HK1121105B - Contact lens mold assemblies and systems and methods of producing same - Google Patents

Abstract

Methods and apparatus are provided for making an ophthalmic lens. Apparatus are provided for filling contact lens shaped cavities of contact lens molding assemblies. Methods of coupling and fusing contact lens mold sections are also provided and generally include providing first and second mold sections which when coupled together are effective to form a lens-shaped cavity and contact regions between the mold sections. One or both of the mold sections may include one or more recessed regions or projections which provide areas of non-fusion and areas of fusion, respectively, when the mold sections have been filled with a contact lens precursor material and are fused together, for example, by means of focused ultrasound energy.

Description

Contact lens mold assemblies and systems and methods for manufacturing the same

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. application No. 11/200,648, filed on 8/9/2005, and is hereby incorporated by reference in its entirety.

Technical Field

The present invention relates generally to devices, systems, and methods for manufacturing contact lenses, such as silicone hydrogel contact lenses or contact lenses comprising silicone hydrogel materials. More particularly, the present invention relates to systems for providing polymerizable compositions to mold sections, systems for fusing mold sections together to form a mold assembly, and mold assemblies made therefrom.

Background

One method of manufacturing lenses, such as intraocular lenses and contact lenses, is by injection molding.

Injection molding of contact lenses is well known. See, for example, U.S. patent No. 5,466,147 to Appleton et al, U.S. patent No. 6,405,993 to Morris, and U.S. patent No. 6,732,993 to Dean.

A single mold assembly for molding a single contact lens product typically includes a female mold section having a concave optical surface defining the anterior surface of the lens to be manufactured and a male mold section having a convex optical surface defining the posterior surface of the lens to be manufactured. Thus, when the male and female mold sections are assembled together, a contact lens shaped cavity is formed between the concave surface of the female mold section and the convex surface of the male mold section.

The female and male mold sections are typically manufactured by injection molding techniques. A common method of forming the lens mold sections is to form the molding surfaces of the mold sections with a metal working insert that has typically been lathed to define the desired contact lens surface.

The process of injection molding the lenses is as follows. A polymerizable lens material (e.g., a monomer material or other lens precursor material) is placed on the concave surface of the contact lens mold sections. This is typically accomplished by manually withdrawing the precursor material from a bulk container containing the lens precursor material with an eppendorf (eppendorf) tube and dispensing a quantity of the precursor material onto the mold half or mold portion. Typically, the einbeck tube may be filled with material and about 30 μ Ι _ to about 50 μ Ι _ are dispensed to the concave surface of the mold portion. Such a process can be labor intensive, can present a substantial hazard to persons handling the precursor materials, and can result in increased waste of precursor materials, as large amounts of materials remain in the canister over time, which can degrade or deteriorate over time.

Once the first mold section is filled, a second mold section is placed on top of the first mold section to form a lens shaped cavity containing a lens precursor material. For example, the contact lens precursor material is cured by the application of heat and/or light or other suitable polymerization means to fill the mold assembly to produce a contact lens product or contact lens between the mold sections. The contact lens product is then removed from the mold section. During this removal step, the mold sections are often damaged. The contact lens products are often unfinished contact lenses that are subjected to one or more finishing steps, such as conventional finishing steps (such as hydration), to produce the final contact lens.

One obstacle associated with injection molding processes is the proper placement and fixation of the mold sections, particularly after the lens precursor material has been placed between the mold sections and before the material polymerizes. For example, it can be difficult to secure two mold sections together to form a mold assembly without forming haze, pits, or bubbles in a lens cup (e.g., the region of the mold section containing the lens precursor material). In addition, it can also be difficult to form mold assemblies in which the lens precursor material has a substantially uniform thickness, or in other words, the lens has no unwanted refractivity (prism) due to the increased thickness of the lens precursor material at one region of the lens cup relative to another region.

In addition, due to the potentially fragile nature of the polymerized contact lens product, the mold sections should be separable without causing cracking or destruction of the lens product.

In non-automated production laboratories, conventional methods of placing one mold section on another and then securing the two sections in a relatively fixed position, such as by loading or clamping, are used with a variety of settings. While this may be a somewhat acceptable practice based on small-scale production, it may not meet all of the requirements for large-scale and/or automated high-speed manufacturing of contact lenses.

Directed energy techniques, such as ultrasonic welding, for permanently joining materials, such as polymers, without regard to later separation are known in the art.

U.S. patent No. 5,759,318 to Galas describes an apparatus and method that includes the use of ultrasonic energy to releasably secure assembled sections of a lens molding assembly using ultrasonically generated fusion rings that fully circumscribe contact lens forming material contained between the assembled sections.

There is a need for more efficient and reliable methods and systems for manufacturing lenses, such as filling and coupling mold sections, during contact lens manufacturing.

Disclosure of Invention

The present systems and methods relate to filling individual contact lens mold sections with a contact lens precursor material, such as a photo-initiated polymerizable composition, closing the filled mold sections with another mating mold section, and causing the assembled mold sections to become fused together such that the filled and assembled mold sections remain stationary during one or more subsequent contact lens manufacturing steps.

The systems and methods are suitable for automated manufacturing of contact lenses, such as silicone hydrogel contact lenses, including daily wear lenses and extended or continuous wear lenses. For example, the present system can fill contact lens mold sections using an assembly that includes a removable, replaceable Ultraviolet (UV) blocking reservoir containing a relatively large amount of contact lens precursor composition and a dispensing mechanism directly connected to the reservoir containing a relatively small amount of contact lens precursor composition. The reservoir may be a syringe barrel. A diaphragm valve may be operatively positioned between the reservoir and the dispensing assembly. The dispensing mechanism includes a dispensing tip. A conveyor is provided to convey the unfilled mold portions beneath the dispensing mechanism. A stepper motor may be used to cause the dispensing mechanism to automatically dispense a substantially precise and accurate amount of precursor composition from the dispensing tip into each desired lens cup or female mold section conveyed beneath the dispensing tip. When the dispensing device is empty, the valve between the reservoir and the dispensing mechanism connected thereto is opened to refill the dispensing mechanism. When the reservoir itself becomes empty, the reservoir can be easily and quickly replaced with a filled reservoir.

Accordingly, in a broad aspect of the present invention, methods and systems are provided for manufacturing lenses, for example, silicone hydrogel lenses, such as contact lenses.

In one aspect, the invention comprises a method of manufacturing a contact lens comprising providing a plurality of first mold sections and second mold sections, each mold section comprising a lens shaped surface and a flange region circumscribing the lens shaped surface, each first mold section comprising an annular circumferential projection extending longitudinally from the flange region, and a plurality of circumferential recessed regions not completely surrounding the lens shaped surface of the first mold section and extending longitudinally into the flange region toward the annular projection, wherein the first mold sections are located in a cassette comprising a stack of mold sections; placing the cassette within a frame assembly configured such that the uppermost mold portions in each stack lie in the same plane; transferring the first and second mold portions to a nesting device; dispensing a polymerizable composition on the lens-shaped surface of the first mold section located in the nesting apparatus; coupling the first and second mold sections together such that each of the coupled mold sections defines a lens-shaped cavity between the lens-shaped surface of one of the mold sections and the lens-shaped surface of the other of the mold sections, and the flange region of the first mold section is in contact with the flange region of the second mold section; fusing the coupled mold sections to form a plurality of circumferential fused regions between the flange regions, the plurality of circumferential fused regions not completely surrounding the lens-shaped surface of the coupled mold sections; and polymerizing the polymerizable composition in the lens shaped cavity.

In another aspect, the invention comprises a contact lens mold assembly comprising a first mold section having a lens shaped surface that is a negative of the anterior or posterior surface of a contact lens; a flange region circumscribing the lens-shaped surface; an annular circumferential projection on the flange region and circumscribing the lens-shaped surface; and a plurality of circumferential recessed regions that do not completely encircle the lens-shaped surface of the first mold section and extend longitudinally into the flange region; a second mold section of the same construction as the first mold section, the second mold section being fused to the first mold section at a plurality of circumferential fused regions between the flange regions of the first and second mold sections that do not completely surround the lens shaped surface of the first mold section and are not fused to the first mold section at the plurality of circumferential recessed regions; and a polymerizable composition on the lens shaped surface.

According to aspects of the present invention, a lens-shaped cavity of a contact lens mold section is filled with a polymerizable material, the filled mold section is assembled with a mating contact lens mold section, and the assembled mold sections are secured together to form a mold assembly. In certain embodiments, the mold sections are fused or welded together using vibrational energy, such as ultrasonic energy, to form a non-annular or discontinuous circumferential weld around the polymerizable material. In other embodiments in which non-ultrasonic methods and devices are used to form the mold assembly, the mold sections can be coupled together in a continuous annular ring.

The contact lens mold sections each comprise a lens shaped section or surface and a flange region circumscribing the lens shaped section or surface. For example, a mold assembly for forming a contact lens can comprise a first mold section and a second mold section, wherein the first mold section comprises a generally concave lens-shaped surface defining the anterior surface of the contact lens and the other of the mold sections comprises a generally convex lens-shaped surface defining the posterior surface of the contact lens. When the first and second mold sections are coupled together, they form a lens-shaped cavity between the lens-shaped surface of the first mold section and the lens-shaped surface of the other mold section, and assemble one or more regions where the surfaces of the flanges of the mold sections contact each other. According to an embodiment of the invention, a first mold portion and a second mold portion are provided which, when coupled together, form a non-circumferential contact zone and one or more gaps separating the non-circumferential contact zone along the flange. A non-circumferential contact zone or fused zone refers to a section of a contact lens mold assembly where two mold sections are in contact or fused together and which does not completely surround the circumferential extension of the lens-shaped cavity of the mold assembly without interruption.

In a particularly advantageous embodiment of the invention, at least one of the first mould part and the second mould part, preferably both, is a "universal" mould part. In other words, each of the first and second mold portions may be substantially identical, such as having less than about a 5% difference in weight or radius or other property from one another. In this embodiment, the mold sections each comprise a first lens shaped surface defining an anterior surface of the contact lens and a substantially opposing second lens shaped surface defining a posterior surface of the contact lens.

To form a contact lens according to the present invention, a polymerizable composition is deposited on the concave lens shaped surface of an individual mold section as a plurality of such mold sections are moved along a production line. The polymerizable composition can comprise a contact lens precursor material having at least one monomeric component (e.g., a silicon-containing monomeric component).

According to one aspect of the present invention, a dispensing apparatus is provided that is adapted to provide a polymerizable composition to a lens shaped surface of a contact lens mold section. The dispensing apparatus generally includes a dispensing unit having a dispensing tip sized to dispense an amount of the polymerizable composition into the mold section or a portion thereof and a syringe assembly configured to contain a quantity of the polymerizable composition and that is couplable and decouplable with the dispensing unit. The dispensing unit may comprise a diaphragm valve. The syringe assembly is configured to provide the polymerizable composition to the dispensing unit when it is directly coupled with the dispensing unit.

In some embodiments, the dispensing apparatus includes a control assembly operatively coupled to the dispensing unit and configured to control dispensing of the polymerizable composition through the dispensing tip. The dispensing apparatus preferably further comprises a fitment positioned between and connecting the dispensing unit and the syringe assembly. The fitment is constructed and arranged to facilitate coupling and decoupling of the syringe assembly to the dispensing unit. The fitting may comprise an elbow conduit.

The syringe assembly may include a barrel adapted to contain the polymerizable composition and a plunger disposed in the barrel and movable therein. In some embodiments, the cartridge comprises a hollow space having a volume or capacity in a range between about 20cc and about 200cc or between about 40cc and about 100 cc. In a particular embodiment, the cartridge contains about 55cc of the polymerizable composition.

In some embodiments, the syringe assembly, fitment, and/or dispensing unit preferably comprise one or more polymerization radiation effective to block polymerization radiation that would be effective to cause or initiate polymerization of the polymerizable composition contained in or passing through the dispensing apparatus

Material of the path of (e.g., light). For example, the syringe assembly, fitting, and/or dispensing unit may include a material effective to substantially block the passage of ultraviolet light.

Once the mold sections have been filled with the polymerizable composition, the mating mold sections are placed on the filled mold sections to form the contact lens mold assembly.

In another aspect of the invention, methods and systems are provided for joining coupled mold sections, for example, to cause fusion between coupled mold sections.

In a preferred embodiment, the mold sections are constructed such that vibrational energy (e.g., ultrasonic energy) can be used to fuse the assembled mold sections together. According to one aspect, focused ultrasonic energy is radiated into a contact zone at a flange of a mating mold portion using an ultrasonic horn.

The mold sections may comprise materials that can be effectively joined using the focused ultrasonic energy. In some embodiments, the mold portions comprise polyethylene vinyl alcohol (EVOH) which is a material suitable for ultrasonic welding. It will be appreciated that other materials may be used to manufacture the lens mold sections of the present invention. For example, materials suitable for use in the present invention include polymeric materials, e.g., thermoplastic polymeric materials, e.g., amorphous polymeric materials, such as polystyrene, polycarbonate, acrylonitrile/butadiene/styrene compositions, cyclic olefin copolymers, acrylics, and/or polysulfones. Semi-crystalline resins such as acetals, polypropylenes, polyethylenes, nylons, polyethylene terephthalate, polyetheretherketones, other polyolefins, and liquid crystalline polymers are also suitable. In certain materials, one or more additives may be provided in the mold sections to enhance the properties of the contact lens. Advantageously, the mold sections containing EVOH do not require additives such as wettability enhancers and the like.

Other methods of the present invention may use directing different types of energy into the mold assembly to cause the mold sections to fuse, such as focused infrared radiation, radio frequency energy, and/or other forms of thermal friction. Additionally, in certain embodiments, alternative devices or methods may be used to hold the mold sections together, such as by mechanically clamping using a plate or other suitable structure, or by providing an interference fit between the male and female mold sections. In embodiments where ultrasonic energy is used, the fusion or weld is not in a continuous loop around the lens cup of the mold section. In embodiments using non-ultrasonic energy coupling techniques, the contact between the male and female mold sections may be continuous around the lens cup.

In some embodiments, the mold sections are configured to facilitate fusion of the coupled mold sections.

For example, the mold sections can include one or more longitudinally extending projections positioned radially outward from the lens-shaped surface. In some embodiments, the at least one longitudinally extending projection is positioned radially outward from only a portion of the lens shaped surface of the mold section. For example, the projections may comprise a plurality of longitudinally extending projections, such as 3 or more than 3 longitudinally extending projections, the projections being circumferentially spaced from one another, such as equidistantly circumferentially spaced.

In other embodiments, the at least one projection comprises a substantially complete annular projection substantially completely circumscribing the lens shaped surface of the first mold section.

The projections are effective to facilitate fusion of the mold sections by providing discrete contact areas between the mold sections where vibrational energy is effectively focused.

Other embodiments of the mold section may include one or more recesses in a portion of the mold section. For example, the flange of the mold section can include a plurality of spaced apart recesses extending radially outward from the lens cup. When a portion of the mold section, such as a ridge portion, is in contact with the flange surface in which the recess is located, the ultrasonic engagement of the flange surface with the ridge portion provides a discontinuous contact zone around the periphery of the eyeglass cup, even when an ultrasonic device having an annular ultrasonic transmission device, such as a continuous or annular ultrasonic horn, is used.

The method of the present invention may include the step of coupling the first mold section and the second mold section together such that the projections are proximate to or in direct contact with the second mold section. According to some embodiments, the coupled mold sections are fused at least a portion of the projection to form at least one fused region between the first mold section and the second mold section.

Advantageously, the fused region holds the mold sections together sufficiently firmly that the mold assembly can withstand one or more post-fusion procedures without the mold assembly inadvertently wandering or separating. The post-fusion procedure can include, for example, subjecting the mold assembly to polymerizing radiation to polymerize the lens precursor material in the lens-shaped cavity, and mechanical lifting and other transport of the mold assembly between the various post-fusion processing stations.

For example, once the mold sections are filled, assembled, and joined, the polymerizable composition in the lens shaped cavity of the mold assembly is polymerized to form a polymerized contact lens product. In some embodiments, the step of polymerizing the polymerizable composition comprises exposing the filled mold assembly to polymerizing light (e.g., ultraviolet light). The mold sections can then be decoupled or separated to expose the contact lens product, for example, by conveying a cutting device (e.g., a blade) through the fused zone and removing one mold section from the contact lens product.

As discussed herein, in particularly advantageous embodiments of the invention, the flange region of the mold section comprises one or more recessed regions, preferably at least one non-circumferential recessed region that does not extend the entire circumferential length of the flange. For example, three spaced apart recessed regions may be provided along the circumferential surface of the flange.

The recessed areas may be provided in addition to or instead of longitudinally extending projections.

Generally, according to the present invention, although the projection is preferably provided on the lens-shaped surface side of the mold section, the recessed area is provided on the mold section side opposite to the lens-shaped surface side of the mold section. For example, a projection such as an annular ridge may be provided on an upper surface of the flange of the mold section around the lens cup section and a recess may be provided on a lower surface of the flange of the mold section.

When two of the mold sections having the recessed area are assembled together to form a mold assembly, the recessed area provides a gap that divides the contact area between the mold sections. While not wishing to be bound by any particular theory of the invention, the gap may advantageously prevent cavitation of the unpolymerized lens material during the ultrasonic fusion step, which may occur by allowing gas to escape between the abutting unfused flange surfaces. Other benefits may also be obtained due to the presence of gaps in the contact region.

In another aspect of the invention, a device is provided that is suitable for fusing coupled contact lens mold sections together. The device generally includes an energy assembly configured to be effective to provide vibrational energy (e.g., ultrasonic energy), and a contact assembly operatively coupled to the energy assembly and effective to transfer the vibrational energy from the energy assembly to the assembled first and second mold sections such that fusion between the two occurs.

More specifically, the contact assembly can include an ultrasonic horn comprising a distal end configured to contact one or more discrete spaced apart portions in a circumferential region of one mold section surrounding a lens shaped cavity. For example, the distal end of the ultrasonic horn may comprise a plurality of distally projecting regions, such as about 3 or more than 3 distally projecting regions. In some embodiments of the invention, the distal end of the contact assembly can be described as having a somewhat "castellated" morphology in that the distal end has a configuration defined by a plurality of protruding regions (e.g., rectangular protruding regions) separated by recessed slots. The ultrasonic horn radiates ultrasonic energy into the mold assembly at an interface between the raised region and the mold assembly to which it is coupled, causing fusion at a plurality of discrete, spaced-apart locations between the mold sections within the mold assembly.

However, as discussed herein, other ultrasonic devices may have a continuous annular ring ultrasonic horn or an ultrasonic horn with a planar distal surface, and still achieve the desired discontinuous fusion between the mold portions due to the presence of the recesses described herein.

Each feature described herein and each combination of two or more such features is included within the scope of the present invention provided that the features included in such a combination are not mutually inconsistent. In addition, any feature or combination of features may be specifically excluded from any embodiment of the present invention.

These and other aspects of the present invention are apparent in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.

Drawings

FIG. 1 is a schematic exploded view showing a device suitable for fusing two contact lens mold sections together in accordance with the present invention.

Fig. 1A is a plan view of the distal end of the device shown in fig. 1.

FIG. 1B is a perspective view of a portion of a molding assembly aligned with the distal end of the device shown in FIGS. 1 and 1A in accordance with another aspect of the invention.

Fig. 1C is a plan view of an alternative distal end of the device shown in fig. 1.

FIG. 2 is a perspective view of a portion of the molding assembly shown in FIG. 1B.

FIG. 3 is a cross-sectional view of the molding assembly taken along line 3-3 of FIG. 2, showing the molding assembly prior to ultrasonic fusion of the mold sections.

FIG. 4 is a top plan view of one mold section of the molding assembly shown in FIG. 2.

FIG. 5 is a bottom plan view of the mold section shown in FIG. 4, showing the mold section including three longitudinally extending spaced apart projections.

FIG. 5A is a bottom plan view of a mold section according to another embodiment of the invention, wherein the mold section includes six longitudinally extending spaced apart projections.

Fig. 6 is a cross-sectional view similar to fig. 3 engaged with the distal end of the device shown in fig. 1 and 1 b.

FIG. 7 is a cross-sectional view similar to FIG. 6, showing the molding assembly after fusion with the device shown in FIGS. 1 and 1B.

FIG. 8 is a cross-sectional view of another molding assembly according to the present invention.

FIG. 9 is a cross-sectional view of another molding assembly according to the present invention.

Fig. 9A and 9B are top and cross-sectional views, respectively, of a molding assembly according to an embodiment of the invention, wherein the molding assembly includes a pair of mold sections each having three spaced apart projections providing a fused region between the mold sections, wherein the fused region is designated by the dashed line in fig. 9A.

10A and 10B are top and cross-sectional views, respectively, of a molding assembly according to another embodiment of the invention, wherein the molding assembly includes a pair of mold sections each having three spaced apart recessed regions that provide a gap between the fused regions between the mold sections, wherein the gap is designated by the dashed line in FIG. 10A.

FIG. 11 is a schematic view of a monomer dispensing system according to another aspect of the present invention.

Detailed Description

The present invention will generally be described herein in terms of methods and systems suitable for use in the manufacture of contact lenses, but it will be appreciated that, with appropriate modifications thereto, the methods and systems of the present invention are generally applicable to the manufacture of other types of lenses and other photopolymerizable articles. In a preferred embodiment, the present systems, methods, and components thereof are suitable for use in the manufacture of silicone hydrogel contact lenses or contact lenses comprising silicone hydrogel materials. For example, the present systems, methods, and components thereof may be particularly useful in the manufacture of extended-wear silicone hydrogel contact lenses and/or daily-wear silicone hydrogel contact lenses.

In a broad aspect of the present invention, there is provided a method of manufacturing a contact lens, the method generally comprising at least one of the following steps: providing a first mold section and a second mold section, each mold section comprising a lens-shaped surface, the first mold section and the second mold section configured to be coupled or placed together to form a lens-shaped cavity therebetween; providing a polymerizable composition in a lens-shaped cavity of one mold section; coupling or placing a first mold portion with a second mold portion; fusing the coupled first and second mold portions together; and polymerizing the polymerizable composition in the lens-shaped cavity to form the lens-shaped product.

Turning now to fig. 1, the methods of the present invention generally comprise providing a device suitable for fusing together coupled mold sections defining a contact lens shaped cavity. The device 10 generally includes an energy assembly 12 constructed and effective to provide vibrational energy, such as ultrasonic energy, and a contact assembly 14 operatively coupled to the energy assembly 12 and effective to transfer the vibrational energy from the energy assembly 12 to a pair of coupled mold sections forming a lens-shaped cavity. Preferably, the contact assembly 14 is configured to radiate vibrational energy into the coupled mold sections in a manner that causes fusion at discrete (preferably spaced apart) regions between the coupled mold sections.

The contact assembly 14 includes a horn 18 having a distal end configured to be couplable with or placeable on a contact lens mold assembly or a portion thereof. The horn 18 is preferably configured to effectively transmit ultrasonic energy into the pair of mold sections so as to cause fusion or welding of discrete, spaced-apart regions at the interface in the mold sections.

The device 10 may further include a power source 20 connected with the energy assembly 12. For example, power supply 20 may be a power supply that effectively converts 60Hz line current to a frequency in the range of about 20kHz to about 40kHz by utilizing a solid state power device. This high frequency electrical energy is supplied to the converter 22. The transducer 22 converts electrical energy into ultrasonic mechanical vibratory energy at a frequency of the converted electrical energy supply, typically about 20kHz to about 40 kHz.

The vibratory ultrasonic acoustic energy may then be transmitted through an amplitude adjustment device or booster 24. The booster 24 is a passive (i.e., passive) device that is used to adjust the output amplitude of the converter 22 before the output amplitude reaches the horn 18.

In at least one embodiment of the present invention, the horn 18 is configured to provide substantially discrete regions of vibrational energy, such as discrete regions of focused ultrasound waves. For example, the horn 18 of the contact assembly 14 may advantageously be configured to contact or more precisely acoustically couple only a portion of the circumferential region of the coupled mold sections.

For example, FIG. 1A shows a plan view of the distal end of the horn 18 shown in FIG. 1. In this embodiment, the contact assembly 14 includes a distal end 18a having protruding regions 18b separated by recessed regions 18 c. The area of acoustic coupling between the distal end 18a of the horn 18 and a pair of contact lens mold sections is not defined by a solid "ring" or circumferential zone of acoustic coupling.

FIG. 1B shows the distal end 18a of the contact assembly 14 aligned with a contact lens molding assembly 40 comprising a pair of coupled contact lens mold sections 42a and 42B of an embodiment of the present invention. The somewhat "castellated" configuration of the ultrasonic horn 18 is effective to fuse the mold sections 42a and 42b of the molding assembly 40 together at discrete, spaced-apart locations generally at the interface of the mold sections 42a and 42 b. The configuration of the distal end 18a of the horn 18 may be manufactured by machining the distal end of a conventional ultrasonic horn, such as one having a planar distal surface (e.g., a continuous ring horn) appropriately sized.

When the distal end of the horn 18 is placed in contact with the molding assembly 40 to be fused, only the distal end surface of the projection region 18b of the horn 18 is coupled with the molding assembly 40. Ultrasonic energy transmitted from the energy assembly (not shown in FIG. 1 b) into the horn 18 and molding assembly 40 will be focused in discrete spaced apart zones (e.g., located zones) within the molding assembly 40, typically when the zones are longitudinally aligned with the protruding zones 18b of the horn 18.

Although only three protrusions 18b are shown in fig. 1A, it should be understood that other embodiments of the present invention may include less than three protrusions or more than three protrusions. For example, in other embodiments of the present invention, the distal end of the horn may comprise a single non-annular protrusion, such as a protrusion having a substantially C-shaped cross-section, effective to form a non-annular fused region (e.g., a C-shaped fused region). As another example, an end view of another embodiment of the present invention having six projections 18b is shown in FIG. 1C (similar to the view of FIG. 1A).

In a preferred embodiment of the present invention, the molding assembly 40 and its mold sections 42a and 42b comprise polyethylene vinyl alcohol (EVOH) which is a material suitable for ultrasonic welding. It will be appreciated that other materials may be used to manufacture the lens mold sections of the present invention. For example, the other materials include polymeric materials, such as thermoplastic polymeric materials, amorphous polymeric materials, such as polystyrene, polycarbonate, acrylonitrile/butadiene/styrene compositions, cyclic olefin copolymers, acrylics, and polysulfones. Semi-crystalline resins such as acetals, polypropylenes, polyethylenes, nylons, polyethylene terephthalate, polyetheretherketones, other polyolefins, and liquid crystal polymers may also be bonded using ultrasonic energy.

Several factors can affect the weldability of vibrational energy (e.g., ultrasonic energy) to a material. One factor is the melting or softening temperature of the material of the mold sections, the higher the melting or softening temperature of the material, the more energy is required to produce the weld. The other is the hardness of the material to be welded, which generally affects the ability of the material to transfer energy to the joint interface. Generally, harder materials have better transport capabilities.

While the present invention is generally described herein as utilizing vibratory energy, and more specifically ultrasonic energy, to fuse or weld contact lens mold sections together, a variety of other directed energy techniques and apparatus may alternatively or additionally be employed.

For example, linear vibration welding and suitable mold materials may be used to join the mold sections together. Linear vibration welding is accomplished by an apparatus in which the mold sections are held together with a suitable force, one section being held stationary while the other vibrates in a direction perpendicular to the direction of the contact force. The friction generated by the vibration melts or softens the material at the point of contact and the parts fuse together. Typical frequencies for linear vibration welding transmitters are 200Hz to 300 Hz. Preferred materials for making mold sections suitable for linear vibration welding include polyamides, polystyrenes or polystyrene-containing compositions.

Another method of joining mold sections of suitable material is hot plate welding, which uses an apparatus containing a heated platen with controlled temperature and heat transfer, where one section to be formed is placed on or near the heated platen emitter. The surfaces of the mold sections are softened or melted and then quickly forced together under compression after removal from the platen. Preferred materials for hot plate welding and suitable for use as contact lens mold sections include polyethylene, polypropylene and polyvinyl chloride.

Another method and apparatus within the scope of the present invention is radio frequency welding wherein a mold portion of suitable material is placed within the field of an emitter that generates electromagnetic energy at frequencies in the range of about 1MHz to about 200 MHz. The electromagnetic energy increases the molecular vibration of certain molecules in the material to the point of generating sufficient heat to soften or melt the mold portions. The mold sections are clamped together under pressure and the energy delivered is controlled to a particular depth or to accommodate a particular material used as part of the lens mold sections to fuse the mold sections together. A preferred material suitable for making the lens mold sections for radio frequency welding is polyvinyl chloride.

Another method suitable for welding lens mold sections is an apparatus that emits and focuses infrared energy in discrete zones within a common plane, thereby melting or softening discrete, spaced-apart zones within a particular plane of material rather than softening the entire planar mold section. Focused infrared welding softens or melts the lens mold material with radiant energy. The mold sections are clamped under pressure until fusion when the radiant energy source is in place or shortly after its removal. Preferred ophthalmic mold materials suitable for focused infrared welding include polyethylene, polypropylene, polyvinyl chloride, polystyrene, or polystyrene-containing compositions.

In another aspect of the present invention, a molding assembly 40 is provided that is suitable for use in the manufacture of lenses, such as silicone hydrogel contact lenses. In yet another related aspect of the invention, a mold section is provided that upon coupling with another mold section forms a mold assembly that can be fused together using ultrasonic energy.

For example, the molding assembly 40 shown in FIG. 1B and more clearly in FIGS. 2 and 3 generally includes a first mold portion 42a having a convex lens shaped region 46 and a second mold portion 42B having a concave lens shaped region 48. The convex lens shaped area 46 is a negative of the front surface of the lens and the concave lens shaped area 48 is a negative of the back surface of the lens. The two mold portions 42a and 42b may be substantially identical in structure and form before they are welded together. The lens-shaped zone may also be referred to as a lens cup of the mold section.

Fig. 2 shows the upper surface of the molding assembly 40. Within the molding assembly 40, the first mold section 42a includes a flange region 49 that circumscribes the monomer-filled lens-shaped cavity. It is this flange region 49 that is preferably coupled to or positioned on the ultrasonic horn during fusion of mold portions 42a and 42 b. As shown most clearly in fig. 3, when the first and second mold sections 42a, 42b are coupled, the convex lens shaped regions 46 and the concave lens shaped regions 48 of the first and second mold sections 42a, 48 define a monomer-filled lens shaped cavity 50.

Fig. 4 and 5 show top and bottom views, respectively, of mold portion 42 a. It should be appreciated that fig. 4 and 5 may refer to mold portion 42b, as in the embodiment shown, mold portion 42a and mold portion 42b are substantially identical to one another prior to fusing.

The mold section 42a includes a negative impression of the back surface of the lens and a negative impression of the front surface of the lens. For example, mold portion 42a includes a concave lens defining surface 48' (shown in fig. 4) substantially opposite a convex lens defining surface 46 (shown in fig. 5).

The flange region 49 circumscribing the lens defining surfaces 46 and 48 'generally includes a first flange surface 58 circumscribing and positioned radially outward from the concave lens defining surface 48' (see fig. 4). The flange region 49 further includes a substantially opposing second flange surface 59 (see fig. 5) circumscribing and positioned radially outward from the convex lens defining surface 46. In the illustrated embodiment, the first flange surface 58 can be understood to be an upper or top surface of the mold portion, and the second flange surface 59 can be understood to be a lower or bottom surface of the mold portion.

In some embodiments, at least one of the first flange surface 58 and the second flange surface 59 includes longitudinally extending projections, such as shown in fig. 1B, for example, one or more longitudinally extending projections, or longitudinally extending projections that are substantially annular and circumscribe the lens shaped surface.

For example, as shown in fig. 1B, the longitudinally extending projections may include at least three individual spaced apart projections 60 (hereinafter sometimes referred to as "pips 60"). In this particular embodiment, three pips 60 are provided, which are longitudinally extending projections located radially outward from only a portion of the convex lens defining surface 48. As shown in FIG. 5, the pip 60 is located on the second flange surface 59 circumscribing the convex lens defining surface 46. The pips 60 are spaced apart and define regions of relief (rased relief) relative to radial surface portions between the pips 60. While the pips 60 are shown as being generally circular in structure, the pips may alternatively comprise linear regions of relief or shapes other than circular. For example, the pip may include arcuate segments, each arcuate segment partially circumscribing the lens-shaped surface. Many other shapes, sizes and numbers of pips 60 may be provided, wherein the pips 60 together do not define the entire circumference circumscribing the lens shaped surface, e.g., the pips do not define a continuous annular ring circumscribing the lens shaped surface.

The pips 60 or other longitudinally extending projections may have a height, measured from the flange surface between the pips 60, of between about 0.2mm and about 1.2mm, preferably about 0.6 mm. In the illustrated embodiment of the invention, the three pips 60 are substantially circumferentially spaced equidistant from each other by about 120 °.

Turning briefly back to FIG. 2, the molding assembly 40 may include a pair of "common mold sections" because the mold sections 42a and 42b are substantially identical. Each mold section 42a and 42b includes a plurality of pips 60, wherein when the mold sections are assembled, the pips 60 of the first mold section 42a are substantially aligned with the pips 60 of the second mold section 42 b.

Fig. 5A illustrates another mold section 140 of the present invention similar to mold section 40, except that the mold section 140 has six pips 160 (instead of three) located radially outward from the lens forming surface 154. This mold section 140 can be effectively fused in six regions defined by pips 160 using an ultrasonic horn according to the present invention having a distal end as shown in fig. 1c and described elsewhere herein.

It should be appreciated that mold portions according to other embodiments of the present invention may have any number of pips having any suitable height, width and shape. For example, the present invention can provide mold portions having less than three pips, more than three pips (e.g., four pips or more).

Advantageously, each pip 60 is constructed and positioned to effectively act as a discrete or localized fusion zone between mold sections 42a and 42b when ultrasonic energy is applied thereto.

The objects, aspects and advantages of the construction of the present invention will be more clearly understood with reference to fig. 1, 1B and 6. As shown, the castellated ultrasonic horn 18 of the apparatus 10 is configured to releasably fuse mold sections of a lens molding assembly, such as the mold sections 42a and 42b of the molding assembly 40, together. The ultrasonic horn 18 may be sized and configured such that the output region 18a of the horn 18 mates with the peripheral portion 58 of the mold section 42 a. For example, the ultrasonic horn 18 may have an outer diameter substantially equal to the outer diameter of each mold section 42a and 42b, such as a diameter of about 20 mm. More preferably, the output region 18a of the horn 18 is sized and configured such that the protruding region 18b will be substantially aligned with the mold section projection 60.

The invention also provides methods of manufacturing contact lenses. For example, the method of the present invention generally comprises the steps of providing a first mold section having a convex lens shaped surface and a flange zone positioned circumferentially around the lens shaped surface and a second mold section having a concave lens shaped surface and a flange zone positioned circumferentially around the lens shaped surface. At least one of the first mold section and the second mold section includes a projection, for example, and a substantially annular projection circumscribing the lens shaped region or a plurality of spaced apart projections such as described elsewhere herein. The method further comprises providing a monomer composition in the concave lens shaped surface of the second mold section and assembling the mold sections together such that at least a portion of the flange region of one mold section is in substantial contact with at least a portion of the flange region of the other mold section.

More specifically, the first mold portion and the second mold portion are coupled together such that the one or more longitudinally extending projections are located between the mold portions and provide a point of contact between the mold portions. The method further includes applying vibrational energy (e.g., ultrasonic energy) to one or more discrete regions of the coupled first and second mold sections that include at least a portion of the one or more projections to soften and fuse the first and second mold sections together in discrete spaced-apart regions, preferably in a fused region that does not combine to define a complete annular fused region surrounding the lens-shaped cavity. The method further can further include polymerizing the monomer component in the lens shaped cavity to form the lens product.

For example, referring now specifically to fig. 1B and 6, a molding assembly 40 is provided wherein the mold assembly includes two similar or identical "universal" mold sections each including a male mold surface and a female mold surface. Each mold section 42a and 42b includes three equidistantly spaced projections or pips 60, respectively. In this embodiment, the ultrasonic horn 18 is placed on the assembly 40 such that the protruding region 18b of the horn 18 is aligned with the pip 60. The mold portion 42a adjacent the ultrasonic horn 18 vibrates due to the acoustic energy emitted by the ultrasonic horn 18. The other mold section 42b is held in a relatively fixed position such that relative movement of the mold sections 42a and 42b at the interface occurs at the pip 60. The mold assembly may be restrained in any suitable manner during the welding process. The vibrational energy at the discrete regions of the molding assembly 40 comprising the pips 60 is converted by friction into heat, which in turn softens and deforms the plastic material of the assembled mold sections, thereby softening the pips 60.

Turning now specifically to fig. 1B, it can be appreciated that the regions 66 located between the pips 60 (generally aligned with the recessed regions 18c of the horn 18) are not exposed to any significant level of vibrational energy, and therefore these regions 66 do not fuse together, or at least do not fuse together to any significant extent.

The acoustic vibration may be stopped when the softened state is reached at the mold section projections 60. Pressure may be temporarily maintained on the mold assembly (in the direction of arrow 70 of fig. 1B and 6) while the polymeric material solidifies to create molecular bonds between the mold portions 42a and 42B at discrete, spaced-apart regions. The whole cycle can be completed in a very short time. For example, in some embodiments of the present invention, the fusing between the portions is completed from about 0.3 seconds to about 1 second. The strength of the bond in the discrete regions is about that of the parent material, particularly since for thermoplastic materials, melting and subsequent solidification of the material does not substantially affect its mechanical properties.

It will be readily appreciated by those skilled in the ophthalmic art that it is important that the mold sections 42a and 42b be properly aligned with one another.

Turning now to FIG. 7, a molding assembly 40 including fused mold sections 42a and 42b is shown. The molten pip 60' of mold portion 42a has solidified and provided discrete, spaced-apart fused regions between mold portions 42a and 42 b.

The fill cavity 50 between the fused mold portions 42a and 42b is preferably unaltered by the fusing process. It is generally undesirable to cause any deformation of the monomer-filled cavity 50. The protrusions 74 of mold section 42b are brought into intimate contact with mold section 42a to form the lens edge without deformation or fusion of the protrusions 74. As shown, another projection (e.g., an annular projection 76) is also provided that is positioned radially outward from the projection 74. In some embodiments of the invention, this structure provides an interference fit against the structure 78 of the adjoining mold section 42a, and/or is adapted to promote proper alignment of the mold sections on their assembly. The annular protrusion 76 stabilizes the position of the mold portions 42a and 42b relative to each other.

Advantageously, constructing the mold assembly of the present invention provides a way to ultrasonically fuse the mold sections 42a and 42b without causing any significant negative effects that may be caused by the ultrasonic energy transmitted to the monomer-filled cavity 50. For example, it may be desirable to apply vibrational energy at a location remote from the cavity 50 so as not to cause cavitation of the polymerizable composition. Advantageously, projections 74 and 76 define a snap-retention region 82 between pip 60' and filled cavity 50. A further description of another suitable structural arrangement of the fast retention regions is provided in U.S. patent No. 6,405,993 to Morris.

Fig. 8 and 9 show alternative molding assemblies 240 and 340, respectively. These molding assemblies 240 and 340 are substantially similar to molding assembly 40, with the primary differences being the shape of the pips and the location of the pips. More specifically, the molding assembly 240 includes mold portions 242a and 242b that are substantially identical to one another, and includes a tapered or conical pip 260 'in that the pip 260' has a first end that is secured directly to the mold portion body 242a and a second end that extends longitudinally from the first end, and the first end has a larger cross-section than at or near the second end. The molding assembly 340 includes mold portions 342a and 342b, the mold portions 342a and 342b being substantially identical to one another and including a tapered or conical pip 360 'similar to the pip 260' but positioned further inward from the outer edge 90 of the mold portion 342 a.

One advantage of the molding assembly 340 is that the female side of the upper mold portion 342a has a peripheral area above the pip 360' that can more easily accommodate the castellated horn 18.

The polymerizable composition may be supplied into the cavity through a conventional two-part sprue (sprue) and a riser, or the parts may be joined or held in place under vacuum and the monomer injected into the interface. The polymerizable composition can be dispensed onto the concave lens shaped female mold surface using a pipette or syringe. The mold sections 42b may be supplied with a monomer mixture, such as a silicone hydrogel-forming mixture, or any monomer mixture useful for contact lenses or any implantable lens device, such as a gas permeable conventional hydrogel material, and then the mold sections 42a and 42b welded or fused as described elsewhere herein. As is known in the art, the polymerizable composition is polymerized by a suitable method, such as exposure to ultraviolet light or thermal curing for a suitable duration.

Another molding assembly suitable for use in the manufacture of contact lenses in accordance with another aspect of the invention is shown generally at 140 in the plan view of FIG. 9a and in the cross-section of FIG. 9 b. The mold assembly 140 is substantially identical to the mold assembly 40, unless otherwise specified herein. As with the mold assembly 40, the mold assembly 140 includes two "universal" mold sections 152a and 152 b. Each mold section 152a and 152b includes an optical zone 158a and 158b, respectively, having a convex male mold surface and a substantially opposing concave female mold surface. Each mold section 152a and 152b includes a flange zone 161a and 161b circumscribing the optical zone 158a and 158b, respectively.

The primary difference between mold assembly 140 and mold section 40 is that universal mold sections 152a and 152b include a substantially annular, longitudinally extending projection 165 suitable for fusing, rather than a plurality of spaced apart pips 60. As shown, annular projection 165b of mold portion 152b is fused with a portion of the flange region of mold portion 152b at discrete spaced apart locations, such as those shown (in phantom in fig. 9 a), as fused or welded regions 171 along substantially annular projection 165 b. Referring also to fig. 9B, welded portions 171 along projection 165B are separated by unfused or welded regions 173. These areas 173, which are not fused or welded, are defined by surface portions of the projections 165b that are in contact with or opposite but not in conjunction with corresponding surface portions of the flange area 161a of the other mold portion 152 a. The fused regions 171 are preferably obtained by using the contact assembly 14 of the device 10 to create discrete fused regions. The contact assembly 14 of the device 10 having castellations (shown most clearly in fig. 1 b) is shown and described elsewhere herein.

FIGS. 10A and 10B illustrate one particular example of a mold assembly. In this embodiment, the features of the mold assembly 140 are similar to the embodiment of fig. 9A and 9B, with the exception that region 171 (designated by dashed lines) is a gap or region that is not welded or fused, and region 173 is welded. In this embodiment, the flange surface contains an annular ridge 165 circumscribing the lens shaped cavity on the upper surface of the flange. The lower surface of the flange contains a plurality of recesses 171 that extend into the flange region. When the first mold portion is positioned on the second mold portion, the lower surface of the flange of the first mold portion contacts the upper surface of the annular ridge. The annular ridge facilitates stacking of the lens cups prior to and during formation of the mold assembly. The annular ridge may also be effective to reduce refraction (prism) of a lens-forming material, such as a monomer composition, during formation of the mold assembly.

The ultrasonic horn may be positioned to contact an upper surface (such as a flange) of the first mold portion. The ultrasonic horn transmits ultrasonic energy and fuses the first mold section to the second mold section. The fusion of the two mold sections is discontinuous around the lens cup or flange region of the mold sections. This discontinuous fusion may be achieved using a conventional ultrasonic horn having a substantially planar distal surface (such as a continuous loop ultrasonic horn) or may be achieved using the castellated ultrasonic horn disclosed herein. The fusing may occur at the outer edge of the ridge, or it may occur at the upper surface of the ridge and comprise a portion of the outer edge, or the fusing may comprise a portion of the inner edge of the ridge.

Such discontinuous fusion of the first mold section and the second mold section can provide substantial benefits over other types of mold assemblies, such as mold assemblies having a continuous fusion ring around the lens cup. For example, where little haze, craters, or bubbles form in the lens cup, an ultrasonic horn may be used to fuse the mold sections of the present invention with recesses in the flange surface.

Although the fusion of the two mold portions may not be continuous, the two mold portions are still firmly secured to each other so that the mold portions do not easily separate during other processing steps. Further, as discussed herein, in embodiments where ultrasonic energy is not used to attach one mold section to another mold section, the melt zone or contact zone may be continuous around the lens cup. For example, if a first mold portion engages a second mold portion by an interference fit between the two mold portions, the contact may be a continuous contact zone. Similarly, if the first and second mold portions are attached to each other by a plate or other clamping means, the contact zone may be a continuous structure.

Turning now to fig. 11, the present invention further provides an apparatus 510 suitable for providing a monomer composition, such as a silicone hydrogel lens precursor material, in a contact lens shaped cavity of a contact lens molding assembly 514. The contact lens shaped cavity is preferably a concave lens shaped cavity such as the mold sections described and shown elsewhere herein according to other aspects of the invention. It should be appreciated that the apparatus 510 may also be used to provide a monomer composition to conventional contact lens molds.

The apparatus 510 generally includes a dispensing unit 520 having a dispensing tip 522 sized and configured to dispense an amount of the monomer composition onto a contact lens shaped surface of a mold section and a syringe assembly 530 for directing the monomer composition into the dispensing unit 520. As shown, the syringe assembly 530 is directly coupled with the dispensing unit 520, for example, with a fitting 532. Fitting 536 may include an elbow joint or similar coupler configured to facilitate coupling and decoupling syringe assembly 530 from dispensing unit 520.

The dispensing unit 520 may comprise a pneumatically operated diaphragm valve.

In a particular example, the syringe assembly 530 includes a barrel 540 and a plunger 542 inserted therein. To dispense, for example, a photoinitiating monomer to make silicone hydrogel lenses, the syringe assembly 530 is preferably a UV blocking or filtering syringe, such as a syringe assembly that blocks about 95% to 100% UV radiation. In one embodiment, the barrel 540 of the syringe assembly 530 contains about 55cc of the monomer composition 544. When the dispensed monomer composition is not a UV reactant, a non-UV blocking syringe assembly may be used.

Prior to its use, syringe assembly 530 is filled with the monomer composition while piston 542 is in the fully inserted position to ensure that no air is trapped in barrel 540. The syringe assembly 530 and cap 548 are designed to prevent contamination of the monomer composition by particles and the like and to prevent oxygen uptake. After filling the can 540, the lid 548 is then placed on the can 540. The cap 548 is locked to the barrel using a luer lock mechanism. The filling syringe assembly 530 may then be stored until needed.

It is important that the monomer composition not come into contact with air prior to dispensing into the mold assembly, as contact with air can create air bubbles/voids in the final contact lens product. Accordingly, it is desirable to purge the monomer composition, for example, using nitrogen or other inert gas, to exclude oxygen from the monomer composition prior to deposition of the composition in the syringe assembly 530. The filled syringe assembly is stored in a water jacket effective to maintain the monomer composition at a desirable temperature of between about 4 ℃ and about 36 ℃. In certain embodiments, the monomer mixture may be maintained at a substantially constant temperature, such as room temperature, for example, between about 20 ℃ and about 25 ℃, for example, between 20 ℃ and 22 ℃.

In a specific example, the apparatus 510 comprises an "EFD CLT" valve dispensing unit having part number 752V-CLT-E and an amber 55cc syringe and piston set having part number 5113LBP-B, both manufactured by EFD Inc., EastProvidence, RI 02914 USA. Suitable components are also available from a company known as PPG Industries, such as a light blue 55cc syringe part No. 365523 and a piston part No. 363035. Both versions are UV blocking and have the same luer lock attachment.

In a particular example, the dispensing unit 520 contains an amount of monomer composition sufficient to produce about 3 contact lenses. Piston 542 is pneumatically operated using air pressure line 552. The dispensing unit 520 is connected to an air pressure conduit 554.

The apparatus 510 includes a valve controller 558 configured to control the valve open time of one and preferably both of the syringe assembly 530 and the dispensing unit 520. The valve controller 558 is preferably microprocessor-based and programmed to reliably and accurately open and close the valves of the apparatus 510. Suitable valve controllers are sold under the name "7000 valnematecontroller" and are available from EFD, inc. Alternatively, separate valve controllers may be provided to control the syringe assembly 530 and the dispensing unit 520.

After dispensing one or more increments of the monomer composition through the dispensing tip 522, the dispensing unit 520 draws more monomer composition from the syringe assembly 530 through the elbow joint 532. When all of the monomer composition 544 in syringe barrel 540 has been spent, syringe assembly 530 is disconnected from dispense unit 520 and replaced with a new monomer-filled syringe assembly. This can be accomplished by shutting off the air line 552 feeding the cap 548 on the syringe assembly 530 and removing the cap 548. The syringe assembly 530 is then simply unscrewed off the elbow coupler 532 and a new pre-filled syringe assembly 530 with a plunger already in place is connected to the elbow coupler 532. The cap 548 is then placed over the new syringe assembly and locked. The air is then released into the conduit 552. This conversion takes only a few seconds to complete.

The apparatus 510 can be mounted, such as by means of a carriage 566, to remain stationary relative to a moving table 568 or conveyor belt carrying the mold assembly portions 514 to be filled. The operation of the entire apparatus 510 and the translation stage 568 may be controlled automatically.

In view of the above disclosure, one example of a method of filling a mold section and forming a mold assembly for manufacturing a contact lens can be described as follows. The following is provided by way of example only and should not be construed to limit the invention in any way.

A cassette containing 8 stacks of 64 mold sections is transferred from a form/demold module into the filling module or system of the invention described herein.

The cassette is placed on the frame assembly. The frame assembly is configured to direct the mold sections toward the plate surface. More specifically, the frame assembly includes components that incrementally move the mold sections so that the upper mold sections in each stack are located in substantially the same plane or at the same height. By placing the uppermost mold sections at the same height or in the same plane, the mold sections can be removed and transferred using a robotic plate, 8 at a time.

In an embodiment, the frame assembly includes one or more offset members effective to move the stack of mold sections. For example, the frame assembly may include a plurality of spring-loaded cylinders or pneumatically controlled cylinders. The biasing member forces the mold sections through the holes in the plate. In the illustrated embodiment, the mold sections have extension members or panhandle extending radially outward from the lens cavity or flange. The extension member points toward the center of the four (2 x 2) arrays of lens mold sections. The mold sections are forced or pressed against a rod or other structure that extends over a portion of the holes of the plate. The bars act as stops for the mold portions that are forced toward the plate surface.

A robotic arm located between the two sets of four mold sections moves between the extension members such that the extension members are oriented off-center of the array. The robot controls the vacuum device to pick up the mold sections and transfer the individual mold sections to the nesting equipment. The nest of mold-containing portions is transferred to a dispensing apparatus as described herein. Air is used to drive the syringe plunger and dispense the monomer composition into the concave lens cavity of the mold section. The volume of the dispensed monomer composition is typically from about 20 μ L to about 50 μ L per mold section.

The nest with the filled mold sections is moved to a station where a second unfilled mold section is placed on top of the first filled mold section as discussed herein to form a mold assembly containing a lens precursor material. The nest with the mold assembly is moved to a welding station where an ultrasonic delivery device uses 40kHz ultrasonic energy to fuse the two mold sections together. During welding, the excess monomer mixture may be removed from the mold sections and discarded.

The mold assemblies (fused mold sections) are then placed on a loading tray having a plurality of apertures for receiving the lens cups of the lens mold assemblies. The holes are offset from row to row so that the extension members do not interfere with each other on the tray. Each tray can accommodate 256 mold assemblies. Other configurations are possible.

The above-described method may include one or more authentication or tracking steps, such as scanning an identifier provided on an extension member of a mold portion. The method may also include one or more inspection steps, such as inspecting for bubbles in the monomer composition prior to fusing or closing the mold portions.

The above method may also include the step of dipping or contacting the second mold section with the monomer composition prior to placing the second mold section on the first mold section containing the monomer composition in the lens cup.

The tray of mold assemblies can then be transferred to a curing station where the polymerizable composition is polymerized or cured, such as by exposing the mold assemblies to ultraviolet light.

Certain aspects and advantages of the present invention may be more clearly understood and/or appreciated with reference to the following commonly owned U.S. patent applications, filed on even date herewith, the disclosure of each of which is hereby incorporated by reference in its entirety: U.S. patent application No. 11/200,848 entitled Contact lenses Molds and Systems and Methods for Producing Same and attorney docket No. D-4124; U.S. patent application No. 11/200,644 entitled "Systems and Methods for producing Contact Lenses from a Polymerizable Composition" and attorney docket No. D-4126; U.S. patent application No. 11/201,410 entitled "Systems and Methods for Removing letters patents Molds" and attorney docket No. D-4127; U.S. patent application No. 11/200,863 entitled "Contact Lens Extraction/Hydration Systems and Methods of processing fluid used therein" and attorney docket No. D-4128; U.S. patent application No. 11/200,862 entitled "contact lenses Package" and attorney docket No. D-4129; U.S. patent application No. 60/707,029 entitled "Compositions and Methods for Producing silicon Hydrogel Contact Lenses" and attorney docket No. D-4153P and U.S. patent application No. 11/201,409 entitled "Systems and Methods for Producing silicon Hydrogel Contact Lenses" and attorney docket No. D-4154.

A number of publications and patents have been cited above. Each of the cited publications and patents is incorporated herein by reference in its entirety.

Although certain preferred embodiments have been described herein, it is to be understood that the invention is not limited thereto and that modifications and variations will be apparent to those skilled in the art.

Claims (7)

1. A method of manufacturing a contact lens, comprising:

providing a plurality of first mold sections and second mold sections, each mold section comprising a lens shaped surface and a flange region circumscribing the lens shaped surface, each first mold section comprising an annular circumferential projection extending longitudinally from the flange region, and a plurality of circumferential recessed regions not completely surrounding the lens shaped surface of the first mold section and extending longitudinally into the flange region toward the annular projection, wherein the first mold sections are located in a cassette comprising a stack of mold sections;

placing the cassette within a frame assembly configured such that the uppermost mold portions in each stack lie in the same plane;

transferring the first and second mold portions to a nesting device;

dispensing a polymerizable composition on the lens-shaped surface of the first mold section located in the nesting apparatus;

coupling the first and second mold sections together such that each of the coupled mold sections defines a lens-shaped cavity between the lens-shaped surface of one of the mold sections and the lens-shaped surface of the other of the mold sections, and the flange region of the first mold section is in contact with the flange region of the second mold section;

fusing the coupled mold sections to form a plurality of circumferential fused regions between the flange regions, the plurality of circumferential fused regions not completely surrounding the lens-shaped surface of the coupled mold sections; and

polymerizing the polymerizable composition in the lens-shaped cavity.

2. The method of claim 1, wherein the fusing step comprises applying energy to the coupled first and second mold portions.

3. The method of claim 2, wherein the energy is ultrasonic energy.

4. The method of claim 1, wherein the first mold portion and the second mold portion are identically configured.

5. A method according to claim 2, wherein the fusing step is carried out such that the first and second mould parts are fused together along a region of contact of the abutting flange surfaces, and such that the regions of contact are spaced apart by a gap defined by the plurality of circumferentially recessed regions in one of the flange regions.

6. A contact lens mold assembly, comprising:

a first mold portion having: a lens-shaped surface that is a negative of the anterior or posterior surface of the contact lens; a flange region circumscribing the lens-shaped surface; an annular circumferential projection on the flange region and circumscribing the lens-shaped surface; and a plurality of circumferential recessed regions that do not completely encircle the lens-shaped surface of the first mold section and extend longitudinally into the flange region;

a second mold section of the same construction as the first mold section, the second mold section being fused to the first mold section at a plurality of circumferential fused regions between the flange regions of the first and second mold sections that do not completely surround the lens shaped surface of the first mold section and are not fused to the first mold section at the plurality of circumferential recessed regions; and

a polymerizable composition on the lens shaped surface.

7. The contact lens mold assembly of claim 6, wherein the plurality of recessed zones of each of the first mold section and the second mold section extend longitudinally into the flange zone in a direction toward the annular, circumferential projection.