The present invention concerns a spectacle lens comprising a base lens and a thin structure.
Combining a film with a spectacle base lens in order to provide additional properties and functions to the resulting spectacle lens is known. These properties and functions are produced by the film independently of the spectacle base lens. For example, the film may have an optical function, such as an anti-reflecting function; a mechanical function, such as an anti-impact or anti-scratch function; an anti-dirt function; an antistatic function; etc. Optionally, the film may have a complex thin structure that is able to produce a particular function. In particular, such a thin structure may comprise a layer of cells that each contain an optically active substance, such as a photochromic substance, a photo-transformable substance or liquid crystals. In the context of the present patent application, the more general terminology of thin structure is adopted, to designate both a film optionally carrying layers and a more complex structure, the external surfaces of which are parallel.
Such a combination of a thin structure with a spectacle base lens is different from producing a spectacle lens of variable power in the form of a reservoir with flexible faces that is filled with refracting liquid. Such a variable-power spectacle lens is in particular described in the document WO 2004/023167. The refractive liquid is then essential for the dioptric function of the lens to be achieved. However, the optical power of such a spectacle lens is not defined precisely, and the use of liquid for the ophthalmic application may reduce the safety of the spectacle wearer. Such a spectacle lens structure with variable optical power is outside the subject matter of the present patent application.
In a known manner, a thin structure may be assembled with a spectacle base lens by bonding on one of the faces of the latter, anterior or posterior. For this purpose, an intermediate layer of adhesive material is disposed between the thin structure and the spectacle base lens.
However, such an assembly method has the following drawbacks:
One object of the invention is then to propose another method of assembling a thin structure with a spectacle lens that does not have the above drawbacks.
To achieve this object and others, the present invention proposes a spectacle lens that comprises:
The spectacle lens is characterised in that the spacer comprises:
The central part of the spacer and the peripheral part of the spacer may form a single piece of complex shape or be two different elements assembled together, it being understood that a spacer comprising only a central part is not the subject matter of this invention.
The spacer also has a constant thickness between its first and second support surfaces. In addition, a separation volume that is determined by the spacer between the spectacle base lens and the thin structure contains a gaseous medium during a use of the spectacle lens by a wearer.
Thus a spectacle lens according to the invention has all the advantages that result from its formation in two components: the spectacle base lens on the one hand and the thin structure on the other hand. In particular, these two components can be obtained using manufacture and supply channels that are independent. An overall efficiency in production of the complete spectacle lens is thus improved.
According to the invention, the thin structure is not in contact with the spectacle base lens in an optically useful part thereof, outside the support surfaces of the spacer. The optical characteristics of the resulting spectacle lens are therefore not impaired by variations in the separation distance between the thin structure and the base lens. Thus such variations do not cause a reduction in the efficiency of manufacture of the final spectacle lens.
In addition, for the same reason, the assembly of the thin structure with the spectacle base lens does not require applying a compression force in parts of the thin structure and base lens that are optically useful. The risk of creating visible defects in these useful parts is thus eliminated, even if the thin structure is fragile and liable to be degraded by crushing.
The spacer may furthermore have one or other of the following features, or several of these combined with each other:
In a first embodiment of the invention, the thin structure and the spectacle base lens are assembled permanently by assembly means. These assembly means comprise first assembly means and second assembly means. The first assembly means hold the first support surface of the spacer against the first surface of the spectacle base lens and form a first fixed material connection. The second assembly means hold the second support surface of the spacer against the first surface of the thin structure and form a second fixed material connection. For example, the first and second assembly means may consist of respective portions of adhesive material that are disposed on the support surfaces of the spacer.
In second embodiments of the invention, the thin structure and the base spectacles are assembled removably by assembly means. These assembly means comprise first assembly means and second assembly means. The first assembly means hold the first support surface of the spacer against the first surface of the spectacle base lens and may comprise a first rim of the spacer that enters a recess in the spectacle base lens, situated on the peripheral edge thereof. The spacer is then assembled with the base lens by inserting its first rim in the recess in the base lens. Such an assembly is simple and inexpensive and can be removed quickly. The second assembly means hold the second support surface of the spacer against the first surface of the thin structure and can themselves be permanent or removable. When they are permanent, the second assembly means may form once again a fixed material connection between the second support surface of the spacer and the first surface of the thin structure. When they are removable, the second assembly means comprise a second rim of the spacer that projects onto the second surface of the thin structure so that the latter is gripped between the second support surface and the second rim of the spacer.
The invention also proposes a method of producing a spectacle lens as described previously, which comprises the following steps:
/1/ obtaining a characterisation of a lens housing form in a frame that is intended to receive the spectacle lens;
/2/ trimming the spectacle base lens and producing the spacer in accordance with the housing in the frame;
/3/ cutting the thin structure in accordance with the first surface of the base lens;
/4/ assembling the spacer with the thin structure using the second assembly means; and then
/5/ after step /4/, assembling the whole comprising the thin structure and the spacer with the spectacle base lens using the first assembly means.
It is then possible to manufacture separately the whole that comprises the thin structure and the spacer assembled together, and to obtain moreover the spectacle base lens. For example, the thin structure can be assembled with the spacer in a dedicated workshop, for example in a centralised laboratory. Then the whole of the thin structure with the spacer can be sent between steps /4/ and /5/ to an optician, who in turn assembles it with the spectacle base lens. Such an embodiment of the final spectacle lens is both economical and compatible with the existing method of distributing ophthalmic equipment.
Other particularities and advantages of the present invention will appear in the following description of non-limitative example embodiments, with reference to the accompanying drawings, in which:
a and 1b are in-plan view and side-view, respectively, of a spectacle base lens that can be used for implementing the invention;
a to 2c are respective cross-sectional views of three thin structures that can be used for implementing the invention;
a and 3b are perspective views of spacers that can be used for implementing the invention, according to two variants of a first embodiment of the invention;
a and 4b are respective cross-sectional views of the spacers of
a and 5b are cross-sectional views of spectacle lenses produced according to the invention, respectively for the two variants of the first embodiment of the invention in
a to 6c are respective cross-sectional views of spacers that can be used for implementing the invention, according to three variants of a second embodiment of the invention; and
a to 7c are cross-sectional views of spectacle lenses produced according to the invention, respectively for the three variants of the second embodiment of the invention in
For sake of clarity, the dimensions of the elements that are shown in these figures correspond neither to actual dimensions nor to actual ratios of dimensions. Furthermore, identical references that are indicated in different figures designate identical elements or ones that have identical functions.
In accordance with
In accordance with
The thin structure 2 may also have a cellular configuration, for example of the type in
In accordance with
According to a first possible configuration, the thin structure 2 may comprise at least:
c shows a second possible cell-configuration for the thin structure 2. According to this second configuration, the thin structure 2 may comprise at least:
The connection means 290 may be an intermediate layer of adhesive material, according to one of the embodiments of such a layer that is known to persons skilled in the art.
Compositions of the functional coatings 23 and 24, possible materials for the films listed above, dimensions and embodiments of all these components, are also assumed to be known, so that it is not necessary to repeat them here. Likewise, it is known that the cells C may contain one or more active substances that confer on the thin structure 2 one or more additional optical functions.
Hereinafter, and by way of non-limitative illustration, it will be assumed that the spectacle base lens 1 and the thin structure 2 are assembled according to the invention with the surface 10 of the base lens 1 and the surface 20 of the thin structure 2 facing each other. In this assembly configuration, the surfaces 10 and 11 of the base lens 1 are respectively its first and second surface in the designation method that was used for the general part of the description of the invention. Thus the first optical surface of the spectacle base lens 1 may be convex. Likewise, the surfaces 20 and 21 of the thin structure 2 correspond respectively to its first and second surfaces, thus designated in the general part of the description.
The assembly then results in arranging the base lens 1 and the thin structure 2 with their respective faces 10 and 20 facing each other. In other words, the first respective surfaces of the base lens and of the thin structure are facing each other in the resulting spectacle lens. A separation space that is then present between the base lens and the thin structure is filled with a gaseous medium, for example air. Advantageously, the thin structure may have a curved shape, with a direction of curvature of the first surface of the thin structure opposite to that of the first optical surface of the spectacle base lens. This is because the separation space between the spectacle base lens and the thin structure may thus have a thickness that is substantially constant. The total thickness of the resulting spectacle lens is thus limited, so that this lens is more aesthetic.
In the spectacle lens that results from the assembly, the first optical surface of the spectacle base lens is protected by the thin structure. Such a configuration is particularly suitable when the first optical surface of the spectacle base lens has a discontinuity with a jump in sagittal height at at least one point on the surface. This is because the thin structure prevents dirt from being deposited in the surface discontinuity, and may impair the contribution of this discontinuous surface to the optical power of the base lens. In particular, the first optical surface of the spectacle base lens may thus be provided with a Fresnel structure, without problems of dirt and cleaning resulting therefrom.
Moreover, in order to reduce an increase in the total light reflection of the spectacle lens that might result from the presence of the separation space between the base lens and the thin structure, this separation space being filled with a gaseous medium, the respective first surfaces of the spectacle base lens and thin structure may advantageously be provided with respective non-reflecting coatings. Reference 13 in
In the first variant permanent assembly, the spacer is comprised of two different pieces, a central part: the bead, and a peripheral part: the peripheral bead.
The central part of the spacer 30 consists of a bead of constant thickness e (
According to an improvement to this first assembly method, a peripheral bead may be added straddling over a peripheral limit of the thin structure 2 that connects the first and second surfaces thereof, and over at least part of an external edge of the spacer 30 that connects its two support surfaces. Such a bead may have at least two functions. A first of these functions may consist of forming an edge sealing of the thin structure 2, in particular when the latter has a cellular structure as shown in
In the second variant of permanent assembly, the spacer 30 is formed by several beads each of constant thickness. In other words, the spacer may comprise a stack of at least two spacer units, with a direction of the stack connecting the first respective surfaces of the spectacle base lens and the thin structure. Successive spacer units along the stack direction are then connected to each other by additional connection means.
The left and right parts of
In a preferred manner, the assembly is removable at the level of the first assembly means 31, between the spectacle base lens 1 and the spacer 30. For this purpose, the first assembly means 31 may comprise a first rim of the spacer 30 that enters a groove in the spectacle base lens 1, situated on the peripheral edge 12 thereof. The direction D, perpendicular to the surfaces of the base lens 1 and to the thin structure 2 in the final lens, is transferred in
thickness e of the spacer 30, measured in the direction D and corresponding to the thickness of the separation space between the spectacle base lens 1 and the thin structure 2 in the final lens: 250 μm;
thickness e1 of the spacer 30, measured in the direction D and corresponding to the distance between the first surface 10 and the groove that is situated in the peripheral edge 12 of the base lens 1: 400 μm;
thickness e31 of the spacer 30, measured in the direction D and corresponding to the width of the groove that is situated in the peripheral edge 12 of the base lens 1: 550 μm;
width Δr1 of the first rim 31, measured perpendicular to the direction D and corresponding to the depth of the groove that is situated in the peripheral edge 12 of the base lens 1: 600 μm; and
width Δr2 of the second support surface of the spacer 30 measured perpendicular to the direction D and corresponding to the second assembly means 32: 900 μm.
Simultaneously and independently, the assembly may be either permanent or removable at the second assembly means 32, between the thin structure 2 and the spacer 30.
b and 7b illustrate a second variant in which the first assembly means 31 are again removable, and the second assembly means 32 are again permanent. The difference with the previous variant lies in the presence of a rib 35 around the second support face of the spacer 30. In this way, the spacer 30 has a profile with a cross-section with a re-entrant angle A from the second support surface. This angle A is then adapted to receive a peripheral limit of the thin structure 2, thus forming an alignment guide for assembly of the spacer 30 with the thin structure 2. The rib 35 may have a height e2 of 350 μm, for example, measured parallel to the direction D. The thin structure 2 may then again be assembled with the spacer 30 by gluing or adhesion on the second support surface of the latter, in the angle A.
Finally, the assembly may also be removable at the second assembly means 32, between the thin structure 2 and the spacer 30, in addition to the first removable assembly means 31. Such a third variant is illustrated by
thickness e3 measured in the direction D: 250 μm; and
width measured perpendicular to the direction D: identical to that of the first rim 31.
Optionally, the second rim 32 may be provided with a bevel at its end towards the centre of the spectacle lens and on the anterior side thereof.
Naturally, the dimensions of the spacer 30, which have not been repeated for the second and third variants of the removable assemblies, may be identical to those cited for the first variant. The same applies to the possible materials for constituting the spacer 30 in the last variants. In particular, in the third variant, the thin structure 2 may be introduced easily between the second support surface and the second rim 31 of the spacer 30, momentarily deforming it.
To make it possible to easily mount in an ophthalmic mount spectacle lenses that result from the above removable assemblies, it may be convenient to adapt the spacer according to the type of mount. As with
A method for producing a spectacle lens according to the invention is now described. First of all, the form of the housing of the lens in the mount is characterised, in a way that may be one of those known to persons skilled in the art. The spectacle base lens 1 and the spacer 30 are then produced in accordance with the housing of the mount. When the base lens 1 is intended itself to be directly in contact with the mount, as in the case in
When the spacer 30 is in accordance with
The thin structure 2 is also cut from a supply sheet provided with this structure, in accordance with the first surface 10 of the base lens 1, delimited by its peripheral edge 12.
According to one feature of the method of the invention, the thin structure 2 and the spacer 30 are first of all assembled with each other, separately from the base lens 1. This partial assembly may thus be effected in a specialist laboratory, using the second assembly means 32 in the way already described for each embodiment of the invention. The assembly that is thus obtained may then be sent to a retail optician, who will assemble it with the base lens 1, using the first assembly means 31 that have also already been described.
However, before being assembled with the base lens 1, the thin structure 2 or the assembly that comprises the thin structure 2 and the spacer 30 assembled with each other by the second assembly means 32 may be preformed in order to confer curvature on it. This performing may preferably be carried out after the spacer 30 has been assembled with the thin structure 2, when this assembly is permanent as in the case in
Finally, when the thin structure 2 and the spacer 30 are assembled with each other permanently, the supplementary peripheral bead 41 or 42 can be applied as described with reference to
Naturally, the invention can be reproduced by introducing various modifications compared with the detailed description given above, while keeping at least some of the advantages mentioned. In particular, alternative embodiments that concern different parts of the spectacle lens of the invention can be combined with each other in any way. Furthermore, the dimensions and materials that have been cited were cited only by way of example to enable the invention to be reproduced, it being understood that these materials and dimensions may also be modified.
Number | Date | Country | Kind |
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1060573 | Dec 2010 | FR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/FR11/52817 | 11/29/2011 | WO | 00 | 10/17/2013 |