EP4382249A1 - Verfahren zur erzeugung eines bearbeitungssollwerts zum abschrägen einer ophthalmischen linse - Google Patents

Verfahren zur erzeugung eines bearbeitungssollwerts zum abschrägen einer ophthalmischen linse Download PDF

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Publication number
EP4382249A1
EP4382249A1 EP22306806.5A EP22306806A EP4382249A1 EP 4382249 A1 EP4382249 A1 EP 4382249A1 EP 22306806 A EP22306806 A EP 22306806A EP 4382249 A1 EP4382249 A1 EP 4382249A1
Authority
EP
European Patent Office
Prior art keywords
lens
frame
value
inclination angle
process according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22306806.5A
Other languages
English (en)
French (fr)
Inventor
Thierry Allouis
Benoit Holvoet-Vermaut
Damien BOUYNET
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EssilorLuxottica SA
Essilor International SAS
Original Assignee
Essilor International Compagnie Generale dOptique SA
Essilor International SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Essilor International Compagnie Generale dOptique SA, Essilor International SAS filed Critical Essilor International Compagnie Generale dOptique SA
Priority to EP22306806.5A priority Critical patent/EP4382249A1/de
Priority to PCT/EP2023/084541 priority patent/WO2024121238A1/en
Publication of EP4382249A1 publication Critical patent/EP4382249A1/de
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B9/00—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor
    • B24B9/02—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground
    • B24B9/06—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain
    • B24B9/08—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain of glass
    • B24B9/14—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain of glass of optical work, e.g. lenses, prisms
    • B24B9/148—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain of glass of optical work, e.g. lenses, prisms electrically, e.g. numerically, controlled

Definitions

  • the present invention generally relates to the field of eyeglasses.
  • the technical part of the work of an optician which consists in mounting a pair of ophthalmic lenses in a spectacle frame selected by a customer, may be split into four main operations:
  • the edging of the lens consists in machining a bevel all around the edge face of the lens by means of a bevelling tool.
  • the base of the lens (the radius of curvature of its front face) is greater than a threshold, it is known to machine the lens so that the bevel is oriented as an extension of the lens edge.
  • closest bevel sphere defined as the sphere that is the nearest from the apex curve of the bevel to be edged. The edge is to be machined normal to this closest bevel sphere at all points around the lens. In this case, the bevel extends perpendicularly from this tilted edge and has a varying inclination.
  • the tilt of the bevel can be unnecessarily too high. It can also generate bad aesthetic aspect.
  • the apex curve of the bevel to be edged has a shape of a circle, there are an infinite number of closest bevel spheres, so that the inclination of the bevel is often randomly determined.
  • the present invention provides a new process for generating a machining setpoint for bevelling an ophthalmic lens.
  • the bevel inclination angle is determined as a function of lens parameters and frame parameters.
  • the inclination of the bevel will depend not only on the shape of the frame, but also of the shape of the lens (its shape before or after edging). Consequently, constraints relative to possible collision between lens and frame can be taken into account.
  • the invention also relates to a bevelling device for bevelling an ophthalmic lens, comprising:
  • FIG. 1 shows a rimmed eyeglass frame 10 having two rims 11 (or surrounds), each serving to receive an ophthalmic lens and to be positioned in front of a respective one of the two eyes of a wearer when said frame is being worn.
  • the two rims 11 are connected together by a bridge 12. They are also each fitted with a nose pad 13 suitable for resting on the wearer's nose and a temple (earpiece) 14 suitable for resting on one of the wearer's ears.
  • Each temple 14 is hinged to the corresponding rim by means of a hinge 15.
  • Each rim 11 of the eyeglass frame 10 presents an inside face including an inside groove, commonly referred to as a bezel 16.
  • the bezel 16 presents a V-shaped cross-section.
  • the bezel could be shaped so as to present a profile of some other shape.
  • the bottom of the bezel 16 defines an outline in two or three dimensions (the third dimension being roughly orthogonal to the mean plane of the rim).
  • rim sphere Relative to each of the rims 11, there is defined a mean sphere, referred hereinafter as the "rim sphere".
  • This rim sphere is defined as the sphere that comes closest to the set of points making up the bottom edge of the bezel 16. The characteristics of this sphere may be obtained, for example, by applying the least squares method to the coordinates of a plurality of points of the bottom of the bezel 16.
  • the ophthalmic lens 20 machined to be engaged in this rim 11 presents front and rear optical faces 21 and 22, together with an edge face 23.
  • the ophthalmic lens 20 presents optical characteristics and geometrical characteristics.
  • the spherical refringent power of the lens which is the magnitude that characterizes and quantifies the "magnifying glass” effect of the lens on the beam under consideration.
  • the edge face 23 of the lens initially presents an outline that is circular. Nevertheless, the lens is designed to be shaped to match the shape of the corresponding rim of the eyeglass frame 10, so as to enable it to be engaged therein.
  • the lens is more precisely designed to be shaped so as to present on its edge face 23 an engagement ridge (named "bevel 26").
  • the bevel 26 described herein presents a V-shaped section with a top edge 27 that runs along the edge face 23 of the lens, with front and rear flanks on either side of the top edge 27.
  • the bevel 26 is for instance located so as to remain at a constant distance from the front face of the lens, all around the lens. Therefore, the shape of its top edge cannot follow exactly the one of the bottom of the bezel 16 (unless the mounting of the lens in the rim deforms the frame).
  • the shape of the top edge of the bevel is deduced from the 2D outline of the bezel 16 and (for the third dimension) from the curvature of the lens.
  • the bevel 26 to be shaped will be characterized by the 3D outline of its top edge 27, and by an inclination angle.
  • lens sphere Relative to the lens, there is defined a mean sphere, referred hereinafter as the "lens sphere".
  • This lens sphere is defined as the sphere that comes closest to the set of points making up the top edge 27 of the bevel 26.
  • the characteristics of this sphere may be obtained, for example, by applying the least squares method to the coordinates of a plurality of points on the top edge 27 of the bevel 26.
  • the ophthalmic lens 20 has a main axis A1, that can be formed by the axis where the magnifying glass effect is null (also called optical axis).
  • the edge face 23 of the lens can be machined so as to present an inclination relative to this main axis A1 that is not null.
  • the edge face 23 defines a straight line (if we do not consider the bevel) oriented along an axis A2 that is tilted relative to the main axis A1 by said inclination angle, name hereinafter "angle ⁇ ".
  • This angle ⁇ defines the inclination of the bevel 26. Indeed, the bevel 26 rising here perpendicularly to the edge face 23, and it is therefore oriented along an axis that is tilted relative to the main axis A1 with an angle equal to 90°- ⁇ .
  • the shaper appliance used to machine the bevel 26 on the ophthalmic lens 20 may be in the form of any machine for cutting or removing material and that is suitable for modifying the outline of the ophthalmic lens 20 in order to match it to the rim 11 of a selected frame, and that is suitable to make the angle ⁇ varying.
  • the shaper appliance is constituted, in known manner, by an automatic grinder (no shown) that comprises:
  • the bevelling tool 200 may have a cylindrical working face 201 with, at its center, a V-shaped ridge 202 able to generate the bevel 26, all faces constituting respective surfaces of revolution about the tool axis A3.
  • the shaper appliance can be described as a "five-axes edger" since its bevelling tool is carried by a carriage (not shown) that is movable not only in translation along the axis A1 or A3, but also in rotation about an axis perpendicular to this tool axis A3 in order to adjust the angle ⁇ .
  • the shaping method is implemented by means of this shaper appliance.
  • the method consists in machining the edge face 23 of the ophthalmic lens 20 to reduce it to the shape of the rim 11 of the eyeglass frame 10.
  • a processing unit has to generate a machining setpoint.
  • This machining setpoint is a list of instructions enabling the shaper appliance to machine the lens.
  • the shape of the bevel to be machined has to be characterized.
  • This processing unit comprises a processor or a controller, or any combination thereof. It also comprises a memory and various input and output interfaces.
  • the processing unit is suitable for receiving parameters relative to the frame, to the lens and, if any, other required information.
  • the processing unit is suitable for sending the machining setpoint to the controller of the shaper appliance.
  • the processing unit stores a computer application, consisting of computer programs comprising instructions, the execution of which by the processor enables the processing unit to implement the process described below.
  • this process comprises a first acquisition operation that consists in acquiring frame parameters and lens parameters.
  • the frame parameters comprise the shape of the bezel 16, here in the form of the coordinates of a great number of points located in the bottom of the bezel 16.
  • the lens parameters comprise information relative to the shape of the ophthalmic lens, for instance its base and its thickness at several points.
  • the processing unit can determine the shape of the top edge 27 of the bevel 26 to be machined, here in the form of the coordinates of a great number of points located on this top edge 27.
  • the second operation consists in deducing the angle ⁇ for shaping the bevel.
  • this angle ⁇ can be the same all around the lens, for aesthetic reasons.
  • the third operation consists in determining the machining setpoint so that, once machined, the lens bevel has the required inclination.
  • the second operation that form the core of the invention, is illustrated in Figure 3 . It comprises many steps successively performed by the processing unit.
  • the first step S1 consists in determining if a five-axes edger is available or not.
  • this second operation ends and another kind of process is used to determine the machining setpoint.
  • This other process, performed with a three-axes edger, is well known from the one skilled in the art and will not be described here.
  • the processing unit determines during a second step S2 if this lens is of a non-standard category. In other words, it checks whether the machining of the lens requires a five-axes edger or not.
  • the processing unit determines if the mounting of the lens in the rim will have to face any constraint.
  • the constraint(s) are relative to possible collision(s) between the lens and frame.
  • the processing unit has to answer at least one of the following questions (here, it has to answer all these questions):
  • the processing unit uses the lens and frame parameters acquired during the first operation.
  • the processing units considers in the following that the mounting is constraining and the value "1" is assigned to a Boolean ⁇ . Else, this Boolean is considered equal to zero.
  • the processing unit successively determines which one of ten successive conditions is fulfilled. As soon as one condition is fulfilled, a determined value is assigned to the angle ⁇ , which enables to generate the searched setpoint. As long as none of the previously verified conditions is fulfilled, the processing unit continues to check if one of the following conditions is fulfilled.
  • the lenses to be engaged into narrow rims are difficult to machine since there is a risk of collision between the bevelling tool 200 and the shafts that hold the ophthalmic lens 20. Consequently, it is preferable to have a non-zero angle ⁇ to avoid such collisions.
  • the other lenses are here designed by adapting the angle ⁇ to the rim shape and to the lens shape.
  • This angle ⁇ can be, depending on the configuration:
  • the angle is increased (by a fixed value or by a percentage of inclination) all around the lens when a constraint is detected (showing a potential collision between the lens edge and the frame).
  • the first condition relates to the vertical length V box of the boxing rectangle.
  • the probability of problem in machining the lens is higher when this length is small.
  • the first threshold T1 is comprised between 22 and 27 millimetres and is equal to 25 millimetres.
  • the values ⁇ 1 and ⁇ 2 are constant and predetermined.
  • the value ⁇ 1 is less than the value ⁇ 2 of at least 0.5°.
  • This value ⁇ 1 is comprised between 2 and 3°.
  • the value ⁇ 2 is comprised between 3 and 6°.
  • the processing unit determines if the vertical length V box is less than a second threshold T2 greater than the first threshold T1.
  • the second condition is considered fulfilled.
  • the second threshold T2 is comprised between the first threshold T1 and 30 millimetres, and is equal to 27 millimetres.
  • the values ⁇ 3 and ⁇ 4 are constant and predetermined.
  • the value ⁇ 3 is less than the value ⁇ 4 of at least 0.5°. It is fewer than the value ⁇ 1.
  • This value ⁇ 3 is comprised between 2.5 and 3.5°.
  • the value ⁇ 4 is almost equal to the value ⁇ 2.
  • the third condition relates to the general shape of the rim. It consists in determining (if no previous condition is fulfilled) whether the rim is round-shaped or not. Indeed, as explained above, problems often occur when it is round-shaped.
  • One method consists in determining the center of the boxing rectangle, and to verify if the distances between this center and each point of the 2D outline of the bezel 16 are sensibly the same, for instance with an accuracy of a few percent.
  • the values ⁇ 5 and ⁇ 6 are constant and predetermined.
  • the value ⁇ 5 is less than the value ⁇ 6 of at least 1 ° (here 2°).
  • This value ⁇ 5 is comprised between 2 and 4°.
  • the value ⁇ 6 is comprised between 4 and 6°.
  • All the other conditions relate to the shape of the frame and the difference in shapes between the lens and the frame.
  • the bevel curve BEVC may be equal to the radius of the lens sphere. But here, it is preferably the closest radius to the frame curve FCRV considering the lens base (i.e. the lens curvature) and the lens edge thickness.
  • the frame curve FCRV is here calculated according to a standard commercial index. This curve could be converted into the radius of the rim sphere or may be equal to the latter. But here, to avoid any non-aesthetical disparity, the frame curve depends on the radius of the two rim spheres (the sphere of the right rim and the one of the left rim). In practice, the frame curve FCRV is here equal to the average of the frame curves of both rims.
  • these two rim frame curves can differ, for instance due to a frame deformation during tracing (the tracing being an operation of feeling the bezel to determine its contour), or when the frame is not new and is deformed...
  • gap ⁇ that is the difference between the bevel curve BEVC and the frame curve FCRV.
  • the probability of problem in the mounting of the lens into the frame rim is considered as depending on these curves and this gap, that is why they are considered.
  • the fourth condition consists in determining (if no previous condition is fulfilled) if the frame curve FCRV is low (lower than a third threshold T3) and if the gap ⁇ is negative or null.
  • the third threshold is comprised between 3 and 5 and is here equal to 4.
  • the values ⁇ 7 and ⁇ 8 are constant and predetermined.
  • the value ⁇ 7 is less than the value ⁇ 8 of at least 1°.
  • This value ⁇ 7 is comprised between 2.5 and 4.5°.
  • the value ⁇ 8 is comprised between 4.5 and 6.5°.
  • the fifth condition consists in determining (if no previous condition is fulfilled) if the frame curve FCRV is low (lower than a third threshold T3) and if the gap ⁇ is positive.
  • the value ⁇ 9 is less than the value ⁇ 10 of at least 1°.
  • the value ⁇ 9 is comprised between 2.5 and 4.5° and the value ⁇ 10 is comprised between 4.5 and 6.5°.
  • This auto-inclination process consists in orientating the bevel so that it arises, in all points of the edge around the lens, perpendicularly to the outline of the top edge 27 of the bevel 23 (that is to say as an extension of the lens edge).
  • fixe or variable values are used according to the bevel curve BEVC: below a certain threshold, the auto-inclination process would give an inclination value that would not be high enough to be visible, so that a fixed angle value is required. Over another threshold, the auto-inclination process would give a too high inclination value to obtain an aesthetic result, so that a fixed angle value is needed. Between these two thresholds, the auto-inclination process can be used (with some limitations depending on the cases that have been evaluated and tested to get the best aesthetic as possible).
  • the sixth condition consists in determining (if no previous condition is fulfilled) if the frame curve FCRV is comprised between the third threshold T3 and a fourth threshold T4 and if the gap ⁇ is lower than -1 or equal to -1.
  • the fourth threshold T4 is greater than the third one and is comprised between 5 and 7 and is here equal to 6.
  • the value ⁇ 11 is less than the value ⁇ 12 of at least 1°.
  • the value ⁇ 11 is comprised between 2.5 and 4.5° and the value ⁇ 12 is comprised between 4.5 and 6.5°.
  • the seventh condition consists in determining (if no previous condition is fulfilled) if the frame curve FCRV is comprised between the third threshold T3 and the fourth threshold T4 and if the gap ⁇ is comprised between -1 and 1.
  • the height condition consists in determining (if no previous condition is fulfilled) if the frame curve FCRV is comprised between the third threshold T3 and the fourth threshold T4 and if the gap ⁇ is greater than 1 or equal to 1.
  • the value ⁇ 15 is less than the value ⁇ 16 of at least 1°.
  • the value ⁇ 15 is comprised between 2.5 and 4.5° and the value ⁇ 16 is comprised between 4.5 and 6.5°.
  • the ninth condition consists in determining (if no previous condition is fulfilled) if the frame curve FCRV is higher than the fourth threshold T4 and if the gap ⁇ is negative or null.
  • the value ⁇ 17 is less than the value ⁇ 18 of at least 1°.
  • the values ⁇ 17 and ⁇ 18 are constant.
  • the value ⁇ 17 is comprised between 2.5 and 4.5° and the value ⁇ 18 is comprised between 4.5 and 6.5°.
  • the tenth condition consists in determining (if no previous condition is fulfilled) if the frame curve FCRV is higher than the fourth threshold T4 and if the gap ⁇ is positive. We note that, at this step, this condition will necessarily be fulfilled, so that it is not required to check whether it is fulfilled or not.
  • the value ⁇ 19 is less than the value ⁇ 20 of at least 1°. These values are constant (all around the lens).
  • This value ⁇ 19 is comprised between 2.5 and 4.5° and the value ⁇ 20 is comprised between 4.5 and 6.5°.
  • the value of the angle ⁇ is determined and can be used to generate the setpoint for bevelling the lens according to a well-known method that will not be described here.
  • this value can be corrected depending on the detected constraints. For instance, if at least two constraints are detected, the angle ⁇ value can be increased of a percentage or of a predetermined value.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Eyeglasses (AREA)
EP22306806.5A 2022-12-07 2022-12-07 Verfahren zur erzeugung eines bearbeitungssollwerts zum abschrägen einer ophthalmischen linse Pending EP4382249A1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP22306806.5A EP4382249A1 (de) 2022-12-07 2022-12-07 Verfahren zur erzeugung eines bearbeitungssollwerts zum abschrägen einer ophthalmischen linse
PCT/EP2023/084541 WO2024121238A1 (en) 2022-12-07 2023-12-06 Process for generating a machining setpoint for bevelling an ophthalmic lens

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP22306806.5A EP4382249A1 (de) 2022-12-07 2022-12-07 Verfahren zur erzeugung eines bearbeitungssollwerts zum abschrägen einer ophthalmischen linse

Publications (1)

Publication Number Publication Date
EP4382249A1 true EP4382249A1 (de) 2024-06-12

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EP22306806.5A Pending EP4382249A1 (de) 2022-12-07 2022-12-07 Verfahren zur erzeugung eines bearbeitungssollwerts zum abschrägen einer ophthalmischen linse

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EP (1) EP4382249A1 (de)
WO (1) WO2024121238A1 (de)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100112908A1 (en) * 2006-10-13 2010-05-06 Essil Or International (Compagnie Générale D'optiq Method of shaping an ophthalmic lens
US20140340633A1 (en) * 2011-11-30 2014-11-20 Essilor International (Compagnie Generale D'optique) Method of preparing an ophthalmic lens

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100112908A1 (en) * 2006-10-13 2010-05-06 Essil Or International (Compagnie Générale D'optiq Method of shaping an ophthalmic lens
US20140340633A1 (en) * 2011-11-30 2014-11-20 Essilor International (Compagnie Generale D'optique) Method of preparing an ophthalmic lens

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Publication number Publication date
WO2024121238A1 (en) 2024-06-13

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