Vacuum blocking piece and method for manufacturing eyeglass lenses

Abstract

A vacuum-blocking piece for vacuum-blocking a lens blank is provided. The vacuum-blocking piece includes a support element having an upper portion and a lower portion, the lower portion adapted to engage with a clamping device for securing the vacuum-blocking piece. The vacuum-blocking piece further includes a fluid-permeable blank contact element, the blank contact element being fluid-permeable, and at least an upper surface of the blank contact element adapted to contact the lens blank being made of an elastic material, the blank contact element further having a lower surface (24) that contacts the upper portion of the support element. The vacuum-blocking piece is adapted to secure the lens blank to the upper surface of the blank contact element by applying a vacuum within the blocking piece to provide a suction force across essentially the entire upper surface of the blank contact element, thereby attracting the lens blank to the upper surface of the blank contact element and attracting the blank contact element to the upper portion of the support element.

Description

[Technical Field]

[0001] A blank contact element, a vacuum blocking piece, and a method for manufacturing an eyeglass lens are provided.The present disclosure therefore relates to the manufacture of eyeglass lenses.

[0002] Accordingly, embodiments relate to systems, apparatus, and methods for blocking lens blanks and for manufacturing ophthalmic lenses, particularly spectacle lenses. [Background technology]

[0003] In the industrial mass production of spectacle lenses made of plastic material or mineral glass, particularly in the case of spectacle lenses with free-form surfaces, lens blanks are blocked onto blocking pieces using a device that can be called a blocking device, which is separate from the machining device for grinding or cutting the lens blank. Blocking the lens blank is necessary to mechanically and resiliently fix the lens blank in a predetermined position so that it can withstand milling or grinding processes for individualizing the optical power of the lens blank. The blocking pieces onto which the lens blank is blocked allow the lens blank to be fastened via the blocking pieces to a grinding or cutting machine in a snap-in and / or press-fit manner.

[0004] According to the prior art, a lens blank is attached to a blocking piece using a metal alloy with a low melting point. The lens blank is positioned with respect to the blocking piece so that the finished front surface of the lens blank faces the blocking piece, the surface normal of the lens blank and the surface normal of the blocking piece are at a predetermined angle relative to each other, and the space between the blocking piece and the front surface of the lens blank is filled with a liquid metal alloy. The blocking piece is then quenched by a cooling device built into the blocking device, hardening the metal alloy and fixing the lens blank to the blocking piece. The blocking method can be performed manually or automatically. After the metal alloy has hardened, the blocking piece and the attached lens blank can be removed from the blocking device.

[0005] After the blocking step, the following manufacturing steps are typically performed on the blocked lens blank: cutting the edge contour of the spectacle lens, imparting the desired refractive power to the posterior surface of the lens blank by milling, polishing the milled surface in a polishing device into which the blocked lens blank is inserted, and applying a signature mark to the optical surface to enable accurate positioning of the optical surface.

[0006] Finally, the finished eyeglass lens is removed from the blocking piece. If a metal alloy was used in the blocking, the metal alloy is heated, melted, and sent to a recycling process.

[0007] The use of metal alloys for blocking lens blanks is environmentally unfavorable. To improve this, attempts are being made to avoid using metal alloys for blocking lens blanks for environmental reasons. An alternative blocking method is described in DE 10 2005 038 063 A1, which proposes using polymer adhesives or thermoplastic materials that can be cured by irradiation with light.

[0008] When polymeric or thermoplastic materials are used for blocking, it is often uneconomical to reuse the blocking material after deblocking due to contamination of the blocking material during the manufacturing process and due to mechanical and / or chemical changes in the material over time.

[0009] An alternative lens blank blocking approach proposed in the prior art is described in EP 2266754 B1. According to the proposed method, a blocking piece having a support surface containing ring-shaped recesses is used to fix the lens blank to the support surface by vacuum. However, this approach often results in unwanted deformation of the lens blank due to these recesses.

[0010] JP 03121763A describes a vacuum adapter with several interlocking cylindrical sections. DE 2531134A1 shows a vacuum adapter in which a flexible sealing ring contacts the lens. U.S. Pat. No. 3,134,208A discloses a vacuum adapter with a circular recess that can be evacuated. Other vacuum adapters are described in U.S. Pat. No. 4,089,102A and DE 3,924,078A1.

[0011] An alternative lens blank blocking method known in the art is vacuum blocking, as described in EP 4035832 A1, which is considered to be the closest prior art to the present application. This technique uses a vacuum blocking piece, the lower part of which corresponds to the lower part of other conventional blocking pieces and is adapted to be attachable to conventional machines for mechanically processing the posterior surface of the lens blank.

[0012] U.S. Pat. No. 6,126,520 describes a fixture and a method for coupling optical components to a machine using a vacuum. U.S. Patent Application Publication No. 2015 / 0217420 A1 discloses a processing machine having a lens holding device for holding a lens before machining in the processing machine, the lens being held on the holding device by adhesive elements. DE Patent Application Publication No. 2531134 A1 describes an apparatus for machining spectacle lenses, in which the lens holder includes an elastically deformable sleeve connecting the outer edge of the shell to the outer edge of the support collar.

[0013] The upper part of a conventional vacuum blocking piece has an element made of a rigid porous material, such as ceramic, designed to receive a lens blank. This element is adapted in diameter and curvature to the convex surface of the lens blank to be vacuum blocked, and is airtightly embedded in a cylindrical support element, firmly bonded and / or screwed thereto. An air valve on the underside of the adapter allows a vacuum to be applied, evacuating most of the air content of the porous material / ceramic, thereby firmly adhering the lens blank to the surface of the element. A rubber circumferential sealing lip on the outer edge of the upper part can be provided to tightly seal the vacuum area against the outside. The adhesion between the surface of the lens blank and the vacuum adapter, necessary to transmit the forces and torques generated during mechanical processing of the lens blank, is approximately 8.0-8.5 N / cm to the lens blank. 2 and the adhesion between the protective film bonded to the lens blank surface and the elements of the vacuum blocking piece. To loosen the connection between the lens blank and the vacuum blocking piece, the interior of the vacuum blocking piece can be vented through an air valve, thus turning off the vacuum.

[0014] In conventional vacuum blocking processes, the existing final front surface of the lens blank, which faces the blocking piece when blocked, is coated with a suitable protective film or varnish before blocking, thereby keeping this front surface of the lens blank protected from damage due to contact with the blocking piece during processing. Furthermore, a protective film or varnish may be necessary in conventional blocking schemes to ensure sufficient adhesion between the lens blank and the blocking piece, due to the effect of adhesives or micro-serrations, etc., that provide a mechanical connection between the lens blank and the blocking piece that is resilient to forces and moments generated during mechanical processing. Summary of the Invention [Problem to be solved by the invention]

[0015] In view of EP 4035832 A1 as the closest prior art to the present application, the technical problem targeted by the subject matter of the claims can relate to providing an improved vacuum blocking piece and an improved method for manufacturing eyeglass lenses, and optionally to providing an improved vacuum blocking piece and an improved method for manufacturing eyeglass lenses that increases environmental sustainability and reduces the costs of manufacturing eyeglass lenses. [Means for solving the problem]

[0016] This problem is solved by a blank contact element, a vacuum blocking piece and a method with the features of the respective independent claims. Optional embodiments are provided in the dependent claims and the description.

[0017] In a first aspect, there is provided a blank contact element adapted for use with a vacuum blocking piece suitable for vacuum blocking a lens blank, the blank contact element being fluid permeable and characterized in that at least the top surface of the blank contact element adapted to contact the lens blank is made of an elastic material.

[0018] In another aspect, a vacuum-blocking piece for vacuum-blocking a lens blank is provided. The vacuum-blocking piece includes a support element having an upper portion and a lower portion, the lower portion adapted to engage with a clamping device for securing the vacuum-blocking piece. The vacuum-blocking piece further includes a fluid-permeable blank contact element, the blank contact element being fluid-permeable, and at least an upper surface of the blank contact element adapted to contact the lens blank being made of an elastic material, the blank contact element further having a lower surface (24) for contacting the upper portion of the support element. The vacuum-blocking piece is adapted to secure the lens blank to the upper surface of the blank contact element by applying a vacuum within the blocking piece to provide a suction force across essentially the entire upper surface of the blank contact element, thereby attracting the lens blank to the upper surface of the blank contact element and attracting the blank contact element to the upper portion of the support element.

[0019] In yet another aspect, a vacuum-blocking piece for vacuum-blocking a lens blank is provided. The vacuum-blocking piece includes a support element having an upper portion and a lower portion, the lower portion adapted to engage with a clamping device for securing the vacuum-blocking piece. The vacuum-blocking piece further includes a fluid-permeable blank contact element, the blank contact element being fluid-permeable, and at least an upper surface of the blank contact element adapted to contact the lens blank being made of a resilient material, the blank contact element further having a lower surface adapted to contact the upper portion of the support element. The vacuum-blocking piece is adapted to secure the lens blank to the upper surface of the blank contact element by applying a vacuum within the blocking piece to provide a suction force across essentially the entire upper surface of the blank contact element, thereby attracting the lens blank to the upper surface of the blank contact element and attracting the blank contact element to the upper portion of the support element. The upper portion of the support element is adapted to support the fluid-permeable blank contact element and is formed of a rigid, fluid-permeable material.

[0020] In another aspect, a vacuum blocking piece for vacuum blocking a lens blank is provided. The vacuum blocking piece includes a support element having an upper portion and a lower portion, the lower portion adapted to engage a clamping device for securing the blocking piece. The vacuum blocking piece further includes a fluid-permeable blank contact element according to the present disclosure, the blank contact element further having a lower surface for contacting the upper portion of the support element. The blocking piece is adapted to manually secure the lens blank to the upper surface of the blank contact element by applying a vacuum within the blocking piece to provide a suction force across essentially the entire upper surface of the blank contact element, thereby attracting the lens blank to the upper surface of the blank contact element and attracting the blank contact element to the upper portion of the support element.

[0021] In yet another aspect, a method for manufacturing an eyeglass lens is provided. The method includes providing a vacuum-blocking piece for vacuum-blocking a lens blank, the vacuum-blocking piece including a fluid-permeable blank contact element having an upper surface adapted to contact the lens blank, at least the upper surface of the fluid-permeable blank contact element being made of a resilient material, and the vacuum-blocking piece including a support element having an upper and lower portion, the lower portion adapted to engage a clamping device for securing the blocking piece, and the upper portion supporting the fluid-permeable blank contact element. The method further includes placing the lens blank on the upper surface of the blank contact element such that the front surface of the lens blank covers the entire upper surface. The method further includes applying a vacuum within the vacuum-blocking piece to provide a suction force through the fluid-permeable resilient blank contact element to attract the lens blank to the entire upper surface of the fluid-permeable resilient blank contact element, and mechanically machining at least a portion of the rear surface of the lens blank while the front surface of the lens blank is vacuum-blocked to the vacuum-blocking piece.

[0022] In yet another aspect, a method for manufacturing an eyeglass lens is provided. The method includes providing a vacuum blocking piece according to the present disclosure. The method further includes placing a lens blank on top of the blank contact element such that the front surface of the lens blank covers the entire top surface. The method further includes applying a vacuum within the vacuum blocking piece to provide a suction force through the fluid-permeable elastomeric blank contact element to attract the front surface of the lens blank to the entire top surface of the fluid-permeable elastomeric blank contact element, and mechanically machining at least a portion of the posterior surface of the lens blank while the front surface of the lens blank is vacuum-blocked to the vacuum blocking piece.

[0023] In yet another aspect, the present disclosure relates to the use of a blank contact element according to the present disclosure to provide an interface between a vacuum blocking piece and a lens blank.

[0024] A lens blank may refer to an unprocessed precursor of an eyeglass lens, for example, a lens blank having an unprocessed front surface and an unprocessed rear surface. The lens blank may be provided by a molding process. However, a lens blank may also refer to a partially processed precursor of an eyeglass lens. For example, a lens blank may have a front surface that is partially or fully processed and may be covered with a protective foil or coating. According to common understanding and the definition in ISO 13666:2019(E)3.8.1, a lens blank may be a piece of optical material, one of whose surfaces is optically finished, for producing a lens.

[0025] According to common understanding and the definition in ISO 13666:2019(E)3.5.2, a spectacle lens may be an ophthalmic lens according to the definition in ISO 13666:2019(E)3.5.1 that is worn in front of the eye, without contact with it.

[0026] The blocking piece relates to an adapter piece for mounting a lens blank to a processing device, in particular a processing device for machining and / or grinding and / or cutting and / or polishing the rear surface of the lens blank according to prescription data and / or for edging an eyeglass lens according to provided edging data. On one side, the blocking piece is adapted to contact the lens blank, and on the other side, the blocking piece is adapted to engage with a processing device for processing the lens blank. The blocking piece is adapted to reversibly block the lens blank, and the blocked lens blank can be unblocked in a way that maintains the integrity of the lens blank, in particular its front surface, which may optionally be protected with a protective foil or coating. The blocking piece may be a block according to the general understanding and the definition in DIN 58766 (2017). A vacuum blocking piece relates to a blocking piece that fixes a lens blank to the vacuum blocking piece primarily or exclusively using vacuum forces, i.e., pressure due to suction within the vacuum blocking piece, as described for example in EP 4035832 A1. Vacuum blocking a lens blank therefore means fixing the lens blank to a blocking piece primarily or exclusively using vacuum forces, i.e., pressure due to suction within the vacuum blocking piece.

[0027] The blank contact element being fluid permeable means that a gaseous fluid stream, in particular an air stream, can be generated through the blank contact element. In particular, a suction force can be generated through the blank contact element by creating a pressure difference between the outside and the inside of the blocking piece.

[0028] An elastic material is understood to be a material that has elastic mechanical properties. Therefore, an elastic material can be mechanically deformed when a mechanical force is applied to the material, and this deformation is at least partially reversible. When the applied mechanical force is removed, the elastic material can at least partially return to its original shape.

[0029] It should be understood that at least the top surface of the blank contact element is made of a resilient material, meaning that at least the surface that is adapted to contact the lens blank when blocking the lens blank is made of a resilient material. Optionally, the entire blank contact element may be made of a resilient material. The blank contact element may be made as a single piece of resilient material.

[0030] The blank contact element may be provided as a separate component from the vacuum-blocking piece. However, according to some optional embodiments, the blank contact element may form an integral part of the vacuum-blocking piece. When the blank contact element is adapted to be used with the vacuum-blocking piece, it means that the blank contact element and the vacuum-blocking piece may be provided as an assembly for vacuum-blocking the lens blank. The blank contact element may provide an interface between the lens blank and the vacuum-blocking piece when blocking the lens blank.

[0031] By suction force throughout "essentially the entire upper surface" of the blank contact element, we mean that the suction force and the resulting airflow are not limited to a specific small area of ​​the upper surface of the blank contact element, such as a recess or hole provided only within that small area of ​​the upper surface of the blank contact element. Instead, "essentially the entire upper surface" means that the suction force is provided over a large portion of the upper surface, particularly over an area of ​​more than 90% of the usable portion of the upper surface, and preferably over the entire usable upper surface. By "a portion of the upper surface being usable," we mean that the portion of the upper surface is not covered by the lens blank but is available for contact with it. This can be achieved by providing a porous, resilient material and / or by providing holes distributed throughout the upper surface of the blank contact element.

[0032] The term "vacuum" relates to a pressure much lower than the surrounding atmospheric pressure. However, a vacuum in this sense does not require a complete absence of matter, as might be inferred from a strict scientific definition. Instead, pressures at least 0.3 bar, optionally at least 0.5 bar, optionally at least 0.7 bar, optionally at least 0.8 bar lower than atmospheric pressure (i.e., total pressures of 0.7 bar, 0.5 bar, 0.3 bar, 0.2 bar, respectively) are considered vacuums within the meaning of this specification.

[0033] The present disclosure provides an advantage in that the interface between the blank contact element and the lens blank, i.e., the upper surface of the blank contact element, provides mechanically soft properties that prevent damage to the lens blank during vacuum blocking of the lens blank. Due to the elastic properties of the upper surface of the blank contact element, the upper surface of the blank contact element is softer than the lens blank, and therefore mechanical damage, such as scratches, to the lens blank during vacuum blocking of the lens blank can be avoided. This provides another advantage in that it can be omitted to apply protection to the anterior surface of the lens bank that contacts the blank contact element during vacuum blocking, since there is no or negligible risk of mechanical damage to the anterior surface of the lens blank resulting from contact with the blank contact element. As a result, additional steps for applying and removing protection means to the lens blank can be omitted, thus reducing the manufacturing costs of spectacle lenses. Furthermore, there is no need to provide and maintain machinery for applying and removing protection means, which can further reduce costs.

[0034] Furthermore, the risk of damaging the lens blank during the process of applying and / or removing the protective means, such as a protective foil, may be reduced. Conventional processes for applying and / or removing protective foils often subject the lens blank to mechanical stresses, which may result in edge damage to the lens blank. Such damage may be avoided according to the present disclosure, since the application and / or removal of a protective foil is not required.

[0035] Furthermore, the amount of waste generated during the production of spectacle lenses may also be reduced, since the application of a protective coating and / or protective foil to the front surface of the lens blank may be omitted, which may further improve the environmental sustainability of the spectacle lens manufacturing process.

[0036] Additionally, the present disclosure provides the advantage that the elastic material can provide adequate static friction between the blank contact element and the lens blank, and between the blank contact element and the vacuum blocking piece, for performing mechanical processing of the rear surface of the blocked lens blank, eliminating the need for additional adhesive or fastening. The provided static friction can be suitable for transmitting torques of up to 12 Nm, or even 15 Nm, which corresponds to typical values ​​achievable with conventional blocking pieces based on alloy blocking of eyeglass lens blanks and is therefore well suited for mechanical processing of the blocked lens blank. However, optionally, an adhesive can also be applied between the blank contact element and the lens blank, thereby increasing the transmittable torque. The adhesive can be a two-component adhesive. One or more adhesive spots can be applied to the front surface of the lens blank and / or to the top surface of the blank contact element.

[0037] In particular, elastic materials may provide significantly higher static friction than rigid porous materials, such as porous ceramic materials as described in EP 4035832 A1.

[0038] The blank contact element may be made entirely of a resilient material, which may allow the blank contact element to be formed as a single part made of a single material, and therefore may facilitate manufacturing of the blank contact element.

[0039] The elastic material may include at least one material selected from the group consisting of polyurethane-based materials and rubber-based materials. Optionally, the elastic material may be formed as a foil made of one or more of these materials. Optionally, the polyurethane-based material may include or consist of polyurethane foam. These materials may have the advantage of providing a suitable coefficient of friction with respect to the smooth front surface of the lens blank and with respect to the upper surface of the support element, which may be made of, for example, a ceramic material, SiC, Al2O3, or porous aluminum. Furthermore, rubber-based materials and / or polyurethane-based materials, such as polyurethane foils, may provide suitable permeability to fluids, such as air, suitable for applying a suction force to vacuum-block the lens blank through the blank contact element. Furthermore, these materials may have the advantage of having a compression set of less than 5% as specified by ISO 1856:2000. Furthermore, these materials may have a compression set of less than 3 N / mm as specified by ISO 1827:2022. 2 The vacuum blocking piece may be adapted to provide a static friction between the blank contact element and the support element with a coefficient of friction of up to 2.5. This may be achieved, at least in part, by selecting a suitable elastic material for the blank contact element, such as a rubber-based material and / or a polyurethane-based material. The elastic material used may be selected to have a Shore hardness of 50 to 80.

[0040] The elastic modulus of the porous polyurethane foil is approximately 3 N / mm 2 ~Approx. 10N / mm 2 The range may be:

[0041] The blank contact element can be applied to the top of the support element by coating the top surface of the support element. Alternatively or additionally, the blank contact element can be pre-manufactured separately from the vacuum blocking piece. For example, the blank contact element can be manufactured by a vulcanization process. Furthermore, the manufacturing process for the blank contact element can include drilling holes in the vulcanized blank contact element.

[0042] The thickness of the blank contact element may be in the range of 0.3 mm to 0.8 mm. This may ensure that the lens blank can be sufficiently protected from mechanical scratches caused by the vacuum blocking piece. Furthermore, this may absorb and / or attenuate mechanical shocks transmitted from the vacuum blocking piece to the blocked lens blank, especially during machining of the lens blank. In addition, the blank contact device may absorb and / or attenuate shocks to the lens blank, ensuring that the blocking of the lens blank is not endangered by the shocks.

[0043] The elastic material may be at least partially porous, with the fluid permeability of the blank contact element being at least partially achieved by the porosity of the elastic material. This may optionally be achieved by forming the blank contact element at least partially from a foam material, such as polyurethane foam. The elastic material may exhibit open porosity, allowing a fluid stream to pass through the porous material. Such a fluid stream through the holes may be used to provide a suction force that generates pressure to secure the lens blank to the blank contact element and the blank contact element to the blocking piece during the blocking process. This may ensure an even distribution of the fluid stream across the surface of the blank contact element.

[0044] Alternatively or additionally, the fluid permeability of the blank contact element is achieved at least in part by one or more holes formed therein. The blank contact element may include a plurality of holes distributed on the top surface of the blank contact element. These holes may be through-holes extending through the entire thickness of the blank contact element. The through-holes may extend straight through the blank contact element, i.e., along the direction of pressure acting on the lens blank to secure the lens blank to the blank contact element. Alternatively or additionally, the one or more holes may extend in a direction other than straight through the blank contact element. This may allow the use of an elastic material that is not porous and therefore not fluid permeable. Furthermore, this may allow the fluid permeability of the blank contact element to be adjusted by adjusting the number and size of the holes provided in the flank contact element.

[0045] Optionally, the blank contact element may be made of a porous material and exhibit one or more holes, which may allow the fluid permeability of the blank contact element to be achieved in part by the porosity of the elastic material and in part by the one or more holes, which may combine the aforementioned advantages of both approaches.

[0046] The shape and size of the upper surface of the blank contact element correspond to the shape and size of the lens blank to be blocked. This may allow the blank contact element and the blocked lens blank to be positioned flush. Such a flush positioning may reduce the risk of mechanical shock to the blank contact element other than the portion of the upper surface that contacts the lens blank, which may otherwise disrupt the vacuum seal formed between the lens blank and the blocked blank contact element and result in the blocked lens blank being unintentionally released. Alternatively, if a sealing lip is provided, the size and / or shape of the sealing lip may be tailored to the size and / or shape of the lens blank. For example, the difference in diameter of the blank contact element and / or sealing lip compared to the lens blank may optionally deviate by 0.5 mm or less. This may facilitate the machining process of the edge of the lens blank.

[0047] The blank contact element may further include a sealing lip disposed around the periphery of the blank contact element, the sealing lip being adapted to assist in providing a vacuum within the blocking piece and between the lens blank and the top surface of the blank contact element. The sealing lip may be advantageous for providing a snug fit of the blank contact element to the curved anterior surface of the lens blank. Optionally, the sealing lip may be different from the inner portion of the blank contact element and may provide less porosity or no porosity at all. This may prevent or reduce infiltration of fluid streams from the periphery of the blank contact element into the blank contact element when the lens blank is blocked.

[0048] The sealing lip may form an integral part of the blank contact element and / or the support element. Alternatively, the sealing lip may be provided as a separate part of the blank contact element and that does not form part of the support element.

[0049] The sealing lip may be made of a material different from the material of the blank contact element and the material of the support element. This may allow the properties of the sealing lip to be adjusted independently from the properties of the blank contact element and the support element. The porosity of the material of the sealing lip may be different from the porosity of the material of the blank contact element and the support element. The sealing lip may be made of a non-porous material. This may provide vacuum sealing at the outer edge between the blank contact element and the blocked lens blank and increase the area of ​​the vacuum applied to the blocked lens blank. This may increase the area over which suction force is applied to the blocked lens blank, thus increasing the stability of the blocking. Alternatively or additionally, this may allow a smaller pressure difference between ambient pressure and the applied vacuum.

[0050] The sealing lip may extend radially outwardly of the vacuum blocking piece at the periphery of the blank contact element.

[0051] The sealing lip may be made of a resilient material, such as a polyurethane-based material and / or a rubber-based material, which may improve the ability of the sealing lip to conform its shape to the front surface of the blocked lens blank facing the blank contact element.

[0052] The blank contact element may further include a lower surface adapted to contact the vacuum blocking piece, and the blank contact element may include one or more protrusions extending from the lower surface of the blank contact element. The one or more protrusions may be adapted to engage with the blocking piece when the blank contact element is attached to the vacuum blocking piece. Thus, the upper surface of the support element of the vacuum blocking piece may include one or more recesses, and the blank contact element may include one or more protrusions adapted to mechanically engage with the one or more recesses on the upper surface of the support element when the blank contact element is attached to the support element. This may allow the blank contact element and the blocking piece to interlock, increasing the stability of the connection between the blank contact element and the vacuum blocking element, particularly during rotational movements that occur when machining the rear surface of the blocked lens blank. In other words, the upper surfaces of the blank contact element and the support element may be adapted to interlock with each other, thereby preventing rotational movement of the blank contact element and the support element relative to each other. Alternatively or additionally, the blank contact element and the support element may be adapted to mechanically interlock with each other at an outer peripheral portion of the blank contact element.

[0053] The fluid permeable blank contact element may be adapted to mate with an interface of the support element that forms an interface with the blank contact element, which may impede or eliminate relative movement between the blank contact element and the lens blank, thus improving the mechanical stability of the assembly including the blocking piece, blank contact element, and ultimately the blocked lens blank.

[0054] The upper part of the support element can be adapted to support a fluid-permeable blank contact element and can be formed of a rigid, fluid-permeable material. The rigid, fluid-permeable material of the support element can include or consist of one or more of the following materials: ceramic materials, carbide materials, particularly silicon carbide, oxide materials, particularly aluminum oxide, and aluminum foam. These materials can offer the advantage that they can inherently exhibit open porosity or can be manufactured to exhibit open porosity. Additionally, these materials offer the advantage of high rigidity and therefore high stability under pressure. These materials therefore offer a suitable combination of fluid permeability and mechanical stability, making them suitable materials for use in blank contact elements. For example, porous materials with a specific (open) porosity conventionally used in grinding or cutting processes can be used. By way of example, such a material can be silicon carbide (referred to as 10C) with a medium hardness of "M" and a medium grain size of 60 according to the DIN 69100 specification. A support element having an upper surface made of such a material may provide suitable support for a fluid-permeable blank contact element made of an elastic material, and may enable suction of fluid through the blank contact element and support element, in particular for vacuum blocking the lens blank.

[0055] The vacuum blocking piece may include an adhesive that secures the lower surface of the blank contact element to the upper surface of the support element, which may further enhance the fixation of the blank contact element to the vacuum blocking piece and therefore further improve the stability of the assembly including the blank contact element, the vacuum blocking piece, and the lens blank blocked thereto.

[0056] The vacuum blocking piece may further include a sealing lip formed separately from the blank contact element. This may allow the vacuum area to be reliably sealed from the outside. To help achieve this goal, a rubber circumferential sealing lip may be provided on the outer edge of the upper portion. Furthermore, because the sealing lip may be separate from the blank contact element, mechanical impacts to the sealing lip will not affect the mechanical contact between the lens blank and the blank contact element.

[0057] The front surface of the lens blank and / or the top surface of the blank contact element may be plasma treated in a vacuum chamber prior to blocking the lens blank. Alternatively or additionally, a polishing step may be performed on the front surface of the lens blank and / or the top surface of the blank contact element. This may remove contaminants from the surface, increase the surface energy, and / or increase the adhesion between the lens blank and the blank contact element.

[0058] The upper surface of the blank contact element may have a concave shape. In other words, the upper surface of the blank contact element may have a depression in its center, and the edge of the blank contact element may have a height higher than the center of the upper surface of the blank contact element. This may facilitate contact with the front surface of an eyeglass lens blank, which has a convex shape. The concave shape of the blank contact element may be adapted to the convex shape of the lens blank to be blocked by the vacuum blocking piece including the blank contact element.

[0059] Any disclosure and all features shown with respect to the blank contact element shall also be considered to be disclosed for the vacuum blocking piece and vice versa. Any disclosure and all features shown with respect to the blank contact element and / or the vacuum blocking piece shall also be considered to be disclosed for the method of manufacturing an eyeglass lens and vice versa.

[0060] It will be understood by those skilled in the art that the features described above and shown in the following description and drawings are not only disclosed in the explicitly disclosed embodiments and combinations, but also in other technically feasible combinations as well as individual features, which are included in the present disclosure. In the following, some optional embodiments and specific examples are described with reference to the drawings for illustrating the present disclosure, and the present disclosure is not limited to the described embodiments.

[0061] In the following, optional embodiments of the present disclosure will be illustrated with reference to the drawings, which show: [Brief explanation of the drawings]

[0062] [Figures 1A-1E] Vacuum blocking pieces according to various optional embodiments. [Figure 2A-2B] 10 is a schematic diagram of a blank contact element according to an optional embodiment. [Figure 3] 10 is a schematic diagram of a blank contact element according to yet another optional embodiment. [Figure 4] A method according to an optional embodiment for manufacturing an eyeglass lens. DETAILED DESCRIPTION OF THE INVENTION

[0063] In the figures, the same reference numbers are used for corresponding or similar features between different drawings.

[0064] FIG. 1A shows a vacuum blocking piece 10 according to an optional embodiment for vacuum blocking a lens blank 12 (see FIG. 1C). The vacuum blocking piece 10 includes a support element 14 having an upper portion 16 and a lower portion 18, the lower portion 18 adapted to engage a clamping device for securing the blocking piece 10. The vacuum blocking piece 10 includes a fluid-permeable blank contact element 20. The blank contact element includes an upper surface 22 adapted to contact the lens blank 12 and made of a resilient material. The blank contact element further has a lower surface 24 that contacts the upper portion of the support element 16. The blocking piece 10 is adapted to secure the lens blank 12 to the upper surface 22 of the blank contact element 20 by applying a vacuum within the vacuum blocking piece 10 to provide a suction force across essentially the entire upper surface 22 of the blank contact element 20, thereby adhering the lens blank 12 to the upper surface 22 of the blank contact element 20 and adhering the blank contact element 20 to the upper portion 16 of the support element 14.

[0065] The blank contact element 20 may be fabricated entirely from an elastic material. The elastic material may include at least one material selected from the group consisting of a polyurethane-based material and a rubber-based material. The elastic material may be at least partially porous, and the fluid permeability of the blank contact element 20 may be achieved, at least in part, by the porosity of the elastic material.

[0066] The shape and size of the upper surface of the blank contact element 20 may optionally correspond to the shape and size of the lens blank 12 to be blocked.

[0067] The blank contact element 20 and / or the support element 14 of the vacuum blocking piece 10 may further include a sealing lip 26 disposed around the blank contact element 20, which assists in providing a vacuum within the vacuum blocking piece 10 and between the lens blank 12 and the upper surface 22 of the blank contact element 20. According to this embodiment, the sealing lip 26 and the blank contact element 20 are formed as a single part. In addition, the part forming the blank contact element 20 and the sealing lip 26 may have an extension 28 extending outside the upper part of the support unit and secured to the support element 14 of the vacuum blocking piece. This may allow the blank contact element 20 and the sealing lip 26 to be secured to the support element 14 in a particularly rigid configuration. Optionally, the extension 28 may be sandwiched between the upper part 16 and the lower part 18 of the support element 14.

[0068] 1A, the sealing lip 26 and the blank contact element are formed together as one single piece. However, according to other embodiments, the blank contact element 20 may be formed without the sealing lip 28, and optionally, the sealing lip 28 may be provided separately from the blank contact element 20.

[0069] The operating principle of the vacuum blocking device 10 may correspond to that of a vacuum blocking device as described in EP 4035832 A1.

[0070] The fluid-permeable blank contact element 20 may be adapted to mate with an interface of the support element 14 that forms an interface with the blank contact element. The upper portion 16 of the support element 14 may be adapted to support the fluid-permeable blank contact element 20 and may be fabricated from a rigid fluid-permeable material.

[0071] The vacuum blocking piece 20 may be adapted to provide static friction between the blank contact element 20 and the support element 14 having a coefficient of friction of 2.5 or greater. The vacuum blocking piece may include an adhesive that secures the lower surface 24 of the blank contact element 20 to the upper surface of the upper portion 16 of the support element 14. This may further increase static friction between the blank contact element 20 and the support element 14.

[0072] 1B shows in perspective view the blank contact element 20 attached to the support element 14 of the vacuum blocking piece 10. As demonstrated here, the top surface 22 and sealing lip 26 of the blank contact element 20 are formed as one unitary piece.

[0073] Figure 1C shows in schematic form the vacuum-blocking piece 10 shown in Figure 1A with a lens blank 12 vacuum-blocked thereto. The diameter of the sealing lip 26 may be 69 mm and the diameter of the lens blank 12 may be 70 mm.

[0074] FIG. 1D shows in perspective view a lens blank 12 vacuum blocked in a vacuum blocking apparatus according to the optional embodiment of FIG. 1B.

[0075] 1E shows a perspective view of the vacuum blocking device 10 with the flank contact element 20 and sealing lip 26 attached thereto. The sealing lip 26 is provided separately from the blank contact element 20.

[0076] FIG. 2A schematically illustrates a blank contact element 20 in a top view having a plurality of holes 30, shown as dots, provided throughout the thickness of the top surface of the blank contact element 20. The holes may be distributed throughout the top surface of the blank contact element 20 to allow for uniform fluid flow through the top surface of the blank contact element 20. The blank contact element 20 may be made of an elastic material, which may be fluid permeable or impermeable. Fluid flow may be induced solely by the holes 30 or may additionally be induced by optional fluid permeability properties of the elastic material. The holes may be uniformly distributed or randomly distributed. The holes may be the same size and / or shape or may vary in size and / or shape.

[0077] FIG. 2B shows a schematic cross-sectional view of a blank contact element 20 .

[0078] 3 shows a schematic diagram of a blank contact element 20 according to another optional embodiment. According to this optional embodiment, the lower surface 24 of the blank contact element 20, which is adapted to contact the vacuum blocking piece 10, includes a plurality of protrusions 32 extending from the lower surface 24 of the blank contact element 20. The one or more protrusions are adapted to engage the blocking piece 10, and in particular the upper portion 16 of the support element 14, when the blank contact element 10 is attached to the vacuum blocking piece 10. The upper portion 16 of the support element 14 may include a plurality of recesses arranged, sized, and shaped to allow the protrusions 32 to engage the support element 14. This may provide increased mechanical stability and prevent relative movement of the blank contact element 20 with respect to the support element 14 when machining a lens blank 12 vacuum-blocked to the vacuum blocking piece 10.

[0079] FIG. 4 shows a schematic diagram of a method 400 for manufacturing an eyeglass lens.

[0080] The method 400 includes, at step 402, providing a vacuum-blocking piece 10 for vacuum-blocking a lens blank 12, the vacuum-blocking piece 10 including a fluid-permeable blank contact element 20 having an upper surface 22 adapted to contact the lens blank 12, at least the upper surface 22 of the fluid-permeable blank contact element 12 being made of a resilient material. Further, the blank contact element 20 includes a support element 14 having an upper portion 16 and a lower portion 18, the lower portion 18 being adapted to engage a clamping device for securing the vacuum-blocking piece 10, and the upper portion 16 supporting the fluid-permeable blank contact element 20.

[0081] The method 400 includes, at step 404 , placing the lens blank 12 on the top surface 22 of the blank contact element 20 such that the front surface of the lens blank 12 completely covers the top surface 22 .

[0082] In step 406, the method 400 includes applying a vacuum within the vacuum blocking piece 10 to provide a suction force through the fluid-permeable elastomeric blank contact element 20, causing the front surface of the lens blank 12 to adhere to the entire upper surface 22 of the fluid-permeable elastomeric blank contact element 20.

[0083] At step 408 , the method 400 includes machining at least a portion of the back surface of the lens blank 12 while the front surface of the lens blank 12 is vacuum blocked to the vacuum blocking piece 10 . [Explanation of symbols]

[0084] 10 Vacuum Blocking Pieces 12 Lens Blanks 14 Supporting Elements 16 Upper part of supporting element 18 Lower part of supporting element 20 blank contact elements 22 Top surface of blank contact element 24 Bottom face of blank contact element 26 Sealing Lip 28 Blank Contact Element Extension 30 holes 32 Protrusion 400 ways 402-408 Method Steps

Claims

1. A vacuum blocking piece (10) for vacuum blocking a lens blank (12), a support element (14) having an upper part (16) and a lower part (18), said lower part (18) being adapted to engage with a clamping device for fixing said vacuum blocking piece (10); a fluid-permeable blank contact element (20), the blank contact element (20) being fluid-permeable and at least its upper surface (22), which is intended to be in contact with the lens blank (12), being made of an elastic material, and further having a lower surface (24) for contacting the upper part (16) of the support element (14); Including, A vacuum blocking piece (10) configured to fix the lens blank (12) to the upper surface (22) of the blank contact element (20) by applying a vacuum within the blocking piece (10) to provide a suction force across essentially the entire upper surface (22) of the blank contact element (20), thereby adsorbing the lens blank (12) to the upper surface (22) of the blank contact element (20) and adsorbing the blank contact element (20) to the upper portion (16) of the support element (14).

2. 2. The vacuum blocking piece (10) of claim 1, wherein the blank contact element (20) is made entirely of the elastic material.

3. 3. The vacuum blocking piece (10) of claim 1 or 2, wherein the elastic material comprises at least one material selected from the group consisting of polyurethane-based materials and rubber-based materials.

4. A vacuum blocking piece (10) according to any one of claims 1 to 3, wherein the elastic material is at least partially porous, and the fluid permeability of the blank contact element is at least partly achieved by the porosity of the elastic material.

5. A vacuum blocking piece (10) according to any one of claims 1 to 4, wherein the fluid permeability of the blank contact element is achieved at least in part by one or more holes (30) formed in the blank contact element (20).

6. A vacuum blocking piece (10) according to any one of claims 1 to 5, wherein the shape and size of the upper surface (22) of the blank contact element (20) corresponds to the shape and size of the lens blank (12) to be blocked.

7. A vacuum blocking piece (10) as described in any one of claims 1 to 6, further comprising a sealing lip (26) arranged around the periphery of the blank contact element (20), the sealing lip (26) being adapted to assist in providing a vacuum within the vacuum blocking piece (10) and between the lens blank (12) and the upper surface (22) of the blank contact element (20).

8. 8. A vacuum blocking piece (10) as claimed in any one of claims 1 to 7, wherein the blank contact element further includes a lower surface (24) adapted to contact the support element (14), and the blank contact element (20) includes one or more protrusions (32) extending from the lower surface (24) of the blank contact element (20), the one or more protrusions (32) adapted to engage with the support element (14) when the blank contact element (20) is attached to the support element (14).

9. 9. The vacuum blocking (10) piece according to any one of claims 1 to 8, wherein the fluid-permeable blank contact element (20) is adapted to mate with an interface of the support element (14) that forms an interface with the blank contact element (20).

10. A vacuum blocking piece (10) according to any one of claims 1 to 9, wherein the upper part of the support element (14) is adapted to support the fluid-permeable blank contact element (20) and is formed of a rigid fluid-permeable material.

11. The vacuum blocking piece (10) according to any one of claims 1 to 10, wherein the vacuum blocking piece (10) is adapted to provide static friction between the blank contact element (20) and the support element (14) having a coefficient of friction of 2.5 or greater.

12. A vacuum blocking piece (10) as claimed in any one of claims 1 to 11, wherein the upper surface of the support element (14) includes one or more recesses, and the blank contact element (20) includes one or more protrusions (32) adapted to mechanically engage with the one or more recesses in the upper surface of the support element (14) when the blank contact element (20) is attached to the support element (14).

13. The vacuum blocking piece (10) of any one of claims 1 to 12, wherein the vacuum blocking piece (10) includes an adhesive that fixes the lower surface (24) of the blank contact element (20) to the upper surface of the support element (14).

14. In a method (400) for manufacturing a spectacle lens, - providing (402) a vacuum blocking piece (10) according to any one of claims 1 to 13; - placing (404) a lens blank (12) on the upper surface (22) of the blank contact element (20) so that the front surface of said lens blank (12) completely covers said upper surface (22); - applying a vacuum within the vacuum blocking piece (10) to provide a suction force through the fluid-permeable elastomeric blank contact element (20) to attract (406) the front surface of the lens blank (12) onto the entire top surface (22) of the fluid-permeable elastomeric blank contact element (20); - mechanically (408) machining at least a portion of the rear surface of said lens blank (12) while said front surface of said lens blank (12) is vacuum blocked to said vacuum blocking piece (10); A method comprising:

15. A vacuum blocking piece (10) for vacuum blocking a lens blank (12), a support element (14) having an upper part (16) and a lower part (18), said lower part (18) being adapted to engage with a clamping device for fixing said vacuum blocking piece (10); a fluid-permeable blank contact element (20), the blank contact element (20) being fluid-permeable and at least its upper surface (22), which is intended to be in contact with the lens blank (12), being made of an elastic material, and further having a lower surface (24) for contacting the upper part (16) of the support element (14); Including, a vacuum blocking piece (10) configured to fix the lens blank (12) to the upper surface (22) of the blank contact element (20) by applying a vacuum within the blocking piece (10) to provide a suction force across essentially the entire upper surface (22) of the blank contact element (20), thereby adsorbing the lens blank (12) to the upper surface (22) of the blank contact element (20) and adsorbing the blank contact element (20) to the upper portion (16) of the support element (14); and the upper portion of the support element (14) is configured to support the fluid-permeable blank contact element (20) and is formed of a rigid, fluid-permeable material.

16. 16. The vacuum blocking piece (10) of claim 15, wherein the blank contact element (20) is made entirely of the elastic material.

17. 17. The vacuum blocking piece (10) according to claim 15 or 16, wherein the elastic material comprises at least one material selected from the group consisting of polyurethane-based materials and rubber-based materials.

18. A vacuum blocking piece (10) according to any one of claims 15 to 17, wherein the elastic material is at least partially porous, and the fluid permeability of the blank contact element is at least partly achieved by the porosity of the elastic material.

19. A vacuum blocking piece (10) according to any one of claims 15 to 18, wherein the fluid permeability of the blank contact element is achieved at least in part by one or more holes (30) formed in the blank contact element (20).

20. A vacuum blocking piece (10) according to any one of claims 15 to 19, wherein the shape and size of the upper surface (22) of the blank contact element (20) corresponds to the shape and size of the lens blank (12) to be blocked.

21. A vacuum blocking piece (10) as described in any one of claims 15 to 20, further comprising a sealing lip (26) arranged around the periphery of the blank contact element (20), the sealing lip (26) being adapted to assist in providing a vacuum within the vacuum blocking piece (10) and between the lens blank (12) and the upper surface (22) of the blank contact element (20).

22. 22. A vacuum blocking piece (10) as claimed in any one of claims 15 to 21, wherein the blank contact element (20) further comprises a lower surface (24) adapted to contact the support element (14), and the blank contact element (20) comprises one or more protrusions (32) extending from the lower surface (24) of the blank contact element (20), the one or more protrusions (32) adapted to engage with the support element (14) when the blank contact element (20) is attached to the support element (14).

23. 23. The vacuum blocking (10) piece of any one of claims 15 to 22, wherein the fluid-permeable blank contact element (20) is adapted to mate with an interface of the support element (14) that forms an interface with the blank contact element (20).

24. The vacuum blocking piece (10) according to any one of claims 15 to 23, wherein the vacuum blocking piece (10) is adapted to provide static friction between the blank contact element (20) and the support element (14) having a coefficient of friction of 2.5 or greater.

25. A vacuum blocking piece (10) as claimed in any one of claims 15 to 24, wherein the upper surface of the support element (14) includes one or more recesses, and the blank contact element (20) includes one or more protrusions (32) adapted to mechanically engage with the one or more recesses in the upper surface of the support element (14) when the blank contact element (20) is attached to the support element (14).

26. The vacuum blocking piece (10) of any one of claims 15 to 25, comprising an adhesive that fixes the lower surface (24) of the blank contact element (20) to the upper surface of the support element (14).

27. In a method (400) for manufacturing a spectacle lens, - providing (402) a vacuum blocking piece (10) according to any one of claims 15 to 26; - placing (404) a lens blank (12) on the upper surface (22) of the blank contact element (20) so that the front surface of said lens blank (12) completely covers said upper surface (22); - applying a vacuum within the vacuum blocking piece (10) to provide a suction force through the fluid-permeable elastomeric blank contact element (20) to attract (406) the front surface of the lens blank (12) onto the entire top surface (22) of the fluid-permeable elastomeric blank contact element (20); - mechanically (408) machining at least a portion of the rear surface of said lens blank (12) while said front surface of said lens blank (12) is vacuum blocked to said vacuum blocking piece (10); A method comprising:

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