Casting lenses with surface microstructures

Abstract

A mold element (350) is manufactured (305, 310, 315) using a first mold (5), wherein the microstructures (323) are integrally formed in relief on the mold element (350). A lens (340) is cast (320, 325, 330, 335) using a second mold (7) comprising the mold element (350), such that the microstructures (337) are integrally formed on the lens (340).

Description

background Technical Field

[0002] This disclosure relates to the casting of thermosetting lenses with microstructures on their surfaces. More specifically, instead of using typical glass or metal molds, plastic molds with microstructures on their surfaces are proposed for casting lenses. Optionally, the plastic mold may be pre-coated with a reverse hard multi-coating (HMC) stack to produce HMC-coated thermosetting lenses with surface microstructures. Background Technology

[0004] Myopia is a prevalent eye condition; according to the Brian Holton Vision Research Institute in Australia, approximately 23% (1.4 billion people) worldwide were myopic in 2000, and this figure is projected to reach 50% (4.8 billion people) by 2050. High myopia increases the risk of vision-threatening problems such as retinal detachment, cataracts, and glaucoma. Therefore, slowing the progression of myopia in children is crucial. Several studies in recent years have shown that using microlenses on the anterior (convex) surface of conventional single-vision (SV) lenses to introduce peripheral myopic defocus is highly effective in slowing myopia progression.

[0005] Casting thermoset lenses with surface microlenses (or other microstructures, such as Fresnel) requires molds with microlenses on concave or convex surfaces. However, even with micromachining, manufacturing glass molds with precise microlenses on their surfaces is technically infeasible. Furthermore, nickel molds replicated directly from master molds are extremely expensive, especially considering the large number of molds required for the casting operation. Therefore, a cost-effective solution for manufacturing casting molds with surface microlenses and / or other microstructures is crucial for the reasonable cost and widespread availability of thermoset lenses with surface microlenses, particularly for those in need to help combat the myopia epidemic. Summary of the Invention

[0006] One method according to this disclosure includes:

[0007] A thermoplastic mold element is manufactured using a first mold via thermoplastic injection molding, wherein a microstructure is integrally formed on the thermoplastic mold element in a concave-convex form; and

[0008] The lens is cast using a second mold and a thermosetting casting technique. The second mold includes the thermoplastic mold element, which causes a microstructure pattern to be integrally formed on the lens, wherein the microstructures on the thermoplastic mold element are raised or recessed relative to the microstructure pattern on the lens.

[0009] These cast thermosetting lenses are typically ophthalmic lenses. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of a thermoplastic injection molding process that can be used in conjunction with embodiments of this concept.

[0011] Figure 2 This is a schematic block diagram of a thermosetting casting process for lenses that can be used in conjunction with embodiments of this concept.

[0012] Figure 3 This is a schematic block diagram illustrating the example lens casting process that can be implemented in this embodiment.

[0013] Figure 4 This is a schematic block diagram of an optional coating process that can be used in conjunction with this embodiment.

[0014] Figure 5 This is a flowchart illustrating an exemplary lens casting process that can be implemented in this embodiment. Detailed Implementation

[0015] This disclosure is best described by way of certain embodiments thereof, which are described in detail herein with reference to the accompanying drawings, wherein similar reference numerals always refer to similar features. It should be understood that, when used herein, the term “disclosure” is intended to refer to the inventive concept upon which the embodiments described below are based, and not merely the embodiments themselves. It should also be understood that the general inventive concept is not limited to the illustrative embodiments described below, and the following description should be read in this manner.

[0016] Furthermore, the term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment of a construction, process, design, technique, etc., specified herein as exemplary is not necessarily to be construed as being more preferred or advantageous than other such embodiments. Specific qualities or suitability of examples indicated herein as exemplary are neither intended nor should be inferred.

[0017] Figure 1This is a schematic block diagram of a typical thermoplastic injection molding process 100. In operation 110, a mold cavity 115 is formed between a concave (CV) mold insert 112 and a smooth convex (CX) insert 114. The concave mold insert has concave microlenses disposed on its concave surface, which are typically shown at microlenses 117 and are typically referred to herein as microlenses(a plurality of) 117. Each microlens 117 may be configured with specific optical properties, such as focal length, numerical aperture, etc. In operation 120, molten thermoplastic (e.g., polycarbonate (PC), poly(methyl methacrylate) (PMMA), and polyamide (PA, also known as Nylon)) is injected into the cavity 115. The mold can be cooled, and after the cooling period, process 100 can transition to operation 130, whereby the SV lens 135 having the microlenses 137 disposed on its convex surface can be ejected from the mold or otherwise released.

[0018] Typically, the CV insert 112 is a steel insert with a nickel-phosphorus (NiP) plating. The concave microlens 117 is created in the insert by micromachining the NiP. This method has been shown to successfully produce SVPC lenses with microlenses on CX surfaces, such as SV lens 135 with microlenses 137 disposed thereon, with good quality.

[0019] Figure 2 This is a schematic block diagram of the thermosetting casting process 200 for lenses. Casting thermosetting lenses with surface microstructures such as microlenses remains very challenging. One difficulty is the lack of a cost-effective solution for manufacturing casting molds with concave microlenses (convex microlenses in a concave-convex form) on their surfaces. Figure 2 As shown, the thermosetting lens casting process 200 uses a mold 10 comprising two mold elements 212 and 214, which are sealed with a gasket 215 or other sealing mechanism (such as tape). In operation 210, a cavity 217 is formed by means of the gasket 215, which keeps the two mold elements 212 and 214 separate from each other. In operation 220, the cavity 217 of the mold 10 is filled with a monomer 222. After filling, process 200 transitions to operation 230, whereby the entire mold 10 is placed in an oven to thermocure the monomer for several hours. In operation 240, the resulting lens 248 is demolded from the mold 10.

[0020] Unlike continuous injection molding process 100, thermoset lens casting process 200 (especially the curing step) is a very lengthy batch process that requires processing many mold components simultaneously to meet volume requirements and cost targets. Therefore, the number of molds required for thermoset lens casting operations is enormous. Typically, glass and / or nickel replicas are used to construct the casting molds. Due to the high cost, the molds must be cleaned and reused, necessitating very extensive mold cleaning operations.

[0021] There is a need for a cost-effective solution for manufacturing casting molds with surface microlenses and / or other microstructures. Embodiments of the present invention produce casting mold elements via injection molding. As described above, SV PC lenses with microlenses on the CX surface can be successfully produced by injection molding. Therefore, one idea of ​​this disclosure is to use PC (or other thermoplastic) lenses as mold elements with surface microlenses (or other microstructures) to cast thermoset lenses.

[0022] Figure 3 This is a schematic block diagram of an example lens casting process 300 that can implement the contents of this disclosure. Operations 305, 310, and 315 can be similar to those in the reference. Figure 1 Operations 110, 120, and 130 are described and performed. Specifically, the first mold 5, comprising the CV insert 312 and CX insert 314 forming a cavity 315 therebetween, is filled with thermoplastic, cooled, and ejects the lens 350. However, in this case, the lens 350 is a component of the second mold 7 used to cast the final thermoset lens 340, and will be referred to herein as mold element 350 of mold 7. It should be noted that the microstructures formed on the CX insert 314 are the same as those appearing in the final lens 340, meaning that the microstructures on mold element 350 are in a raised / concave form relative to the manner in which the microstructures are set on the final lens 340.

[0023] Once the mold element 350 has been manufactured, operations 320, 325, 330, and 335 of process 300 can be performed similarly to those in the reference. Figure 2 Operations 210, 220, 230, and 240 are described and performed. Specifically, mold element 350 can be paired with a second mold element 324, which can be manufactured using a process similar to that used to manufacture mold element 350. The mold pair 350 and 324 can be held apart by a gasket 321 to form a chamber or cavity 327 therebetween. Cavity 327 (which includes a microstructured pattern 323) can be filled with a monomer 322, which is then cured and demolded into a lens 340 having a microstructured pattern formed on its CX surface.

[0024] Figure 4This is a schematic block diagram of an optional coating process 400 that can be used in conjunction with this disclosure. The PC mold 9 may include mold elements 350 and 324, and the aforementioned gasket 321, wherein mold element 350 has surface microlenses formed thereon in a concave-convex form. Furthermore, in operation 410, a reverse hard multi-coating (HMC) stack 442 may be applied to the mold 9 such that in operation 420 the HMC stack 442 is appropriately transferred to the resulting thermosetting lens 340. Another advantage of doing so is that the microlens design is preserved, which is typically affected by the application of the hard coating.

[0025] Figure 5 This is a flowchart of an exemplary lens casting process 500 that can implement this concept. In operation 505, a microstructure is formed on a first mold, and in operation 510, the first mold is filled with thermoplastic. In operation 515, it is determined whether the thermoplastic has solidified; if so, process 500 can transition to operation 520, in which a second mold is formed from mold elements produced by a thermoplastic injection molding operation. In operation 525, HMC can be applied to the microstructure side of the thermoplastic mold elements, and in operation 530, the second mold is filled with a thermosetting monomer, such as one of the monomers described herein. In operation 535, the second mold is heated below its glass transition temperature, as described below. In operation 540, it is determined whether the thermosetting plastic has sufficiently solidified; if so, in operation 545, the resulting lens with the microstructure formed thereon can be removed from the second mold.

[0026] Other variations of this disclosure may also be implemented. For example, microstructures may be placed on the surface of a convex PC mold to produce a thermosetting lens with microstructures on a concave surface. Alternatively, microstructures may be present on both the concave and convex PC molds to cast a thermosetting lens with microstructures on both sides. Furthermore, a reverse HMC stack may be applied to a convex PC mold to produce a lens with HMCs on both sides, which is particularly suitable for casting finished lenses.

[0027] Furthermore, besides PC, many transparent or opaque thermoplastic materials (such as polyamide, polysulfone, polyester, and polyetheretherketone (PEEK)) can be used to produce casting molds. When the mold material is UV-transparent, like many transparent thermoplastics that do not contain UV absorbers (UVA), UV-curable monomers can be used to replace or supplement thermocurable monomers to cast lenses. The main limitation is that the glass transition temperature (Tg) of the mold material needs to be significantly higher than the curing temperature (Tc) of the casting process. 固化 This is to prevent mold deformation from causing poor optical performance of the resulting lens. Preferably, Tg ≥ T. 固化+20 (°C). Special attention should also be paid to the thermal expansion of the mold material, as this can lead to dimensional errors in the resulting thermosetting lenses, especially in the surface microstructure. The thermal expansion of thermoplastics is typically characterized by the "coefficient of linear thermal expansion (CTE)" in ISO 11359-2. It is preferable to keep the CTE ≤ 1E-4 (1 / °C) to avoid dimensional errors in the cast lenses.

[0028] Although this disclosure describes the casting of thermoset lenses via injection molding using thermoplastic molds, molds can also be constructed by directly micromachining plastic lenses or blocks. Of course, this method is not as cost-effective as injection molding. However, it is still a lower-cost solution than using nickel molds.

[0029] Examples of monomers that can be used in this disclosure include allyl carbonates, acrylates, isocyanates and thiols, cyclic sulfides, etc.

[0030] Finally, some advantages of this embodiment are: thermosetting casting molds with surface microstructures can be mass-produced using NiP-plated steel inserts via PC injection molding; the cost of PC molds is significantly lower than nickel replicas, they are disposable, and they can be recycled. In addition to thermosetting monomers, UV-curable monomers can also be used. Pre-coating the PC mold with HMC maintains the accuracy of the microlens design, thereby preventing optical errors due to the hard coating.

[0031] The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of the systems and methods according to various embodiments of this disclosure. In this respect, each box in a flowchart or block diagram may represent a module, segment, or portion of code, which includes one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions marked in the boxes may not appear in the order indicated in the figures. For example, two boxes shown consecutively may actually be executed substantially simultaneously, or sometimes these boxes may be executed in reverse order, depending on the functions involved. It will also be noted that each box in the block diagrams and / or flowcharts, and combinations of boxes in the block diagrams and / or flowcharts, may be implemented by a system based on dedicated hardware or a combination of dedicated hardware and computer instructions that performs the specified function or action.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the embodiments. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of declared features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more features, integers, steps, operations, elements, components, and / or groups thereof.

[0033] All means or steps in the following claims, plus the corresponding structures, materials, actions, and equivalents of the functional elements, are intended to include any structure, material, or action for performing a function in conjunction with other claimed elements as specifically claimed. The description in this disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limiting to the form of the disclosure. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of this disclosure. The embodiments were chosen and described in order to best explain the principles and practical application of the invention and to enable others skilled in the art to understand the disclosure of various embodiments with various modifications suitable for the particular intended use.

[0034] The foregoing description is intended to illustrate possible implementations of the inventive concept and is not restrictive. Many variations, modifications, and substitutions will become apparent to those skilled in the art upon reading this disclosure. For example, components equivalent to those shown and described can be replaced, allowing for the combination of individually described elements and methods, and discrete elements can be distributed across many components. Therefore, the scope of this disclosure should not be referred to in connection with the foregoing description but rather determined by reference to the appended claims and all their equivalents.

Claims

1. An injection molding method, comprising: Using a first mold (5), a thermoplastic upper mold element (350) is manufactured (305, 310, 315) by thermoplastic injection molding, wherein microstructures (323) are integrally formed on the thermoplastic upper mold element (350) in a concave-convex form; as well as For the second mold (7, 9), a thermoplastic upper mold element (350), a thermoplastic lower mold element (324), and a gasket or tape (321) are used to cast (320, 325, 330, 335) lens (340) in the second mold (7, 9) by thermosetting casting technology to keep the thermoplastic upper mold element (350) separate from the thermoplastic lower mold element (324) and thereby form a cavity (327), filling the cavity with monomer (322) and curing it by thermosetting, so that a microstructure pattern (337) is integrally formed on the lens (340), wherein the microstructure (323) on the thermoplastic upper mold element (350) is concave-convex relative to the microstructure pattern (337) on the lens (340).

2. The method as described in claim 1, wherein, The thermosetting casting process (320, 325, 330, 335) includes using (320) thermoplastic material for the thermoplastic lower mold element (324).

3. The method as described in claim 2, wherein, The thermoplastic lower mold element (324) is manufactured by thermoplastic injection molding.

4. The method of claim 2, wherein, In the thermoplastic injection molding manufacturing steps (305, 310, 315), the thermoplastic upper mold element (350) and the thermoplastic lower mold element (324) are made of a polymer, which is one of polycarbonate, alicyclic polycarbonate copolymer, poly(methyl methacrylate), poly(methacrylimide), thermoplastic polyurethane, cyclic olefin copolymer, polyacrylate, polyamide, polysulfone, polyester and polyetheretherketone, or any combination thereof.

5. The method of claim 4, wherein, In the thermoplastic injection molding manufacturing steps (305, 310, 315), both the thermoplastic upper mold element (350) and the thermoplastic lower mold element (324) are manufactured by thermoplastic injection molding (305, 310, 315) from the same polymer.

6. The method of claim 1, further comprising: Before casting the lens (340), a hard multi-coating layer (442) is applied (410) to the thermoplastic upper mold element (350). as well as Remove (545) the lens (340) from the second mold (9) such that the hard multi-coating (442) is transferred (420) to the lens (340).

7. The method of claim 1, further comprising, in the thermosetting casting process (320, 325, 330, 335), heating the second mold (7, 9) to a temperature below the glass transition temperature of the thermoplastic upper mold element (350) to solidify the monomer into the lens (340).

8. The method of claim 1, wherein, In the thermoplastic injection molding manufacturing steps (305, 310, 315), the first mold (5) includes metal inserts (312 and 314), wherein at least one (314) has a micro-machined microstructure (317) thereon micro-machined to form the microstructure (323) in a concave-convex form on the thermoplastic upper mold element (350).

9. The method of claim 1, wherein, The microstructure (323) is a microlens optically configured with its own focal point.

10. The method of claim 9, wherein, The lens (340) is a single-vision lens used to correct myopia.

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