WO2007012713A1

WO2007012713A1 - Method for trimming an ophthalmologic lens with reacquisition of an initial centering reference frame

Info

Publication number: WO2007012713A1
Application number: PCT/FR2006/001537
Authority: WO
Inventors: Fabien Divo
Original assignee: Essilor International (Compagnie Generale D'optique)
Priority date: 2005-07-26
Filing date: 2006-06-30
Publication date: 2007-02-01
Also published as: FR2889319A1; FR2889319B1

Abstract

The invention concerns a method for trimming an ophthalmologic lens (L1) including the following steps: initially locking the lens in an initial locking point (Pb1) deduced based on a computing rule for the desired contour (C1) of the lens, trimming the lens, unlocking the lens, and relocking the lens in a relocking position (Pb2) for its rework. The operation for determining the position of the relocking point consists in acquiring the contour (C2) of the lens as obtained after the first trimming and deducing therefrom the relocking position.

Description

METHOD FOR DISTRESSING AN OPHTHALMIC LENS WITH REACQUISITION

FIELD OF THE INVENTION The present invention relates generally to the mounting of ophthalmic lenses of a pair of corrective eyeglasses on a frame and more particularly to a method of trimming an ophthalmic lens. with unlocking and re-locking of the lens.

BACKGROUND

The trimming of a lens for mounting in or on the frame chosen by the future carrier is to change the contour of the lens to adapt to the frame and / or the lens shape. The trimming includes edging for shaping the periphery of the lens and, depending on whether the fixture is rimmed, drilled or slotted type, beveling or proper creasing of the lens and / or drilling.

The optician must also carry out a certain number of measuring and / or marking operations on the lens itself, before trimming, to identify some of its characteristics such as for example the optical center in the case of a unifocal lens or the cross mounting in the case of a progressive lens.

In practice, each lens is generally delivered by the manufacturer with marks on its convex front face, some of which are representations of a centering repository of the lens. If these marks are not sufficiently visible or absent, the optician performs optical measurements and defers certain characteristic points with a sharp point on the ophthalmic lens itself. These marks are used to position and fix on the lens an adapter or acorn centering and drive to properly position the ophthalmic lens in the grinding machine to give it the desired contour, corresponding to the shape of the frame chosen. The positioning and deposition of the glans can be done manually or automatically, with a device called center-blocker. Anyway, this glans is most often stuck temporarily on the lens with a double-sided adhesive. This operation is usually called centering the lens, or by extension locking the lens in the the acorn then allows to block, that is to say immobilize, the lens on the means of its trimming in a geometric configuration known thanks to this acorn.

After placing the centering glans, the lens thus equipped is placed in the clipping machine where it is given the shape corresponding to that of the chosen frame. The centering glide makes it possible to define and physically materialize on the lens a geometric reference frame in which the points and the characteristic directions of the lens, necessary for the coherence of this lens with the position of the pupil, and the values are identified. of clipping so that these points and characteristic directions are properly positioned in the frame.

When the trimming of the lens does not result in a first fitting in the mount, the operator resumes machining. With this intention, it puts the lens in the machine and blocks it with the same acorn, which makes it possible to recover the initial clipping repository.

However, the use of a glued acorn is a disadvantage in that it must be removed after mounting the lens, which is time consuming and labor intensive. In addition, the lens is secured to the glans by gluing which can lead to intensive cleaning of the lens surface after treatment, resulting in a risk of scratching. Finally, these operations of laying and removal of the glans being relatively complex and delicate, they require a skilled and careful workforce and are in practice time-consuming and therefore expensive; and for the same reasons, it is difficult to automate them. Thus, in the context of this research work, the applicant wishes to overcome the centering by glans because of the aforementioned constraints.

In this hypothesis, according to which the optician frees himself from the placement of an acorn, prior to the first machining, the lens is centered and blocked with the aid of optical measuring means and / or mechanical manipulation means on the clamping and drive shafts. Optical measurements provide an initial locking point defining a first centering reference of the ophthalmic lens in the clamping shafts. The lens is then cut by machining by means of cylindrical roughing and finishing grinding wheels whose edging faces are parallel to the axes of rotation of the clamping and driving shafts, belonging to the main wheels and rotatably mounted around the wheel. axis of rotation of the wheel train.

After this first machining, the lens is unlocked and is thus detached from the locking noses of the clamping shafts. It results from this release a loss of the position of the initial blocking point and therefore the first centering reference. In the case where the trimming of the lens previously performed by means of the first machining is not in accordance with the desired result, the optician must resume trimming by means of a second machining.

A second series of optical measurements can then provide a re-lock point. But this optical refocusing is delicate and leads to an extension of the duration of the lens processing process. On the other hand, the optical refocusing is a source of error: given the uncertainties of the optical measurements or the impossibility, without marks, of refocusing or reaxing by optical measurement of the planar or unifocal lenses, the position on the lens of the reblocking point does not correspond with sufficient accuracy to the position of the initial blocking point to properly resume trimming the lens. The profile of the lens being curved, the lens thus re-locked according to the re-locking point distinct from the initial locking point has a certain inclination, called tilt, with respect to its initial geometrical configuration. As a result, the edging face of the grinding wheel is no longer parallel to the edge of the lens to be picked up which does not allow a precise recovery of the trimming of the edge of the lens and creates on this edge facets unwanted . In addition, for a lens having a bevel, the positioning error of the lens relative to the grinding wheel that, when resuming machining, the flange face of the wheel grinds the bevel unsymmetrically. Finally, the reblocking point has become the center of a new centering repository for the recovery of trimming and piloting of the working wheel must be adapted accordingly.

Patent EP 0961669 proposes a method according to which it is intended to re-lock the lens at any point then to make a probing on the contour of the cut-away lens. According to this method, it is then expected to compare the shape obtained from the lens to that desired and thus adapt the function of restitution of the beam at the point of reblocking.

However, the lens is reblocked at a re-locking point substantially different from the initial blocking point of this lens. The lens therefore undergoes, due to the curvature of its front and rear faces, a tilting or "tilt", that is to say that it has a certain inclination with respect to its initial geometrical configuration obtained during the initial blocking. When the lens rotates its motion is then veiled, compared to its rotational movement during its initial trimming. This results firstly that the bevel will be trimmed irregularly and secondly that irregular facets will appear on the edges of the lenses. In addition, the clipping will be imprecise. This method therefore does not meet the requirements of precision required for the recovery of edging of the edge of the lens.

OBJECT OF THE INVENTION The object of the present invention is to refocus an ophthalmic lens, after trimming, according to a centering reference system as close as possible to that obtained during said trimming of this lens.

For this purpose, it is proposed according to the invention a method of trimming an ophthalmic lens comprising the steps of initial locking of the lens to an initial blocking point deduced according to a rule of calculation of the desired contour of the lens, trimming of the lens. lens, unblocking of the lens, and re-locking of the lens to a reblocking point for resumption thereof, according to which provision is made for the determination of the position of the reblocking point to acquire the contour of the lens such as obtained after the first trimming and deduced the position of the re-locking point. The deduction of the position of the re-locking point is such that the position of the re-locking point is closer to that of the initial blocking point.

Thus, thanks to the method according to the invention, it is possible after a first trimming to determine the position of the initial locking point of the lens, before the unblocking thereof, with the help of the contour obtained after trimming the lens without making optical measurements on the lens to be resumed.

In addition, thanks to this refocusing of the lens substantially to the initial blocking point of the lens used for the first trimming of the edge of the lens, said lens is not tilted after its reblocking, that is to say does not present no tilt difference after re-locking with respect to its geometric configuration after initial blocking. It is therefore not necessary to adapt the axial control of the grinding wheel to compensate for a possible phenomenon of warping of the reblocked lens. Finally, thanks to the absence of tilt during the reblocking of the lens, the edging face of the grinding wheel is parallel to the edge of the lens to be resumed and the recovery of the trimming of the edge of the lens can be achieved precisely by avoiding the appearance of facets on his song.

After reblocking the lens to resume at its re-locking point whose position is closer to that of the initial locking point, for some fixtures such as drilled fixtures or slotted fixtures, it is not necessary to change the control function of the grinding wheel relative to the contour of the lens to be resumed. Only the radial depth of trimming is increased by the optician to decrease the desired amount of the radius at each point of the outline (or edge) of the lens. According to a first advantageous characteristic of the method according to the invention, between the step of acquiring the contour obtained from the lens and the step of determining the position of the reblocking point, a step of orienting the contour obtained from the lens .

The orientation of the shape of the contour obtained from the lens to be taken up makes it possible to determine the horizontal and vertical directions associated with the lens in the configuration of the wearer to correctly machine this reblocked lens at its re-locking point on the clamping shafts. rotational drive.

According to another advantageous characteristic of the method according to the invention, the acquisition of the contour obtained from the lens being carried out by means of a digital image taking device, the step of orienting the contour obtained from the lens is achieved by physical positioning with a predefined orientation of the lens in the digital imaging device.

This physical positioning with a predefined orientation of the lens to be resumed in the digital imaging device simplifies the implementation of the clipping method according to the invention.

According to another advantageous characteristic of the method according to the invention, the acquisition of the contour obtained from the lens being carried out by means of a digital image pickup device, marking marks present on the lens being also acquired by the device. taking pictures numerical, the lens orientation step obtained from the lens is performed by a computer processing of the registration marks.

When the lens has registration marks, the acquisition and the computer processing of these marking marks can accurately determine the orientation of the lens to resume and thus proceed with its recovery with very good accuracy.

According to another advantageous characteristic of the method according to the invention, the desired contour of the lens being stored in computer memory, the step of orienting the contour obtained from the lens is performed by a calculation of virtual matching of the contour obtained from the lens. and the desired contour of the lens.

The shape of the contour obtained and that of the desired contour being very close, the resulting contour being only larger than the desired contour, the virtual matching of these two shapes, taking into account the scale factor due to the difference in magnitude. between these two contours, allows, from the knowledge of the orientation of the desired contour, to know that of the contour obtained. Indeed, after matching the two contours, the horizontal and vertical directions associated with the two contours are substantially the same. According to a first embodiment according to the invention of the method according to the invention, the reblocking point is defined such that its position relative to the desired contour of the lens, after matching said desired contour with the contour obtained of the lens, the same as the relative position of the initial blocking point with respect to the desired contour of the lens. The shape of the contour obtained and that of the desired contour are very close, the resulting contour being only larger than the desired contour. The mapping of the two contours by virtual superposition of the two contours allows, by projecting or "shifting", the relative position of the initial blocking point with respect to the desired contour of the lens, on the surface delimited by the contour obtained from the lens, to obtain the relative position of the desired reblocking point with respect to the obtained contour. Indeed, the shapes of the two contours being very close, the position of the reblocking point corresponding to that of the initial blocking point of the lens before loosening is substantially that of the blocking point, associated with the desired contour, projected, or "transferred" . According to a second embodiment according to the invention, the reblocking point is deduced from the contour obtained from the lens according to the same calculation rule as that used for the deduction of the initial blocking point of the desired contour of the lens. The shape of the contour obtained and that of the desired contour are very close, the resulting contour being only larger than the desired contour. As a result, the position of the re-locking point of the lens, calculated according to the same calculation rule as that used for the deduction of the relative position of the initial blocking point from the desired contour of the lens, is substantially the same as the position of the initial locking point of the lens before it is released.

Thus, this second embodiment does not require the shape of the desired contour, nor the relative position of the initial blocking point with respect to this desired contour. This second embodiment only uses the shape of the contour obtained and the calculation rule used during the initial locking of the lens to deduce the initial blocking point of the desired contour.

According to a third embodiment of the method according to the invention, the reblocking point of the lens is positioned relative to the contour obtained from the lens so that the distance ratio between, on the one hand, the position of each point of the lens. obtained contour of the lens and the position of the re-locking point and, secondly, the position of each corresponding point of the desired contour of the lens and the relative position of the initial blocking point with respect to this desired contour of the lens, is substantially constant.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT The following description with reference to the accompanying drawings of an embodiment, given by way of non-limiting example, will make it clear what the invention consists of and how it can be achieved. In the accompanying drawings:

- Figure 1 is a schematic top view of an automatic preparation device for mounting ophthalmic lenses; FIG. 2 is a perspective view of the interior of the automatic preparation device;

- Figure 3 is a perspective view of the carousel and seats forming the reception means and first and second transfer; FIG. 4 is a perspective view of the preparation device in a relay passage configuration, where the first lens is held by both the probing, gripping and third transfer means and by the locking and clamping means. rotating the clipping device;

FIG. 5 is a perspective view of a device for trimming and drilling an ophthalmic lens;

FIG. 6 is a schematic representation of the contour obtained from the lens and the desired contour according to a first embodiment of the clipping method according to the invention;

FIG. 7 is a schematic representation of the contour obtained from the lens and the desired contour according to a second embodiment of the clipping method according to the invention;

- Figure 8 is a schematic representation of the contour obtained from the lens and the desired contour according to a third embodiment of the clipping method according to the invention.

The term "job", commonly used in the ophthalmic optics industry, covers a pair of associated lenses L1 and L2 belonging to the same pair of spectacles and therefore mounted on the same frame to equip a wearer.

COMPONENTS OF THE AUTOMATIC PREPARATION DEVICE As shown more particularly in FIGS. 1 and 2, an assembly preparation device 1 comprises several subassemblies mounted on a common chassis: a measuring device 5 for the automatic measurement of various characteristics of the devices; L1 and L2 lenses and in particular the measurement of local ophthalmic power at remarkable points such as the optical center of a single-lens, and the measurement of at least one locating characteristic, such as a centering characteristic, 'Axing, locating reference points for distance vision and near vision, of the lens;

a device for trimming and drilling 6 ophthalmic lenses;

combined reception means and first and second transfers 2 designed and arranged to receive one or more ophthalmic lens jobs L1, L2, and to circulate them between a loading position and unloading, a measurement position in which the ophthalmic lens is presented opposite the measuring device 5 for measuring its locating characteristics and an intermediate position for its support by the probing means, capture and third transfer provided ci below; probing, grasping and third transfer means 7 designed and arranged to firstly palpate each ophthalmic lens in preparation and secondly to grasp this lens with a view to transferring it from the reception and first and second means; second transfers 2 to the trimming and drilling device 6; an electronic and computer system 100 designed for executing an automated processing method according to the invention;

a cowling enclosing the assembly for its protection and having a restricted access door (not shown); Measuring device The measuring device 5 has several functions for measuring various characteristics of the lens. Among these various functions, there are two main functions which consist, for one, in measuring the local optical powers of the lens at remarkable points thereof, and for the other, in detecting and locating characteristics of the lens. centering or locating the lens in order to establish and properly position the optical reference system of the lens in a known global repository of the device.

The measuring device 5 has two main complementary measurement systems to determine the characteristics of a lens. The first system is a global optical measurement system of the lens obtained by interferometry (or deflectometry ...). This measurement implements in particular a camera responsible for recording an image distorted by the lens in order to compare it with the initial image to determine, for example, the various optical powers of a lens at one or more remarkable points of the lens. lens. The second system is an imaging system. The system, by means of the camera, directly captures images of the lens and sends them to the electronic and computer system 100 which processes the information by image recognition. This system can thus determine, for example, the position of the marks engraved or plotted on the lens in order to determine its reference frame and to keep them in memory. As described below, this imaging system also makes it possible to acquire the contour of the lens by image processing. Detour device

The trimming function of the trimming and drilling device 6 can be performed in the form of any cutting or material removal machine adapted to modify the contour of the ophthalmic lens to match that of the frame or "circle" of a selected mount. Such a machine may consist for example of a grinder, a laser cutting machine or jet water, etc. As shown in Figure 5, the shaping device comprises, in a manner known per se, an automatic grinder 610, commonly called digital. This grinder comprises, in this case, a flip-flop 611, which is pivotably mounted around a first axis A1, in practice a horizontal axis, on a frame 601. For the immobilization and the rotational drive of a Ophthalmic lens such as L1 to be machined, the grinder is equipped with support means able to clamp and rotate an ophthalmic lens. These support means comprise two shafts and rotation drive 612, 613. These two shafts 612, 613 are aligned with each other along a second axis A2, called locking pin, parallel to the first axis A1. The two shafts 612, 613 are rotated synchronously by a motor (not shown), via a common drive mechanism (not shown) embedded on the flip-flop 611. This common synchronous rotation drive mechanism is of type current, known in itself. Alternatively, it will also be possible to drive the two shafts by two separate motors synchronized mechanically or electronically.

The ROT rotation of the shafts 612, 613 is driven by a central electronic and computer system (not shown) such as an integrated microcomputer or a dedicated integrated circuit assembly (ASIC). As shown in FIG. 4, each of the shafts 612, 613 has a free end facing the other and which is equipped with a locking nose 101. These locking noses 101 are not always fixed on the shafts 612 , 613. They are in fact previously used by the probing, grasping and third transfer 7 before being transferred to the present clipping and piercing device 6 while remaining in contact with the transferred lens.

The shaft 613 is movable in translation along the blocking axis A2, facing the other shaft 612, to effect the compression in axial compression of the lens L1 between the two locking noses 101. The shaft 613 is controlled for this axial translation by a drive motor via an actuating mechanism (not shown) controlled by the central electronic and computer system. The other shaft 612 is fixed in translation along the blocking axis A2. The trimming and drilling device 6 comprises, on the other hand, a train of at least one grinding wheel 614, which is locked in rotation on a third axis A3 parallel to the first axis A1, and which is also duly rotated. by a motor not shown.

In practice, the grinder 610 comprises a train of several grinding wheels 614 mounted coaxially on the third axis A3, for a roughing and finish of the edging of the ophthalmic lens L1 to be machined. These different grinding wheels are each adapted to the material of the cut-out lens and the type of operation performed (roughing, finishing, mineral or synthetic material, etc.).

The grinding wheel is attached to a common shaft of axis A3 ensuring their rotational drive during the edging operation. This common shaft, which is not visible in the figures shown, is rotated by an electric motor 620 driven by the electronic and computer system.

The wheel train 614 is also movable in translation along the axis A3 and is controlled in this translation by a drive motor. Concretely, the entire wheel train 614, its shaft and its motor is carried by a carriage 621 which is itself mounted on slides 622 secured to the frame 601 for sliding along the third axis A3. The translational movement of the wheel trolley 621 is referred to as "transfer" and is denoted TRA in FIG. 5. This transfer is controlled by a motorized drive mechanism (not shown), such as a screw and nut system or rack, driven by the central electronic and computer system.

To allow a dynamic adjustment of the distance between the axis A3 of the grinding wheels 614 and the axis A2 of the lens during the edging, the pivoting capacity of the lever 611 about the axis A1 is used. This pivoting provokes indeed a displacement, here substantially vertical, of the lens L1 sandwiched between the shafts 612, 613 which brings the lens closer to or away from the grinding wheels 614. This mobility, which makes it possible to restore the desired and scheduled shape of the edging in an electronic and computer system, is called restitution and is noted RES in the figures. This RES restitution mobility is controlled by the central electronic and computer system.

For the machining of the ophthalmic lens L1 along a given contour, it is necessary to move accordingly a nut 617 along the fifth axis A5, under the control of the motor 619, to control the restitution movement and, on the other hand, to jointly pivoting the support shafts 612, 613 about the second axis A2, in practice under the control of the motor that controls them. The transverse restitution movement RES of the flip-flop 611 and the rotational movement ROT of the shafts 612, 613 of the lens are controlled in coordination by an electronic and computer system (not shown), duly programmed for this purpose, so that all the points the contour of the ophthalmic lens L1 are successively reduced to the correct diameter.

The grinder illustrated in FIG. 5 further comprises a finishing module 625 which embeds chamfering and grooving grinders 630, 631 mounted on a common axis 632 and which is movable according to a degree of mobility, in a direction substantially transverse to the axis A2 of the trees 612, 613 for maintaining the lens as well as the axis A5 of the restitution RES. This degree of mobility is called retraction and is noted ESC in the figures.

In this case, this retraction consists of a pivoting of the finishing module 625 around the axis A3. Specifically, the module 625 is carried by a lever 626 integral with a tubular sleeve 627 mounted on the carriage 621 to rotate about the axis A3. For the control of its pivoting, the sleeve 627 is provided, at its end opposite the lever 626, a toothed wheel 628 which meshes with a pinion (not visible in the figures) fitted to the shaft of an electric motor 629 integral with the trolley 621. It is observed, in summary, that the degrees of mobility available on such a trimming machine are:

the rotation of the lens making it possible to rotate the lens around its holding axis, which is generally normal to the general plane of the lens, restitution, consisting of relative transverse mobility of the lens (ie in the general plane of the lens) relative to the grinding wheels, making it possible to reproduce the different rays describing the contour of the desired shape of the lens the transfer, consisting of an axial relative mobility of the lens (that is to say, perpendicular to the general plane of the lens) relative to the grinding wheels, making it possible to position the lens and the grinding wheel selected clipping.

- The retraction, consisting of a transverse relative mobility, in a direction different from that of the restitution of the finishing module with respect to the lens, to put in position of use and store the finishing module.

With regard to the drilling function the module 625 is provided with a drilling tool 636.

This drilling tool 636 is mounted on the module 625 to pivot about an axis of orientation A7 substantially transverse to the axis A3 of the grinding wheels 614 and the restitution axis A5 and, consequently, substantially parallel to the ESC retraction direction of the module 625. The drilling axis A6 is thus orientable about the axis of orientation A7, that is to say in a plane close to the vertical.

This pivoting orientation of the drilling tool 636 is noted PIV in the figures. This is the only degree of mobility dedicated to drilling.

Combined means of reception and first and second transfers The means of reception and first and second transfers 2 take the form of a carousel which includes (see Figure 3):

a loading and unloading platform 30 mounted on the common chassis for rotating, under the control of control means (in this case an electric motor not shown) controlled by the electronic and computer system 100, about an axis of rotation passing substantially through its center and perpendicular to the plane of this plateau;

a support frame 31 integral with the common frame; reception seats 34, 35 on which the lenses L1 and L2 are intended to rest when they are loaded on the plate 30.

- On the loading and unloading platform 30, at least three loading places 36 to 38 and at least four unloading places 41 to 44. immobilization means 32 of the lenses L1 and L2 loaded onto the plate 30 at the loading places 36 to 38.

In the illustrated example, the loading places 36 to 38 are constituted by a corresponding number of indentations or recesses. These three indentations 36 to 38 are identical and each have a substantially circular shape of diameter slightly greater than that standard

(about 70 mm) L1 and L2 lenses to be cut. The three indentations are arranged emerging on the periphery of the loading and unloading tray 30. These openings allow access to at least two seats 34, 35 on which the lenses to be cut. Next to the loading places 36 to 38 are articulated clamps 32 constituting the means for immobilizing the lenses (FIG. 3).

The four unloading places 41 to 44 are constituted by recesses or cuvettes formed on the surface of the plate 30. These hollows or depressions are circular in shape with a diameter always greater than that of the lenses L1 and L2 after trimming.

Virtually radial slots 45 are provided from the center of each unloading cavity 41 to 44 to the peripheral edge of the plate 30 on which these openings open. These lights are intended to allow removal and depositing of the lenses by the third transfer means.

The locking means 32 of the lenses comprise clips 46 to 48 which are each located directly above the loading places 36 to 38.

Preferably, the measuring device 5 and the probing, gripping and third transfer means 7 are located side by side. The measuring device 5 is at least partly located in line with the path traveled by the loading places 36 to 38 and unloading 41 to 44 so that the lenses L1, L2 remain carried by the loading and unloading platform 30 when determining their characteristics.

In addition, the trimming and drilling device 6 is placed adjacent to the loading and unloading platform 30, and the probing, gripping and second transfer means 7 are interposed between the measuring device 5 and this clipping device. and drilling 6.

Combined probing, gripping and third transfer means After the determination of certain characteristics of the lens L1 by means of the measuring device 5 according to, in particular, the method explained at the beginning of the present description, the loading and unloading tray 30 is again rotated to bring, in a second transfer, the lens L1 facing the probing means, gripping and third transfer 7. The lens L1 is then in said intermediate position.

These probing, gripping and third transfer means 7 take the form of a member or arm ensuring on the one hand the probing of the lenses L1 and L2 and on the other hand the manipulation of these lenses with a view to their transfer (third transfer) to the trimming and drilling device 6.

For this purpose, the probe, gripping and third transfer arm 7 has a wrist 81 movable relative to the common frame according to five controlled axes, with a horizontal translation along the axis X ₁ a vertical translation along the axis Z three rotations around the axes X, Y, Z. The control of these axes of mobility is achieved in this case by motorized electric means. But the skilled person may provide for the implementation of other control means such as pneumatic or other means. Whatever the nature, the control of these five axes of mobility is controlled by the electronic and computer system 100. In practice, the wrist 81 is articulated on a bearing stub 80 so as to be pivotable relative to the ci along the X and Y axes. The stump 80 is itself mounted mobile in vertical translation along the Z axis on a vertical beam 82 forming for this sliding effect. This vertical beam 82 is carried at its lower end by a turret which is rotatably mounted along the axis Z on a carriage. This carriage is mounted on a horizontal beam 83, associated with the common frame and forming a slide, for sliding along the X axis. These five degrees of freedom of the wrist 81 in the fixed frame of reference (X, Y, Z) are controlled by different motors. electric controlled by an electronic card of appropriate power, by the electronic and computer system 100. To allow the separate probing functions on the one hand and gripping on the other hand, the wrist 81 of the arm 7 is provided with probing means and gripping means which are distinct and independent of one another. The probing means are arranged to palpate independently or jointly the two main faces (front or convex and rear or concave) L1 lenses. L2.

The gripping means take the form of a locking clamp which consists of an upper jaw 95 and a lower jaw 96 movable in translation or pivot facing each other. In the example shown, the lower jaw 96 is movably mounted on the wrist 81 to slide on a rail in the same direction of translation as the probe branch 90. The upper jaw 95 is itself fixedly mounted on the wrist 81.

The jaws 95, 96 are of substantially rectilinear shape, generally parallel to the probing branches 90, 91, and are provided at their free end with means for releasably fixing by clip (clipping means) 97 which here have the shape of a ring C-shaped open elastic band forming a clip. These clipping means are intended to accommodate noses 101 for gripping and locking the lens.

The pair of noses 101 thus mounted at the end of the gripping jaws 95, 96 makes it possible to carry out the gripping and, later on the clipping means, the sandwich locking of a lens. In general, each nose has on the one hand axial fixing means and on the other hand transverse fixing means. Both noses are transferred, by means of the probe arm, gripping and second transfer 7, with the lens that they carry or block, from the carousel of reception and first transfer 2 to the device of clipping and drilling 6 This is the third transfer of the lens concerned. However, attention is now drawn to an important characteristic of double interoperability of each nose: the transverse fixing means are arranged to cooperate with the arm 7 and the axial fixing means are arranged to cooperate with the shafts 612, 613 of clamping and rotating drive the grinder. The nose 101 thus have a dual function. When they are associated with the arm 7, they constitute gripper tips for gripping and transferring the lens. When they cooperate with the shafts 612, 613 of the grinder, they constitute stops for locking and driving in rotation of the lens. We understand the major advantage of this third transfer the lens operated with the nose in contact with the lens: it avoids any loss of reference.

The noses 101 are able to be transferred to the clipping means with the lens that they seize and then realize without further repositioning of the lens its locking on the clipping means.

As mentioned above, the noses 101 have a dual function. They are first used to achieve the gripping of the lens from its loading location on the plate 30 of the carousel of first and second transfers 2, when they present the lens in the intermediate position. Then, the lens being thus grasped, by means of the noses 101, by the probing, grasping and third transfer arm 7 the latter operates the third transfer of the lens towards the shaping and piercing means 6. When the lens is supported by these clipping means (relay passage), the nose retains a holding role by tightening the lens and then exert a second function, derived from the first, which consists in making the lens lock in view either the machining of the lens in cooperation with the clamping shafts and rotation of the shaping and drilling means 6. The nose then constitute drive stops forming an integral part of the shaping and drilling means 6. For its mechanical interfacing with the shafts 612, 613 of the trimming and drilling means 6, each of the noses 101 cooperates with the free end of the shaft 612, 613 corresponding by an em system. housing with complementary male and female parts forming, in cooperation with each other, a free-spinning drive. The mounting preparation device 1 also comprises a nose magazine placed in the vicinity of the feeler, gripping and transfer arm 7. This store houses staged three pairs of nose adapted to the different kinds of lenses.

These combined probing, gripping and third transfer means 7 are therefore designed to operate with semi-finished (i.e., uncut) ophthalmic lenses.

Electronic and computer control system

The device 1 comprises an electronic and computer control system 100 consisting here of an electronic card designed to drive in coordinating the measuring means, the trimming device, the reception and first and second transfer means and the probing, gripping and third transfer means for automatically processing a lens.

The electronic and computer system 100 comprises for example conventionally a motherboard, a microprocessor, a random access memory and a permanent mass memory. The mass memory contains an execution program of the automated assembly preparation method. This mass memory is preferably rewritable and is advantageously removable to allow its rapid replacement or programming on a remote computer via a standard standard interface. PROCESS OF RETURNING DETOURAGE

Prior to the trimming, that is to say, the trimming of the edge of the ophthalmic lens L1, the lens L1 is raw circular edge, that is to say not cut off. Before proceeding with the first trimming of the lens, the desired contour C1 of the lens L1 (see FIG. 6) is stored electronically by the electronic and computer system 100 of the device 1. Can the acquisition of the desired contour C1 of the lens L1 be possible? be performed by a reading device (not shown) of the inner contour of the circles of the frame or by reading an electronic file provided (by the manufacturer of frames, for example). This desired contour C1 of the lens L1 has an associated own mark O1, H1, V1 whose axes H1 and V1 respectively define the horizontal axis and the vertical axis in the configuration of the wearer equipped with the frame.

A reference O, XO, YO, fixed is associated with the measuring device 5. The reference O, XO, YO is here a fixed reference considered as absolute in which the various functional elements of the device 1 such as the carousel, the gripping arm 7, the trimming and drilling device 6 and the measuring device 5 cooperate with each other. For simplification, here, the reference 01, H1, V1 of the desired contour C1 of the lens L1 coincides with the fixed reference O, XO, YO. The reference 01, H1, V1 of the desired contour C1 of the lens L1 and the fixed reference O, XO, Y0 of the measuring device 5 may not be confused. In this case, it suffices to use the known matrix of passage between the two marks to pass from one to the other.

Firstly, the raw lens is positioned in the measuring device 5. The initial blocking of the lens is realized at an initial blocking point Pb1 deduced according to a rule of calculation of the desired contour C1 of the lens L1, and the optical characteristics of centering and orientation of the lens, as well as the morphological characteristics of the wearer.

The relative position of this initial blocking point Pb 1 relative to the desired contour C1 of the lens L1, that is to say the position of this initial blocking point Pb1 in the proper frame 01, H1, V1, is also known. of the desired contour C1 of the lens Ll

After the first trimming of the raw lens centered and blocked, according to the initial locking point Pb1 determined, on the clamping shafts and rotating drive 12, 13, the cut-out lens thus obtained is loosened and positioned in the frame. The unlocking of the lens after its first trimming results in the loss of the position of the initial locking point Pb1 with respect to the obtained contour C2 of the lens L1 and the loss of the reference associated with this initial blocking point PbI. initial blocking Pb1 of the lens before its trimming is also the locking point of the lens L1 after its trimming and before loosening the clamping shafts and rotating drive 12, 13.

When the trimming of the lens does not succeed at first blow to a good mounting in the frame, it is necessary to perform a recovery of trimming of the lens L1.

For the sake of simplification, the lens L1 which has to be cut off again will be designated by the expression "lens to be resumed", that is to say, the trimming of the edge must be resumed. To be able to carry out this recovery of clipping correctly one implements a method making it possible to reacquire the reference of initial centering of the lens L1 by determining the position of a reblocking point Pb2 and the orientation of the lens L1 around this point of Pb2 reblocking. The deduction of the position of the reblocking point Pb2 is such that the position of the reblocking point Pb2 is at best approaching that of the initial locking point PbI. This method is here applied to the lens L1 of the lens job L1 and L2 and can obviously be applied to the L2 lens.

The lens L1 is then positioned according to an unknown position and orientation in the measurement system 5. This measuring system 5 integrates as detailed above a camera serving as a digital image taking device. (not shown) The positioning of the lens L1 in the measurement system 5 can be carried out directly by the optician himself or automatically using the carousel or the gripping arm 7.

The first step of this method consists of the acquisition by the digital image taking device of the resulting contour C2 of the lens to be resumed.

The digital image taken by the digital image taking device is then processed by computer. So at each point of the contour obtained C2 of the lens

L1 is associated geometric coordinates in the fixed reference O, XO, YO of the measuring device 5, and at each point of the desired contour C1 of the lens L1 is associated geometric coordinates in the same frame O,

XO, YO.

As for the desired contour C1 of the lens L1, the resulting contour C2 has a proper mark 02, H2, V2 whose axes H2 and V2 respectively define the horizontal axis and the vertical axis in the configuration of the wearer equipped with The mount.

As illustrated by FIG. 6, the lens L1 being positioned in an unknown orientation in the measuring device 5, the second step for determining the re-locking point Pb2 of the lens L1 consists in determining the orientation of the obtained contour C2, c that is to say the orientation of the axes H2 and V2 of this lens with respect to those H1 and V1 of the known own frame of the desired contour C1 of the lens L1.

It is recalled that the orientation of the axes H1 and V1 of the reference 01, H1, V1 is known in the fixed reference O, XO, YO and here the axes of these two marks are merged two by two. The calculations can therefore easily be performed in one or the other of these two references.

After the first trimming of the lens L1, the resulting contour C2 of the lens L1 and the desired contour C1 of the lens L1 are very close. Indeed, generally it is the optician himself who adds a margin of safety relative to the amount of material to be removed on the contour of the raw lens. Thus, the resulting contour C2 of the lens L1 has a shape substantially identical to that of the desired contour C1 of the lens L1 and the resulting contour C2 is larger than the desired contour C1.

The desired contour C1 of the lens L1 being stored in computer memory, the step of orienting the resulting contour C2 of the lens L1 is performed by a calculation of virtual matching of the obtained C2 contour of the lens L1 and the desired contour C1 of the lens L1 Precisely, to determine the orientation of the axes H2 and V2 of the own mark of the resulting contour C2 of this lens L1 compared to those H1 and V1 of the proper mark of the desired contour C1 of the lens L1, a superposition algorithm of the desired contour C1 of the lens L1 is used with the resulting contour C2 of the lens L1.

The superposition algorithm of the two contours C1 and C2 is implemented as follows. The desired contour C1 is defined by a set of N contour points whose coordinates are known in the coordinate system O ₁ ₁ XO YO. In the same way, when the measuring device 5 acquires the obtained contour C2, a set of M points of the resulting contour C2 is defined. The coordinates of these M points are then known in the frame O ₁ XO ₁ YO. It is thus possible to carry out distance calculations between the different points of the contours in the frame O ₁ XO ₁ YO. In order to proceed to the "virtual" superposition of these two contours C1 and

C2 one determines the transformation which makes it possible to realize this superposition. A transformation is defined by a translation Tx along the axis XO ₁ a translation Ty along the axis YO, a rotation Rz about a Z axis transverse to the plane XO, YO and, optionally, a rotation about a contained axis in the plane XO, YO. This transformation Rz ₁ Tx ₁ Ty is then assigned to the desired contour C1. We then obtain the desired transformed contour C1 'defined by the N transformed points of the desired contour Cl

Then, we count the number Nsup of points among the N points of the transformed contour C1 ¹ which are located in a close vicinity of a point of the obtained contour C2. "Close neighborhood" means that the two points concerned are situated at a distance from each other below a given distance, for example a few tenths of a millimeter, each point of the transformed contour C1 'situated in a close neighborhood of one of the M points of the resulting contour C2 is considered to be superimposed at this point of the resulting contour C2. If the number Nsup of points of the contour CT tranformed thus superimposed is greater than 90% of the number N, it is considered that the transformation is suitable and so the two contours are superimposed. On the other hand, if the number Nsup is less than or equal to 90%, the values fixed for the rotation Rz and the translations Tx, Ty are varied according to a determined range of values and using a sufficiently small increment, until a combination of these values provides an Nsup number of points greater than 90% of the number N.

The threshold value of 90% can be modified according to the desired precision as well as the given distance defining the close neighborhood between two points. Finally one can carry out the calculations in a reference other than the mark O ₁ XO ₁ YO, as long as the basic change between these two marks is known.

The mapping of the two contours C1 and C2 can be performed by taking a limited number of points on a part of each of the contours C1, C2 or by taking the entire contours C1 and C2. When the desired contour C1 of the lens L1 is digitally superimposed, by means of the superposition algorithm, on the resulting contour C2 of the lens L1, the desired contour C1 of the own index lens L1, H1, V1 becomes the rotation and translation adapted to the superposition of the two contours, the desired contour C1 ¹ of the lens L1 'own reference 01', H1 \ V1. This proper mark 01 ', H1 \ V1 ¹ is then chosen as being the proper mark 02, H2, V2 of the resulting contour C2 of the lens L1, the axis H2 thus defining the horizontal axis of the lens and the axis V2 the vertical axis of the lens in the configuration of the wearer equipped with the frame.

During the initial blocking of the lens L1, the relative position of the initial blocking point Pb1 relative to the desired contour C1 of the lens L1 is memorized. The relative position of the initial blocking point with respect to the desired outline C1 ', of its own mark 01 ', H1', V1 ¹ , superimposed on the resulting contour C2 is here denoted Pb1 '. the reblocking point Pb2 is then defined so that its relative position relative to the desired contour C1 'of the lens L1 is the same as the relative position of the initial blocking point PbI ¹ relative to the desired contour C1' of the lens L1 during initial blocking.

The orientation of the obtained contour C2 of the lens L1 and the position of its re-locking point Pb2 are now known in the fixed reference O, XO, YO of the measuring device 5, the gripping arm 7 can then grip the lens L1 and position it correctly according to its locking point Pb2 and in a known orientation on the clamping shafts 12, 13 of the shaping and drilling device 6. The clipping recovery of the contour C2 of the lens L1 is then performed by reducing the radius of the lens L1 at each point of its contour C2 by the desired amount.

As an alternative to the step of determining the orientation of the lens to be resumed, it can also be provided that after being positioned in an unknown orientation in the measuring device, the latter acquires marks of microscopic type on the lens to resume, thereby determining its orientation in the fixed reference O, XO, YO of the measuring device. The step of determining the orientation of the lens can also be performed by determining the main axes of inertia of the shape of the contour obtained and matching them to the main axes of inertia of the shape of the desired contour. It is also possible to match the vertical and horizontal axes of the shape of the contour obtained with those of the shape of the desired contour, in the configuration of the carrier. It is also possible to provide for matching the width and the height of the rectangle in which the shape of the contour obtained, called "boxing", is inscribed with the width and height of the boxing of the shape of the desired contour, orienting the shape of the contour obtained so that the widths and heights of these two boxing coincide. As a variant, it is possible to provide that the step of orienting the contour obtained

C2 of the lens L1 is achieved by physical positioning with a predefined orientation of the lens L1 in the digital image taking device. The optician can then grasp the lens L1 and position it substantially in the horizontal direction for the wearer defined in the fixed reference O, XO, YO of the measuring device 5, that is to say here along the axis XO ( or H1) (see Figure 7). Obviously, the optician must then appreciate of itself the horizontal direction, that is to say, the orientation of the H2 axis of the lens L1.

It can also be provided that it is the gripping arm 7 which positions the lens L1 in the measuring device 5 in a predetermined direction. This positioning direction is not necessarily along the XO axis, but must be predetermined, that is to say known, for example by implementing one of the methods for determining the orientation of the exposed lens. above. This predetermined direction is obtained before positioning the lens L1 in the measuring device 5 in another device. measurement or imaging. Alternatively, it is conceivable to obtain this predetermined direction in the measuring device 5. Indeed, once the direction of the orientation of the lens automatically identified by the measuring device 5, the location of the orientation of the lens thus produced is used by the central unit to control the manipulator arm in order, if necessary, to reposition the lens in the measuring device in another direction of orientation judged to be better adapted (for example the direction of the XO axis).

Another variant of the first embodiment (FIG. 6) of the method according to the invention is proposed. After determining the orientation of the obtained contour of the lens to be resumed according to one of the methods described above, the re-locking point of the lens is positioned relative to the resulting contour of the lens so that the distance ratio between, d on the one hand, the position of each point of the contour obtained from the lens and the position of the re-locking point and, on the other hand, the position of each corresponding point of the desired contour of the lens and the relative position of the initial blocking point relative to this desired contour of the lens, is substantially constant and close to 1.

A second embodiment of the method according to the invention which is an alternative embodiment of the first embodiment (FIG. 6) is illustrated by FIG. 7. The reblocking point Pb2 is deduced from the obtained contour C2 of the lens L1 according to FIG. same calculation rule as that used for the deduction of the initial blocking point Pb1 of the desired contour C1 of the lens L1. A point commonly used for the initial blocking of the lens L1 is the point called "boxing center". The boxing center, well known to those skilled in the art, is the point of intersection of the diagonals of the horizontal rectangle in which is inscribed the shape of the desired contour of the lens after trimming in the configuration of the worn (defining the horizontality). In this embodiment, the position of the initial locking point Pb1 of the lens L1 has been deduced from the desired contour C1 of the lens L1 by this calculation rule for obtaining the boxing center.

The orientation step of the resulting contour C2 is carried out according to one of the above methods. Knowing the orientation of the axes H2 and V2 of the reference associated with the obtained contour C2 of the lens L1, the boxing center Cb2 of the shape of the obtained contour C2 of the lens L1 is then determined.

Indeed, the shape of the resulting contour C2 of the lens L1 and that of the desired contour C1 of the lens L1 being very close, the relative position of the center boxing Cb2 with respect to the obtained contour C2 of the lens L1 substantially corresponds, in the respective eigenmarks of the two contours C1 and C2 of the lens L1, to the relative position of the boxing center Cb1 with respect to the desired contour C1 of the lens L1. position of the reblocking point Pb2 is then chosen as confused with that of the boxing center Cb2. It is also possible for the position of the initial blocking point Pb1 of the lens L1 to be defined in the proper frame 01, M, V1 with respect to the boxing center CbI. As previously, the position of the boxing center Cb2 with respect to the contour is then determined. obtained C2 from the lens L1 and positioning the reblocking point Pb2 with respect to the boxing center Cb2, in the proper frame 02, H2, V2 of the obtained contour C2 of the lens L1, in the same manner as the initial blocking Pb1 with respect to the boxing center Cb1, in the proper frame 01, H1, V1 of the desired contour C1 of the lens L1 It is also possible to position the reblocking point Pb2 with respect to the boxing center Cb2, in its own frame 02, H2 , V2 by adapting the distance of the reblocking point Pb2 from the boxing center Cb2 to the difference in magnification (or difference in scale) between the two shapes of the contours C1, C2 of the lens L1. According to this second embodiment of the method die according to the invention described above, the deduced initial locking point of the desired contour of the lens is the boxing center; however, any other point obtained by a calculation rule depending on the desired contour of the lens can be used. Thus, it is possible to use as the initial blocking point the centroid of the desired contour of the lens, or the point whose distance from all the points of the desired contour has a minimum standard deviation.

A third embodiment of the method according to the invention which is an alternative embodiment of the first (FIG. 6) and the second (FIG. 7) embodiment is illustrated in FIG. 8. This third embodiment of the invention is proposed to determine the re-locking point Pb2 on the resulting contour C2 of the lens L1, when the initial locking point Pb1 has been defined from a point deduced from the desired contour C1 of the lens L1 such that the boxing center CbI La L1 lens is positioned according to an unknown configuration in the measuring device 5. As for the first embodiment, its orientation is then determined by the desired contour superimposition algorithm C1 with the resulting contour C2. Knowing then the horizontal direction H1 ¹ and vertical VT of the proper mark OT, HT, VT of the desired contour CT of the lens LI ₁ can be similarly to the second embodiment (FIG. 7) determine the boxing center CbT with respect to the desired contour CT of the Ll lens

The relative position of the boxing center CbT with respect to the desired contour CT corresponds substantially to that of the initial blocking point Pb1 (the boxing center Cb1) with respect to the desired contour C1. As for the first embodiment, the position of the re-locking point Pb2 is chosen such that its position relative to the desired contour CT is the same as the relative position of the boxing center CbT with respect to the desired contour CT of the lens L1.

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant within his mind. According to the embodiments of the method according to the invention and their variants, presented above, the deduction of the position of the reblocking point is such that the position of the reblocking point approaches at best that of the initial blocking point . However, one could consider choosing a re-locking point distinct from the initial blocking point, after having deduced on the lens to resume the position occupied by the initial blocking point. The important thing is obviously in this case to know with sufficient precision, as proposed by the method according to the invention, the position of the initial blocking point to be able to adapt the program that controls the grinding wheel to the reference associated with the reblocking point . As a variant of the previous embodiments and for frames of the type without a circle, it is advantageous to use the method according to the invention for refocusing the lens on the clamping shafts and rotating drive to perform, after the loss of reference due to disassembly and reassembly of the lens, piercing of the lens on the trimming and drilling device by means of the piercing tool.

The reacquisition of the initial centering reference by the method according to the invention can also be used for the recovery (trimming and / or drilling) of a lens on which is applied a tassel maintenance if it was removed after the first clipping and must be reapplied.

Claims

1. A method of trimming an ophthalmic lens (L1) comprising the following steps:

initial blocking of the lens at an initial blocking point (Pb1) deduced according to a rule for calculating the desired contour (C1) of the lens (L1),

- trimming of the lens (L1),

- unlocking of the lens (L1),

- Reblocking the lens to a reblocking point (Pb2) for resumption, characterized in that, for determining the position of the reblocking point (Pb2), acquiring the contour (C2) of the lens (L1 ) as obtained after the first trimming and deduces the position of the reblocking point (Pb2).

2. Method according to claim 1, characterized in that the deduction of the position of the reblocking point (Pb2) is such that the position of the reblocking point (Pb2) is closer to that of the initial blocking point (Pb1) ).

3. Method according to one of the preceding claims, characterized in that it comprises, between the step of acquiring the obtained contour (C2) of the lens (L1) and the step of determining the position of the point of reblocking (Pb2), a step of orientation of the obtained contour (C2) of the lens (L1).

4. Method according to claim 3, characterized in that, the acquisition of the obtained contour (C2) of the lens (L1) being carried out by means of a digital image pickup device (2), the step d orientation of the obtained contour (C2) of the lens (L1) is achieved by physical positioning with a predefined orientation of the lens (L1) in the digital image taking device (2).

5. Method according to claim 3, characterized in that, acquisition of the resulting contour (C2) of the lens (L1) being performed by means of a digital image pickup device (2), tracking marks present on the lens (L1) being also acquired by the digital image taking device (2), the step of orienting the obtained contour (C2) of the lens (L1) is performed by a computer processing of the marks of tracking.

6. Method according to claim 3, characterized in that, the desired contour (C1) of the lens (L1) being stored in memory, the step of orienting the obtained contour (C2) of the lens (L1) is carried out by a calculation of implementation virtual correspondence of the obtained contour (C2) of the lens (L1) and the desired contour (C1) of the lens (L1).

7. Method according to one of the preceding claims, characterized in that the reblocking point (Pb2) is defined such that its position relative to the desired contour (C1) of the lens (L1), after matching said desired contour (C1) with the obtained contour (C2) of the lens (L1), the same as the relative position of the initial blocking point (Pb1) with respect to the desired contour (C1) of the lens (L1).

8. Method according to one of claims 1 to 6, characterized in that the position of the reblocking point (Pb2) is derived from the resulting contour (C2) of the lens (L1) according to the same calculation rule as that used for the deduction of the position of the initial blocking point (Pb1) of the desired contour (C1) of the lens (L1).

9. Method according to one of claims 4 to 6, characterized in that the reblocking point (Pb2) of the lens (L1) is positioned relative to the resulting contour (C2) of the lens (L1) so that the ratio of distance between, on the one hand, the position of each point of the obtained contour (C2) of the lens (L1) and the position of the reblocking point (Pb2) and, on the other hand, the position of each corresponding point the desired contour (C1) of the lens (L1) and the relative position of the initial blocking point (Pb1) with respect to this desired contour (C1) of the lens (L1) is substantially constant.