the lens can be:
A linear combination of these previous geometric parameters can also be used.
The following characteristic parameters of the frame F are usable to determine one of the geometric parameters presented above:
The range of the geometrical parameter values can depend on a type of the frame F and/or a tint of the lens.
When the geometric parameter is the thickness of the edge of the lens, the range of the geometrical parameter values can be chosen as one the following ranges:
Using the above presented method the widest possible refraction coverage can be obtained while maintaining a suitable aesthetics, by selecting the semi-finished lens blank (according to the base-curve and the material of the semi-finished lens blank). This selection allows the thicknesses of the lens to be within a predetermined range and the base-curve of the lens to be adapted to the base of the frame. As described previously, the method can also comprise the determination of different parameters used for the edging and/or for the mounting of the lens (L1 or L2) in the frame F.
In other words, the method of this divulgation allows the use of aesthetic rules to determine semi-finished lens blank, more precisely its base-curve and its material, that will be used to manufacture the lens.
The aesthetic rules involve defining aesthetic limits in terms of thickness of the lenses but also on base-curve matching between the base-curve of the lens and the base of the frame F. The method comprises a base-curve management and a material lens management. Both of these managements can be based on the optimisation of the thickness of the lens. The thickness of the lens is optimized by debasing the lenses (flatter) and choosing a refractive index adapted to the prescription.
A database can comprise, for different semi-finished lens blanks (characterized by their base-curves, material) and prescriptions, the value of different geometrical parameters of the lens L1 or L2.
The method can also output an aesthetic score of the lens (for example based on the geometrical parameters of the lens, such as the thickness of the lens) associated with the selected base-curve and material.
The method can also comprise different levels of aesthetic and for each level different threshold of the geometrical parameters.
In the method, the test semi-finished lens blank that is selected in the beginning can be adapted to the base of the frame F. To ease the implementation of the method the base of different possible frames can be grouped in ranges of bases. Each range is associated with a base-curve of a test semi-finished lens blank to select at first. For example, each range, except the first one that can cover 4 dioptres, covers two dioptres. At first a test semi-finished lens blank with its base-curve equal to the low limit of the range on which the base-curve of the frame belongs is selected. The selection of the low limit allows the lens to be flatter, therefore the lens to be thinner.
Therefore,
When the geometrical threshold is the thickness of the lens, this thickness can be defined according to aesthetic levels. For a first level of aesthetic the edge thickness must be of a maximum of 7.5 mm, for a second level of aesthetic the edge thickness must be between 7.5 mm and 10 mm and for a third level of aesthetic, the edge thickness can be superior to 10 mm.
The more the base-curve of the lenses are curved, the thicker the lenses are. The base-curve 8 shows maximum edge thicknesses. The choice of polar (with film thickness constraints) and a large diameter Uncut product shows the worst case.
Using the above presented method, the aesthetics of the eyewear EY more precisely the lenses is optimized by changing their bases-curve and material of the semi-finished lens blank used to realize the lens. Lowering a flatter base-curve allows to maintain a suitable aesthetic (1 to 3 flatter bases maximum) and as previously explained, this allows to reduce the thicknesses.
By combining with the choice of the flatter base-curve, a change of refractive index of the material of the lens allows the reduction of the thickness of a peripheral part of the lens and so to obtain a more aesthetic lens mounted in the frame.
The method of the
The method of the
This section is an example, for illustrative purposes only, of how the method of the
The first plurality P1 has a refractive index of 1.53, the second plurality P2 has a refractive index of 1.59 and the third plurality has a refractive index 1.67.
The base of the frame F is in this example of 6.6. The geometrical parameter of the lens L1 or L2 can be the thickness of the edge of the lens L1 or L2. The range of the geometrical parameter values is in this example 1 mm to 7 mm. The base-curve threshold is in this example 3 dioptres.
At first the semi-finished lens blank SF3 of the plurality P1 is considered. Indeed, the base-curve of the semi-finished lens blank SF3 of the plurality P1 is the one matching with the base of the frame F. If, in this example, the thickness of the lens, that could be realized from the semi-finished lens blank SF3 of the plurality P1, is 9 mm, this thickness is outside of the range of the geometrical parameter values and therefore the semi-finished lens blank SF3 of the plurality P1 is not adapted.
The semi-finished lens blank SF2 of the plurality P1 is then considered. If, in this example, the thickness of the lens, realized based on the semi-finished lens blank SF2 of the plurality P1, is 8 mm, again outside the range of the geometrical parameter values and therefore the semi-finished lens blank SF2 of the plurality P1 is not adapted.
The next semi-finished lens blank to be considered is the semi-finished lens blank SF1 of the plurality P1. It has a base-curve of 2 and as the difference with the base of the frame is greater than 3 dioptres, this semi-finished lens blank SF1 does not fulfil the above-mentioned base-curve threshold.
The plurality P2 is then considered and more precisely the semi-finished lens blank SF2 of this plurality. If, in this example, the thickness of the lens realized based on the semi-finished lens blank SF2 of the plurality P2 is 7.5 mm, this thickness is outside the range of the geometrical parameter values and therefore the semi-finished lens blank SF2 of the plurality P2 is not the adapted one. The plurality P3 is considered and more precisely the semi-finished lens blank SF2. The base curve of the semi-finished lens blank SF2 of the plurality P3 is not equal to the base curve of the semi-finished lens blank SF2 of the plurality P2, however the semi-finished lens blank SF2 of the plurality P3 is the one with the base-curve the closest to the semi-finished lens blank SF2 of the plurality P2.
If, in this example, the thickness of the lens realized based on the semi-finished lens blank SF2 of the plurality P3 is 6.9 mm, this thickness is within the range of the geometrical parameter values and therefore the semi-finished lens blank SF2 of the plurality P3 is the adapted semi-finished lens blank.
The modification of the base-curve allows a reduction of 10% of the thickness of the lens and a modification of the material of the lens allows a reduction of 18% of the thickness of the lens. The combination of both modifications allows a reduction of 26% of the thickness of the lens.
In a second embodiment the method for selecting a semi-finished lens blank usable to manufacture the lens (L1 or L2) adapted to the frame F of the eyewear EY can be realized by determining for a plurality of eyewear with lens manufactured using different semi-finished lens blanks at least one geometrical parameter value of the lens. After that the method can comprise the selection of the semi-finished lens blank based on the at least one geometrical parameter value. For example, the semi-finished lens blank associated with a geometrical parameter value within the range of geometrical parameter values of the first embodiment or semi-finished lens blank associated with the optimal geometrical parameter value can be selected.
As already mentioned, the geometrical parameter value can be represented as part of an aesthetic score of the assembly comprising the lenses L1 and L2 and the frame F. This geometrical parameter can be directly determined or measured from a part of the eyeglass EY, for example from the lens (L1 or L2) or the frame F. In other words, each of the geometric parameter values can be combined and weighted to each other so that a global aesthetic score can be determined.
Many configurations of eyewear EY can be evaluated combining a semi-finished lens blank (associated potentially with a base-curve and a material), edging and mounting rules associated with the frame intended to receive the lenses (L1 and L2) and the prescription of the user applied on the lenses (L1 and L2). The method will determine for each configuration at least one geometrical parameter value or a global aesthetic score obtained by combining the value of a plurality of geometrical parameters.
The advantage of the method is to predict for a plurality of eyewear EY a geometric parameter value of the eyewear EY or of the lens, without a full calculation of the parameters of the lens. This full calculation is time consuming and does not allow a real time evaluation.
To realize the determination of the geometrical parameter value of the lens L1 or L2 or the global aesthetic score, a supervised machine learning approach can be used. For example, a convolutional neural network can be used.
The use of the machine learning can be realized using the following steps represented in
During the step of selecting 406, the geometrical parameter values of the lens L1 or L2 associated with different eyewear EY can be compared to a range of geometrical parameter values. The semi-finished lens blank allowing the geometrical parameter value of the lens to be within the range of geometrical parameter values is selected. The Pareto-optimal semi-finished lens blank can also be selected.
The geometric parameters used in the second embodiment are identical to the ones used in the first embodiment. As a reminder these geometric parameters are:
A linear combination of these previous geometric parameters can also be used.
The following characteristic parameters of the frame F are usable to determine one or more of the geometric parameters presented above:
Each of the eyewear of the first and second plurality are different from the others. More precisely, the shape of the frame F (more precisely the base-curve of the frame F), the prescription, the material (more precisely the refractive index of the material) and the base-curve of the lens L1 or L2 are different.
The machine learning model can also be used the following way. From an order of a lens to a user, the machine learning model is used with each possible eyewear EY (defined specifically by the base-curve of the semi-finished lens blank and the material of the semi-finished lens blank) to determine geometrical parameter values of the lens. Then, the eyewear EY associated with the optimal geometrical parameter value is selected. The optimal values provide the most aesthetic eyewear EY.
The method of the
As an example, the method of the second embodiment can be used with the following parameters:
Using the machine learning model, the value of the following geometrical parameters can be determined:
The values of the geometrical parameters are represented in the following table. All of the values are obtained using the machine learning model. Because of the “follow front” mounting type the value of the parameter C3 is the same for all the semi-finished lens blank SF1 to SF3.
Using these values, a global aesthetic score can be determined. For example, this global aesthetic score can be the sum of the value of the four geometrical parameters.
Using the global aesthetic score, the semi-finished lens blank SF3 provides the best aesthetics and is selected.
Alternatively. The selection can be made on a unique geometric parameter for example on the geometrical parameter C1 if this parameter is considered to be the most important one.
The method, according to the second embodiment, can also comprise the determination of a plurality of optimal configurations, more precisely of optimal semi-finished lens blanks associated potentially with optimal mounting and edging rules and to display to an eye care professional the plurality of the optimal semi-finished lens blanks and potentially the optimal mounting and edging rules. These semi-finished lens blanks or the mounting and edging rules can be optimal in the sense of «Pareto».
The aesthetics of eyeglasses can be described by several geometrical parameters, as has been previously explained. When considering a plurality of semi-finished lens blanks, there can be one that is better than all other, for all geometrical parameters. This semi-finished lens blank is clearly optimal. However, an optimal semi-finished lens blank does not always exist. This is especially true if some of the geometrical parameters are antagonistic, such as “lens thickness” and “curvature deviation between the lens front curvature and the frame curvature”. In the case where no optimal semi-finished lens blank exists. In this case a sub-set of Pareto-optimal semi-finished lens blanks can be determined.
By definition, a “dominated semi-finished lens blank” is a semi-finished lens blank for which there exists another semi-finished lens blank which is better or equal for all parameters.
If a semi-finished lens blank is not dominated, then it is Pareto-optimal. In other words, a Pareto-optimal semi-finished lens blank cannot be improved according to one parameter, without making it worse according to another parameter. In simpler terms: Pareto-optimal semi-finished lens blanks represent the set of “optimum compromises”. They are a subset of the plurality of the semi-finished lens blanks.
| Number | Date | Country | Kind |
|---|---|---|---|
| 22305544.3 | Apr 2022 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2023/057145 | 3/21/2023 | WO |
