EP2091689A2

EP2091689A2 - Device for determining the position and/or transverse dimension of a drill hole in a lens for the presentation of spectacles with a rimless frame

Info

Publication number: EP2091689A2
Application number: EP07872397A
Authority: EP
Inventors: Philippe Pinault
Original assignee: Essilor International Compagnie Generale dOptique SA
Current assignee: EssilorLuxottica SA
Priority date: 2006-12-20
Filing date: 2007-12-19
Publication date: 2009-08-26
Anticipated expiration: 2027-12-19
Also published as: FR2910644A1; WO2008093015A3; US8320710B2; DE602007004648D1; ATE456424T1; WO2008093015A2; EP2091689B1; US20100092068A1; FR2910644B1

Abstract

The device has an acquisition device (53) e.g. camera, for capturing an image set of an extraction opening (110) of an ophthalmic lens (100) along a lighting direction (D51, A52) or capturing an image (A53). A processing system (54) processes the image when the lens is carried by a support (55), and determines a center position of a mouth of the opening from the image set of the opening and/or transversal dimension of the mouth of the opening corresponding to a required transversal dimension, where the mouth emerges on front surface (98) of the lens.

Description

"Device for determining the position and / or transverse dimension of a drilling hole of a spectacle lens with a rimless spectacle"

TECHNICAL FIELD TO WHICH THE INVENTION REFERS

The present invention generally relates to the mounting of ophthalmic lenses of a pair of spectacles on a mount of the type without a circle and more particularly to a device for determining the position and / or a transverse dimension of a drilling hole. a presentation lens (serving as a model) for drilling, at said position and / or at said transverse dimension, a mounting lens that is to be assembled to a spectacle frame of the type without a circle.

BACKGROUND ART When an eyeglass frame is of the type without a circle, the clipping of each of the lenses intended to equip this frame is followed by the appropriate drilling of each lens to allow the fixation of the branches and the nose bridge of the frame without a circle. . Drilling can be performed on a grinder or on a separate drilling machine by means of a drill bit. Most often, the following drilling method is implemented.

First of all the future carrier chooses the frame, equipped with presentation lenses, that he wishes. The optician then places the presentation lenses one after the other in a device for determining the position of the drilling holes. Each presentation lens is already pierced on its temporal and nasal parts and then serves as a model for the trimming and proper drilling of the corresponding left or right correction lens intended to equip the future wearer with the mount he has chosen.

The presentation lens is thus placed in a support between projected vision lighting means and image capture means, the front face of the lens being directed towards the lighting means. A frosted glass plate makes it possible to form the image of the shadow of the lens, in projected vision, on the capture means.

The image of the shadow of the presentation lens is acquired. This gives an overall image of the drilling hole which has a complex geometric shape. This overall image is displayed on a screen. There is provided a virtual registration ring that the operator visualizes and moves on the screen to superimpose, sizing and centering on the overall image of the drilling hole of the presentation lens. The operator validates this positioning and this dimensioning and the processing system stores the position of the center and the transverse dimension (ie its diameter if the hole is round) of the registration ring as being the position of the center and the transverse dimension of the drilling hole to be made on the correction lens.

After trimming of the correction lens along the contour of the presentation lens, a drill bit having a suitable diameter is brought, vis-à-vis the correction lens, to the stored position of the hole to be drilled. The correction lens is then pierced by means of a relative advance movement of the drill bit relative to the lens along the axis of rotation of the drill bit. If the diameter of the drill bit is smaller than the desired diameter, the hole obtained is widened to the right diameter by means of a suitable transverse displacement of the drill bit.

However, it is observed, in particular for highly curved lenses, that there is often a large error between the position and size of the piercing hole made on the correction lens and the actual position and dimension of the piercing hole of the lens. presentation. This error of position and size of the hole induces difficulties of mounting the lens on the branches and the nasal bridge and even leads in some cases to an impossible assembly or poor quality, or forces the optician to perform a recovery operation time consuming and demanding a high level of expertise. It can also result in a bad positioning of the lens facing the eye of the wearer, which degrades the optical correction performance.

OBJECT OF THE INVENTION

The object of the present invention is to determine accurately the position and / or a transverse dimension of a drilling hole to be made on a lens that is to be assembled to a bezel mount of the type without a circle. For this purpose, the invention proposes a device for determining the position and / or a transverse dimension of a drilling hole of a spectacle lens with rims without a circle, comprising:

means for supporting the lens,

means for capturing an overall image of the drilling hole of the lens in a direction of illumination or of image capture,

means for processing said image when the lens is carried by the support means, wherein the processing means are able to determine, from said overall image of the drilling hole, the position of the center of the mouth of the piercing hole opening on one of the faces of the lens and / or the transverse dimension of said mouth of the piercing hole corresponding to the desired transverse dimension. During the drilling of the corrective lens, for example on the side of the front face of the lens, the drill pierces the corrective lens at a point on the face of the lens which becomes the center of the front mouth of the drilling hole in progress of realization. In the state of the art, the drill is brought opposite the front face of the lens to the position associated with the center of the overall figure of the drilling hole of the presentation lens which corresponds generally to the position of the center the overall image of the drilling hole of the presentation lens projected on a plane perpendicular to the direction of illumination or image capture. Due to the curvature of the presentation lens, the axis of the piercing hole of this lens is inclined with respect to the image capture direction, so that, viewed in the direction of illumination or capture of image, there are:

on the one hand, an offset between the center of the projected volume of the drilling hole and the center of the mouth on the front face, or rear, of this drilling hole and,

on the other hand, a difference between the transverse dimension of the piercing hole (ie the transverse dimension of its mouths) of the presentation lens and the transverse dimension of the overall image of the piercing hole acquired in the direction of lighting or image capture. There is therefore an initial error in the acquisition even of the position or size of the drilling hole. This explains that the position and the transverse dimension of the drilling hole obtained on the pierced corrective lens are in practice erroneous.

With the device according to the invention, the position of the center of the mouth of the piercing hole opening on one of the faces of the lens, for example the front face, is calculated from the acquired overall image. as well as its transverse dimension, which then makes it possible to correctly position the drill opposite this determined position of the center of the mouth on the front face and / or to size and control this drill to obtain a hole whose transverse dimension corresponds precisely to to that of the hole of the presentation lens. The drilling hole obtained on the corrective lens is then correctly positioned and / or dimensioned.

According to a first embodiment of the invention, the processing means comprise: means for acquiring the position of the center of the overall image of the drilling hole and

first correction means capable of calculating the position of the center of the mouth of the drilling hole on said face, from the position of said center of said overall image and according to at least one data representative of the angle of inclination of the drilling hole formed between the direction of illumination or image capture and the axis of the piercing hole. Advantageously then, the overall image comprising a first and a second image rings which are formed by the images, on the capture means, of the mouths of the piercing hole and which are superimposed partially on one another, said acquisition means comprise:

means for generating a registration ring, means for superimposing this registration ring on the overall image,

means for memorizing the position of the center of this registration ring and

means for associating the memorized position of the center of this registration ring with the position of the center of the overall image of the piercing hole.

According to another aspect of this first embodiment of the invention, the processing means comprise:

means for acquiring the transverse dimension of the acquired overall image of the drilling hole and

first correction means capable of calculating the transverse dimension of the mouth of the drilling hole on said face, starting from the transverse dimension of said overall image and as a function of at least one datum representative of the angle drilling hole inclination formed between the illumination or image-capturing direction and the axis of the piercing hole.

Advantageously then, the overall image comprising a first and a second image rings which are formed by the images, on the capture means, of the mouths of the piercing hole and which are superimposed partially on one another, said acquisition means comprise: means for generating a registration ring,

means of superposition, with dimensioning, of this registration ring on the overall image,

means for memorizing the transverse dimension of this locating ring; and means for associating the stored transverse dimension of this locating ring with the transverse dimension of the overall image of the drilling hole. According to another advantageous characteristic, said first correction means operate further according to the index and / or the thickness of the presentation lens. This corrects the image capture errors resulting from the prismatic deviations generated by the presentation lens on its own image.

According to a second embodiment of the invention, the overall image comprising a first and a second image rings which are formed by the images, on the capture means, the mouths of the drilling hole, and which are superimposed in part one on the other, the processing means comprise: means for acquiring the center of the image ring formed by the image of the mouth of the piercing hole opening on said face,

means for defining, with or without correction, the position of the center of the mouth of the drilling hole opening on said face, as a function of the position of said center of this image ring. Advantageously then, said means for defining the position of the center of the mouth of the drilling hole opening on said face operate a calculation of the first correction as a function of the index and / or the thickness of the presentation lens. This corrects the image capture errors resulting from the prismatic deviations generated by the presentation lens on its own image.

According to another aspect of this second embodiment of the invention, the overall image comprising a first and a second image rings which are formed by the images, on the capture means, of the mouths of the piercing hole, and which are superimposed on each other, the processing means comprise:

means for acquiring the transverse dimension of the image ring formed by the image of the mouth of the piercing hole opening on said face and

first correction means capable of calculating the transverse dimension of the mouth of the drilling hole opening on said face, from the transverse dimension of said image ring and as a function of at least one datum representative of the angle of tilting of the drilling hole formed between the illumination or image-capturing direction and the axis of the piercing hole.

Advantageously then said first correction means operate further depending on the index and / or the thickness of the presentation lens. This corrects the image capture errors resulting from the prismatic deviations generated by the presentation lens on its own image. According to another advantageous characteristic of the invention, applicable to all the embodiments defined above, the processing means are able to determine, from said overall image of the drilling hole, a relative distance in projection, between the center of said mouth of the drilling hole of the presentation lens and the edge of the presentation lens, projected in said direction of illumination or image capture in an acquisition plane substantially perpendicular to said direction d lighting or image capture.

Advantageously then, the processing means comprise second correction means capable of calculating, from this relative distance in projection and as a function of at least one datum representative of the angle of inclination of the drilling hole formed between the direction for illuminating or capturing images and the axis of the drilling hole, a real relative distance between the center of said mouth and the edge of the presentation lens, considered in the plane perpendicular to the axis of the drilling hole .

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The description which follows, with reference to the accompanying drawings, 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 axial sectional view of a device for acquiring the position of the drilling holes of a presentation lens according to a first embodiment of the invention;

FIG. 2 is a mixed view, with an upper part showing in axial section the drilling hole of the presentation lens of FIG. 1 and a lower part showing, in a transverse plane, the projected overall shadow image. this drilling hole on the acquisition means, some points are used for calculating the position of this drilling hole according to a first method; FIG. 3 is a mixed view similar to FIG. 2 on which the position of an additional point has been added for the calculation of the position of this drilling hole according to a variant of the first method;

FIG. 4 is a transverse plane view similar to the lower part of FIGS. 2 and 3 of the projected overall image of the drilling hole, showing the points that are useful for calculating the position of the centering hole according to a second method; ;

FIG. 5 is a view similar to FIG. 4, showing the useful points calculating the position of the centering hole according to a variant of the second method;

FIG. 6 is a diagrammatic view in axial section of a device for acquiring the position of the drilling holes of a spectacle lens lens according to a second embodiment;

FIG. 7 is a view showing, in a transverse plane, the overall image of the drilling hole of the presentation lens of FIG. 6 perceived by the acquisition means of the device of FIG. are used for calculating the position of this drilling hole. In Figure 1, there is shown a device for acquiring the position of the drilling holes of a spectacle lens presentation. This acquisition device comprises lighting means 51, 52, a support 55 of the presentation lens 100 and capture means 53 of an image.

The lighting means 51, 52 comprise a collimation lens 52 of axis A52 and a light source 51 placed at the focus of the collimation lens 52. After passing through the collimation lens 52, the light rays are thus directed in parallel. to the axis A52 of the collimation lens 52. The illumination direction D51 is thus parallel to the direction of the axis A52.

The capture means 53 comprise a camera 53 provided with a lens having an optical axis A53. The device for acquiring the position of the drilling holes comprises an optical axis defined as the axis A52 of the collimation lens 52 and the axis A53 of the objective of the acquisition means 53. image by the acquisition means 53 is confused with the direction of illumination. D51. The support 55 of the presentation lens 100 is designed such that the presentation lens 100 extends in the plane transverse to the direction of illumination D51. The lens 100 is then illuminated in front. The support 55 of the lens 100 is here in the form of a transparent glass plate perpendicular to the direction of illumination D51, so that neither the front face 98 nor the rear face 99 are visually masked by the support 55 .

This presentation lens 100 has two piercing holes, a first piercing hole 110 located on the side of the temporal area and another piercing hole (not shown) located on the side of the nasal area of the lens. The following description only details the acquisition of the drilling hole 110, but this description also applies to the acquisition of the other drilling hole. As shown in the upper part of FIG. 2, the drilling hole 110 comprises, on the one hand, a mouthpiece 111 that opens onto the front face 98 of the lens 100 and, secondly, a mouth 112 which opens on the rear face 99 of the lens 100. It also defines the center C2 of the drilling hole 110 itself which is also the average of the positions of the centers C1, C3 of the front mouthpieces 111 and rear 112. The image capturing means 53 are also connected with processing means 54 of this image. As explained below, the processing means 54 of this image are designed to deduce from the acquired image the position of the center C1 of the mouth 111 of the drilling hole 110 in the front face 98. Of course, alternatively as explained hereinafter, the processing means 54 may also be designed to deduce from the acquired image, the position of the center of the mouth 112 of the drilling hole 110 on the rear face 99.

According to a main embodiment of the invention shown in FIGS. 1 to 5, the device for acquiring the position of the drilling holes is designed such that the camera 53 sees the lens in projected vision. In this main embodiment, the lighting means 51, 52 and the camera 53 are distributed on either side of the support of the lens.

As shown in Figure 1, it is expected to have a frosted glass plate 50 between the camera 53 and the support 55 of the lens. The frosted glass plate 50 is centered on the axis A52 of the collimating lens 52 and extends in the plane transverse to this axis A52. The frosted glass plate 50 makes it possible to form the shadow of the lens 100 and in particular the shadow of the drilling hole 110 of the lens.

The image of the shadow of the drilling hole 110 of the lens is acquired by the acquisition device 53. This image shown in the lower part of Figure 2 shows an overall figure 90 of the drilling hole.

The overall figure 90 of the piercing hole comprises two rings 40, 41 of substantially oval shape which intersect each other. The first ring 40 is the projected shadow of the mouthpiece 111 on the front face of the drilling hole 110, and the second ring 41 is the projected shadow of the mouth 112 on the rear face. The portion constituted by the superposition of the two rings 40, 41 is clear. Indeed, this portion is the result of the projection of a portion of the piercing hole which is traversed by the light rays without meeting the material of the lens. Conversely, the non-superposed portions of the two rings are dark due to the reflection or diffusion of these rays by the side wall of the drilling hole.

Several points of this overall figure 90 of the drilling hole 110 and the corresponding points of the piercing hole of the lens are defined. The point 102 of the drilling hole 110 results from the intersection between, on the one hand, a cutting plane of the lens passing through an axis parallel to the illumination direction D51 and the axis A110 of the drilling hole 110 and on the other hand, the part of the contour of the mouth 111 in the front face 98 of the lens, located towards the outside of the lens. Similarly point 101 is defined as the point of intersection of the cutting plane of the lens with the portion of the contour of the mouth 111 of the front face 98 of the lens, located towards the inside of the lens. The points 105 and 104 are defined as the points of intersection of the cutting plane of the lens with the portion of the mouth 99 on the rear face 99 of the lens, located respectively outwardly and inwardly of the lens. lens.

As illustrated in the lower part of FIG. 2, a straight line D1 is also defined, which is the straight line passing through the center of the two rings 40, 41. This straight line D1 corresponds approximately to the trace on the screen 50 of the plane passing through the axis A52 of the lens 100 and the center C2 of the hole 110. The points M1 and M2 are the intersection points of the line D1 with respectively the right and left parts of the ring 40 as shown in Figure 2B. These points M1 and M2 are the image points of the points 101 and 102. Similarly, the points M4 and M5 are the points of intersection of the line D1 with respectively the right and left parts of the second ring 41 as represented in FIG. 2B. These points M4 and M5 are the image points of the points 104 and 105. XM1, XM2, XM4, XM5 denote the positions of the points M1, M2, M4, M5 on the line D1.

The point MC1 is the image point on the line D1 of the center C1, in projection in the image capture plane, whose position XMC1 is to be calculated. Once the position XMC1 of the center C1 is determined we calculate its distance from a reference point of the edge of the lens.

According to a first method of execution of the main embodiment, illustrated in FIG. 2, it is planned to determine the position XM90 of the center M90 of the overall figure 90 of the drilling hole and to deduce therefrom the position of the center C1 of the mouthpiece 111 on the front face 98 of this drilling hole 110.

The processing system 54 includes a user interface and a display screen (not shown) which displays the overall image 90 of the drilling hole 110. The processing system 54 is also designed to allow display on the display. 60. This ring has dimensions that can be modified by the operator. The treatment system 54 is also designed such that this locating ring 60 is movable by the operator on the display screen. The displacement of the registration ring 60 as well as the adjustments of its dimensions can be obtained using control tools integrated in the user interface of the processing system 54.

The operator sizes and centers the registration ring 60 on the overall image 90 of the drilling hole 110. For centering the registration ring

60 in the overall figure 90, the operator can, for example as illustrated in Figure 2, superimpose the locating ring 60 in the overall figure 90 so that the locating ring 60 passes through the backgrounds of the M1 M4 segments and

M2M5. The optician may alternatively provide for adjusting the position and the dimension of the registration ring 60 to make it pass through the points M1 and M5 bordering the clear part of the overall figure 90. It can further adjust the position and the dimension of the registration ring 60 to make it pass through the points M2 and M4 bordering the dark part of the overall figure 90.

Once the ring is centered on the image of the shadow of the drilling hole, the processing system 54 automatically detects and stores the position of the center M60 of the registration ring 60. The position of the center M60 is associated by the processing means 54 at the XM90 position of the center M90 of the overall figure 90.

Alternatively, it can be provided that the operator points on the screen, with a tool integrated in the user interface such as a mouse or a stylus, the center M60 of the registration ring 60 which is then stored.

The processing system 54 calculates the position of the center C1 of the mouth of the drilling hole 110 opening on said face from the position of the center M90 of said overall figure 90 and as a function of the angle of inclination ALPHA the drilling hole 110 and the thickness E of the lens.

The angle of inclination ALPHA is the angle formed between the average direction of illumination D51 and the axis A110 of the drilling hole. The angle ALPHA and the thickness E of the lens can be measured by probing the lens, for example, or manually entered by the operator using an on-screen input interface provided for this purpose. . The considered thickness of the lens may be the local thickness of the lens around the piercing hole or the average thickness of the lens.

The calculation of the position XMC1 of the center C1 is as follows:

XMC1 = XM90 - E / 2. sin ALPHA.

The processing system 54 then associates said calculated position with the desired position of the center C1 of the mouth of the drilling hole 110 opening on the front face 98 of the lens 100.

Of course, if the desired position is the XMC3 position of the center C3 of the mouth on the back of the drilling hole, we have the relation:

XMC3 = XM90 + E / 2. sin ALPHA.

The calculation of the value of the diameter D of the hole 110 depends on the method of superposition of the registration ring 60 in the overall figure 90 used. In the case where the registration ring 60 is superimposed on the overall figure 90 so that the registration ring 60 passes through the media of the segments M1 M4 and M2M5, the diameter D is:

D = DA / cos ALPHA, where DA is the diameter of the registration ring 60.

In the case where the position and the dimension of the registration ring 60 is adjusted to make it pass through the points M1 and M5 bordering the clear part of the overall figure 90:

D = (DA + E.sin (ALPHA)) / cos (ALPHA).

In the case where the position and the dimension of the registration ring 60 is adjusted to make it pass through the points M2 and M4 bordering the dark part of the overall figure 90:

D = (DA - E.sin (ALPHA)) / cos (ALPHA).

According to a variant of this first embodiment, the detection of the center M60 of the registration ring 60 is performed automatically by the processing system 54, which is then designed to superimpose (with proper centering and sizing) automatically the register ring 60 on the overall image 90 of the drilling hole 110 and thus deduce the position and the diameter of the center M60 of this ring.

According to an alternative embodiment, illustrated in FIG. 3, of the first method (FIG. 2), it is planned to improve the precision of the calculation of the position XMC1 of the projection MC1 of the center C1, starting from the position XM90 of the M90 center of the overall figure 90, taking into account the prismatic deviations induced by the presentation lens 100 and therefore the index of this lens. The index of the presentation lens is then different from 1, and is here, for example, 1, 5. In the case where the registration ring 60 is superimposed on the overall figure 90 so that the registration ring 60 passes through the middle of the segments M1M4 and M2M5 (example envisaged in FIG. 3), the position of the center C1 is given by the following equation:

XMC1 = XM90 - E. (sin (ALPHA)) / 2 - DC / 4 with DC = E.sin (ALPHA - arcsin ((sin (ALPHA)) / n))

/ (cos (arcsin ((sin (ALPHA)) / n))).

Similarly, the accuracy of the calculation of the diameter D of the hole in taking into account the index of this lens. The calculation of the value of the diameter b 'of the hole 110 depends on the method of superposition of the registration ring 60 in the overall figure 90 used.

In the case where the registration ring 60 is superimposed on the overall figure 90 so that the registration ring 60 passes through the middle of the segments M1M4 and M2M5, the diameter D is:

D = (DA + DC / 2) / cos (ALPHA),

DA being the diameter of the locating ring 60 and with

DC = E.sin (ALPHA-arcsin ((sin (ALPHA)) / n)) / (cos (arcsin ((sin (ALPHA)) / n))).

According to a second method of execution of the main embodiment, illustrated in FIG. 4, the position of the center of the overall figure of the drilling hole is not determined, but the positions of points M1 and M2 are acquired. The points M1, M2, as recalled above, are the intersections of the line D1 with the right and left parts of the ring 40.

The acquisition of the positions of the points M1 and M2 can be performed by an algorithm for automatically detecting the position of these points. This algorithm can be designed so as to take, on the one hand, the leftmost position of the darkest point of the overall figure 90 to obtain the position XM2 of the point M2 and, on the other hand, the position of the rightmost point of the clear portion of the overall figure 90 to obtain the position XM1 of the point M1. It is also possible, alternatively, that the overall figure is displayed on a screen and that the operator points on the screen the positions of the points M1 and M2.

The center X12 of the segment M1, M2 is then determined. The processing means 54 then associate the position of the center X12 of the segment M1, M2 to the position XMC1 of the center C1 of the mouth of the drilling hole 110 opening on the front face. It is understood that, in this example, the offset of the point M2 due to the prismatic effects of the lens 110 is not taken into account, which is an approximation. The corrected diameter D of the hole 110 is also calculated using the following formula:

D = D40 / COS (ALPHA), with D40 = abs (XM1-XM2), the "abs" function returning the absolute value. According to an alternative embodiment, illustrated in FIG. 5, of the second method (FIG. 4), it is intended to improve the accuracy of the calculation of the position XMC1 of the center C1, from the position of the points M1 and M2 of the figure 90, as well as the precision of the calculation of the diameter D of the hole 110, taking into account the index n of the presentation lens 100. The index n of the presentation lens is then different from 1, and here, for example n = 1, 5.

The points M1, M4 and M5 were not shifted during the projection of the points 101, 104 and 105 in the image capture plane, the rays emerging from these points having not been deviated by the lens of On the other hand, when a ray passes through point 102, it then passes through the lens and is then deviated by a certain distance which depends on the angle ALPHA, the index n of the lens and the the average thickness E of the lens. The ray ends at the point M2. Thus, as shown in FIG. 3, the projected distance on the line D1 between the point 102 and the point 105 is actually equal to the distance between a point M3 and the point M5. The position of the point M3 corresponds to the theoretical position of the projection on the line D1 of the point 102 along the optical axis of the optical device, without prismatic deflection by the presentation lens 100. It is thus considered in this variant embodiment that, in projection on the straight line D1, the position X13 of the center of the segment defined by the two points M1, M3 corresponds to the corrected position, taking into account the prismatic deviations, from the center C1 of the mouth 111 of the drilling hole 110.

The distance DM2M3 between the points M2 and M3 is the following one: DM2M3 = E.sin (ALPHA - arcsin ((sin (ALPHA)) / n))

/ (cos (arcsin ((sin (ALPHA)) / n)))

We then deduce from the acquired position XM2 of the point M2 and the calculated distance DM2M3, the position XM3 of M3.

The position XMC1 of the desired center C1 is then obtained by the equation XMC1 = (XM1 + XM3) / 2

The corrected diameter D of the hole 110 is also calculated using the following formula: D = abs (XM1-XM3) / cos (ALPHA).

Alternatively, one can also easily determine the position XMC3 of the projection MC3 of the center C3 of the mouth on the back side with the points M4 and M5 of the ring 41 which has not been deformed by the lens. We then deduce the position XMC1 of the projection MC1 of the center C1 and the corrected value of the diameter D of the hole 110 by the following equations:

XMC1 = XMC3 - E.sin (ALPHA).

D = abs (XM4-XM5) / cos (ALPHA) According to another embodiment illustrated in FIGS. 6 and 7, the presentation lens 100 is seen by the camera 53 in direct vision. The camera 53 is arranged in such a way that the optical axis of its objective is parallel with the direction of illumination and that the optical center of its lens is located at the focus 51 of the collimation lens 52. A backlight assembly, consisting of a matrix of light sources such as LEDs 56 and a plate of diffusion 57, is disposed on the side of the support plate 55 opposite to the lens 100. The camera 53 then sees directly, that is to say without intermediate projection screen, the presentation lens 100 on the front face.

As before, the lens of the camera acquires the image of the lens. The overall image of the piercing hole that the lens is acquired is shown schematically in FIG. 7. The ring 41, resulting from the projection view of the rear mouth of the piercing hole, flattens out the optical deviation of the light rays from the portions of the contour of the mouth on the rear face located on the inner side of the lens.

The various embodiments described above (FIGS. 2 to 5) implemented in projected vision for calculating the position of the mouthpiece on the front or rear face of the drilling hole can be implemented in direct vision while being adapted to the new arrangement of points M1, M2, M4 and M5 as shown in FIG.

More generally, the exact position XMC1 of the center of the mouth on the front face is easily obtained since there is no deviation of light rays by the lens.

XMC 1 = (XM2 + XM1) / 2

The diameter D41 = abs (XM4 - XM5) of the ring 41 along the X axis is, on the other hand, smaller than the diameter D40 = abs (XM1 - XM2) due to the deformation due to the prismatic deviations generated by the lens. This deformation can be corrected in a manner similar to that described above. But it is more convenient to directly read the diameter D40 of the ring 40 and to apply to it the geometric projection correction under the angle ALPHA. The corrected diameter of hole 110 is then calculated: D = D40 / cos (ALPHA), with D40 = abs (XM1-XM2)

On the rear face, however, the deflection of the rays by the lens 110 must be taken into account. The position XMC3 of the center C3 of the mouth on the rear face is given by:

XMC3 = (XM2 + XM1) / 2 + abs (XM5-XM2) According to another embodiment (not shown), it is intended to further improve the accuracy of calculation of the position of the center of the mouth of the face before the drilling hole taking into account at least one characteristic of corrective lens to pierce. This embodiment can also be applied to the rear face.

The position of the center of the mouthpiece on the front face of the drilling hole is calculated according to one of the preceding embodiments which takes into account, in the calculation of the position of the drilling hole, the angle ALPHA formed between the mean direction D51 and the A110 axis of the drilling hole.

The angle formed between an axis of the corrective lens and the normal to the face of the corrective lens is also acquired at the determined position of the drilling hole to be produced. Then the position of the drilling hole to be made on the corrective lens is corrected according to the difference in value between said angle and the angle ALPHA between the average illumination direction D51 and the axis A110 of the drilling hole.

In the embodiments described above for which it is intended to calculate the position XMC1 of the center of the mouth on the front face of the lens, it is possible to apply an operation, which consists in calculating not the distance in projection on the line D1 between the edge of the lens and the center C1, but the distance between the edge of the lens and the center of the hole following the surface of the lens. It is in fact the determination of the distance along the surface of the lens which makes it possible to perform a correct drilling and therefore a correct mounting of the lens on the frame.

The measurement of this distance along the surface of the lens is carried out, in a manner known per se, from the position of the center of the mouth of the drilling hole determined according to one of the embodiments described above, of the XMB position of the reference point of the edge of the lens in the image plane and from the value of the base of the lens.

The calculation, as a first approximation, of the distance following the surface DSURFC1 from the center C1 with respect to the edge of the lens, is as follows:

DSURFC1 = abs (XMC1-XMB) / COS (ALPHA), with

XMB being the position in projection on the line D1 of a point of reference of the edge of the lens,

ALPHA = (R.B / (n-1)),

Where R is the distance, projected on the line D1, from the center C1 to the geometric center of the contour of the lens (obtained by image processing), B being the base of the lens, and n being the index of the lens. The base of the lens can be entered manually by the operator using an on-screen input interface, or obtained, for example, by a spherometer. It is also possible to calculate the angle ALPHA from the positions XM 1 and XM4 of the points M1 and M4 with the following equation, in the previously defined measurement configuration in projected vision (FIGS. 3 to 5):

ALPHA = arcsin (abs (XM1-XM4) / E) = arcsin (abs (XM5-XM3) / E). In the case of a measurement in direct vision (FIG. 7), the angle ALPHA is analogously calculated with the equation:

ALPHA = arcsin (abs (XM5-XM2) / E).

The thickness E of the lens can be measured for example by probing or be fixed at an average value of about 2 millimeters. 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.

Whatever the embodiment described above, it is possible to provide an alternative embodiment in which the orientation of the lens is reversed. It is then the rear face of the lens which is oriented towards the lighting means 51, 52. The calculations are made in a similar manner taking into account the fact that the angle ALPHA is reversed. It follows that in projected vision, in the overall figure 90, it is no longer the point from the projection of the point of the outward mouth to the outside which is deflected, but the point of the front mouth located towards the inside of the lens. Similarly in direct vision, it is no longer the point from the projection of the point of the rear mouth located inward which is deflected, but the point of the front mouth located towards the outside of the lens.

Claims

A device for determining the position and / or transverse dimension (D) of a piercing hole (110) of a presentation lens (100) of rimless spectacle frames, comprising:

support means (55) for the lens (100),

means for capturing (53) an overall image (90) of the drilling hole (110) of the lens (100) in a direction of illumination (D51, A52) or of image capture (A53 ), means (54) for processing said image when the lens is carried by the support means (55), characterized in that the processing means (54) are able to determine, from said overall image of the drilling hole (110), the center position (C1) of the mouth of the piercing hole (110) opening on one of the faces (98) of the lens (100) and / or the transverse dimension of said mouth of the piercing hole (110) corresponding to the transverse dimension

(D) Wanted.

2. Device according to claim 1, wherein the processing means (54) comprise: - means for acquiring the position of the center (M90) of the overall image (90) of the drilling hole (110) and

first correction means able to calculate the position of the center (C1) of the mouth of the piercing hole (110) on said face, from the position of said center (M90) of said overall image (90) and as a function of at least one data representative of the inclination angle (ALPHA) of the drilling hole (110) formed between the illumination direction (D51, A52) or the image capture direction (A53) and the axis (A110) of the drilling hole (110).

3. Device according to the preceding claim, wherein, the overall image (90) comprising a first and a second image rings (40, 41) which are formed by the images, on the capture means (53), mouthpieces (111, 112) of the piercing hole (110) which are superimposed partially on one another, said acquisition means comprise:

means for generating a registration ring (60),

means of superposition of this registration ring (60) on the overall image (90),

means for storing the position of the center (M60) of this locating ring (60) and means for associating the stored center position (M60) of this registration ring (60) with the center position (M90) of the overall image (90) of the piercing hole (110).

4. Device according to one of the preceding claims, wherein the processing means (54) comprise:

means for acquiring the transverse dimension (DA) of the overall image (90) acquired from the drilling hole (110) and

first correction means capable of calculating the transverse dimension (D) of the mouth of the piercing hole (110) on said face, starting from the transverse dimension (DA) of said overall image (90) and function of at least one data representative of the tilt angle (ALPHA) of the drilling hole (110) formed between the illumination direction (D51, A52) or the image capture direction (A53) and the axis (A110) of the piercing hole (110).

5. Device according to the preceding claim, wherein, the overall image (90) comprising a first and a second image rings (40, 41) which are formed by the images, on the capture means (53), mouthpieces (111, 112) of the piercing hole (110) which are superimposed partially on one another, said acquisition means comprise:

means for generating a registration ring (60), superimposition means, with dimensioning, of this registration ring (60) on the overall image (90),

means for memorizing the transverse dimension (DA) of this locating ring (60), and

means for associating the memorized transverse dimension (DA) of this registration ring (60) with the transverse dimension (DA) of the overall image (90) of the drilling hole (110).

6. Device according to one of claims 2 to 5, wherein said first correction means operate further according to the index (n) and / or the thickness (E) of the presentation lens (100). .

7. Device according to claim 1, wherein, the overall image

(90) comprising first and second image rings (40, 41) which are formed by the images, on the capture means (53), the mouths (111, 112) of the piercing hole (110), and which are superposed partially on one another, the processing means (54) comprise: - means for acquiring the center (MC1) of the image ring (40) formed by the image of the mouth of the hole piercing device (110) opening onto said face (98), means for defining, with or without correction, the position of the center (C1) of the mouth of the drilling hole (110) opening on said face (98), as a function of the position of said center (MC1) of said ring image (40).

8. Device according to the preceding claim, wherein said means for defining the position of the center (C1) of the mouth of the drilling hole.

(110) opening on said face (98) perform a first correction calculation as a function of the index (n) and / or the thickness (E) of the presentation lens (100).

9. Device according to one of claims 1, 7 and 8, wherein the overall image (90) comprising a first and a second image rings (40, 41) which are formed by the images, on the means of capture (53), mouths (111, 112) of the piercing hole (110), and which are superimposed on each other, the processing means (54) comprise:

means for acquiring the transverse dimension (D40) of the image ring (40) formed by the image of the mouth of the piercing hole (110) opening on said face (98) and

first correction means capable of calculating the transverse dimension (D) of the mouth of the drilling hole (110) opening on said face, from the transverse dimension (D40) of said image ring (40) and as a function of at least one data representative of the angle of inclination (ALPHA) of the drilling hole (110) formed between the illumination direction (D51, A52) or the image capture direction (A53) and the axis (A110 ) of the drilling hole (110).

10. Device according to claim 9, wherein said first correction means operate further according to the index (n) and / or the thickness (E) of the presentation lens (100).

11. Device according to one of the preceding claims, wherein the processing means (54) are adapted to determine, from said overall image of the drilling hole (110), a relative distance in projection, between the center (C1) of said mouth of the piercing hole (110) of the presentation lens (100) and the edge of the presenting lens (100), projected in said direction of illumination or image capture in a plane acquisition substantially perpendicular to said direction of illumination or image capture.

12. Device according to the preceding claim, wherein the processing means (54) comprise second correction means able to calculate, from this relative distance in projection and as a function of at least one datum representative of the angle d tilting (ALPHA) of the drilling hole (110) formed between the illumination direction (D51, A52) or the image capture direction (A53) and the axis (A110) of the drilling hole (110), a real relative distance between the center (C1) of said mouth and the edge of the presentation lens (100), considered in the plane perpendicular to the axis (A110 ) of the drilling hole (110).