Patent Description:
The invention further relates to a method configured to be carried out by such a machine for molding by casting an ophthalmic lens.

The international patent application <CIT> discloses a machine and a method for molding by casting an ophthalmic lens, and in particular for an automated filling of a mold assembly of the machine.

The machine comprises a mold assembly formed by two molding shells and an annular closure member configured to join the shells and define a molding cavity.

The shells are made of a transparent material and the annular closure member is made by a scotch tape.

The molding cavity is filled by causing a molding material to flow into the molding cavity through a filling aperture provided in the scotch tape.

This filling aperture is at the periphery of the molding shells so as not to interfere with the optically surface of the ophthalmic lens formed.

The molding material is preferably a polymerizable synthetic material, for instance UHI monomer or MR7 or MR8.

The filling of the molding cavity is here made automatically and in a controlled manner thanks to filling means, acquiring means and control means.

Alternatively, the filling of the molding cavity can be made manually rather than automatically.

Once the molding cavity is fully filled with the molding material, the latter is polymerized thanks to a polymerization device, comprising for instance a lighting and heating source such as a UV source.

Such machine and method carried by the machine allow providing an ophthalmic lens which generally needs to be further processed.

In particular, the lens may comprise some irregularities on its peripheral edge, for instance a wrinkle defect, a twist defect, or a sticky surface defect.

<CIT> discloses a method for producing a plastic lens thanks to two molds joined by an adhesive tape which is wrapped around the molds, in which calculation steps of the inclination of the molds are carried out in order to produce a lens with a high accuracy. The adhesive tape is a bandlike plastic film and an adhesive layer is formed in one surface of the adhesive tape. <CIT> relates to the mechanical strength of the adhesive tape member to ensure only a holding force of the adhesive tape member in the process.

<CIT> relates to a classical method for producing resin lens by casting and <CIT> relates to an automated filling of a mold assembly for molding an ophtalmic lens.

The invention is directed to a similar kind of machine and method for manufacturing an ophthalmic article, which machine and method are improved while remaining simple to implement, compact and economic.

The invention accordingly provides a combination of a machine for manufacturing an ophthalmic article and a polymerizable molding material, comprising a mold assembly having a first molding shell provided with a first predetermined molding surface, a second molding shell provided with a second predetermined molding surface which is arranged for facing the first predetermined molding surface of the first molding shell, an adhesive tape member configured to join said first and second molding shells for forming a sealed molding cavity defined generally by said first and second predetermined molding surfaces and also laterally at least by an intermediate portion of said adhesive tape member, a predetermined volume of the polymerizable molding material and a filling aperture formed in said adhesive tape member for introducing by casting said predetermined volume of a polymerizable molding material into said molding cavity for forming said ophthalmic article; said adhesive tape member having a Young's modulus greater than around <NUM> MPa, when measured at a temperature of polymerization of said polymerizable molding material, and a maximum shear stress smaller than around <NUM> MPa, when measured at said temperature of polymerization, and being configured to form a peripheral case of the mold assembly, peripheral case in which at least said first molding shell is able to be displaced relative to the second molding shell without affecting said intermediate portion of the adhesive tape member; by virtue of which the ophthalmic article molded by casting has a straight peripheral edge.

The combination according to the invention allows to provide an opthalmic article and in particular an ophtalmic lens, which has an acceptable peripheral edge.

In other words, the peripheral edge of the lens formed is straight and without wrinkle defect, twist defect or sticky surface which would imply to further processing after molding by casting.

In particular, when the molding material which includes monomers is polymerised, the predetermined volume of matter diminishes inside the mold cavity, despite a thermal dilatation.

This is due to the fact that the polymers formed are better arranged and takes less place than the individual monomers.

Accordingly, a negative pressure is applied inside the mold cavity by the polymers.

In the present invention, such a negative pressure does not affect the adhesive tape member and in particular its intermediate portion, either directly or indirectly. In other words, the adhesive tape member is not deformed by the pressure inside the mold cavity and is not deformed and displaced either due to the diminishing of the predetermined volume of matter, aslo called shrinkage, or due to the inherent displacement of the at least one molding shell relative to the other.

Therefore, in the machine according to the invention, the adhesive tape member forms a cylindrical tube, also called peripheral case or peripheral belt, in which the at least one molding shell slides relative to the other molding shell, without wrinkling the adhesive tape member.

In the present invention, the adhesive tape member is characterized with mechanical and elastic properties by its Young's modulus and by its maximum shear stress.

The values of Young's modulus and maximum shear stress may be obtained at a predetermined temperature value of around <NUM>, which is a temperature value close to the temperature in the mold cavity during polymerization of a MR8 molding material ; or at a predetermined temperature value comrised between around <NUM> and around <NUM>, which is a temperature value close to the temperature in the mold cavity during polymerization of a MR7 molding material.

MR7 and MR8 materials are materials often used in the field of ophthalmics in order to manufacture optical lenses, especially lenses for spectacle glasses.

Other corresponding values of Young's modulus and maximum shear stress could be obtained at a different temperature value than <NUM>, or <NUM> or <NUM>.

For instance, the adhesive tape member might have a Young's modulus greater than around <NUM> MPa, preferably greater than <NUM> MPa, more preferably greater than <NUM> MPa, when measured at around <NUM>, and a maximum shear stress smaller than around <NUM> MPa, preferably smaller than <NUM> MPa, when measured at around <NUM>.

The properties of the adhesive tape member are obtained by the properties of the glue and of the film that comprises said adhesive tape member.

The properties may be derived from the holding power, the adhesion failure or Peel adhesion, the tensile strength, the tape (or film) thickness and the material used forming the glue and the film.

It will be noted that the glue has fluidic properties and sealing properties, and that the adhesive tape member provides enough rigidity, so that the mold shells may slide preferably without crumpling the adhesive tape member, at least from around <NUM> to around <NUM>°.

It will be noted that the acceptability of the ophtalmic lens formed with the machine may be defined susbstantially according to the measurement of a wrinkle defect.

At this stage, the opthalmic lens may be finished or semi-finished.

The wrinkle defect measurement may be implemented by measuring the number of wrinkle defects along the peripheral edge of the lens formed and further the depth of the wrinkle defect observed.

A visual inspection may be done for locating the wrinkle defects on the peripheral edge and the depth of the wrinkle defects identified may be measured with a metrology equipment including a support and a control device.

An acceptable lens may be defined for instance as being a lens having less than three or three wrinkle defects along its peripheral edge and further having a maximum wrinkle depth smaller or equal to around <NUM>.

By contrast, a lens having for instance more than three wrinkle defects along its peripheral edge or at least one wrinkle of depth greater than around <NUM> could be considered as being unacceptable.

The machine according to the invention allows providing acceptable ophthalmic lens molded by casting.

According to features preferred as being very simple, convenient and economical, the machine furthermore comprises a polymerization device configured to polymerize said polymerizable molding material into said molding cavity at said polymerization temperature for forming said ophthalmic article.

The intermediate portion of the adhesive tape member is not deformed during the polymerization of the polymerizable molding material which is subjected to the polymerization temperature, despite the shrinkage phenomen disclosed above, which shrinkage phenomen could be equated to a given pulling force applied on the the polymerizable molding material.

Therefore, in the machine according to the invention, the cylindrical tube formed by the adhesive tape member is not deformed when subjected to polymerzation.

According to other features preferred as being very simple, convenient and economical for embodying the machine according to the invention:.

It will be noted that for at least one of the polymerizable molding materials, the polymerization temperature may reaches <NUM>. Accordingly, the inventors have selected this temperature as an evaluation temperature for the tape. However, an adhesive tape that would be used only for polymerizable materials with smaller polymerization temperature could have their properties be evaluated at smaller polymerization temperatures, such as <NUM> or <NUM> for example.

According to yet other features preferred as being very simple, convenient and economical for embodying the combination according to the invention:.

The invention also provides a method for manufacturing an ophtalmic article having a predetermined optical power, by using a machine and a polymerizable molding material as described above, comprising the steps of:.

According to features preferred as being very simple, convenient and economical, the method further comprises the step of selecting both the first and second molding shells and/or the adhesive tape member, respectively amongst a plurality of molding shells and adhesive tape members, according to said predetermined optical power of said ophthalmic article to be molded by casting.

According to others features preferred as being very simple, convenient and economical of the method according to the invention:.

The description of the invention now continues with a detailed description of preferred embodiments given hereinafter by way of non-limiting example and with reference to the appended drawings. In these drawings:.

<FIG> illustrates a machine <NUM> for manufacturing an ophthalmic article <NUM> (shown alone in <FIG>).

An ophthalmic article in the present description refers to ophthalmic elements and devices. Non- limiting examples of ophthalmic elements include corrective and non-corrective lenses, including single vision or multi-vision lenses, which may be either segmented or non-segmented, as well as other elements used to correct, protect, or enhance vision, including without limitation magnifying lenses and protective lenses or visors such as found in spectacles glasses, goggles and helmets. The optical article of the present invention is preferably a lens, and more preferably an ophthalmic lens.

The machine <NUM> comprises a mold assembly <NUM>, a filling device <NUM> communicating with the mold assembly <NUM> thanks to a filling duct <NUM>, a polymerization device <NUM> facing the mold assembly <NUM>, and a control unit <NUM> here configured to control at least the filling device <NUM> and the polymerization device <NUM>.

The mold assembly <NUM> is formed by a first molding shell <NUM>, a second molding shell <NUM> located in register to the first molding shell <NUM>, the shells <NUM> and <NUM> being initially at a predetermined distance one to each other.

The mold assembly <NUM> is also formed by an adhesive tape member <NUM> configured to join the first and second molding shells <NUM> and <NUM> for forming a sealed molding cavity <NUM>.

The adhesive tape member <NUM> is arranged for forming a cylindrical tube, also called peripheral case or peripheral belt, surrounding at least partially the first and second molding shells <NUM> and <NUM>.

The filling device <NUM> is here configured to fill the sealed molding cavity <NUM> automatically and in a controlled manner thanks to filling means, acquiring means and control means (not shown), with a polymerizable molding material.

The sealed molding cavity <NUM> is filled by causing a predetermined volume of a polymerizable molding material to flow into the cavity <NUM> through the duct <NUM> which communicates with a filling aperture <NUM> formed in the adhesive tape member <NUM> and which emerges in the cavity <NUM>.

As visible in <FIG>, the filling aperture <NUM> is formed at the periphery of the first and second molding shells <NUM> and <NUM> so as not to interfere with an optically surface of the ophthalmic article <NUM> formed.

For instance, the filling aperture <NUM> is formed by folding an end portion <NUM> of the adhesive tape member <NUM>.

The polymerization device <NUM> is here formed by two lighting and heating units such as UV sources, which each face one of the first and second molding shells <NUM> and <NUM>.

The polymerization device <NUM> is configured to polymerize the predetermined volume of polymerizable molding material introduced by casting into the sealed molding cavity <NUM>, at a predetermined polymerization temperature, in order to form the ophthalmic article.

The mold assembly <NUM> is here configured to form an ophthalmic article and in particular an ophthalmic lens <NUM>, having an optical power comprised for instance between +<NUM> D and -<NUM> D.

The molding material is preferably a polymerizable synthetic material, for instance an ultra high index (UHI) monomer or MR7 or MR8.

We will now describe in detail the mold assembly <NUM>, in particular the first and second molding shells <NUM> and <NUM> and the adhesive tape member <NUM>.

The first and second molding shells <NUM> and <NUM> are here made of a transparent material and have each a diameter comprised for instance between <NUM> and <NUM>.

The first molding shell <NUM> is provided with a first predetermined molding surface <NUM>, with a first external surface <NUM> opposite to the first predetermined molding surface <NUM> and with a first peripheral wall <NUM> joining both the first predetermined molding surface <NUM> and the first external surface <NUM>.

The second molding shell <NUM> is provided with a second predetermined molding surface <NUM>, with a second external surface <NUM> opposite to the second predetermined molding surface <NUM> and with a second peripheral wall <NUM> joining both the second predetermined molding surface <NUM> and the second external surface <NUM>.

The molding assembly <NUM> is arranged so that the first predetermined molding surface <NUM> faces the second predetermined molding surface <NUM> and the second external surface <NUM> is in register with the first peripheral wall <NUM>; while the first and second external surfaces <NUM> and <NUM> each face a respective lighting and heating unit <NUM>.

The adhesive tape member <NUM> is formed by a base layer having inherent mechanical properties and combined with an adhesive layer giving to the adhesive tape member <NUM> inherent adhesive properties.

The adhesive tape member <NUM> comprises an upper portion <NUM> surrounding at least partially the first peripheral wall <NUM> and being in contact with at least a part of the first peripheral wall <NUM>.

The adhesive tape member <NUM> comprises a lower portion <NUM> surrounding at least partially the second peripheral wall <NUM> and being in contact with at least a part of the second peripheral wall <NUM>.

The upper and lower portions <NUM> and <NUM> are joined to each other by an intermediate portion <NUM> which defines generally together with the first and second predetermined molding surfaces <NUM> and <NUM> of the first and second molding shells <NUM> and <NUM> the sealed molding cavity <NUM>.

The upper portion <NUM> and the intermediate portion <NUM>, and optionally the lower portion <NUM>, have each a width which is determined as a function of the optical power of the ophthalmic article <NUM> to be molded by casting.

The adhesive tape member <NUM> is characterized with mechanical and elastic properties by its Young's modulus and by its maximum shear stress.

In particular, the adhesive tape member <NUM> has here a Young's modulus greater than around <NUM> MPa, when measured at around a temperature of polymerization of the polymerizable molding material, and a maximum shear stress smaller than around <NUM> MPa, when measured at around the temperature of polymerization.

The adhesive tape member <NUM> has preferably a Young's modulus preferably greater than around <NUM> MPa, when measured at the polymerization temperature, and/or a maximum shear stress preferably smaller than around <NUM> MPa, or more preferably smaller than around <NUM> MPa, when measured at the polymerization temperature.

The values of Young's modulus and maximum shear stress may be obtained at a predetermined temperature value of around <NUM>, which is a temperature value close to the temperature in the mold cavity <NUM> during polymerization of a MR8 molding material ; or at a predetermined temperature value comrised between around <NUM> and around <NUM>, which is a temperature value close to the temperature in the mold cavity <NUM> during polymerization of a MR7 molding material; but other corresponding values of Young's modulus and maximum shear stress could be obtained at a different temperature value than <NUM>, or <NUM> or <NUM>.

For instance, the adhesive tape member <NUM> might have a Young's modulus greater than around <NUM> MPa, preferably greater than <NUM> MPa, more preferably greater than <NUM> MPa, when measured at around <NUM>, and a maximum shear stress smaller than around <NUM> MPa, preferably smaller than <NUM> MPa, when measured at around <NUM>.

The properties of the adhesive tape member <NUM> are obtained by the properties of the adhesive layer (also called glue) and of the base layer (also called film) that comprises the adhesive tape member <NUM>.

The adhesive tape member <NUM> has here a thickness comprised between around <NUM> and around <NUM>, preferably with a thickness greater than around <NUM>.

For instance, the adhesive tape member <NUM> may be one of tapes selected amongst an OKAMOTO tape, a TAKARA D1 tape, a TAKARA D2 tape. It will be noted that these adhesive tapes are not known as being commercial names of tapes but were made on demand by the Okamoto Company and the Takara Company respectively.

The adhesive tape member <NUM> thus forms a peripheral case of the mold assembly <NUM>, in which the first molding shell <NUM> is able to be displaced relative to the second molding shell <NUM> without affecting the intermediate portion <NUM> of the adhesive tape member <NUM>; by virtue of which the ophthalmic lens <NUM> molded by casting has a straight peripheral edge <NUM> (see below in more detail in reference to <FIG>).

The adhesive tape member <NUM> has here a total width which is determined as a function both of thicknesses of the first and second molding shells <NUM> and <NUM> and of the optical power of the ophthalmic lens <NUM> to be molded by casting.

For instance, the mold assembly <NUM> is configured to mold by casting an opthalmic lens <NUM> having an optical power comprised between +<NUM> D and +<NUM> D, the adhesive tape member <NUM> has a total width equal to <NUM>, the first and second molding shells <NUM> and <NUM> have each a diameter equal to <NUM> and have respectively first and second predetermined thicknesses.

In variant, the mold assembly is configured to mold by casting an opthalmic lens <NUM> having an optical power comprised between <NUM> D and -<NUM> D, the adhesive tape member <NUM> has a total width equal to <NUM>, the first and second molding shells <NUM> and <NUM> have each a diameter equal to <NUM> and have respectively first and second predetermined thicknesses.

In variant, the mold assembly is configured to mold by casting an opthalmic lens <NUM> having an optical power comprised between -<NUM> D and -<NUM> D, the adhesive tape member <NUM> has a total width equal to <NUM>, the first and second molding shells <NUM> and <NUM> have each a diameter equal to <NUM> and have respectively first and second predetermined thicknesses.

It can be seen that those variants correspond to segmenting many different molding shells of different sizes, and different widths of the adhesive tape member and thus of the intermediate portion thereof, in order to form here three ranges of mold assemblies. This segmentation enables operators to have a simplified job when needing to choose the adhesive tape member to be used for a specific mold assembly. It furthers helps to simplify logistics. Furthermore, it will be noted that the width of the adhesive tape member may preferably be chosen, according to a specific mold assembly, so that the adhesive tape member comprises a free upper edge and/or a free lower edge and/or an upper/lower edge at the level or remote to a respective external surface of a respective molding shell.

The first and second predetermined thicknesses of the respective first and second molding shells <NUM> and <NUM> may be equal or different and may vary according to optical power of the opthalmic lens <NUM> and to the total width of the adhesive tape member <NUM>.

It will be noted that when a polymerizable molding material which includes monomers is polymerised, the predetermined volume of matter diminishes inside the mold cavity <NUM>, despite a thermal dilatation.

A negative pressure is applied inside the mold cavity <NUM> by the polymers.

Such a negative pressure does not affect the adhesive tape member <NUM> and in particular its intermediate portion <NUM>, either directly or indirectly.

In other words, the adhesive tape member <NUM> is not deformed by the negative pressure inside the mold cavity <NUM> and is not deformed and displaced due to the inherent displacement of the first and second molding shells <NUM> and <NUM> relative to the other, resulting to accommodate the negative pressure.

Therefore, the adhesive tape member <NUM> forms here a peripheral case in which the at least the first molding shell <NUM> slides relative to the second molding shell <NUM>, furthermore without wrinkling the adhesive tape member <NUM>.

The intermediate portion <NUM> of the adhesive tape member <NUM> is not deformed during the polymerization of the polymerizable molding material even when said tape is subjected to the polymerization temperature; and therefore the peripheral case formed by the adhesive tape member <NUM> is not deformed when subjected to the polymerzation temperature.

It will be noted that the acceptability of the ophtalmic lens <NUM> formed with the machine <NUM> may be defined susbstantially according to the measurement of a wrinkle defect.

It will also be noted that after polymerizing the molding material, the opthalmic lens <NUM> formed may be a finished lens or a semi-finished lens (see <FIG>).

The opthalmic lens <NUM> manufactured by using the machine <NUM> has a first optical surface <NUM> which is here convex and which has a shape matching with the first predetermined molding surface <NUM>, a second optical surface <NUM> opposite to the first optical surface <NUM>, which is here concave and which has a shape matching with the second predetermined molding surface <NUM>, and a peripheral edge <NUM> joining the first and second optical surfaces <NUM> and <NUM> (<FIG>).

The wrinkle defect measurement may be implemented by measuring the number of wrinkle defects along the peripheral edge <NUM> of the lens <NUM> formed and further the depth of the wrinkle defect observed.

A visual inspection may be done for locating the wrinkle defects on the peripheral edge <NUM> and the depth of the wrinkle defects identified may be measured with a metrology equipment including a support and a control device (not illustrated).

A defect free lens may be defined for instance as being a lens <NUM> having no defects along its peripheral edge <NUM>.

An acceptable lens <NUM> may be defined for instance as being a lens <NUM> having less than three or three wrinkle defects along its peripheral edge <NUM> and further having a maximum wrinkle depth smaller or equal to around <NUM>.

The machine <NUM> thus allows to provide an opthalmic lens <NUM> which has at least an acceptable peripheral edge <NUM>, and which has most often a defect free peripheral edge <NUM>.

In other words, the peripheral edge <NUM> of the lens <NUM> formed is straight and without wrinkle defect, twist defect or sticky surface which would imply to further processing after molding by casting.

The machine <NUM> thus allows providing acceptable ophthalmic lens <NUM> molded by casting.

By contrast, a lens <NUM> having a convex optical surface <NUM>, a concave optical surface <NUM> opposite to the convex optical surface <NUM> and a peripheral edge <NUM> joining the convex and concave optical surfaces <NUM> and <NUM> which has for instance more than three wrinkle defects <NUM> along its peripheral edge <NUM> or a wrinkle <NUM> depth greater than around <NUM> could be considered as being unacceptable (<FIG>). This might be the case with a machine devoid of the features of the machine <NUM> described above.

We will now describe in reference to <FIG> the cooperation between the first and second molding shells <NUM> and <NUM> and the adhesive tape member <NUM>, before casting the molding material, during polymerization of the molding material and after such a polymerization.

<FIG> show a mold assembly in which the adhesive tape member <NUM> has a total width substantially equal to the total thickness of the first and second molding shells <NUM> and <NUM> plus the distance between the first and second molding shells <NUM> and <NUM>, defining the sealed molding cavity <NUM> before introducing by casting the molding material into this cavity <NUM>.

In particular, before introducing the molding material (<FIG>), the upper portion <NUM> of the adhesive tape member <NUM> has a free upper edge <NUM> which is in contact with the first peripheral wall <NUM> of the first molding shell <NUM>; and the lower portion <NUM> of the adhesive tape member <NUM> has a free lower edge <NUM> which is in contact with the second peripheral wall <NUM> of the second molding shell <NUM>.

During the introduction of the molding material, the situation remains like in <FIG>.

During the polymerization of the molding material (<FIG>), the first molding shell <NUM> is here displaced towards the second molding shell <NUM> in the peripheral case formed by the adhesive tape member <NUM>, the distance there-between decreases, and the free upper edge <NUM> of the upper portion <NUM> of the adhesive tape member <NUM> protrudes from the first peripheral wall <NUM> and from the first external surface <NUM> of the first molding shell <NUM>.

By contrast, the free lower edge <NUM> of the lower portion <NUM> of the adhesive tape member <NUM> does not protrude from the second peripheral wall <NUM> and from the second external surface <NUM> of the second molding shell <NUM>.

<FIG> show a mold assembly in which the adhesive tape member <NUM> has a total width greater than the total thickness of the first and second molding shells <NUM> and <NUM> plus the distance between the first and second molding shells <NUM> and <NUM>, defining the sealed molding cavity <NUM> before introducing by casting the molding material into this cavity <NUM>.

In particular, before introducing the molding material (<FIG>), both the free upper edge <NUM> and the free lower edge <NUM> respectively protrudes from the first peripheral wall <NUM> and the first external surface <NUM> of the first molding shell <NUM>, and from the second peripheral wall <NUM> and the second external surface <NUM> of the second molding shell <NUM>.

In this case, the free upper and lower edges <NUM> and <NUM> each protrudes for instance of around <NUM> from the first and second peripheral walls <NUM> and <NUM>.

During the polymerization of the molding material (<FIG>), the first molding shell <NUM> is here displaced towards the second molding shell <NUM> in the peripheral case formed by the adhesive tape member <NUM>, the distance there-between decreases, and both the free upper edge <NUM> and the free lower edge <NUM> respectively protrudes even more from the first peripheral wall <NUM> and the first external surface <NUM> of the first molding shell <NUM>, and from the second peripheral wall <NUM> and the second external surface <NUM> of the second molding shell <NUM>.

The inventors have noticed that as long as the free edges of the adhesive tape member protrude less than about <NUM>, preferentially less or equal than about <NUM> during the whole process, a crumpling effect is avoided. Indeed, it is expected that the free edges that protrude are submitted to slight diameter shrinkage at the level of the free edge. Furthermore, when a free edge protrudes more than about <NUM>, the shrinkage leads to a contact of the adhesive tape member with the external surfaces of the mold shell, itself leading to limiting the possibility for the mold shell to slide in the casing formed by the adhesive tape member.

<FIG> show a mold assembly in which the adhesive tape member <NUM> has a total width smaller than the total thickness of the first and second molding shells <NUM> and <NUM> plus the distance between the first and second molding shells <NUM> and <NUM>, defining the sealed molding cavity <NUM> before introducing by casting the molding material into this cavity <NUM>.

In particular, before introducing the molding material (<FIG>), the free upper edge <NUM> is in contact with the first peripheral wall <NUM> of the first molding shell <NUM>; and the free lower edge <NUM> is in contact with the second peripheral wall <NUM> of the second molding shell <NUM>.

During the polymerization of the molding material (<FIG>), the first molding shell <NUM> is here displaced towards the second molding shell <NUM> in the peripheral case formed by the adhesive tape member <NUM>, the distance there-between decreases, and both the free upper edge <NUM> and the free lower edge <NUM> remain in contact respectively with the first and second peripheral walls <NUM> and <NUM>.

In other words, neither the free upper edge <NUM> nor the free lower edge <NUM> protrude from the first and second peripheral walls <NUM> and <NUM> and from the first and second external surfaces <NUM> and <NUM>.

During the polymerization of the molding material (<FIG>), both the first and second molding shells <NUM> and <NUM> are here displaced towards each other in the peripheral case formed by the adhesive tape member <NUM>, the distance there-between decreases, and both the free upper edge <NUM> and the free lower edge <NUM> respectively protrudes even more from the first peripheral wall <NUM> and the first external surface <NUM> of the first molding shell <NUM>, and from the second peripheral wall <NUM> and the second external surface <NUM> of the second molding shell <NUM>.

In <FIG>, the first molding shell <NUM> has a flat facette <NUM> formed on the first predetermined surface <NUM> and joining the latter to the first peripheral wall <NUM> of the first molding shell <NUM>.

The upper portion <NUM> of the adhesive tape member <NUM> is here in contact at the location of the junction between the flat facette <NUM> and the first peripheral wall <NUM>.

The flat facette <NUM> has a length for instance comprised between around <NUM> and around <NUM>, preferably equal to around <NUM> +/- <NUM>.

The flat facette <NUM> is to prevent that a sharp edge having an acute angle is provided on the lens <NUM> formed.

The flat facette <NUM> has here an angle relative to the peripheral wall <NUM> which is comprised between aroubd <NUM>° and around <NUM>°, and preferably equal to around <NUM>°.

Accordingly, once the molding material has been polymerized and a lens <NUM> is formed and removed from the mold, the lens has a flat facette surrounding the edge of its external surface, instead of having a sharp edge; thus preventing optional issues caused by such a sharp edge when the lens <NUM> is manipulated.

In <FIG>, the second molding shell <NUM> has a straight portion <NUM>, also called chamfer, having a constant inclination and joining the second peripheral wall <NUM> to the second external surface <NUM> of the second molding shell <NUM>.

The lower portion <NUM> of the adhesive tape member <NUM> is here in contact at the location of the junction between the straight portion <NUM> and the second peripheral wall <NUM>.

The straight portion <NUM> may have an inclination comprised between around <NUM>° (excluded) and <NUM>° and may be configured so that the width of the second peripheral wall <NUM> which is in contact with the lower portion <NUM> is comprised substantially between around <NUM> and around <NUM>.

The straight portion <NUM> also allows to control a back-force generated by the contact between the adhesive tape member <NUM> and the second peripheral wall <NUM>.

<FIG> is a block diagram illustrating steps for manufacturing the ophthalmic lens <NUM> by using the machine <NUM>.

The method comprises the step <NUM> of providing the first and second molding shells <NUM> and <NUM> having respectively the first and the second predetermined molding surfaces <NUM> and <NUM>.

The first and second molding shells <NUM> and <NUM> may be selected amongst a plurality of molding shells, according to the predetermined optical power of the ophthalmic lens <NUM> to be molded by casting.

The method furthermore comprises the step <NUM> of providing the adhesive tape member <NUM> having a Young's modulus greater than around <NUM> MPa, when measured at around the polymerization temperature of the polymerizable molding material, and a maximum shear stress smaller than around <NUM> MPa, when measured at around the temperature of polymerization.

The adhesive tape member <NUM> may be selected amongst a plurality of adhesive tape members, according to the predetermined optical power of the ophthalmic lens <NUM> to be molded by casting.

The method furthermore comprises the step <NUM> of arranging the first and second molding shells <NUM> and <NUM> so that the first predetermined molding surface faces the second predetermined molding surface <NUM> and <NUM>.

The method furthermore comprises the step <NUM> of arranging the adhesive tape member <NUM> to join the first and second molding shells <NUM> and <NUM> for forming the sealed molding cavity <NUM> and to form the peripheral case of the mold assembly <NUM>, peripheral case in which at least the first molding shell <NUM> is able to be displaced relative to the second molding shell <NUM> without affecting the intermediate portion <NUM> of the adhesive tape member <NUM>.

The method furthermore comprises the step <NUM> of introducing by casting the predetermined volume of a polymerizable molding material into the molding cavity <NUM>, thanks to the filling aperture <NUM> formed in the adhesive tape member <NUM>, to the filling duct <NUM> and to the filling device <NUM>.

The method furthermore comprises the step <NUM> of polymerizing the predetermined volume of molding material for forming the ophthalmic lens <NUM> having a straight peripheral edge <NUM>, without wrinkle defect, thanks to the polymerization device <NUM>.

Claim 1:
Combination of a machine for manufacturing an ophthalmic article (<NUM>) and a polymerizable molding material, the machine comprising a mold assembly (<NUM>) having a first molding shell (<NUM>) provided with a first predetermined molding surface (<NUM>), a second molding shell (<NUM>) provided with a second predetermined molding surface (<NUM>) which is arranged for facing the first predetermined molding surface (<NUM>) of the first molding shell (<NUM>), an adhesive tape member (<NUM>) configured to join said first and second molding shells (<NUM>, <NUM>) for forming a sealed molding cavity (<NUM>) defined generally by said first and second predetermined molding surfaces (<NUM>, <NUM>) and also laterally at least by an intermediate portion (<NUM>) of said adhesive tape member (<NUM>), a predetermined volume of the polymerizable molding material and a filling aperture (<NUM>) formed in said adhesive tape member (<NUM>) for introducing by casting said predetermined volume of a polymerizable molding material into said molding cavity (<NUM>) for forming said ophthalmic article (<NUM>); said adhesive tape member (<NUM>) having a Young's modulus greater than around <NUM> MPa, when measured at a temperature of polymerization of said polymerizable molding material, and a maximum shear stress smaller than around <NUM> MPa, when measured at said temperature of polymerization, and being configured to form a peripheral case of the mold assembly (<NUM>), peripheral case in which at least said first molding shell (<NUM>) is able to be displaced relative to the second molding shell (<NUM>) without affecting said intermediate portion (<NUM>) of the adhesive tape member (<NUM>); by virtue of which the ophthalmic article (<NUM>) molded by casting has a straight peripheral edge (<NUM>).