Patent Description:
Mass production of ophthalmic lenses, in particular hard or soft contact lenses, is usually performed in a fully automated manufacturing process. In an embodiment of such fully automated mass production the contact lenses are manufactured with reusable casting molds comprising male and female mold halves. The female mold halves are filled with a lens-forming material and the casting molds are subsequently closed with the corresponding male mold halves. Suitable lens-forming materials include but are not limited to polymers or pre-polymers based on polyvinyl alcohols (PVA) or silicone hydrogels (SiHy) as well as materials based on polyethylene glycols (PEG). The lens-forming material within the casting molds is then polymerized and/or cross-linked by irradiation with ultraviolet radiation. After polymerization and/or cross-linking the molds are opened and the formed contact lenses are removed from the male or female mold halves and transported to subsequent processing stations.

The male and female mold halves of reusable casting molds are provided with lens-forming surfaces which are typically made from highly finished glass, for example quartz glass. Lens-forming surfaces which are made of glass or quartz glass are durable regarding exposure to UV-light and organic solvents. They are reliably cleanable, resistant to abrasion, and therefore suitable for multiple use in the mass production of ophthalmic lenses.

In order to meet the needs of the users, large numbers of contact lenses with different parameters must be produced, in particular as regards contact lenses for single use only. Such parameters include but are not limited to the refraction power of a contact lens, the base curve, the toric shape of the lens, etc. Thus, for the manufacture of all types of contact lenses a large number of different casting molds is required and must be held on stock.

Considerable care must be taken in the logistics and handling of the casting molds in order to avoid a mix-up of casting molds as they are prepared for use in the fully automated manufacturing process. Typically, in preparation of production a plurality of such casting molds are mounted to a mold carrier which is then placed on the manufacturing line. Since casting molds having different parameters may be mounted to the same mold carrier at different locations on the mold carrier, it is essential that the individual casting molds having the desired parameters are mounted to the mold carrier at the intended positions on the mold carrier before the mold carrier is placed on the manufacturing line so as to avoid production of contact lenses having parameters different from those originally intended.

Therefore, one object of the invention is to facilitate the logistics and handling of a large number of casting molds with different parameters and to avoid mix-up of casting molds as they are prepared for use in the fully automated manufacturing process. In addition, it is desirable to allow for an automated verification of the casting molds even after they have been placed on the manufacturing line.

<CIT> discloses a casting mold made of glass having markings thereon.

One aspect of the present invention, therefore, relates to a casting mold for the manufacture of ophthalmic lenses according to independent claim <NUM>.

In some embodiments of the casting mold according to the invention the permanent marking comprises information about optical parameters of the ophthalmic lens to be produced.

In some further embodiments of the casting mold according to the invention the permanent marking at least partially comprises the information in an encoded manner.

In particular, a circumferential position of the permanent marking may comprise information on specific lens parameters of the ophthalmic lens to be produced.

In still some further embodiments of the casting mold according to the invention the permanent marking comprises an embossed relief.

In particular, the permanent marking may have the shape of a bas-relief, with raised portions of the bas-relief protruding from the surface of the peripheral zone of the lens-forming surface and having a height which is in a range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM>.

In yet some further embodiments of the casting mold according to the invention, the permanent marking in the non lens-forming annular edge surface is made by laser engraving.

A further aspect of the present invention relates to a casting mold assembly according to claim <NUM> comprising a mold carrier and a plurality of casting molds arranged in the mold carrier in side-by-side configuration. At least one of the casting molds arranged in the mold carrier is a casting mold according to claim <NUM>.

Still a further aspect of the present invention relates to a method of manufacturing an ophthalmic lens according to claim <NUM>, in particular a hard or a soft contact lens. The method comprises providing at least one casting mold comprising a male mold half and a female mold half, each of the male and female mold halves comprising a lens forming surface defining a cavity therebetween when the male and female mold halves are arranged in a predetermined spatial relationship. The method further comprises introducing a lens forming material into the cavity and curing the lens forming material in the cavity to form an ophthalmic lens. The step of providing at least one casting mold comprises providing at least one casting mold according to claim <NUM>.

In some embodiments of the method according to the invention, a plurality of ophthalmic lenses are produced at the same time, and the step of providing at least one casting mold comprises providing a casting mold assembly according to claim <NUM>.

Using a casting mold according to the invention an unambiguous identification of the casting mold is ensured with the aid of the permanent marking. The term "permanent" is intended to denote a marking which is not removed from the casting mold after the mold has been used to produce an ophthalmic lens. Rather, the marking remains on the casting mold and is present on the casting mold as this casting mold is reused in the subsequent manufacture of additional ophthalmic lenses. While not being limited thereto, examples for such permanent markings include markings produced by embossing, engraving, etching, laser marking, or any other suitable techniques. Thus, in addition to allowing for a verification of the casting molds at the time of their preparation for use in the fully automated manufacturing process (for example verification of the casting molds arranged on the mold carrier before the mold carrier is placed onto the manufacturing line), the permanent marking also allows for verification of the casting molds after they have been placed onto the manufacturing line. For example, such verification of the casting molds can be performed using an optical inspection system present in the manufacturing line. With this in-line inspection and comparison with respective position data stored in a programmable logic control unit of the manufacturing line it can be ascertained that the correct casting mold is indeed arranged at the correct position on the respective mold carrier in the manufacturing line. This may be of advantage in particular in fully automated manufacturing processes, in which not only a plurality of contact lenses are manufactured simultaneously with the aid of a plurality of casting molds which are arranged on a mold carrier in side-by-side configuration, but also in which a plurality of mold carriers are used in the manufacturing line. In this respect, it should be noted again that the contact lenses produced with the molds arranged on the same carrier need not have the same optical parameters but may all have different optical parameters. By using casting molds with respective markings, it can be easily verified if the correct casting mold is present at the respective position on a respective mold carrier and if the data stored in the programmable logic control unit of the manufacturing line are in accordance therewith.

The permanent marking may provide a plurality of information to the observer. For example, such information may contain information about the manufacturing site, the type of casting mold, etc.. More importantly, though, in an embodiment of the casting mold according to the invention the permanent marking may comprise information about optical parameters of an ophthalmic lens which is manufactured with the respective casting mold. Such information may include, but is not limited to, the type of the lens geometry (lens design), diopters, toric shape of the lens, etc..

Again by way of example, the permanent marking may be present in "clear text", that is the permanent marking may be constituted of alphanumeric characters. In order to be able to include even more information the permanent marking may at least partially comprise the information in an encoded manner. Such code may be embodied as or comprise a bar-code, a two-dimensional QR-code, a dot-code, a symbol-code, or any combination of different kinds of codes. For example, the meaning of the different codes may be stored and accessed in the programmable logic control unit of the manufacturing line.

Also, the circumferential position of the permanent marking on the non lens-forming annular edge surface may comprise information on specific lens parameters of the ophthalmic lens produced with the mold. For example, an angular deviation from a reference position may be used to encode the diopters of an ophthalmic lens produced with the respective casting mold. The angular deviation from the reference position may have positive and negative values, thus representing positive and negative diopters of the corrective optical power.

Precision molding is a process which allows the production of surfaces of optical quality without the need of grinding and polishing. Precision molding has the advantage that it allows for a cost-efficient production of surfaces even if these surfaces have complex geometries such as, for example, aspheric geometries.

Generally, the permanent marking may be applied to the male mold surface of the male mold half or to the female mold surface of the female mold half, or to both.

Glass is a material which may be shaped and finished in the desired manner. It is enduring and may be refinished relatively easily, for example by the afore-mentioned precision glass molding process. In particular, the highly finished glass may be quartz glass.

As regards the casting mold assembly according to the invention, the method according to the invention, and the ophthalmic lens produced with such casting mold or casting mold assembly, the advantages are already discussed in connection with the embodiment of the casting mold, so that they are not reiterated here.

Additional features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, reference being made to the schematic drawings, in which:.

<FIG> shows an embodiment of a casting mold <NUM> for use in an automated manufacturing line for ophthalmic lenses, in particular hard and soft contact lenses. The casting mold <NUM> comprises a male mold half <NUM> and a female mold half <NUM>. When assembled in a predetermined spatial relationship the male and female mold halves <NUM>, <NUM> define a mold cavity <NUM> therebetween, in which the contact lens is formed from a lens-forming material. Male mold half <NUM> and female mold half <NUM> may be made of highly finished glass, for example of quartz glass or any other suitable glass.

<FIG> shows a plan view of the male mold surface of the male mold half <NUM> shown in <FIG>. The male mold half <NUM> has a generally convexly shaped male mold surface <NUM> which comprises a lens-forming surface <NUM> which is encircled by a non lens-forming annular edge surface <NUM>. As shown in <FIG>, a permanent marking <NUM> is arranged on the annular edge surface <NUM> which does not participate in the shaping of the lens during production of the lens. The permanent marking <NUM> may be made by laser engraving.

<FIG> show a section and a plan view of the female mold half <NUM> of <FIG>. The female mold half <NUM> comprises a generally concavely shaped female mold surface <NUM> comprising a lens-forming surface <NUM> and a non lens-forming annular edge surface <NUM> which encircles the lens-forming surface <NUM>. The lens-forming surface <NUM> comprises a central optical zone <NUM> and a non-optical peripheral zone <NUM>. The annular edge surface <NUM> does not participate in the shaping of the lens during production of the lens. A permanent marking <NUM> is arranged on the lens-forming surface <NUM> in the non-optical peripheral zone <NUM> thereof.

As can be seen in <FIG>, the permanent marking <NUM> on the lens-forming surface <NUM> in the non-optical peripheral zone <NUM> (see <FIG>) thereof has the shape of an embossed relief, a bas-relief, in which regions of highest elevation above the lens forming surface <NUM> extend from the lens forming-surface <NUM> a height h in the range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM> (in case the permanent marking or relief is provided in the annular edge surface <NUM> the height may be in the range of <NUM> to <NUM>). When a lens is produced using a female mold half <NUM> having such permanent marking <NUM> thereon, the permanent marking <NUM> is transferred to a non-optical peripheral zone of the front surface of the lens. The transferred marking corresponds with the permanent marking <NUM> on the lens-forming surface <NUM> and has the shape of a recessed relief. Thus, on the produced lens there are no elevated regions which might protrude beyond the lens surface and which might impair the comfort of a user of the lens.

The permanent marking <NUM> in the non-optical peripheral zone on the lens forming surface <NUM> may comprises clear text, that is to say it may comprise alphanumeric characters, or may be provided in coded form. Regardless of whether comprising clear text or being provided in coded form the permanent marking <NUM> may contain information about optical parameters of the lens which is formed using a respective female mold half <NUM>. Such information includes, but is not limited to, information about the type of lens geometry, diopters, toric shape of the lens, etc..

In the embodiment of a female mold half <NUM> of a casting mold shown in <FIG> the permanent marking <NUM> comprises a bar code. In another embodiment of a female mold half <NUM> of a casting mold shown in <FIG> the permanent marking <NUM> comprises a two-dimensional QR (Quick Response) code. Further code types include one-dimensional or two-dimensional dot codes, matrix codes, symbol-codes, etc. or any combination of different kinds of codes. The information corresponding to the different code patterns may be stored and accessed in the programmable logic control unit of the manufacturing line.

<FIG> show in a side view (<FIG>) and in a plan view (<FIG>) a male mold half <NUM> having the generally convexly shaped male mold surface comprising the lens forming surface <NUM> and the non-lens forming annular edge surface <NUM>. The lens-forming surface <NUM> comprises a central optical zone <NUM> and a non-optical peripheral zone <NUM> (see <FIG>) and in this peripheral zone <NUM> bears the permanent marking <NUM>. In the depicted embodiment the permanent marking <NUM> comprises a bar code. It should be noted, however, that the permanent marking <NUM> may comprise any other suitable kind of code, such as the afore-mentioned two-dimensional QR code, a dot-code, a symbol-code, etc., or any combination of different kinds of codes. The permanent marking <NUM> may also comprise clear text (alphanumeric characters) or may be a combination of clear text and coded information. As in the case of the female mold half <NUM> shown in <FIG> the permanent marking <NUM> has the shape of an embossed relief, in particular a bas-relief protruding beyond the lens forming surface <NUM> a height in the range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM> (in case the permanent marking is provided in the annular edge surface <NUM> the height may be in the range of <NUM> to <NUM>). When a lens is produced with such male mold half <NUM> the permanent marking <NUM> is transferred to the rear surface of the lens in a peripheral non-optical zone of the lens.

In a further embodiment of a male mold half <NUM> shown schematically in <FIG> the permanent marking <NUM> is provided on the annular edge surface <NUM> which encircles (encloses) the lens forming surface <NUM>, but does not contribute to the shaping of the lens during the lens forming process. The permanent marking <NUM> may be in coded form or, as shown in <FIG>, may comprise clear text in the form of alphanumeric characters. Because the annular edge surface <NUM> does not contribute to the shaping of the lens the permanent marking may either be of a raised shape or it may have a recessed shape. In the case of alphanumeric characters the permanent marking <NUM> may be made by laser engraving.

The embodiments schematically shown in <FIG> (side view) and <FIG> (plan view) of a female mold half <NUM> of the casting mold with the lens-forming surface <NUM> shall serve for the illustration of another form of the encoding of information by a permanent marking <NUM>. In addition to the permanent marking <NUM> arranged in the non-optical peripheral zone <NUM> of the lens-forming surface <NUM>, the female mold half <NUM> may be provided, for example, with further engraved markings <NUM> on the annular edge surface <NUM>. On the surface of the non-optical peripheral zone <NUM> of the lens-forming surface <NUM> a permanent marking having the shape of protruding dots may be provided. For example, a larger dot <NUM> at the twelve o'clock position may serve as a reference position. A smaller dot <NUM> may be positioned an angular distance β from the larger dot <NUM> representing the reference position. The larger dot <NUM> and the smaller dot <NUM> are both located at the same perimeter in the non-optical peripheral zone <NUM> of the lens-forming surface <NUM>. The angular distance β of the smaller dot <NUM> from the larger dot <NUM> may serve, for example, as an indicator for the diopters of a lens produced with the specific female mold half. The depiction of a larger number of smaller dots <NUM> in <FIG> is for illustration purposes only and is intended to show different possible locations of the smaller dots <NUM> along the respective perimeter in the non-optical peripheral region <NUM> of the lens-forming surface <NUM>. Each smaller dot <NUM> has a different angular distance from the larger dot <NUM>, thus representing a different positive diopter. While in <FIG> only locations of the smaller dots <NUM> are shown in clockwise distances (to the right) from the reference position, the smaller dots <NUM> may also be located at counterclockwise distances (to the left) from the reference position, thus indicating negative diopters of a lens which is produced using such female mold half <NUM>.

It should be noted that the representation of the reference position by a larger dot <NUM> and of the diopter indicator by a smaller dot <NUM> is by way of example only. Various other forms of encodings by permanent markings on specific circumferential positions are conceivable. It should be further noted that a similar circumferential encoding may be carried out also with the aid of the male mold half. By providing both mold halves with permanent markings in clear text and/or in encoded form even more information may be expressed. The information corresponding to the respective encodings may be stored and accessed, for example, in the programmable logic control unit of the manufacturing line. When mold halves are inspected in-line in the automated manufacturing line, the encoded information may be communicated to an operator through a visual output device in clear text.

It should further be noted that the provision of at least one permanent marking on the male mold half and/or on the female mold half may not only be used for information purposes, but in case of toric lenses it may also be utilized to produce markings on the produced lenses for a proper alignment of the toric lens.

Claim 1:
Casting mold (<NUM>) for the manufacture of hard or soft contact lenses, comprising a male mold half (<NUM>) made of highly finished glass having a generally convexly shaped male mold surface (<NUM>) shaped by precision glass molding and a female mold half (<NUM>) made of highly finished glass having a generally concavely shaped female mold surface (<NUM>) shaped by precision glass molding, each of the male and female mold surfaces (<NUM>, <NUM>) comprising a lens-forming surface (<NUM>, <NUM>) which is encircled by a non-lens-forming annular edge surface (<NUM>, <NUM>), the lens-forming surface (<NUM>, <NUM>) comprising a central optical zone (<NUM>, <NUM>) and a non-optical peripheral zone (<NUM>, <NUM>) surrounding the central optical zone (<NUM>, <NUM>), at least one of the male and female mold halves (<NUM>, <NUM>) being provided with at least one permanent marking (<NUM>; <NUM>; <NUM>, <NUM>) which is arranged only on the non-lens-forming annular edge surface (<NUM>, <NUM>).