HK1121110B - Contact lens molds and systems and methods for producing same - Google Patents

Abstract

Contact lens molds and systems and methods for producing contact lens molds are described. The contact lens mold sections include two optical quality surfaces, a flange circumscribing at least a portion of the two optical quality surfaces, and an elongate member extending from the flange. Two mold sections can contact one another to form a mold assembly having a contact lens shaped cavity. The mold sections are structured to form a contact lens having an edge that does not require further physical modification before placement on an eye. Systems and methods are described which direct a molten polymeric material into cavities corresponding to the mold sections.

Description

Contact lens molds and systems and methods for making same

This application claims priority to U.S. application No. 11/200,848, filed on 8/9/2005, and is hereby incorporated by reference in its entirety.

Technical Field

The present invention relates generally to the manufacture of contact lenses, and more specifically to molds used in the manufacture of contact lenses and systems and methods of manufacturing contact lens molds.

Background

One method of manufacturing lenses, such as intraocular lenses and contact lenses, is by cast molding. Cast molding of contact lenses is well known. Reference is made, for example, to Appleton et al, U.S. patent No. 5,466,147, Morris, U.S. patent No. 6,405,993, Dean, U.S. patent No. 6,431,706, and Dean, U.S. patent No. 6,732,993.

Mold assemblies for manufacturing a single contact lens typically include a female mold section having a concave optical surface defining the front surface of the lens to be manufactured and a male mold section having a convex optical surface defining the back surface of the lens to be manufactured. When the individual 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.

A contact lens precursor material (e.g., a curable mixture of polymerizable monomers) is placed or deposited in the lens shaped cavity, or more specifically, the lens precursor material is placed in contact with the concave surface of the first mold section and the second mold section is placed on the first mold section such that the convex surface of the second mold section contacts the lens precursor material and maintains the lens precursor material in the lens shaped cavity. The lens precursor material is cured in the mold assembly to form a contact lens. The contact lens is removed from the mold section and further processed and ultimately packaged for consumer use.

The male and female mold sections themselves used in the above-mentioned contact lens manufacturing methods are typically formed by using an injection molding process. These mold sections may be molded from thermoplastic materials such as polystyrene or polypropylene.

U.S. patent No. 6,039,899 to Martin et al discloses a method and apparatus for automatically manufacturing contact lens blanks at high speeds. The apparatus includes an injection molding station for manufacturing contact lens mold sections for forming a blank.

EP 1136222 a1 discloses a method of manufacturing a contact lens in which resin molds are formed in a mold assembly, then the resin molds are filled with a contact lens molding material, and the filled resin molds are assembled to form a contact lens between the resin molds.

EP 1352736 a1 discloses a contact lens mold assembly comprising a plurality of identical stackable contact lens molds.

U.S. Pat. No. 4,565,348 to Larsen discloses another prior art method of making ophthalmic molds. According to this method, an array of contact lenses is formed using an array of molding surfaces carried on a polystyrene frame. One mold frame carries a 2 x 4 array of female front or female mold halves and the other mold frame carries a 2 x 4 array of male base or male mold halves.

Other patents and publications disclosing methods and/or apparatus for making molds used in the manufacture of ophthalmic lenses include U.S. patent application publication No. US 2003/0203066 a1 to Lust et al, U.S. patent No. 6,592,356 to Lust et al, U.S. patent No. 5,540,410 to Lust et al, and U.S. patent No. 6,180,032 to panell, Sr. et al.

While the foregoing methods and apparatus have increased the speed and efficiency of contact lens manufacture, there remains a need for even more effective, efficient methods and systems that meet the high demands currently placed on contact lenses.

Disclosure of Invention

Novel contact lens molds, mold assemblies, and systems and methods of manufacturing contact lens mold assemblies are disclosed. The apparatus and systems of the present invention are particularly useful for facilitating high-speed manufacture of high-quality contact lenses, such as, but not limited to, soft hydrophilic silicon-based contact lenses. More specifically, the mold sections, mold assemblies, molding systems and methods of the present invention are useful for the manufacture of silicone hydrogel contact lenses or contact lenses comprising silicone hydrogel materials, including daily wear lenses and extended or continuous wear lenses (e.g., contact lenses that can be worn continuously on the eye for days or weeks (e.g., about 30 days)).

The present mold assemblies comprise contact lens mold sections, each section comprising a lens-defining surface, which when assembled together define a contact lens shaped cavity therebetween. The mold sections themselves may be molded using injection molding techniques. As discussed herein, the mold assembly is formed by placing two mold sections in contact with each other to form a contact lens shaped cavity.

A first aspect of the invention provides a contact lens mold section comprising: a lens-defining zone having a first lens-defining surface presenting a master of an optically-functioning front surface of a contact lens, a second lens-defining surface substantially opposing the master presenting an optically-functioning back surface of a contact lens, a flange zone surrounding the first and second lens-defining surfaces, and an elongated zone extending substantially radially outward from the flange zone, the elongated zone including a first portion having a substantially uniform width and a second portion having a diverging width, the second portion being adjacent to the flange zone and thinner than the first portion of the elongated zone; wherein said first lens defining surface and said second lens defining surface are on a single contact lens mold section and the length of said elongated region is at least as large as the diameter of said first lens defining surface.

A second aspect of the present invention is to provide a mold assembly comprising a first mold portion and a second mold portion substantially identical to the first mold portion. The first mold section comprising a lens defining region having a first lens defining surface presenting a negative of the optical quality front surface of the contact lens, a substantially opposing second lens defining surface presenting a negative of the optical quality back surface of the contact lens, a flange region surrounding the first lens defining surface and the second lens defining surface, and an elongated region, extending generally radially outward from the flange zone, the elongated zone including a first portion having a generally uniform width and a second portion having a diverging width, the second portion being adjacent the flange zone and thinner than the first portion of the elongated zone, wherein the first lens defining surface and the second lens defining surface are located on a single first mold portion, and wherein the length of the elongate region is at least as large as the diameter of the first lens-defining surface. The second mold portion is coupled with the first mold portion to define a lens-shaped cavity between a first lens-defining surface of the first mold portion and a second lens-defining surface of the second mold portion.

A third aspect of the invention is to provide a method of manufacturing a contact lens mold section, the method comprising: directing a molten thermoplastic material into a single mold cavity, wherein the mold cavity comprises a first optical performance insert surface and an opposing second optical performance insert surface; a mold flange defining region surrounding the first and second optical performance insert surfaces, the first and second optical performance insert surfaces defining first and second generally opposed lens defining surfaces of a contact lens mold section; and an elongate channel extending generally radially outwardly from the die flange-defining zone, the elongate channel comprising a first portion having a generally uniform width and a second portion having a diverging width, the second portion abutting the die flange-defining zone and being thinner than the first portion of the elongate channel. Wherein the length of the elongate channel is at least as large as the diameter of the first lens-defining surface.

A fourth aspect of the invention provides a method of manufacturing a plurality of contact lenses having different specifications, the method comprising: a plurality of single-piece contact lens mold sections are manufactured in a number of mold cavities, various combinations of the single-piece contact lens mold sections being used to produce a plurality of contact lenses having a plurality of different specifications, wherein the number of different specifications for the plurality of contact lenses is equal to the square of the number of mold cavities. Wherein each one-piece contact lens mold section comprises a lens defining region having a first lens defining surface presenting a negative of the optical quality anterior surface of the contact lens and having a first radius of curvature, a second, substantially opposed lens defining surface presenting a negative of the optical quality posterior surface of the contact lens and having a second radius of curvature, a flange region surrounding the first lens defining surface and the second lens defining surface; and an elongate region extending generally radially outward from said flange region, wherein a length of said elongate region is at least as large as a diameter of said first lens-defining surface.

Advantageously, a mold assembly according to the present invention may comprise a universal mold section. As used herein, "universal mold section" refers to a mold section comprising a convex lens defining surface and a generally opposing concave lens defining surface, both surfaces effective to form an optically acceptable surface of a contact lens. Thus, each mold section can be understood to have two optically acceptable surfaces or two surfaces configured to form a single contact lens having optically acceptable anterior and posterior surfaces. When two of the universal mold sections are assembled together, a lens shaped cavity is defined between the convex lens defining surface of one mold section (e.g., a first mold section) and the concave lens defining surface of the other mold section (e.g., a second mold section). Each lens defining surface is an optical quality or an optically acceptable surface, meaning that each lens defining surface has a smoothness effective to impart a high quality optically smooth surface to a lens product molded therefrom.

The present invention provides systems and methods for manufacturing universal mold sections having generally opposed optical quality surfaces.

In addition, features of the system and method of the present invention are provided that are intended to facilitate automated, highly reliable identification of the various mold sections produced by the system and method. The mold assembly itself can include an identification indicator, such as a structure that facilitates identification and/or tracking of the mold sections during contact lens manufacture. These tracking features may include a generally "panhandle" shaped structure of the mold assembly. For example, each mold section includes an elongated region that extends generally radially outward from the lens-defining surface and includes some form of indicia, preferably indicia that can be reliably read using a machine, such as a laser scanner. The indicia may be placed on the mold section or on the handle of the mold section during the mold section manufacturing process. These and other features of the present invention greatly increase the quality control of downstream lenses and lens manufacturing processes made by the mold assemblies.

For example, according to one embodiment, the present invention provides mold assemblies for the manufacture of lenses, such as contact lenses (e.g., soft silicon-based hydrophilic contact lenses). The mold assembly generally comprises a pair of mold section bodies, each mold section body including an optic region having a lens-defining surface. The lens-defining surface has a surface profile of a master of a front surface of the contact lens or a master of a back surface of the contact lens. Each mold section body further comprises a flange region surrounding, e.g., substantially completely surrounding, the lens-defining surface. In addition, the mold section body further includes an elongated region preferably integrally formed with and extending radially outwardly from the flange region. Another embodiment of the invention relates to individual mold sections for forming a mold assembly.

In some embodiments, the elongated region of the mold section body has a length and geometry effective to provide a desired wall thickness of the optic region or bowl portion of the mold section. For example, the elongated region may have a length of at least about 15mm, measured from the outer periphery of the flange region (where the elongated region joins the flange region) to the distal tip of the elongated region. In some embodiments, the length of the elongated region is between about 20mm and about 40mm, preferably between about 30mm and about 35 mm. In one embodiment, the length is about 30 mm.

The elongated region may have a substantially uniform width along a major portion thereof. In a preferred embodiment, the elongate zone comprises a first portion having a substantially uniform width and a second portion having a width that diverges in a direction away from the first portion toward the flange zone at an angle, for example, between about 10 ° and about 30 °. The first portion may be understood as the proximal portion and the second portion may be understood as the distal portion. Alternatively, the first portion may be a proximal portion, the second portion may be an intermediate portion, and the optic zone and flange may be a distal portion.

In certain embodiments, the elongate region is substantially planar and does not include steps or jumps substantially along its length. For example, the elongated region does not include a ramp having a slope that points from the proximal portion to the distal portion.

In one embodiment, the second portion is thinner than the first portion. For example, the first portion of the elongated region has a substantially uniform first thickness and the diverging second portion has a second thickness that is less than the first thickness.

In certain embodiments, the first thickness of the elongated region is between about 0.4mm or about 0.6mm or about 0.8mm or 1mm and about 1.2mm or about 1.4mm or about 1.6mm or about 2 mm. The first thickness is preferably between about 0.8mm and 1.6 mm. The second thickness of the elongated region preferably does not exceed about 0.4mm and about 1.8 mm. The second thickness is preferably between about 0.8mm and about 1.6 mm.

In accordance with an embodiment of the present invention, a mold assembly comprises two or more universal mold sections assembled together, for example, in a stack and defining a lens shaped cavity between a first lens defining surface of one mold section and a second lens defining surface of another mold section. It can be appreciated that the universal mold section of the present invention provides numerous advantages and benefits. For example, by using the universal mold section of the present invention, a reduced number of different mold sections are required for manufacturing lenses relative to conventional lens mold assemblies that typically utilize a back curve mold section and a different front curve mold section for manufacturing lenses. In addition, the contact lens mold assemblies of the present invention and systems for manufacturing the contact lens mold assemblies require a reduced number of different molding machine components and, for example, enhance management of contact lens mold inventory.

Japanese patent No. JP 05337957a discloses additional information that may be helpful in understanding the concept of a "universal" mold section having opposing lens-defining molding surfaces, which teaches a system for molding contact lenses using stacked identical mold forms.

In another aspect of the invention, a mold section, such as a mold section described elsewhere herein, is provided that includes one or more identifiers or indicia identifying one or more characteristics of the mold section (e.g., characteristics of a lens to be formed using the mold section). For purposes of illustration and not limitation, indicia, e.g., in the form of bands, colors, indicia, textures, etched or roughened surfaces, and the like, and combinations thereof, can be provided suitable for facilitating identification of characteristics relating to information (e.g., optical power, shape, size, and/or other identifying information) relating to a lens to be molded using the mold section. In a particularly advantageous embodiment, the markings are provided as one or more machine-readable strips located on an elongated region of one or more mold sections.

Using the identifying indicia, multiple mold sections can be easily and quickly compared to one another and assembled as appropriate to form one or more mold assemblies having cavities of desirable lens shapes, and ultimately provide desirable lenses that are cost-effective and/or mass produced. For example, the mold portions may each be identifiable or "readable," such as at least one of visually readable, tactilely readable, and/or machine readable, and/or the like, and/or combinations thereof. The indicia may comprise a band of elongated regions of the mold sections, such as a colored surface, a roughened surface, a frosted surface, a marked surface, a shaped surface (such as a band or surface having a width that is different than the width of a similar band or surface on a different mold section, etc.

In a particularly advantageous embodiment of the invention, the mould parts are configured to be automatically identifiable, i.e. can be identified in an automatic manner. For example, the mold sections may include indicia that is readable using a laser scanning system, other automated scanning systems, and the like, and combinations thereof.

In one aspect, the invention comprises a mold section suitable for use in the manufacture of contact lenses by polymerizing a polymerizable composition provided in an assembled mold section. The mold sections of the present invention may themselves be shaped articles of thermoplastic polymeric materials that are transparent or at least translucent to polymerizing radiation (e.g., ultraviolet light).

In an embodiment of the present invention, molding assemblies each comprising a complementary pair of first and second mold sections are used to manufacture hydrogel lenses, hydrogel contact lenses, and the like, such as silicon-containing hydrophilic lenses, silicone hydrogel contact lenses, other hydrophilic lenses, contact lenses, and the like. This is accomplished by molding a composition (e.g., a polymerizable composition) in a lens-shaped cavity defined between two complementary mold sections. For example, the polymerizable composition can comprise one or more monomers and a solvent. The composition is placed or deposited on the concave lens-defining surface of one of the mold sections. Placing another mold section on top of the first mold section to enclose the composition in the lens shaped region defined therebetween. The filled assembled mold sections are coupled together, for example using an ultrasonic horn to weld one or more contact regions located radially outward from the filled lens shaped cavity. The filled and welded mold assembly is then subjected to polymerization conditions, such as irradiation of the assembly with actinic, visible, and/or ultraviolet radiation to produce a polymeric article in the shape of a desired lens.

Upon completion of the polymerization process, the complementary portions of the mold assembly are separated to display a polymerized lens-shaped article on one of the mold sections. The article is then subjected to post-polymerization steps, such as removing and extracting and hydrating the article from the mold portion. For example, after polymerization is complete, the extractable component in the polymeric article can be replaced with a solvent or water to manufacture a hydrated lens, e.g., having a size and shape suitable for placement in an eye of a subject.

In another aspect of the invention, a manufacturing system is provided that is suitable for use in manufacturing a mold section having an optical quality surface or a contact lens mold section. The system is particularly useful for manufacturing mold sections that are subsequently used to mold lenses (e.g., contact lenses).

The manufacturing system generally includes an injection molding assembly and a molding component that can be coupled to the injection molding assembly. The molding component is sometimes referred to as a molding tool and typically has one or more, preferably four or more cavities, such as mold section shaped cavities. The injection molding assembly may be coupled to a supply of molding material (e.g., thermoplastic material). The injection molding assembly is effective, for example, under pressure, to inject thermoplastic material in a fluid state into a cavity in the shape of a mold section. The thermoplastic material is allowed to cool in the cavity, the molding assembly is opened, and the cooled and solidified mold portion is removed therefrom.

In one embodiment of the invention, a mold section shaped cavity includes an optic cavity portion having a lens shaped surface and an elongated cavity portion. A contact lens mold section is manufactured by introducing a quantity of fluid thermoplastic material through an inlet into an elongated cavity section using an injection molding assembly. The system is configured such that when the fluid thermoplastic polymeric material reaches the optical component portion of the mold cavity, its flow characteristics are sufficient to flow to provide an optical quality surface on the final mold portion.

For example, the elongated cavity portion advantageously comprises a structure, such as a fan-blade shaped cavity portion, that allows the flow of thermoplastic material to spread out in a smooth material flow towards the outward flange region. This shape helps to reduce the stress concentration adjacent the optic cavity portion by spreading the opening to the optic cavity portion over a wide area. Advantageously, a desirable flow rate may be obtained without providing steps, ramps or inclined surfaces along the elongated cavity portion.

The present invention preferably provides a system for manufacturing contact lens mold sections wherein the flow characteristics of the fluid thermoplastic polymeric material used to form the mold sections advantageously have the appropriate balance of high flow during introduction of the fluid thermoplastic polymeric material into the mold cavity and rapid cooling and/or solidification of the thermoplastic material once the cavity is filled.

The elongated cavity portion is sized and the inlet is positioned to effectively provide a resulting substantially solid mold portion article having an optical quality surface in the optical cavity portion and to effectively reduce the time to cure the thermoplastic polymeric material relative to a molding apparatus defining substantially identical mold cavity portions without the elongated portion. In one embodiment, the ratio of the length to the depth of the elongated cavity portion is in the range of about 10: 1 or about 15: 1 or about 22: 1 to about 30: 1 or about 44: 1 or about 50: 1. Preferably, the ratio of the length to the depth of the elongated cavity portion is between about 22: 1 to about 44: 1.

The thermoplastic material may be a thermoplastic polymeric material, for example selected from any suitable such material or mixture of such materials. The thermoplastic polymeric material may include, for example, but is not limited to, polymers such as polyolefins (e.g., polypropylene, polyethylene, etc.), polyethylene vinyl alcohol (EVOH), polyamides, polyoxymethylenes, polyethylene terephthalate, cyclic olefin copolymers, polystyrene, polyvinyl chloride, copolymers of styrene with acrylonitrile and/or butadiene, acrylates (e.g., polymethyl methacrylate, etc.), polyacrylonitrile, polycarbonate, polyesters, poly (4-methylpentene-1), etc., and mixtures thereof. Polyethylene vinyl alcohol (EVOH) is a preferred material for forming contact lens mold sections using the system of the present invention.

In yet another aspect of the present invention, a system for manufacturing a plurality of different lens mold sections is provided. The system generally includes an injection molding assembly connectable with a source of molding material and a change plate assembly configured to be removably coupled to the injection molding assembly. The change plate assembly comprises a first plate and a second plate which, when assembled together, define one or more cavities of a mold section shape suitable for use in the manufacture of contact lenses. In an embodiment, the first plate comprises at least one first molding surface defining, for example, an anterior surface of a contact lens. The second plate includes at least one second molding surface that can define, for example, a posterior surface of a contact lens.

In certain embodiments, the first plate and the second plate each comprise a plurality of first molding surfaces and a plurality of second molding surfaces, respectively. Thus, when the first and second plates are assembled to each other, a plurality of mold section shaped cavities are formed. In some embodiments, the first plate comprises a plurality of different first molding surfaces, for example a plurality of convex molding surfaces having different optical component curves. In an embodiment, the molding assembly includes cavities that form 8 substantially identical mold sections in a single molding cycle.

Each first forming surface may be provided by an insert removably coupled to the first plate. Alternatively, each first forming surface may be machined into and integrated with an end face of the first plate. Likewise, each second profiled surface may be provided by an insert removably coupled to the second plate or each second profiled surface may be a surface machined into and integral with an end face of the second replacement plate. The use of inserts may provide advantages such as increased efficiency in changing the properties of the mold sections, such as the shape and size of the optical surfaces of the mold sections.

In one embodiment of the present invention, the change plate assembly is suitable for use in molding contact lens mold sections having first and second generally opposed lens-defining surfaces. For example, a set of first inserts includes a surface corresponding to the front curve of the contact lens, and a set of second inserts includes a surface corresponding to the back curve of the contact lens. The first and second lens shaped surfaces of the mold section are preferably formed using first and second molding inserts, respectively, located on first and second exchange plates, respectively. Advantageously, the first and second inserts are each removably positioned within a bushing, which in turn is mounted in the change plate assembly.

In some embodiments of the present invention, at least one of the first insert and the second insert is a one-piece element or a one-piece having a reference surface machined into the insert and an optic corresponding to a lens edge. This machining can be performed using a specialized optical precision lathe, so that subsequent polishing is not required. Preferably, the first insert and the second insert comprise a datum surface that provides a circular lens edge on the contact lens or is effective to form a circular lens edge on the contact lens. Some molding tools and inserts suitable for use in the manufacture of rounded edge contact lenses and their advantages are described in Dean, U.S. patent No. 6,431,706.

Preferably, the insert for producing the optical replication surface on the mould part is made of a copper-nickel alloy, an aluminium alloy, a pure nickel coated substrate, an iron alloy, an engineering ceramic, an engineering plastic or the like.

A cooling assembly may also be provided in the system of the present invention. The cooling assembly may include a first cooling circuit located within the system to efficiently transfer cooling liquid through the injection molding assembly and a second cooling circuit independent of the first cooling circuit and effective to transfer cooling liquid through the change plate assembly. In this embodiment of the invention, the change plate assembly may be physically removed from the molding system while the first cooling system is still operating to maintain the other components of the cooling system. For example, the first cooling circuit includes a plurality of inlets located on the change plate assembly and may be connected with a source of cooling liquid. The first cooling circuit may include features that facilitate coupling and decoupling of the change plate assembly from the injection molding assembly, for example, the cooling circuit may include a manifold coupler or "multicoupler" to facilitate coupling of the plurality of inlets with a source of cooling fluid.

In another aspect of the present invention, the change plate assembly generally includes a conical locator feature to facilitate positioning of the change plate assembly in the injection molding assembly.

In yet another aspect of the present invention, the system further includes a vacuum assembly for removing gas from the system during molding, wherein the vacuum assembly is advantageously configured to become operable by default when the change plate assembly is coupled to the injection molding assembly. The vacuum assembly is effective to apply a continuous vacuum to the system during the molding process. The vacuum assembly may include a channel between the change plate assembly and the injection molding assembly, the channel being connected to a vacuum source. The vacuum assembly is designed to remove exhaust gases that may otherwise accumulate within the system.

In some embodiments of the invention, the system includes a temperature sensor effective to measure the temperature of the replacement plate assembly. For example, the temperature sensor may comprise one or more surface monitoring thermocouples located at strategic locations of a skin of the injection molding assembly. Similar to the vacuum assembly, the temperature sensor is configured to become operable by default upon coupling the change plate assembly with the injection molding assembly.

The removal and subsequent use of a molded article formed between a first insert and a second insert is greatly facilitated by the positioning of the male or back curve insert on the moving portion of the injection molding tool. This facilitates more efficient handling (e.g., automated handling) of the lenses using the mold sections.

In normal operation, the molded article or contact lens mold section may be adhered to a male insert or a front curve insert. To retain the molded article on the back curve insert instead, the system of the present invention may include a retaining structure or mechanism. For example, according to one embodiment of the present invention, a bushing containing a back curve insert may include a surface having one or more cut-out portions (e.g., grooves or channels) that trap a portion of the thermoplastic material during the molding process. The cut-out portion has a configuration and location effective to facilitate retention of the molded article on the back curve insert. In an embodiment, a generally V-shaped groove is provided, the groove having a depth of between about 0.025mm and about 0.5mm, more preferably between about 0.05mm and about 0.20 mm. For example, a V-shaped groove having a depth of about 0.075mm is provided. The preferred angle of inclination of the grooves is between about 20 ° or about 30 ° and about 70 ° or about 80 °. In a preferred embodiment, the angle of inclination of the grooves is between about 30 ° and about 60 °, for example about 45 °.

Without wishing to be bound by any particular theory of operation, it is believed that when the molten material within the cavity solidifies within the trough, the molded article tends to remain there and thus remain adhered to the second insert when the molding machine or molding assembly is turned on.

Alternatively or additionally, raised structures on the liner of the second insert may be used, e.g., raised portions (e.g., ridges, protrusions, etc.) effective to retain the molded article by the second insert. The raised formation may be located on, e.g. project from, a bush containing the second insert. In one embodiment, the raised projections have a height of about 0.05mm to about 0.5mm, such as about 0.2mm, and a width of about 0.1mm to about 1.0mm, such as about 0.6mm, wherein the undercut is between about 13 ° and about 45 °, such as about 30 °. The raised structures effectively form grooves or recesses in the mold sections. For example, the groove or slot may be formed in a flange portion of the mold portion. In certain embodiments, the insert has a plurality of discrete raised structures to form a plurality of discrete grooves or channels in the flange portion of the mold section. For example, the back surface of the flange region of the mold portion (e.g., the flange surface that abuts the convex surface of the mold portion) can include three grooves positioned around the convex surface. The three grooves may be spaced about 120 degrees from each other and not in contact with each other. The recess is effective to secure the mold section to a surface of the plate that is in contact with the back surface of the mold section. Thus, a mold section having a plurality of grooves as described above can be understood to include a discontinuous ring around the optical component portion of the mold section.

The grooves or recesses and projections on the liner may be intermittent or spaced apart rather than continuously around the insert as described above.

Many different mechanisms can be used to achieve the same manner of retaining the molded article on the second insert.

Preferably, the molding surfaces of the components for the injection molding machine are maintained at a desirable temperature by including a cooling system (e.g., a cooling circuit) that is advantageously used throughout the injection molding system.

For example, the first and second inserts each preferably have a circumferential cooling passage defined therearound that circulates a fluid coolant. In an embodiment, the cooling passage is defined in a liner of the retention insert. According to some embodiments, the insert itself does not include or is substantially free of a fluid circulation passage defined therein.

In addition to the above, it can be appreciated that another aspect of the present invention relates to the use of the mold sections of the present invention in the manufacture of contact lenses, such as silicone hydrogel contact lenses.

Another aspect of the invention relates to a method of manufacturing a contact lens mold section. These methods include the step of directing molten thermoplastic material into a mold cavity as described herein.

Yet another aspect of the invention relates to a method of manufacturing a contact lens using a mold section. For example, an embodiment relates to a method of manufacturing a plurality of contact lenses having different specifications using a universal mold section as 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 perspective view of a mold section showing a concave molding surface that is a negative of a front curve of a contact lens.

FIG. 2 is a cross-sectional view of the mold section taken along line 2-2 of FIG. 1.

FIG. 3 is a perspective view of a molding assembly including two mold sections stacked one on top of the other.

FIG. 4 is a cross-sectional view of the mold assembly taken along line 4-4 of FIG. 3, the mold assembly defining a lens shaped cavity.

FIG. 5 shows a set of mold sections, each mold section including indicia to facilitate distinguishing and/or identifying mold section characteristics, according to an embodiment of the invention.

FIG. 6 is a cross-sectional view of a molding system according to the present invention.

FIG. 7 is a perspective view of a tool of the molding system shown in FIG. 6, namely an insert body and an insert having an optical surface, the tool including features to prevent incorrect rotational orientation of the optical surface.

FIG. 8 is a perspective view of a portion of a change plate assembly of a molding system showing multiple coupling features that facilitate connecting and disconnecting water cooling lines.

Fig. 9 is a top view of the end face of one replacement plate on which 8 newly formed mold portions are disposed, showing two groups of four mold portions, with each group of four mold portions formed with one valve gate cluster.

FIG. 10 is a magnified cross-sectional view of a portion of the mold assembly shown in FIG. 4 showing features of a mold section for producing a smooth edged surface on a contact lens formed in a lens shaped cavity.

FIG. 10A is a magnified cross-sectional view of a portion of a preferred mold assembly including a feature to prevent deformation of a lens edge.

FIG. 11 is an enlarged view of a portion of the mold cavity shown in FIG. 6, showing the grooved ring effective to adhere the molded part to the back curve insert after separation of the molding surfaces.

FIG. 12 is an enlarged view of a portion of a mold cavity similar to the enlarged view shown in FIG. 11, except that a recessed portion in the form of a "dovetail" is provided to retain the molded part on the back curve insert after separation of the molding surfaces.

Detailed Description

Turning now to fig. 1 and 2, the mold sections of the present invention for making contact lenses are shown generally at 10. The mold section 10 generally comprises a mold section body 12 including an optic region 14 having a first lens defining surface 16, the first lens defining surface 16 being illustrated as a negative of the front surface of the contact lens. The body 12 further includes a flange region 18 at least partially surrounding the optic region 14 and a generally non-triangular elongated region 24 extending away from the optic region 14 and generally aligned parallel to the flange region 18. The mold sections, systems, and methods disclosed herein may be used to form toric, aspheric, bifocal, multifocal, and colored contact lenses. The lenses can be made of non-silicone hydrogel materials or silicone hydrogel materials. In a preferred embodiment, the contact lens is a silicone hydrogel contact lens.

The mold portion preferably comprises polyethylene vinyl alcohol (EVOH). For example, embodiments of the mold sections of the present invention, including the illustrated embodiments, may be made from EVOH-based resins that are publicly available under the trade designation SOARLITE S of Nippon Gohsei, Ltd. (Japan). Other suitable molding materials include polypropylene, polyethylene, polyamides, polyoxymethylenes, polyethylene terephthalate, cyclic olefin copolymers, polystyrene, polyvinyl chloride, copolymers of styrene with acrylonitrile and/or butadiene, acrylates such as polymethyl methacrylate, polyacrylonitrile, polycarbonates, polyamides, polyesters, poly (4-methylpentene-1), and the like, and mixtures thereof.

The mold section 10 may be structured to be used as a universal mold section as described elsewhere herein, in that the mold section includes an optically acceptable male and female molding surface. More specifically, in the embodiment shown, the optic region 14 of the mold section includes a first lens defining surface 16 and a generally opposing second lens defining surface 17. In this case, the first lens defining surface 16 is a negative of the front curve of the contact lens and the second lens defining surface 17 is a negative of the back curve of the contact lens. Thus, it should be appreciated that a mold section 10 according to this embodiment of the invention includes two concave molding surfaces 16 for forming the front curve of a lens and a convex molding surface 17 for forming the back curve of a lens on a single mold section 10. Both surfaces are sufficiently smooth to produce a contact lens having two optically acceptable surfaces (such as a silicone hydrogel contact lens) without the need for other surface modifications or treatments that render the lens ophthalmically acceptable.

A mold assembly 26 according to a related aspect of the invention is shown in fig. 3. The mold assembly 26 includes a mold section 10 (hereinafter generally referred to as "first mold section 10") and a similar or substantially identical second mold section 10'.

As shown more clearly in FIG. 4, the mold assembly 26 is used to manufacture a single lens, such as a single contact lens, formed between the first lens defining surface 16 of the first mold section 10 and the second lens defining surface 17 'of the second mold section 10'. Each of surfaces 16 and 17' is a high optical quality surface having few or no imperfections to be transferred to a lens molded with the mold section.

As used herein, the term "optical properties" describing the lens-defining surface of the resulting mold section is intended to mean that the surface is sufficiently smooth such that, when the polymerizable monomer composition is contacted with the surface, it polymerizes into a product having the shape and (if necessary, after hydration) size, refractive properties, and water content of a ready-to-wear contact lens, which may collectively be referred to as "optical properties". Optical quality lenses have surface smoothness and contour accuracy and are sufficiently free of internal defects to provide desirable refractive correction without distortion and/or substantial discomfort to the lens wearer. The smoothness and profile accuracy of the surface can be determined using known analytical techniques such as interferometry.

Referring back to fig. 2, the elongate region 24 of the mold section 10 has a length L extending from an elongate region tip or proximal region 27 to the juncture of the elongate region and the flange region 18. The length L is at least as large as the diameter of the lens-defining surface 16. The length L of the elongated region 24 is between about 20mm and about 40mm, more preferably between about 30mm and about 35 mm.

In the illustrated embodiment, the length L is about 30 mm.

The elongate zone 24 includes a first portion 28 having a generally uniform width and a second portion 30 having a distally increasing or distally diverging width such that at the junction of the second portion and the flange zone 18, the second portion 30 is generally equal in width to the flange zone 18.

In a preferred embodiment, the first portion 28 of the elongated region 24 has a uniform width between its generally parallel opposing longitudinal edges of between about 5mm and about 15 mm. The second portion 30 has opposing edges that diverge at an angle of between about 10 degrees and about 20 degrees, as measured from the substantially parallel edges of the first portion 28.

The first portion 28 has a substantially uniform thickness of between about 0.5mm and about 2.0mm, preferably between about 0.8mm and about 1.6 mm. In a preferred embodiment, the first portion 28 has a thickness slightly greater than the thickness of the second portion 30. The thickness of the optical zone, such as the thickness of the bowl region of the mold portion or the thickness between the concave and convex surfaces of the mold portion, should be about 1.5mm to about 1.7 mm. In one embodiment, the thickness is about 1.6 mm.

According to a particularly advantageous embodiment of the present invention, the ratio of the length L of the elongated region 24 to the average thickness of the elongated region 24 is a ratio between about 22: 1 and about 44: 1.

Turning to fig. 5, the present invention provides an assembly 100 suitable for molding contact lenses, wherein the assembly 100 includes a plurality of mold sections, represented by mold sections 110a, 110b, and 110 c. In this embodiment, each mold section 110a, 110b, and 110c includes indicia 40a, 40b, 40c, respectively, effective for identifying and distinguishing (at least one circumstance) a characteristic of the lens-defining surface of the mold section (e.g., a different characteristic of the mold section relative to the lens-defining surfaces of the other mold sections). For example, mold portion 110a includes indicia 40a that is visually distinguishable from indicia 40b of mold portion 110b and indicia 40c of mold portion 110 c. For example, indicia 40a is effective to identify a radius or optical curve of the lens-defining surface 116a of mold section 110 a. Likewise, indicia 40b is effective for identifying a different radius or optical curve of the lens-defining surface 116b of mold section 110 b. Similarly, indicia 40c is effective for identifying the radius or optical curve of the lens-defining surface 116c of mold section 110 c. In general, the indicia 40a, 40b, 40c may be used to facilitate identification of the particular molding machine or molding tool used to make the mold section 110.

For simplicity, the following discussion will refer specifically to mold portion 110a, but it should be understood that the discussion further applies to mold portions 110b and 110 c. The indicia 40a generally includes a first surface portion 44 along the elongate region 124 that is roughened, sanded, color-coded, etched, textured, etc., relative to an adjacent second surface portion 46 of the elongate region 124. In a preferred embodiment of the invention, the indicia 40a comprises a first surface portion 44 defined by a rough and/or unpolished stripe or band and an adjoining second surface portion 46 defined by a relatively smooth polished surface. Indicia 40a may be formed on mold portion 110a during the molding process by etching the corresponding surface of the tool in which the mold is formed.

Advantageously, in this embodiment, the indicia 40a is machine readable and thus suitable for facilitating automated processing of the lens or lens mold sections. More specifically, mold section 110a can be identified as a mold section for forming a lens having a particular front curve, back curve, or a combination thereof.

Indicia 40a is preferably machine readable using a laser scanning device. For example, in a particular embodiment, indicia 40a are "read" by a suitable device using an optical sensor and a laser beam scanner. As the laser beam passes along the elongated region 124, the beam will be reflected back and detected by the sensor as the beam traverses the polished surface portion 46. When the beam traverses the rough or unpolished surface portion 44, the beam will be scattered so that "no echo" or "no return signal" reaches the sensor. Thus, it will be appreciated that by providing mold portions having one or more rough surface portions of predetermined width and one or more polished or rough surface portions having different locations on the elongate region, the mold portions should be identified and/or distinguished from one another. Advantageously, the indicia 40 may be formed on the mold sections during molding of the mold sections using etched and polished molding surfaces that form the mold sections. In addition to being used to identify the ocular surface characteristics of the mold, indicia may be used as a means to identify the origin of the mold section, the material from which the mold section is made, and/or other characteristics of the mold section that may be used to facilitate automated lens processing and/or to reduce the occurrence of errors during lens processing.

It will be appreciated that the mold sections according to the invention may be manufactured using conventional injection molding machines, such as those known to those skilled in the art. The molding apparatus and aspects and features thereof described in U.S. Pat. No. 5,545,366 and U.S. Pat. No. 5,451,155 may be adapted for use in making the mold sections of the present invention.

As shown in FIG. 6, an improved injection molding system according to another aspect of the present invention is shown generally at 210 in cross-sectional view. The system 210 generally includes an injection molding assembly 212 connectable with a source of molding material 214. The plastic particles of molding material are contained in a hopper (not shown) from which they are dispensed into the heater of the injection molding assembly. In this particular embodiment, the molding material is EVOH, which is melted by a heater to a temperature of about 255 ℃. However, the temperature may vary, and suitable temperatures may be between about 255 ℃ and about 285 ℃.

The system further includes a change plate assembly 216 configured to be removably coupled to the injection molding assembly 214.

In an advantageous embodiment, the change plate assembly 216 may be quickly removed from the integrated system 210 as a single, complete assembly. As will be described in greater detail below, the structure of the change plate assembly 216 allows for the rapid establishment of a system 210 with desirable optical tools. For example, two change plate assemblies may be used, with one change plate assembly connected with the injection molding assembly 212 and the other change plate assembly being "off-line" and carrying a different set of optical tools. Typically, the exchange and connection of one change plate assembly to another offline change plate assembly will take less than about 20 minutes.

In one aspect of the invention, the front face of the change plate has a titanium nitride surface that imparts a high quality finish to the change plate assembly and the molding surface that forms a part thereof. The titanium nitride front surface may be hardened to, for example, about 56 Rc.

The change plate assembly 216 contains the molding tools that form the lens defining surfaces 16 and 17 of the mold section 10 (see FIG. 1) formed in the mold section shaped cavity 217. The elongate zone 24 of the mold section 10 is formed by a hot runner channel 217a that feeds a liquid molding material, such as molten EVOH, to an optical zone 217b of the mold section shaped cavity 217. The molding surface defining the runner channel 217a has a discrete polished surface (highly polished about 6pm Ra) and a discrete roughened surface (about 2.20 μm Ra) to form indicia on the elongated region of the mold portion as described elsewhere herein and as shown in fig. 5. The roughness length is preferably between about 1mm and about 8 mm.

In an embodiment, the change plate assembly 216 includes a first plate and a second plate that define a plurality of mold section shaped cavities therebetween. For example, the first plate includes at least one first molding surface that defines, for example, an anterior surface of a contact lens and the second plate includes at least one second molding surface that can define, for example, a posterior surface of a contact lens to form the "universal" mold section shown in fig. 1.

In a preferred embodiment, the first plate and the second plate each comprise a plurality of first forming surfaces and a plurality of second forming surfaces, respectively. Thus, when the first and second plates are assembled to each other, a plurality of mold section shaped cavities are formed. In some embodiments, the first plate comprises a plurality of different first molding surfaces, for example a plurality of convex molding surfaces having different optical component curves.

Each first forming surface is preferably provided by an insert movably coupled to the first plate. Alternatively, the first forming surfaces are machined in and integrated with the front side of the first plate. Likewise, the or each second profiled surface is provided by an insert that is removably coupled to the second plate as a surface machined into and integral with the front face of the first replacement plate.

For example, referring to fig. 6, in a preferred embodiment, the change plate assembly 216 comprises a first plate 218 (hereinafter sometimes referred to as a "cavity plate") configured to receive a plurality of front curve forming inserts 220 mounted to a front curve insert body 221 and loaded within a cavity liner 222 (only one front curve forming insert 220 and insert body 221 is shown in fig. 6). The first plate 218 may also be referred to as a female mold plate. The first plate 218 is closer to the injection molding apparatus than the second plate 224 of the change plate assembly 216. The second plate 224 (sometimes referred to hereinafter as a "core plate") is configured to receive a plurality of back curve forming inserts 226 (only one back curve forming insert 226 and insert body 227 is shown in fig. 6) mounted to an insert body 227 and loaded within a core liner 228. In this embodiment, the change plate assembly 216 further includes a third plate 230 or, as shown, a "stripper plate" of a stripper bushing 232 disposed around a portion of the core bushing 228. Stripper plate 230 facilitates the withdrawal of the polished mold section from the mold tool. The combination of the stripper plate and the insert may be referred to as a male plate. The stripper plate 230 moves relative to the insert and thus, as discussed herein, may be used to release the mold sections from the insert.

The back curve insert 226 is shown in fig. 6 loaded on the distal end of a generally cylindrical insert body 227. The insert body 227 may include a location feature that prevents the insert body 227 from being misoriented relative to the bushing 228 that holds the insert body 227 in place. The location features are desired to ensure that the insert 226 and its molding surface will be properly aligned in the change plate assembly 216. This is particularly useful for molding toric lens mold sections where the insert may incorporate a non-rotationally symmetric form on its optical surface.

For example, the insert body 227 may be generally cylindrical except for a flattened region along one longitudinal side of the body 227. Thus, the body 227 may have a generally D-shaped cross-section. Accordingly, the core bushing 228 defines a cavity having a corresponding D-shaped cross-section of the load body 227 and the first insert 226. Other configurations are also contemplated and considered within the scope of the present invention.

The back curve insert 226 preferably also includes features to prevent misalignment or misorientation of the lens-shaped surface relative to the insert body 227. For example, as shown in fig. 7, the back curve insert 226 and insert body 227 (now shown removed from the system 210) may include offset slots 235a and corresponding offset protrusions 235b that ensure that the insert 226 can only be positioned in one location on the insert body 227. This is particularly useful for molding toric lens mold sections where the insert may incorporate a non-rotationally symmetric form on its optical surface. Additionally, the insert body 227 may also include features, such as in the form of a D-shaped flange 239 corresponding to a D-shaped opening in the core bushing 228 to facilitate correction of the rotational direction.

Various other alignment features may be provided on one or more components of the molding system 210 without departing from the scope and spirit of the present invention. For example, in another aspect of the present invention, the change plate assembly includes structure that facilitates proper positioning of the three change plates relative to each other. For example, in an embodiment of the present invention, the change plate assembly typically includes conical locator features adapted to ensure proper alignment and connection of the plates.

In another aspect of the invention, the system 210 includes a cooling system that maintains the polymeric material deposited in the mold section shaped cavity 217 at an effective temperature that maintains the desirable flow characteristics of the material.

In a preferred embodiment, the cooling system includes a first cooling circuit positioned to efficiently pass a cooling liquid (e.g., water) through a channel or passage in the injection molding assembly 212, and a second cooling circuit to efficiently pass the cooling liquid through a channel or passage in the change plate assembly 216. Preferably, the first cooling circuit 272 is independent of the second cooling circuit 276, such that the injection molding assembly 212 may continue to be cooled when the change plate assembly 216 is changed to a different change plate assembly.

For example, as shown in fig. 6, the cooling system may include channels 272 defined in the core liner 228, the stripper liner 232, and the cavity liner 222. A separate, stand-alone cooling system is preferably provided to cool the injection molding assembly 212. It should be noted that in the illustrated embodiment, the inserts 220, 226 and insert bodies 221, 227 themselves do not include fluid circulation passages defined therein.

Effectively and efficiently disconnecting and reconnecting water to the change plates 218, 224, and 230 during removal and insertion of the change plate assembly 216 is important to minimize downtime, prevent water loss, and prevent confusion with common appearance connections. To facilitate reduced downtime, reduced water loss, and prevent misconnection, it is preferred to use a series of manifold couplings or "multi-coupling" water connections. One such multiple coupling is shown at 244 in fig. 8.

For example, multicoupler 244 includes valve male connectors 247. The change plate assembly 216 (e.g., a core plate of the change plate assembly) includes respective valve box joints 249 that communicate with cooling circuits (not shown in fig. 8) within the core plate. All of the male 247 and female 249 connectors are preferably self-sealing valve couplers. The female connector 249 is preferably recessed into the surface of the replacement panel to prevent damage after removal from the panel.

All water connections are preferably located in an easily accessible area, such as on the operator side of the system 210, to enable quick connection/disconnection with minimal operator movement and/or operator labor.

Three such multiple couplings are used because there are three change plates 218, 224 and 230. To prevent misconnections, multiple couplings are marked and/or have different pitch pitches in the connection to prevent engagement with the wrong plate. However, the multiple couplings may be inverted in the correction plate, but this is not a problem due to the symmetrical design of the inlet and outlet connections between the plate and the multiple couplings that allows inversion without compromising the effectiveness of the tool cooling. The change plate assembly 216 is cooled in a separate circuit to the hot runner system of the injection molding assembly 212. Advantageously, when the replacement board assembly 216 has been removed, the rest of the system 210 may continue to be cooled, thereby preventing overheating.

Turning now to FIG. 9, in a preferred embodiment, system 210 is a multiple cavity molding system, such as (but not limited to) an eight cavity molding system. Fig. 9 shows a simplified diagram of an arrangement of the forming mold sections 10 disposed on the front face of the stripper plate 230. Two groups of four mold sections 10 are formed from two valve gate clusters 280 connectable to four valve gate pins (not shown in fig. 9). In this embodiment, four pins are operated simultaneously by one pneumatic actuator using a coupling plate. Thus, four cavities are individually but simultaneously filled. It is within the scope of the present invention that the valve gate cluster may be scaled up to 12, 16, 24, etc. cavity tools by simple addition to the injection molding system 210 in a modular fashion.

Further details regarding this feature of the present invention should be known to those skilled in the art of injection molding and therefore will not be disclosed in great detail herein.

In yet another aspect of the present invention, the system 210 can further include a vacuum assembly 288 for removing gas from the system during molding, wherein the vacuum assembly is advantageously structured to become operable by default when the change plate assembly 216 is coupled to the injection molding assembly 212. Vacuum assembly 288 is effective to apply a continuous vacuum to system 210 during the molding process. The vacuum assembly 288 may include a channel 289 located between the change plate assembly 216 and the injection molding assembly 212, the channel 289 connected to a vacuum source 290. In a particular embodiment, the channels are substantially U-shaped channels, severed by the front face of the stripper plate 230. The vacuum assembly is designed to remove exhaust gases that may otherwise accumulate within the system.

In some embodiments of the present invention, the system includes a temperature sensor that is effective to measure the temperature of the change plate assembly 216. For example, the temperature sensor may comprise one or more surface monitoring thermocouples located at strategic locations of a skin of the injection molding assembly. Similar to the vacuum assembly, the temperature sensor is preferably positioned and configured to become operable by default upon coupling the change plate assembly with the injection molding assembly.

In accordance with yet another aspect of the present invention, the back curve insert 226 is preferably manufactured as an integral component. In other embodiments, the insert 226 (not shown) may be a multi-component design.

In a particular embodiment, first insert 220 and second insert 226 are each respectively a one-piece insert that includes an optical quality surface defining one of the front curve or back curve of a contact lens, and further, will define a circumferential surface (hereinafter sometimes referred to as a "datum surface") of a lens edge when a first molded article manufactured using the methods and systems of the present invention is assembled with a second molded article. First insert 220 and second insert 226 each define not only the optical surface of the lens to be manufactured, but also the critical edges of the lens formed by the molding surface, respectively. In other embodiments, the insert is a multi-piece insert.

The mold sections can be shaped to define a critical edge surface of a lens formed between the two mold sections, thus potentially eliminating post-fabrication steps to perform polishing operations directed at smoothing the edge profile of the lens. This will be better understood with reference to fig. 10 and 11, where fig. 10 shows an enlarged view of the respective molding surfaces of the mold sections 10 and 10 'when assembled to form a lens shaped cavity 28 therein, and fig. 11 is an enlarged cross-sectional view of the respective datum surfaces of the inserts used to form the mold sections 10 and 10'.

More specifically, FIG. 10 shows a rounded edge form 28a of the lens-shaped cavity 28 of the mold assembly 26 made from the same mold sections 10 and 10'.

FIG. 10A is a view of the mold assembly 126, which is substantially identical to the mold assembly 26. However, the mold assembly 126 includes another feature intended to substantially prevent deformation of the lens edge 412 during welding of the mold sections 110 and 110'. More specifically, the mold assembly 126 includes a first contact region 422 positioned radially outward from the lens shaped cavity and a second contact region 424 positioned radially outward from and spaced apart from the first contact region 422.

In the mold assembly 126, the second contact zone is positioned marginally away from the edge or first mating surface of the first contact zone. Thus, when the assembly 126 is loaded during soldering, only partial deformation of the edge (up to 20 μm, i.e., porosity) can occur due to overload prior to making contact with the second mating surface, contact with the mating surface transferring force away from the edge of the lens and substantially preventing further deformation thereof. These features are machined on the unitary optical device. Thus, it will be appreciated that the outwardly positioned contact point 424 is effective to reduce defects at the lens edge by reducing pressure from the lens edge contact point 422. Further, it will be appreciated that the mold sections of the present invention are structured or include structural elements to reduce pressure at the contact point of the lens edge when the two mold sections are placed together, as compared to mold sections having only one contact point at or near the lens edge. Thus, the mold assembly of the present invention can be understood to include two mold sections having two contact zones positioned around the circumference of the optical zone of the mold section.

Turning to fig. 11, the inserts 220, 226 each include an optical quality surface defining one of a front curve or a back curve of a contact lens and, in addition, a peripheral surface (hereinafter sometimes referred to as a "datum surface") defining a lens edge when a first molded article (e.g., mold section 10 in fig. 4) is assembled with a substantially identical second molded article (e.g., mold section 10' in fig. 4). A critical portion (hereinafter referred to as a "reference surface") is provided at 292 and 294 of each unitary optical component insert 220 and 226, respectively.

The datum surfaces 292 and 294 are preferably machined on the insert 220 by a specialized optical precision lathe. Thus, the sagittal height of the insert is fixed, thereby fixing the center thickness of the contact lens being molded. Advantageously, the insert does not have to be adjusted to obtain the correct center thickness of the contact lens.

Turning again to FIG. 6, the cavity 217 is supplied with molten thermoplastic material through a valve gate 302 of the injection molding assembly 212. A valve gate 302 is positioned near the end of the cavity extension or "runner" 217 a. The valve gate 302 is positioned to inject the thermoformed material into the runner 217a in a direction substantially perpendicular to the length of the runner 217 a. Preferably, the diameter of the inlet 304 is in the range of about 0.6mm to about 1.6mm, which results in an increased fill rate and a reduced shear of the thermoplastic material, thereby making the optical quality surface better. The valve gate 304 is also configured to substantially prevent gate vestige (gate drool), i.e., an amount of material that may adhere to the molded article due to "gate drool". The gate dimensions are selected to reduce shear stress in the molten thermoplastic material flowing through the cavity. Control of the gate dimensions is achieved by pins that help control the flow rate of the molten thermoplastic material, which (in combination with temperature and heat removal rate) helps control the final dimensional characteristics of the molded part and optimize the handling of the molded article.

In addition, the distance of the valve gate 302 from the optical portion of the mold cavity is sufficient to facilitate the use of sufficiently large cooling channels 272 around the bushings 222 and 232. This allows for very efficient and rapid cooling of the mold cavity 217 b.

In a particular embodiment of the present invention using EVOH as the molding material and a melt temperature of about 255 ℃, the injection speed is about.55 seconds, the cooling time is about 2.5 seconds to about 5.5 seconds, and the holding pressure of the system in the injection molding assembly is about 60 bar. It should be understood that these values are provided for exemplary purposes only, and that different embodiments of the present invention may have different values for melt temperature, injection speed, cooling time, holding pressure, and/or other parameters. These values may be changed empirically by changing a parameter and determining how this change affects the properties of the mold section to obtain the desired weight and radius consistency of the mold section. It may be desirable to manufacture a universal mold section having a weight conformity of the mold section to the mold section with a tolerance of no more than 5% and/or a radius conformity with a tolerance of no more than about 5%.

The mold section shaped cavity 217 is fed through a runner 217a through a gate 302 through a supply portion having a substantially uniform width and depth. Downstream of the supply section, the runner 217a tapers and diverges outwardly in a direction toward the main lens forming section 217a of the mold section cavity 217. The flow passages 217a diverge from the opposite longitudinal edges of the supply portion at an angle of between about 10 and 20 degrees. At this divergent portion of the runner 217a, the cavity 217 is of a lesser depth than the supply portion, thereby forming a relatively thin region 30 in the shape of a fan blade of the mold section 10 shown in FIG. 1.

The runner 217a (i.e., the elongated portion) of the cavity 217 is sized and the inlet 304 is sized and positioned to effectively provide the resulting substantially solid molded article with a higher optical performance surface as defined elsewhere herein relative to a molding apparatus that includes the same molding tool without the elongated portion of the mold cavity.

The shape of the flow channel 217a in which the width of the upstream portion is uniform and the width of the downstream portion is gradually expanded fulfills an important function. The width of the downstream portion, which is generally fan-shaped, gradually tapers from the apex region towards the remainder of the mold cavity, where it feeds thermoplastic material into the flange portion and the optical portion of the cavity. Controlling the flow characteristics imparted by the dimensions of the flow channels in combination with, for example, the supply pressure, flow rate, and temperature of the molten thermoplastic material and the rate of heat removal therefrom, enables the desired characteristics of a finished mold section to be obtained that has at least one and more preferably two opposing optical surfaces on a single mold section. The size of the runners is effectively reduced and preferably eliminates jetting of the flowing molten thermoplastic material, which can create dents, inconsistencies in size, and unacceptable irregularities in the surface of the resulting mold sections.

In accordance with another aspect of the present invention, the back curve insert 226 is located on a moving component of the injection molding machine 210. This facilitates removal of the molded article from the injection molding tool, for example, using a robotic handling device, requiring the use of one step rather than multiple steps if the front curve insert 220 is placed on a moving component of the injection molding tool.

In normal operation, the molded article will naturally adhere to the front curve insert 220 including the convex molding surface. To retain the molded article in the back curve insert 226 instead, efficient mechanical structures may be used on or within the molding surface. For example, turning to fig. 10, the bushing 227 includes a circumferential groove 314 that retains the molded article in the back curve insert 226. The slot 314 may be a single continuous cut in the form of a generally V-shaped slot, or may be a plurality of spaced apart slots disposed along the circumference of the bushing. For example, the grooves 312 have a depth of between about 0.025mm and about 0.5mm, more preferably about 0.075mm, and an inclination angle of at most about 80 °, preferably an inclination angle of about 45 °. When the molten material in the cavity 217 solidifies within the slot 312, the molded article will thus tend to be retained and thus remain adhered in the back curve insert 226 rather than the front curve insert 220 when the molding machine is turned on to display the molded article.

Alternatively or additionally, a raised structure may be used to effectively retain the molded article by the back curve insert 226. For example, as shown in fig. 12, a raised portion 318 in the form of a "dovetail" is provided. Similar to the groove 318 described above, the raised feature 318 may be a continuous circumferential feature, or may be intermittent or spaced apart. Preferably, one or more raised structures 318 are provided that do not define a complete circumferential groove or ring. For example, a mold section formed or molded on the back curve insert will include, for example, at least one non-circumferential groove, e.g., three spaced apart grooves, in the flange surface on the back curve of the mold section.

Preferably, the raised structures 318 are disposed at two, three or more equidistantly spaced portions of the bushing covering between about 10% and about 90% of its circumference.

In a particular embodiment, the retention mechanism includes three equidistantly spaced raised structures 318, each defining an arc of about 30 ° around the circumference of the liner. In this particular embodiment, the raised structures 318 are about 0.2mm to about 0.5mm in height and about 0.6mm in width. The raised structures 318 define opposing notch angles of about 15 ° and about 85 °, more preferably about 70 °.

Removal of the cured mold section from the back curve insert is accomplished as follows. The core plate carrying the back curve inserts, e.g. 8 back curve inserts, is moved away from the cavity plate carrying the front curve inserts. The mold sections are retained on the back curve insert surface of the core plate, for example, using retention features described elsewhere herein. A vacuum assisted robot including a vacuum interface plate having a substantially planar surface and a plurality of vacuum interface plates and actuators enters between the cavity plate and the core plate. The vacuum ports on the positioning plate, in this example 8 vacuum ports, are positioned to receive the mold sections when the robot plate contacts the exposed surface of the flange region on the front curve side of the 8 mold sections. The vacuum interface in combination with the action of the stripper plate moving relative to the optical insert draws and lifts the mold sections away from the back curve insert surface. The robot arm swings away from the core plate and then the vacuum head releases the mold sections (back curve side down) in a vertical stack tray or cassette designed to hold the stacked mold sections. In a particular embodiment, the cassette is sized and configured to hold a stack of 64 x 8 individual mold sections. Advantageously, the mold sections are stacked with the front curve side (concave side) up, which greatly facilitates the downstream filling step.

Once the stack of cartridges is full, the cartridges are transferred to a separate filling and closing area, wherein the mold sections are mechanically detached from the stack from the cartridges, filled with contact lens precursor material and closed with mating contact lens mold sections. The indicia located at the elongated regions of each mold section may be read, for example, using a laser scanner device as described elsewhere herein, to ensure proper matching between mating mold sections during the stacking, unstacking, filling and/or closing steps.

In view of the disclosure herein, it should be appreciated that the present invention relates to contact lens mold sections, assemblies of mold sections, systems and methods of manufacturing contact lens mold sections.

In at least one embodiment, a contact lens mold section comprises two optically acceptable or optical quality lens defining surfaces, a flange substantially circumscribing the lens defining surfaces, and an elongate member in contact with the flange and extending radially away from the lens defining surfaces. These mold portions can be understood as universal molds with handle portions. In other words, two substantially identical or identical mold sections can be coupled together to form a mold assembly defining a lens-shaped cavity from which a handle extends. In contrast, existing mold sections may include an extension section, but do not include two optical quality lens defining surfaces. In certain embodiments, the mold portion includes a plurality of recesses in the flange. The groove may have an arcuate shape, but is not a continuous annular groove. Each mold section can have a plurality of radially spaced apart contact points such that pressure of one mold section against a second mold section is reduced at the lens edge to reduce defects at the lens edge and reduce or eliminate further edge processing. The elongate member can include a machine readable identifier to facilitate tracking and identifying a particular lens or mold section during the manufacturing process.

Examples of the present system for manufacturing such contact lens mold sections include an injection molding assembly and a change plate assembly defining a plurality of mold section cavities from which mold sections as described herein are manufactured. Unlike prior manufacturing systems, because the mold sections of the present invention have two optical quality surfaces, the heaters of the injection molding assembly need not be located remotely from the optical quality surfaces. In other words, the heaters may be located on either side of the mold section cavity. Furthermore, changing the plate assembly can effectively and continuously manufacture contact lens mold sections without the need for ramps or inclines that control the properties of the flowing thermoplastic material.

From the foregoing, it can also be appreciated that at least one aspect of the present invention relates to a method of manufacturing a contact lens. For example, certain embodiments relate to methods of manufacturing a plurality of contact lenses having different specifications. These methods comprise making a plurality of contact lens mold sections in a plurality of mold cavities as described herein. Each contact lens mold section comprises a lens defining region having a first lens defining surface that is a master of an optical quality front surface of a contact lens, a second lens defining surface that is generally opposite of the master of the optical quality back surface of the contact lens, a flange region circumscribing the first lens defining surface and the second lens defining surface. The first lens defining surface can have a first radius of curvature and the second lens defining surface can have a second radius of curvature. Wherein the number of specifications for a batch of contact lenses is the square of the number of mold cavities.

As a specific example, if a contact lens mold manufacturing system comprises 8 mold cavities, and each molding cavity has a front curve insert and a back curve insert, and each insert has a different curvature, then the contact lenses manufactured in these lens molds can obtain 64 different lens powers (lens powers). For example, by mating any one of the front curve inserts with any one of the back curve inserts, it is possible to manufacture a variety of lens powers with little manufacturing downtime attributable to the creation or replacement of the inserts. This is particularly evident when compared to a system comprising all mold cavity injection molding systems that produce the same optical power.

In certain embodiments of the methods of the present disclosure, each mold cavity comprises a removable optical insert, and the number of specifications for this batch of contact lenses is obtained without removing the optical inserts.

The method of the present invention can be understood as producing a one-piece mold or a universal mold. Different combinations of front and back curve surfaces with different radii of curvature may result in a number of diopter or lens specifications equal to the square of the number of mold cavities used to make the one-piece mold.

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. 11/200,648 entitled "Contact Lens molds and Systems and Methods of Producing Same" and attorney docket No. D-4125; 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.

While the invention is described herein in terms of various specific examples and embodiments, it is to be understood that the invention is not so limited and that it can be variously practiced within the scope of the following claims.

Claims (24)

1. A contact lens mold section comprising:

a lens-defining region having a first lens-defining surface presenting a negative of an optically-functional front surface of a contact lens, a substantially opposing second lens-defining surface presenting a negative of an optically-functional back surface of a contact lens, a flange region surrounding the first and second lens-defining surfaces, and

an elongated zone extending generally radially outward from the flange zone, the elongated zone including a first portion having a generally uniform width and a second portion having a diverging width, the second portion being adjacent the flange zone and thinner than the first portion of the elongated zone;

wherein the first lens defining surface and the second lens defining surface are located on a single contact lens mold section; and is

Wherein the length of the elongate region is at least as large as the diameter of the first lens-defining surface.

2. The mold section of claim 1 wherein the elongated region has a length greater than an outer diameter of the flange region.

3. The mold section of claim 2 wherein the length of the elongated region is at least about 15 mm.

4. The mold section of claim 2, wherein the length of the elongated region is between about 30mm and about 35 mm.

5. The mold section of claim 2, wherein the first portion of the elongated region has a thickness between about 0.5mm and about 3.0 mm.

6. The mold section of claim 1 further comprising indicia located on the elongated region.

7. The mold section of claim 6, wherein the indicia comprises a surface of the elongated region that is roughened relative to another surface of the elongated region.

8. The mold section of claim 6 wherein the indicia is a machine readable surface.

9. The mold section of claim 1, wherein the flange region comprises at least one non-circumferential groove.

10. The mold section of claim 9, wherein the groove extends into the flange region from a surface of the flange region adjacent to the second lens defining surface.

11. The mold section of claim 1 wherein the elongated region is substantially flat along its entire length.

12. The mold section of claim 1 wherein at least one lens defining surface has a shape effective to produce a toric contact lens.

13. A mold assembly comprising a first mold section comprising a lens-defining region, the lens-defining region having a first lens-defining surface presenting a negative of an optically-functioning front surface of the contact lens, a substantially opposing second lens-defining surface presenting a negative of an optically-functioning back surface of the contact lens, a flange region surrounding the first lens-defining surface and the second lens-defining surface, and an elongated region, extending generally radially outward from the flange zone, the elongated zone including a first portion having a generally uniform width and a second portion having a diverging width, the second portion being adjacent the flange zone and thinner than the first portion of the elongated zone, wherein the first lens defining surface and the second lens defining surface are located on a single first mold portion, and wherein the length of said elongate region is at least as large as the diameter of said first lens-defining surface; the mold assembly also includes a second mold section substantially identical to the first mold section, the second mold section coupled with the first mold section to define a lens-shaped cavity between the first lens-defining surface of the first mold section and the second lens-defining surface of the second mold section.

14. The assembly of claim 13 wherein the coupling mold sections define a first contact region located radially outside of the lens-shaped cavity and a second contact region located radially outside of the first contact region.

15. The assembly of claim 13, further comprising a polymerizable silicon-containing composition in the lens-shaped cavity.

16. Use of the mold section of claim 1 for the manufacture of a silicone hydrogel contact lens.

17. A method of manufacturing a contact lens mold section, comprising:

directing molten thermoplastic material into a single mold cavity, wherein

The mold cavity comprises a first optical performance insert surface and an opposing second optical performance insert surface; a mold flange defining region surrounding the first and second optical performance insert surfaces, the first and second optical performance insert surfaces defining first and second generally opposed lens defining surfaces of a contact lens mold section; and an elongate channel extending generally radially outwardly from said mold flange defining region, said elongate channel comprising a first portion having a generally uniform width and a second portion having a diverging width, said second portion being adjacent to said mold flange defining region and being thinner than said first portion of said elongate channel, wherein the length of said elongate channel is at least as large as the diameter of said first lens defining surface.

18. The method of claim 17, further comprising forming machine-readable indicia on the mold portion by providing first and second discontinuities along the elongated channel having different roughnesses.

19. The method of claim 17, wherein the first optical quality insert surface is a surface of an insert located in a first plate of a removable change plate assembly and the second optical quality insert surface is a surface of an insert located in a second plate of the removable change plate assembly, and further comprising retaining the mold portion formed in the mold cavity on one change plate when the first plate and the second plate are separated from each other.

20. The method of claim 17, wherein the first optical performance insert surface is a surface of an insert located in a first plate of a removable change plate assembly and the second optical performance insert surface is a surface of an insert located in a second plate of the removable change plate assembly, and further comprising cooling the change plate assembly.

21. The method of claim 17, wherein the first optical performance insert surface is a surface of a single piece insert and the second optical performance insert surface is a surface of a single piece insert.

22. A contact lens mold injection molding system comprising at least one mold section as recited in claim 1.

23. A method of manufacturing a plurality of contact lenses having different specifications, comprising:

a plurality of single-piece contact lens mold sections are manufactured in a number of mold cavities,

each one-piece contact lens mold section comprising a lens defining region having a first lens defining surface presenting a negative of the optical quality anterior surface of the contact lens and having a first radius of curvature, a second, substantially opposed lens defining surface presenting a negative of the optical quality posterior surface of the contact lens and having a second radius of curvature, a flange region surrounding the first and second lens defining surfaces; and an elongate region extending substantially radially outward from said flange region, wherein a length of said elongate region is at least as large as a diameter of said first lens-defining surface, an

Various combinations of the single piece contact lens mold sections are used to produce a plurality of contact lenses having a plurality of different specifications, wherein the number of different specifications of the plurality of contact lenses is equal to the square of the number of mold cavities.

24. The method of claim 23, wherein each mold cavity includes a removable optical insert, and the number of specifications for the plurality of contact lenses is obtained without removing the optical insert.