Eyewear lens fabrication method using additive manufacturing technology with diffuse light

Abstract

A system and method for lens fabrication are disclosed. The method includes initiating the transmission of light from a light source through a diffuser into a container holding a resin and a substrate. The light transmission is performed according to an illumination pattern in which each point in the resin is illuminated by at least 10% of the diffuser. This results in the formation of a lens. To achieve this illumination, at least 15% of the diffuser receives light from the light source. Furthermore, the diameter of the diffuser is greater than or equal to the diameter of the substrate. A system for performing the method includes a polymerization device, and can also include a resin preparation and storage device, a metering unit, a resin discharge device, and optionally a secondary curing device.

Description

[Technical Field] 【0001】 This invention relates to the manufacture of ophthalmic lenses, and more particularly to the manufacture of ophthalmic lenses using additive manufacturing technology. [Background technology] 【0002】 Current eyeglass lens manufacturing technology is based on a cutting and polishing technique called "freeform." This process requires multiple machines, including cutters, generators, and polishers. These machines are expensive and bulky, and their maintenance requires considerable expertise. Furthermore, this technology generates a lot of waste and requires numerous consumables, some of which are hazardous. This technology also necessitates a large inventory of semi-finished lenses. In short, setting up a freeform manufacturing facility requires a significant financial investment, a large workforce, and large facilities. For these reasons, lens manufacturing remains the domain of large corporations. [Overview of the project] [Problems that the invention aims to solve] 【0003】 With the advent of 3D printing, efforts to manufacture lenses using 3D printing technology have begun. However, current 3D printing systems for lens manufacturing are large and very expensive. Furthermore, it is extremely time-consuming, taking as long as 15 minutes to produce a single lens. While approaches based on variations of SLA (stereolithography) are inexpensive, they are still bulky and time-consuming. 【0004】 One 3D printing technology used for lens manufacturing is called "resin jetting." This method involves layering the lens one layer at a time onto a flat surface. These layers consist of tiny UV-curable droplets, and by smoothing the resulting surface, a surface with sufficient optical quality can be obtained. However, resin jetting technology has major drawbacks. One of them is the manufacturing time. It is said that it takes about an hour to print a single lens using resin jetting. This is because it is time-consuming due to the layering process. Furthermore, the machines required to implement resin jetting technology are large and require a large footprint. They are also more expensive than the set shutoff, generator, and polishing equipment required for "freeform" subtractive manufacturing technology. 【0005】 Another drawback of resin jetting technology is that it can only produce lenses with flat surfaces. This is a problem because eyeglass lenses are usually curved or have an uneven shape. One solution is to combine two lenses with flat surfaces to create a single lens with an uneven shape. However, this requires two printing processes, which is time-consuming. Also, the resulting lens becomes significantly thicker. [Means for solving the problem] 【0006】 To enable lens fabrication in ophthalmologists' offices and small and medium-sized enterprises, a simple, rapid, inexpensive, and compact lens fabrication system is needed. and methods It is necessary. Therefore, in order to solve this problem, the present invention provides a method for manufacturing eyeglass lenses, comprising the steps of receiving input information including a lens prescription and wearer information, The present invention provides a method comprising the steps of: calculating a manufacturing instruction based on the input information, wherein the manufacturing instruction includes 1) an irradiation pattern, an exposure time for forming a lens having a lens prescription and wearer information using the transmission of light from the irradiation pattern, and 3) a resin composition; initiating the transmission of light from a light source through a diffuser to a container containing a resin and a substrate, wherein the transmission of light is carried out according to the irradiation pattern, and each point of the resin is illuminated by at least 10% of the area of ​​the diffuser; and stopping the transmission of light when the formed lens satisfies the manufacturing instruction, wherein one polymerization front has the shape of a target surface of an eyeglass lens that conforms to the manufacturing instruction. [Brief explanation of the drawing] 【0007】 [Figure 1A] This is a diagram showing a directional light beam. [Figure 1B] This figure shows an omnidirectional light beam. [Figure 2] This is a diagram showing light propagation within a resin. [Figure 3]It is a diagram showing the propagation of patterned light in a resin. [Figure 4] It is a photograph of a lens fabricated with directional light. [Figure 5] It is a diagram showing the influence of a light diffuser on directional light. [Figure 6] It is a schematic diagram of a system for monomer polymerization for lens fabrication. [Figure 7A] It is a schematic diagram of a first aspect of a polymerization apparatus. [Figure 7B] It is a schematic diagram of a second aspect of a polymerization apparatus. [Figure 8] It is an image showing the incident irradiance pattern. [Figure 9] It is an image showing the deflection of a fringe pattern. [Figure 10] It is a schematic diagram of an exemplary measurement apparatus. [Figure 11] It is a schematic diagram of an exemplary resin discharge apparatus. [Figure 12] It is a schematic diagram of an exemplary secondary curing apparatus. [Figure 13] It is a flowchart showing the operations taken to form a lens using the systems and methods described herein. 【Mode for Carrying Out the Invention】 【0008】 The methods and systems described herein are systems for making eyeglass lenses using a stereolithography technique and light passed through a diffuser according to fabrication instructions based on a wearer's prescription and usage requirements. The fabrication instructions also include specifications for the irradiation pattern. According to the systems and methods described herein, light is transmitted from a light source through a diffuser into a container holding a resin and a substrate. The transmission of light is performed according to the irradiation pattern. The irradiation pattern includes instructions specifying that each point of the resin is illuminated by at least 10% of the diffuser. In some embodiments, at least 15% of the diffuser receives light from the light source to achieve this illumination intensity. Further, in some embodiments, the diameter of the diffuser is greater than or equal to the diameter of the substrate. Additional details regarding the system and method will be described later. 【0009】 The methods and systems described herein are systems for making eyeglass lenses that are simpler than current "freeform" techniques. The systems described herein are lightweight, have limited moving parts, produce less waste compared to "freeform" fabrication, and use very few consumables. As a result, a more inexpensive system can be realized that allows small and medium-sized enterprises, including optical shops, to enter the business of making eyeglass lenses. 【0010】 To better understand the systems and methods described herein, an understanding of directed light beams and non-directed light beams is useful. FIGS. 1A and 1B show the comparison results between a directed light beam and a non-directed light beam. A directed light beam is a beam of light in which the radiance at any point within the beam has a non-negligible value within a narrow solid angle around a single direction. Examples of directed light beams include parallel beams or spherical beams from a point source. A non-directed (or diffused) light beam is a beam of light in which the radiance at any point within the beam has a non-negligible value for a finite range of directions. According to the systems and methods described herein, the non-directed beam is produced by light passing through a light diffuser. 【0011】 Referring here to Figure 1A, a directional light beam (100A) is shown. For any point (101A) in the directional light beam (100A), the radiance is a non-negligible value along one direction (102A). In the nearby direction (103A), the radiance is zero or low, and in other directions it is zero. Referring here to Figure 1B, when the directional light beam (100B) passes through a light diffuser (104), the directional light beam becomes omnidirectional or diffuse (105). This is characterized by having a non-negligible radiance in a large set of directions (102B), (103B) for any point in the diffuse light beam (101B). The systems and methods described herein include a diffuser that directs light to cause a polymerization reaction in a resin in order to produce eyeglass lenses. 【0012】 [Polymerization of photocurable resins] Photopolymerization is a type of polymerization in which light is used to initiate the polymerization reaction. There are two routes for this: free radical polymerization and ionic polymerization. Most examples of this invention are based on free radical polymerization, but ionic polymerization can also be used. This reaction is induced by a photosensitive component called an initiator, which is mixed into the liquid monomer. Typically, the wavelength of light is in the ultraviolet range (e.g., UV-A or chemical UV). However, some initiators are activated by visible light or other wavelengths. In some embodiments, the initiator has an absorption band in the range of 360 nm to 390 nm. 【0013】 As used herein, the term “resin” refers to a mixture comprising a monomer base, an initiator, and, in some embodiments, a polymerization inhibitor. That is, the polymerization inhibitor is optional. The resin is in a liquid state and may contain other components such as stabilizers and light absorbers. Exemplary resin bases include acrylates, epoxy, methacrylates, isocyanates, polythiols, thioacrylates, and thiomethacrylates. Exemplary acrylate resins include pentaerythritol tetraacrylate and 1,10-decanediol diacrylate. The initiator may be free radical or cationic. When using free radical polymerization, exemplary initiators include benzophenone, BAPO (bisacylphosphine oxide), acetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (Irgacure 2959(c) by CIBA), alpha-aminoketone, HAP (2-hydroxy-2-methyl-1-phenyl-propan-1-one), and TPO (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide). When using cationic photopolymerization initiators, exemplary initiators include aryldiazonium salts, triarylsulfonium salts, ferrocenium salts, and diaryliodonium salts. An exemplary polymerization inhibitor is hydroquinone. 【0014】 When an initiator molecule absorbs ultraviolet photons, the molecule is separated into free radicals, which react with monomers. This reaction yields monomers bound to the free radicals. These then react with more monomer molecules to produce polymers with increased molecular weight. This reaction terminates when the chain ends of the free radicals are neutralized. This can typically occur by termination or chain transfer to a polymerization inhibitor. 【0015】 The reactions that occur during polymerization are dissociation, initiation, propagation, termination, and chain transfer to polymerization inhibitors. These are represented by the following equations. 【0016】 【Number】 【0017】 Here, [A] is the concentration of the initiator, [R·] is the concentration of free radicals, [M] is the concentration of the monomer, [M·] , , , , 【0021】 , 【0022】 , , , is an active (with free radicals attached) polymer consisting of i monomers, [M] i is a stable polymer consisting of i monomers, [Z] is a specific polymerization inhibitor that may exist, [M n Z] represents the concentration of the polymer reacted with the polymerization inhibitor. The parameter k d , k i , k p , k t , and k z represent the rate constants for each reaction. I abs represents the amount of energy of the UV radiation absorbed by the initiator. 【0018】 These reactions are generally realized assuming a steady state, and the free radicals generated by the dissociation of the photoinitiator are consumed by the polymerization termination reactions (both recombination and inhibition). The rate of change of the monomer concentration is obtained by the following equation. 【0019】 【Number】 【0020】 In this equation, the concentration [Z] of the polymerization inhibitor may depend on time. The variable φ represents the quantum efficiency of the initiator. Also, k z , k t、 and k p depend on temperature through the Arrhenius relationship. For example, k p is obtained by the following equation. 【0021】 【Number】 <00​​po E is a constant. p Here, is the energy involved in the propagation reaction, and R is the gas constant. Since the polymer propagation reaction is exothermic, the motion constant is expected to change over time. 【0023】 Solving differential equation (2) requires a numerical integration algorithm, but under certain approximations, an analytical solution is shown herein. When applying the method herein, a numerical solution of equation (2) can be used, and an approximate analytical solution can also be used depending on the required precision. In the absence of polymerization inhibitors and at a constant temperature, the monomer concentration over time can be determined by the following equation: 【0024】 【number】 【0025】 Here, M0 is the initial monomer concentration. The polymer produced simultaneously with the monomer is consumed during polymerization. The degree of conversion c is the proportion of monomer converted into polymer and is calculated by the following equation. 【0026】 【number】 【0027】 As the conversion rate increases, the viscosity of the medium increases. The conversion is critical. cr When it reaches a point called , the viscosity increases exponentially, and the mixture solidifies due to the low mobility of large polymer molecules and / or the high crosslinking density between polymer chains. 【0028】 When directional light is irradiated onto a photocurable resin, the irradiance per unit length absorbed by the initiator after propagating through the resin at depth z can be calculated from the Lambert-Beer law using the following equation. 【0029】 【number】 【0030】 Here, α represents the molar absorption coefficient of the initiator, z represents the depth inside the material, γ represents the absorption coefficient of the resin without the initiator, and I0 represents the input intensity. Therefore, absorption is maximum in the initial stage of the material and decays exponentially within it. 【0031】 When directional light is shone onto the resin in the container, the polymerization rate is faster closer to the material interface and decreases exponentially within the material. As shown in Figure 2, a specific portion of the material reaches a critical transformation at a given time. Below this point, all the material becomes solid, while above it remains liquid. This region is called the "polymerization front" and is indicated by reference numeral 240. Referring to Figure 2, the propagation of light 200 through a transparent substrate 220 in a container 210 holding resin 230 is shown. The dashed line 250 represents a surface with the same irradiance. 【0032】 During exposure to light, the polymerization front propagates logarithmically within the resin 230. When exposure stops, a layer of thickness dependent on the exposure time is formed. The thickness of the cured material can be determined by the following formula. 【0033】 【number】 【0034】 Equation (7) can only be applied to directional light if all parameters are constant with respect to time. 【0035】 As shown in Figure 3, when projected light is patterned, the shape of the polymerization front conforms to the radiance pattern. Figure 3 shows the propagation of light 300 through the resin 330 inside the container 310. Here, the light is directional, but it shows a lateral distribution that modifies not only the shape of the polymerization front 340 but also the shape of a surface with the same irradiance 350. 【0036】 When the combination of exposure time and input UV irradiance pattern is correctly adjusted, the shape of the polymerization front can be controlled according to equation (7), and can be controlled more precisely by numerical integration of equation (2). Using this technique, various three-dimensional objects can be fabricated. However, as will be discussed later, the resulting three-dimensional objects typically lack transparency and optical quality due to self-focusing. Therefore, this technique, which utilizes directional light, alone cannot be used to fabricate eyeglass lenses. 【0037】 As used herein, “eyeglass lenses” refers to any type of eyewear worn at a slight distance from the wearer’s eyes. Examples of eyeglass lenses include spherical lenses, aspherical lenses, progressive lenses, bifocal lenses, trifocal lenses, lenticular lenses, and slab-off lenses. A typical formed eyeglass lens may have a diameter of 40mm to 80mm and a thickness of 2mm to 8mm. The systems and methods described herein may also be used to produce larger and smaller lenses, as well as thinner and thicker lenses. 【0038】 The systems and methods described herein are used to manufacture spectacle lenses which may have a fixed surface or a freeform surface. In the case of fixed-surface lenses, the lens is manufactured from a resin that adheres to a substrate. As shown in Figures 2 and 3, the fixed surfaces of substrates 220 and 320 are flat, but the substrate can have any shape. The most convenient substrate shape for spectacle lenses is spherical. However, it is also possible to use more complex substrate surfaces, such as aspherical, torus, non-torus, and multifocal. In some embodiments, electronic circuits or image forming systems can be embedded in the substrate. In other embodiments, the substrate is configured or reinforced to allow the manufacture of lenses with a large edge thickness. In one such embodiment, the substrate may be aspherical or lenticular toward the edge to increase the amount of resin that can be held. In another such embodiment, a cylindrical wall is attached to the edge of the substrate to increase the amount of resin that can be held. The substrate may be made from polycarbonate, allyl diglycol carbonate, polyurethane-based plastic, glass, or similar materials, and may be CR-39® or TRIVEX®, registered trademarks of PPG Industries Ohio, Inc., Cleveland, Ohio. 【0039】 In the embodiments described herein, the fixed surface represents the surface furthest from the eye. In other embodiments, the order can be reversed so that the fixed surface represents the surface closest to the eye. The freeform surface is the surface determined by the position of the polymerization front. In the following embodiments, the freeform surface is the surface closest to the eye. 【0040】 [Self-convergence] As described above, by using a directional light beam with an appropriate irradiance distribution, the polymerization front of the resin can be controlled, thus providing eyeglass lenses with the desired freeform surface shape. However, directional light beams are prone to introducing strong defects into the polymer due to the so-called self-focusing effect. The refractive index of this polymer is usually slightly greater than that of the liquid resin. If there is a small deviation in the local value of the irradiance incident on the liquid resin (this deviation may be present in the profile as noise unavoidable with directional light, or it may be due to dust or defects on the transparent surface holding the resin, or it may arise from the pixel structure of the projector), a local change in refractive index occurs, locally focusing the irradiance. This creates a positive feedback loop, resulting in characteristic needle-shaped defects along the direction of light propagation. As a result, the resulting polymer loses its transparency, and the freeform surface becomes rough. This results in the resulting object having no optical quality or low optical quality. This is illustrated in Figure 4, which includes an image of a lens fabricated with directional light. Here, 410A is a top view and 410B is a perspective view. To overcome this, the methods and systems described herein use diffuse light instead of directional light. 【0041】 [Light diffuser] When a light diffuser is placed between the projector and the resin, the light from each radiating pixel is scattered at multiple angles so as not to follow the initial direction from the projector (see the description of Figures 1A and 1B above). To implement the method described herein, it is desirable to prepare a diffuser plate with properties that approximate Lambert's cosine law as closely as possible. As will be described later, the properties of the diffuser are evaluated using the bidirectional transmission distribution function (BTDF) to measure how close the diffuser is to an ideal Lambert. In an ideal diffuser, the radiance follows Lambert's cosine law. Measurements using BTDF are performed to evaluate the properties of the diffuser. The diffuser is formed from a light diffusing material containing glass and a polymer manufactured with a light-diffusing additive. More specifically, the diffuser may be formed from opal glass, white glass, and an acrylate sheet containing a calcium carbonate additive. In one embodiment, an exemplary light diffuser is a 2 mm thick acrylate sheet formed from 3.3 wt% CaCO3 additive. 【0042】 Referring to Figure 5, a schematic diagram illustrating the effect of the light diffuser 501 on light 502 is shown. The light source 500 directs radiant energy (i.e., light) 502 toward the diffuser 501. The light source 500 may be, for example, an ultraviolet digital photoprocessing (UV DLP) projector or a scanning UV laser. For example, the projector 500 may emit radiation (i.e., UV light) with a peak at 385 nm. The light 502 emitted by the light source has high directivity. Since the diffuser 501 scatters light in all directions, any point Q on the diffuser will emit light in all directions. The radiance of the scattered light depends on the bidirectional transmission distribution function of the diffuser. Therefore, the luminous flux reaching any point P behind the diffuser has contributions from multiple points 503 on the diffuser. 【0043】 According to the systems and methods described herein, the diffuser is placed inside, preferably at the bottom, of a resin container, vat, or chamber. When the diffuser is located at the bottom of a resin-filled container, each point in the resin receives light from multiple points on the diffuser and from multiple directions. In one embodiment, each point in the resin receives light from at least 10% of the diffuser's area. In this way, the light transmitted from the diffuser to the resin is non-directional, eliminating the self-focusing problem described above. To achieve this, i.e., most of the diffuser is illuminated such that every point in the resin receives light from multiple light source positions of at least 10% of the diffuser's area. Specifically, in some embodiments, at least 15% of the diffuser's area is illuminated by light sources. Otherwise, self-focusing will remain or cannot be completely eliminated. Illuminating each point in the resin with at least 10% of the light from the diffuser using the method of illuminating at least 15% of the diffuser yields a polymerization lens having a smooth, transparent, and low-haze freeform surface. The resulting lens has good optical quality. The advantage of this technology is that it is resistant to defects such as dust and dirt in the projector or the medium between the projector and the resin container. 【0044】 [Controlling the shape of the polymerization front] To produce the desired eyeglass lenses, it is necessary to control the shape of the polymerization front. To accurately model the polymerization of the resin within the container, the following factors must be considered: • Propagation of irradiance from the diffuser to the substrate and lens • Changes in the concentrations of polymers, initiators, and polymerization inhibitors over time. • Heat diffusion and temperature changes over time • Diffusion of monomers, initiators, and polymerization inhibitors • Bidirectional transmission distribution function (BTDF) of a light diffuser When using diffuse light, equation (7) is no longer applicable. Furthermore, equation (3) is not applicable when parameters such as reaction rate, initiator, and polymerization inhibitor concentrations change over time. Therefore, when using diffuse light, a careful modeling of reaction (1) is necessary. 【0045】 The desired shape of the freeform lens surface is z L It may be expressed as (x,y). The differential equation corresponding to equation (1) is numerically obtained for the given input irradiance pattern I, and the polymerization front z P (x,y,I) is obtained. Control point (x i ,y i For a fixed set of ), the following merit function is calculated. 【0046】 【number】 【0047】 The merit function is minimized with respect to the parameter that defines the input irradiance pattern (abbreviated as "input pattern"). If the light source is DLP, the irradiance pattern incident on the diffuser is defined pixel by pixel, and matrix I nm This is expressed as follows: where the indices n and m span the rows and columns of the digital image. Other merit functions may also be used, such as the sum of the differences in curvature between the target (freeform surface) and the polymerization front. 【0048】 Information obtained from one or more sensors or sensor systems used to measure the growth of the resin and polymerization front in a container during the monomer polymerization process, input pattern I nm This can be modified. This real-time closed-loop process allows for precise control of the polymerization front and avoidance or compensation of instabilities that may affect its shape. Sensors and sensor systems used in the polymerization process include one or more of the following: visual inspection system (VIS) cameras, infrared (IR) cameras, ultrasonic topography systems, tomography systems, moiré topography systems, interferometric topography systems, temperature sensors, and other similar devices and systems. These technologies are used in the polymerization apparatus described later with respect to Figures 7A and 7B, and in the measurement system described later with respect to Figure 10. 【0049】 [Description of the system and its constituent devices] The lens manufacturing systems described herein include, but are not limited to, the following components: • Resin adjustment and storage device, · Polymerization equipment, • Measuring devices, • Resin discharge device, and · Secondary curing equipment. 【0050】 [Resin adjustment and storage device] The preparation and transformation of the polymerization front depend on several parameters, as described above. Therefore, the resin formulation is strictly controlled. The resin contains a combination of polymerization inhibitors and photoinitiators. The polymerization inhibitors and photoinitiators must be stored and used at specific temperatures. 【0051】 Oxygen is one of the polymerization inhibitors in chain-like photopolymerization reactions. Oxygen can diffuse from the surrounding air into the resin, potentially creating a concentration gradient within the resin. This gradient can lead to non-uniformity in the resin and disrupt the shape of the polymerization front. Therefore, the concentration of all polymerization inhibitors, including oxygen, in the resin must be maintained at a known and appropriate constant level. The resin components must be homogeneous before projecting the input pattern. 【0052】 To achieve a homogeneous resin with the appropriate oxygen concentration, some of the possible options are as follows: • Store the resin in a container with an oxygen-free atmosphere (e.g., nitrogen). • Use an oxygen absorber that is compatible with the resin. • Saturate the resin with oxygen. • Saturate the resin with a gas containing a certain percentage of oxygen (e.g., air), and maintain a constant oxygen concentration below saturation. • Degas the resin. 【0053】 A resin conditioning and storage device is used to hold the liquid resin and maintain its chemical composition appropriately and consistently. One embodiment of the resin conditioning and storage device 600 is shown in Figure 6. The liquid resin 601 is held in a sealed tank 602. Sensors, actuators, and a set of pipes running inside and outside the tank, along with corresponding valves and pumps, are controlled by a controller 613, which includes electronic equipment and software. A mixing mechanism 603 is provided in the tank 602 to activate, agitate, and / or mix the components of the resin. This ensures that the components of the resin are completely mixed and uniformly distributed. Oxygen, clean, dry air, or any preferred mixed gas can be introduced or frothed into the resin via a conduit 607 to increase solubility and aid mixing. Alternatively, a preferred gas can be introduced into the tank 602 to control the partial pressure of each gas in the atmosphere within the chamber via a conduit 608. A venting mechanism is provided to allow changes in the composition of the atmospheric components within the tank and to control the internal pressure. The venting mechanism may include components such as pipes, valves, and pumps. In the embodiment shown in Figure 6, venting can be realized by pipes 606A and 606C, and valve 606B, which are connected to and controlled by controller 613. Sensor 604 is included in tank 602. In one embodiment, a typical sensor array can measure physical and chemical parameters such as temperature, oxygen concentration, and nitrogen concentration. A vacuum can be created in the tank to degas the resin using either or both of pipes 608 and / or 606A. A deoxygenation mechanism (not shown) may optionally be included in the tank to degas the resin. A heater 605 may be included in tank 602 to control the temperature of the resin 601. Pipe 609 is used to extract the resin and supply it to a polymerization apparatus as shown later in Figures 7A and 7B. 【0054】 A filter system 610, consisting of a pump / valve mechanism and a filter, is connected to the tank 602. This removes particles that interfere with lens fabrication, inhibit lens formation, and / or degrade lens quality. In one embodiment, particles larger than 0.5 microns are removed by the filter system 610. The filter system 610 may also remove gel-type polymers formed by spontaneous polymerization or during the printing process. Depending on the specific characteristics of the resin and polymerization process, the filter system 610 may operate continuously or at predetermined time intervals. The filter system may be coupled to and controlled by a controller 613. 【0055】 A resin recovery system 612 may be included in the resin preparation and storage device 600. Residue of liquid resin from a previous polymerization process may be poured into tank 612, filtered through filter 611, and incorporated into the preparation and storage device. The concentrations of initiators and polymerization inhibitors in the resin residue can be measured (e.g., by well-known spectroscopic techniques) before the residue is introduced into tank 612 or when the resin is placed on top of the tank. The concentrations of the resin components may be adjusted by adding appropriate amounts of polymerization inhibitors, initiators, and / or monomers / oligomers before the resin is introduced into the preparation / storage tank 602. 【0056】 [Polymerization equipment] Referring here to Figures 7A and 7B, two exemplary embodiments of a polymerization apparatus are shown. The polymerization apparatus consists of chambers 700A / 700B, in which resin 702 is placed so that UV light passes through a bottom glass plate 705, a light diffuser 704A / 704B, and a substrate 701 to irradiate the resin 702. Lens formation is performed within the polymerization apparatus. Chambers 700A / 700B hold and enclose the components necessary to achieve polymerization, excluding the UV source 708. The upper 711 and bottom 705 are glass plates or other suitable transparent materials. Within chambers 700A / 700B, the substrate 701 is placed on a bed, table, grooved area or other support structure (not shown) and / or may be fixed to the wall of chambers 700A / 700B or an extension to the wall by clips, tabs or other fastening devices (not shown). Resin 702 is poured into the recess of the substrate 701. A curing radiation (i.e., UV light) 709 is emitted from the light source 708. The light source 708 may be a scanning laser or a DLP. The curing radiation passes through the bottom transparent plate 705 and is diffused by the light diffusers 704A / 704B. The diffused light then propagates through the substrate 701 and enters the resin 702, forming the lens 703. 【0057】 In both embodiments of the polymerization apparatus shown in Figures 7A and 7B, the gas atmosphere and pressure within the chamber 700A / 700B are controlled via a vent element including input and output pipes 706 and 707. These pipes introduce nitrogen, oxygen, air, mixtures of these gases, and / or other gases into the chamber 700A / 700B. These pipes may also be used to create a vacuum within the chamber to degas the resin 702. The vent element includes valves and pumps, and pipes 706 and 707 for gas input and output. The valves and pumps of the vent element, as well as the light source, are controlled by a controller 710. The appropriate gas selection depends on the resin formulation. For example, an acrylic resin with a 50% monofunctional monomer to difunctional monomer mixture, 0.5% initiator, and 1% polymerization inhibitor can be used. In this embodiment, oxygen is removed from the regulating and storage unit 600 due to the presence of the polymerization inhibitor, and is also removed by venting nitrogen into the polymerization chamber 700A / 700B. Polymerization may be carried out in a low-pressure nitrogen atmosphere to avoid the formation of air bubbles within the polymerization lens 703. 【0058】 During operation, when curing radiation enters the resin 702 through the glass plate 705, a polymerization front is generated that separates the liquid resin 702 from the polymerization portion that will become the lens 703. As polymerization progresses, the polymerization front separates from the substrate surface, and the growing lens becomes thicker. 【0059】 The irradiance pattern emitted by the light source 708 used to fabricate the formed lens 703 is calculated using equation (1) (see above) and the BTDF of the diffuser 704. This provides the volume density of cured photons in the resin. When the thickness of the formed lens 703 reaches the target value, the polymerization front takes the shape of the target surface according to the optimization algorithm (8) (see above), the lens is completed, and the light source 708 is turned off. 【0060】 In the embodiment shown in Figure 7A, diffuser 704A is flat and positioned adjacent to the base 705 above. In the embodiment shown in Figure 7B, diffuser 704B is curved and has a curvature similar to the curvature of the convex side of the base material 701. Furthermore, in the embodiment shown in Figure 7B, diffuser 704B is positioned adjacent to the base material 701 below. In one embodiment, the curved diffuser 704B may be made of a transparent resin having a photodispersive additive such as calcium carbonate, glass, or titanium. In some embodiments, the photodispersive additive has particles with a size of 1 to 3 microns. The diameter of diffuser 704A / 704B is preferably larger than or equal to the diameter of base material 701. That is, the diameter of diffuser 704A / 704B is preferably not smaller than the diameter of base material 701. 【0061】 In variations of these embodiments, the space between the substrate 701 and the diffuser 704A in the embodiment shown in Figure 7A, or the space between the diffuser 701 and the bottom plate 705 in the embodiment shown in Figure 7B, can be filled with a substance, preferably a liquid, to ensure exponential matching between different surfaces and eliminate or reduce reflections on these surfaces. This exponential matching liquid is transparent and has a refractive index close to or matching that of the substrate and the diffuser. In one embodiment, when the substrate is CR-39® and the diffuser is acrylate, glycerin (refractive index 1.47) may be used as the exponential matching liquid. 【0062】 In some embodiments, the upper window glass 711 is removed. 【0063】 Referring now to Figure 8, an example of an input light pattern 800 that may be applied via the polymerization apparatus shown in Figure 7A is shown. This pattern can be projected for 60 seconds or other suitable time to generate a polymerization front with changing curvature, thereby fabricating a lens 703 as a progressive addition lens. Referring now to Figure 9, a lens 900 obtained as a result of applying the method described herein using the polymerization apparatus shown in Figure 7A with the input pattern shown in Figure 8 is shown. 【0064】 [Measuring device] Additional modules can be attached to the polymerization apparatus shown in Figures 7A and 7B to perform real-time measurements and provide feedback for modifying or improving the optical input pattern during the polymerization process. Referring here to Figure 10, one embodiment of the measurement apparatus 1000 is shown. The measurement apparatus 1000 includes the polymerization apparatus shown in Figure 7A. In this embodiment, the polymerization apparatus shown in Figure 7A is used without the upper glass 711. The measurement apparatus 1000 includes a thermal camera 1005 to sense thermal radiation 1006 within the resin 702 and monitor the temperature distribution of the resin 702 in real time. Since polymerization is an exothermic reaction, spatially dependent optical input patterns result in higher polymerization rates where higher photon densities are provided. Therefore, the optical input pattern, the shape of the polymerization front over time, and the temperature distribution within the resin are correlated. Unexpected fluctuations in the temperature distribution within the resin will similarly correlate with a lack of homogeneity in the resin, the presence of gel-type precipitates, or other impurities. To use the thermal camera 1005, the upper glass plate of the polymerization chamber is removed because it is opaque to thermal radiation 1006. 【0065】 In some embodiments, an additional secondary system included in the measuring device 1000 is used to monitor the shape of the polymerization front as it changes during the polymerization process. This secondary system evaluates the topography using ultrasound. 【0066】 Referring again to the measuring device 1000 shown in Figure 10, an optical system using a camera 1004 is shown. The camera 1004 evaluates the formation of the lens and / or the polymerization front using low-wavelength light that does not polymerize the resin. For example, the camera 1004 may use red light with a wavelength of 635 nm or near-infrared light with a wavelength of 780 nm. The camera 1004 may also use light with other wavelengths that do not interfere with the polymerization of the resin. In one embodiment of the measuring device, a structured light projector projects a fringe pattern onto the resin 702 from above with structured low-wavelength light, and the camera 1004 images the reflected light from the polymerization front. The polymerization front is reflected due to the change in refractive index between the liquid resin and the polymer. 【0067】 The measuring device 1000 may additionally or alternatively include a light source 1002 for sending a structured low-wavelength light beam 1003 from below. This may be achieved by transmitting the measuring light beam 1003 through a lens 703 detected by a camera 1004. In this embodiment, the measuring light beam 1003 and the curing light 709 are mixed in a beam splitter 1001, for example, a dichroic beam splitter that does not affect the amount of curing light projected. 【0068】 Other embodiments of the measuring device 1000 may include other or additional sensors such as an IR camera or an ultrasonic sensor. 【0069】 [Resin discharge device] After the lens is formed by the polymerization apparatus, the remaining resin may be discharged and reused. More specifically, after the target shape is completed by the polymerization apparatus and a lens with the target thickness is formed, the projector is turned off and the projection of the input pattern is stopped. The substrate containing the lens and the remaining unpolymerized resin are then removed from the polymerization apparatus. This can be done manually or in an automated system. After the lens is completed, the remaining liquid resin is discharged from the polymerization apparatus, for example, by removing it, to avoid unwanted polymerization of the resin. 【0070】 Referring here to Figure 11, an exemplary resin discharge device 1100 is shown. A substrate 1116 with a formed lens 1114 and residual liquid resin 1112 is placed on a base 1110 and securely mounted, and then placed on a rotating machine 1101. The base 1110, substrate 1116, lens 1114, and residual resin 1112 are rotated by the rotating machine 1101. Due to centrifugal force, the residual liquid resin is separated from the lens 1114 and substrate 1116 and moved into a tray formed by a conical shelf 1102. The speed of the rotating machine 1101 and the viscosity of the resin 1112, which is highly dependent on temperature, determine the amount of resin remaining on the lens. A cover 1103 prevents resin from splashing out of the resin discharge device 1100. The resin collected by the rotating machine at the top of the conical shelf 1102 is recovered in a discharge pipe 1120, as described above with respect to Figure 6, and recycled and reused. The recovery of residual resin for recycling and reuse can also be done automatically. Here, the resin is fed from the resin discharge device 1100 shown in Figure 11 to the system shown in Figure 6 via the discharge pipe 1120. 【0071】 If there is a large amount of residual resin, the substrate can be tilted before rotation to discard the excess resin. If the resin formulation has a large amount of gelled resin, the remaining resin can be discarded, and the uncured resin can be removed from the substrate and lens pair using an appropriate solvent. 【0072】 In another embodiment, after the resin has been discharged through the pipe 1120, pre-curing of a thin layer of residual liquid resin on the lens surface can be achieved via a diffuse UV light source 1104 contained beneath the cover 1103. According to this embodiment, once this layer is pre-cured, a small amount of liquid hard coat lacquer can be poured onto the lens via an applicator 1105 which may be integrated into the cover 1103. The lacquer can be rotated and dropped by an additional rotational cycle of the rotary machine 1101, leaving a uniform layer that can be further photocured or heatcured by a heater (not shown) which may be included in the resin drainage device 1100. 【0073】 [Secondary curing equipment] Depending on the resin formulation and properties for a particular lens, and the associated process parameters, a secondary curing operation may be performed. Referring here to Figure 12, one embodiment of a secondary curing apparatus 1200 is shown. The secondary curing apparatus 1200 may be used after the residual liquid resin has been discharged in the rotary resin discharger 1100 of Figure 11. In some embodiments, the resin discharger 1100 does not have a built-in UV source and / or heat source, so the film of residual liquid resin formed on the lens after the operation using the resin discharger 1100 needs to be cured using another apparatus. In particular, the resin discharger 1100 may lack a venting system that provides an oxygen-free atmosphere. In this case, the thin layer left on the lens is only a few microns thick and cannot be cured because oxygen continuously diffuses from the atmosphere. In this case, an additional apparatus, such as a secondary curing apparatus, may be required. 【0074】 Referring to Figure 12, the secondary curing apparatus 1200 includes a chamber 1212 in which the substrate 1217 and lens 1215 are placed, accompanied by a sealed lid 1201 transparent to UV radiation. Input and output pipes 1202A and 1203A are included through the walls of the chamber 1212, along with control valves 1202B and 1203B, to allow for the maintenance and control of a suitable atmosphere (i.e., gaseous mixture) within the chamber 1212. Depending on the resin, a high-pressure neutral nitrogen atmosphere may be used to avoid bubble formation on the lens 1215. If the resin is properly degassed, low-pressure nitrogen or vacuum can be used to expel oxygen from the resin. After the atmosphere in the chamber 1212 and the lens 1215 have been freed from oxygen, the source of curing radiation 1205 1204 (e.g., a UV light source) is activated to cure the remaining layer on the lens 1215. Optionally, a heater 1216 may be included and integrated at the bottom of the chamber 1212. The heater 1216 may be used to improve the mobility of unreacted monomers in the polymer matrix and increase the degree of conversion c (see formula 5 above). 【0075】 To equalize the irradiance 1205 reaching the thin layer of liquid resin on the lens 1215, a diffuser 1206 may be incorporated into the lid 1201. 【0076】 [Output product: Lens] The output products of the systems and methods described herein are lenses, i.e., substrate / formed lens composites. In some cases, the formed lens is separated from the substrate, and the formed lens becomes the final lens. In other cases, the formed lens is not separated from the substrate, and the two components come together to form an eyewear lens. In this case, the eyewear lens may have optical properties inherited from the substrate. For example, the substrate can be polarized, colored, or photochromic, provided that a sufficient amount of curing radiation passes through the substrate to polymerize the formed lens. The substrate can also incorporate anti-reflective coatings or hard coatings on its convex surface. Furthermore, the substrate can supply power. Combining the substrate and the formed lens offers significant advantages, as it allows for the production of eyeglass lenses that are not limited to the optical properties of the polymerized resin. 【0077】 In another embodiment, the formed lens is separated from the substrate. As a result, a formed lens composed solely of polymerized resin is obtained. The advantage of this embodiment is that the substrate can be reused. 【0078】 [method] Referring here to Figure 13, Method 1300 is shown, which is used to manufacture eyeglass lenses using the apparatus and method described above. Referring to Block 1301, an input job is received. The input job includes information necessary for lens manufacturing, such as the geometry of the freeform surface, expected or preferred thickness, the geometry of the fixed surface, expected or preferred refractive index, lens diameter or contour shape, user parameters, and user lifestyle parameters. The input job may include some or all of the enumerated information. As used in the input job, user parameters include frame characteristics such as nostril distance, frame pantoscopic, lap angle, and frame vertex distance, field of view, reading distance, working distance, age, health, and other parameters. As used in the input job, user lifestyle may be a designation of the user's primary activities or activities, including outdoor, indoor, sports including specific sports such as swimming and running, driving, reading, desk work, and / or careers such as chef, teacher, lawyer, bus driver, etc. 【0079】 Upon receiving an input job, the lens fabrication instructions are determined. The lens fabrication instructions (or requirements) include input patterns for UV light and resin composition. The irradiation pattern or input pattern is calculated (as shown in block 1302) so that the polymerization front for a given exposure time matches the desired shape of the freeform lens surface. This calculation of the input pattern consists of an optimization process for every point in the resin irradiated by multiple points from a diffuser. 【0080】 Specifically, the calculation starts from the lens surface specified in the input job. The input light pattern is calculated so that the superimposed front after time "t" matches the objective surface, including the following evaluations. (a) The diffuser receives directional light from the light source, and each point of the diffuser emits light in each direction according to its BTDF function. (b) Each point of the resin receives light from multiple light source positions within the diffuser. (c) The light received by the resin initiates the photochemical reaction represented by Equation 1. (d) Due to the photochemical reaction, the degree of conversion changes at each point of the resin according to Equation 5. (e) The polymerization front is defined as the point in the resin where the degree of conversion c is equal to the critical conversion value. 【0081】 Furthermore, during calculation (1302), the resin composition is determined so that the fabrication instructions include the irradiation pattern and resin composition. The resin composition defines the composition of the resin. Calculation (1302) also determines the amount of liquid resin required to fabricate a formed lens with the desired diameter. The resin composition includes specific amounts of photoinitiator and polymerization inhibitor (optional), depending on the information of the input job. For example, thicker lenses may require less light absorption, which can be achieved by using less photoinitiator or more polymerization inhibitor. Therefore, the fabrication instructions include determining both the irradiation pattern and the resin composition. The resin is then prepared and stored according to the procedure described above with respect to Figure 6 (as shown in block 1303). The resin composition can be adjusted to meet the requirements of the fabrication instructions by changing the concentrations of the photoinitiator and / or polymerization inhibitor. 【0082】 Next, polymerization is carried out (as shown in block 1305). Polymerization begins with placing a new, clean substrate in the polymerization chamber, and then pouring the resin into the polymerization chamber (according to block 1304). Polymerization continues by irradiating the diffuser with an input pattern that provides the correct photon density distribution within the resin to achieve the lens surface specified in the input job, according to the irradiation pattern of the fabrication instructions. During polymerization (1305), information from the measuring device may be used to adjust and / or modify the input pattern (as shown in block 1309). 【0083】 Once the formed lens is fabricated in the polymerization chamber, the resin is discharged from the polymerization chamber (as shown in block 1306), and an object consisting of a substrate covered with a gel layer and the formed lens is obtained. 【0084】 During secondary curing (as shown in block 1307), the gel layer is polymerized. The formed lens may then be separated from the substrate. As a result, an eyewear lens is obtained (as shown in block 1308). In some embodiments, if the formed lens is not separated from the substrate, the output product is a composite of the substrate and the formed lens. 【0085】 After removal, the formed lens may be cut before being fitted into the frame to be worn. Other treatments may be applied to the formed lens, such as an anti-reflective coating or a hard coating. 【0086】 [In conclusion] In this specification, the embodiments and examples shown should be considered illustrative and not limiting to the apparatus and procedures disclosed or claimed. Many of the embodiments described herein involve specific combinations of method actions, apparatus, components, or system elements, which may be combined in other ways to achieve the same objective. With respect to methods, processes, and flowcharts, additional and fewer actions may be performed, and actions as illustrated and described may be combined and further improved to achieve the methods described herein. Actions, components, apparatus, elements, and features described in one embodiment are not intended to be excluded from similar roles in other embodiments. 【0087】 As used herein, “plural” means two or more. As used herein, a “set” of elements may include one or more such elements. Note that as used herein or in the claims, terms such as “equipment,” “includes,” “have,” “possess,” “contain,” and “concern” are open-ended, meaning they “include” but are not limited to that. Only the expressions “consist of” and “essentially consist of” are closed-ended or semi-closed with respect to the claims. Terms such as “first,” “second,” and “third” in the claims are used to modify the elements described in the claims and do not themselves imply priority, precedence, or chronological order in the method, but simply as labels used to distinguish components that have the same name as a component of a particular name. As used herein, “and / or” means that the listed elements are alternatives, but may include combinations thereof.

Claims

[Claim 1] A method for manufacturing eyeglass lenses, Steps include receiving input information including lens prescription and wearer information, A step of calculating a manufacturing instruction based on the input information, wherein the manufacturing instruction includes: 1) an irradiation pattern calculated such that the polymerization front for a predetermined exposure time matches a desired shape of the freeform lens surface, the shape of the freeform lens surface that provides a desired spectacle lens; and 2) a resin composition determined such that the manufacturing instruction includes the irradiation pattern and the resin composition. A step of initiating the transmission of light from a light source through a diffuser to a container containing a resin and a substrate, wherein the transmission of light is carried out according to the irradiation pattern, and each point of the resin is illuminated by at least 10% of the area of ​​the diffuser, The step of stopping the transmission of light when the lens formed in the freeform satisfies the manufacturing instructions, including, method. [Claim 2] The method according to claim 1, wherein at least 15% of the area of ​​the diffuser receives light from the light source. [Claim 3] The method according to claim 1, wherein the diameter of the diffuser is greater than or equal to the diameter of the substrate. [Claim 4] The method according to claim 1, further comprising the step of discharging the resin container. [Claim 5] The method according to claim 4, further comprising the step of removing the formed lens from the substrate. [Claim 6] The method according to claim 1, wherein the resin composition includes specifying the amount, portion, or concentration of a polymerization inhibitor, a photopolymerization initiator, and a monomer or oligomer. [Claim 7] The method according to claim 6, wherein the monomer is selected from the group consisting of acrylate, epoxy, methacrylate, isocyanate, polythiol, thioacrylate, and thiomethacrylate. [Claim 8] The method according to claim 6, wherein the polymerization inhibitor is selected from the group consisting of oxygen and hydroquinone. [Claim 9] The method according to claim 6, wherein the photopolymerization initiator is selected from the group consisting of benzophenone, BAPO (bisacylphosphine oxide), acetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (Irgacure 2959(c) by CIBA), alpha-aminoketone, HAP (2-hydroxy-2-methyl-1-phenyl-propan-1-one), and TPO (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide), aryldiazonium salts, triarylsulfonium salts, ferrocenium salts, and diaryliodonium salts. [Claim 10] The method according to claim 6, wherein the diffuser is opal glass, white glass, or an acrylate sheet containing a light-diffusing additive. [Claim 11] The method according to claim 6, wherein the substrate is selected from the group consisting of CR-39 (registered trademark), polycarbonate, polyurethane-based plastic, and glass. [Claim 12] The method according to claim 6, wherein an electronic circuit or an image forming system is embedded in the substrate. [Claim 13] The method according to claim 6, wherein the substrate is polarizing or photochromic. [Claim 14] The method according to claim 6, wherein the substrate is subjected to an anti-reflective coating or hard coating treatment on its convex surface. [Claim 15] The method according to claim 4, further comprising the step of rotating the formed lens to apply a hard coating.

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