Method for manufacturing vacuum blocking pieces and 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 of manufacturing an eyeglass lens are provided. The present disclosure thus relates to the manufacture of eyeglass lenses.

[0002] Thus, embodiments relate to systems, devices, and methods for blocking a lens blank and for manufacturing ophthalmic lenses, particularly eyeglass lenses.

Background Art

[0003] In the industrial mass production of eyeglass lenses made of plastic materials or mineral glass, particularly in the case of eyeglass lenses having a freeform surface, the lens blank is blocked to a blocking piece using a device, which may be called a blocking device, separate from the machining device for grinding or cutting the lens blank. Blocking of the lens blank is necessary to mechanically and elastically fix the lens blank in a predefined position so that it can withstand the milling or grinding operations for individualizing the refractive power of the lens blank. The blocking piece to which the lens blank is blocked allows the lens blank to be fitted and / or press-fitted to a grinding or cutting machine via the blocking piece.

[0004] According to prior art, a lens blank is attached to a blocking piece using a low-melting-point metal alloy. The lens blank is positioned such that, with respect to the blocking piece, 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 to each other, and the space between the blocking piece and the front surface of the lens blank is filled with the liquid metal alloy. The blocking piece is then rapidly cooled by a cooling device incorporated into the blocking apparatus, the metal alloy hardens, and the lens blank is fixed to the blocking piece. The blocking method can be performed manually or automatically. After the metal alloy has hardened, the blocking piece and the lens blank attached thereto can be removed from the blocking apparatus.

[0005] Following the blocking step, the following manufacturing steps are typically performed on the blocked lens blank: cutting the rim contour of the spectacle lens; milling to impart the desired refractive power to the rear surface of the lens blank; polishing the milled surface in a polishing device into which the blocked lens blank is inserted; and marking the optical surface with a signature mark to enable precise positioning of the optical surface.

[0006] Finally, the finished eyeglass lenses are removed from the blocking pieces. If metal alloys were used for the blocking, the metal alloys are heated, melted, and sent to a recycling process.

[0007] The use of metal alloys to block lens blanks is environmentally undesirable. To improve this, attempts have been made to avoid using metal alloys to block lens blanks for environmental reasons. An alternative blocking method is described in German Patent Application Publication No. 102005038063A1, which proposes the use of polymer adhesives or thermoplastic materials that can be cured by light irradiation.

[0008] When polymer or thermoplastic materials are used for blocking, reusing the blocking material after the blocking is released is often uneconomical due to contamination of the blocking material during the manufacturing process, as well as mechanical and / or chemical changes in the material over time.

[0009] An alternative lens blank blocking method proposed in the prior art is described in European Patent No. 2266754B1. According to the method proposed therein, a lens blank is fixed to a support surface by vacuum using a blocking piece having a support surface including ring-shaped recesses. However, in this method, these recesses often cause unwanted deformation of the lens blank.

[0010] Japanese Patent Publication No. 03121763A describes a vacuum adapter having several interlocking cylindrical parts. German Patent Publication No. 2531134A1 shows a vacuum adapter in which a flexible sealing ring contacts a lens. U.S. Patent No. 3134208A discloses a vacuum adapter having a circular recess that can be vacuumed. Other vacuum adapters are described in U.S. Patent No. 4089102A and German Patent Publication No. 3924078A1.

[0011] An alternative lens blank blocking method known in the industry is vacuum blocking, as described in European Patent Application Publication No. 4035832A1, which is considered to be the closest prior art to the present application. This technique uses a vacuum blocking piece whose lower portion corresponds to the lower portion of other conventional blocking pieces and is designed to be attachable to conventional machines for mechanically processing the rear surface of a lens blank.

[0012] U.S. Patent No. 6,126,520 describes a fixture and method for connecting optical components to a machine using vacuum. U.S. Patent Publication No. 2015 / 0217420A1 discloses a machine having a lens holder for holding a lens before machining within the machine, the lens before machining being held on the holder by adhesive elements. German Patent Publication No. 2531134A1 describes a machine for eyeglass 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 portion of a conventional vacuum blocking piece has an element made of a rigid porous material such as ceramic, designed to receive the lens blank. This element is matched in diameter and curvature to the convex surface of the lens blank to be vacuum blocked, and is hermetically embedded within a cylindrical support element, where it is securely bonded and / or screwed. An air valve on the underside of the adapter allows for vacuum to be applied, and by almost completely evacuating the air in the porous material / ceramic, the lens blank can be firmly adhered to the surface of the element. For a strong seal of the vacuum area to the outside, a rubber circumferential sealing lip may be provided on the upper outer edge. The adhesion between the surface of the lens blank and the vacuum adapter, necessary to transmit the forces and torque generated during the mechanical processing of the lens blank, is approximately 8.0-8.5 N / cm to the lens blank. 2 This is achieved through a combination of atmospheric contact pressure and 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, air can be vented into the vacuum blocking piece through an air valve, thus turning off the vacuum.

[0014] In conventional vacuum blocking processes, the existing final front surface of the lens blank that faces the blocking piece when blocked is covered with a suitable protective film or varnish before blocking, thereby protecting this front surface of the lens blank from damage caused by contact with the blocking piece during processing. Furthermore, the protective film or varnish may be necessary in conventional blocking methods to ensure sufficient adhesion between the lens blank and the blocking piece, through the effect of adhesives or microserrations, etc., which provide a mechanical connection between the lens blank and the blocking piece that is elastic against the forces and moments generated during mechanical processing. [Overview of the Initiative] [Problems that the invention aims to solve]

[0015] In view of European Patent Application Publication No. 4035832A1, which is the most recent prior art to the present application, the technical problem that is the subject matter of the patent claims may relate to providing an improved vacuum blocking piece and an improved method for manufacturing spectacle lenses, and optionally, to providing an improved vacuum blocking piece and an improved method for manufacturing spectacle lenses that increases environmental sustainability and reduces the manufacturing cost of spectacle lenses. [Means for solving the problem]

[0016] This problem is solved by blank contact elements, vacuum blocking pieces, and methods having the features of each independent claim. Optional embodiments are provided in the dependent claims and description.

[0017] In a first embodiment, a blank contact element is provided, which is made for use with a vacuum blocking piece suitable for vacuum blocking a lens blank, wherein the blank contact element is fluid permeable, and at least the upper surface of the blank contact element that is made to contact the lens blank is made of an elastic material.

[0018] In another embodiment, a vacuum blocking piece is provided for vacuum blocking a lens blank. The vacuum blocking piece includes a support element having an upper and a lower part, the lower part being configured 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 the upper surface of the blank contact element, configured to contact the lens blank, being made of an elastic material, and the blank contact element further having a lower surface (24) for contacting the upper part of the support element. The vacuum blocking piece is configured to secure the lens blank to the upper surface of the blank contact element by applying a vacuum within the blocking piece to provide an attractive force basically throughout the upper surface of the blank contact element, thereby causing the lens blank to adhere to the upper surface of the blank contact element, and causing the blank contact element to adhere to the upper part of the support element.

[0019] In another embodiment, a vacuum blocking piece is provided for vacuum blocking a lens blank. The vacuum blocking piece includes a support element having an upper and a lower part, the lower part being configured 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 the upper surface of the blank contact element, configured to contact the lens blank, being made of an elastic material, and the blank contact element further having a lower surface for contacting the upper part of the support element. The vacuum blocking piece is configured to fix the lens blank to the upper surface of the blank contact element by applying a vacuum within the blocking piece, providing an attractive force basically throughout the upper surface of the blank contact element, causing the lens blank to adhere to the upper surface of the blank contact element, and causing the blank contact element to adhere to the upper part of the support element. The upper part of the support element is configured to support the fluid-permeable blank contact element and is formed of a rigid fluid-permeable material.

[0020] In another embodiment, a vacuum blocking piece is provided for vacuum blocking a lens blank. The vacuum blocking piece includes a support element having an upper and a lower part, the lower part being configured to engage with 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 contact with the upper part of the support element. The blocking piece is configured to secure the lens blank to the upper surface of the blank contact element by applying a vacuum within the blocking piece, providing an attractive force basically throughout the upper surface of the blank contact element, thereby causing the lens blank to adhere to the upper surface of the blank contact element, and the blank contact element to adhere to the upper part of the support element.

[0021] In another embodiment, a method for manufacturing an eyeglass lens is provided. This method comprises providing a vacuum blocking piece for vacuum blocking a lens blank, the vacuum blocking piece comprising a fluid-permeable blank contact element having an upper surface made to contact the lens blank, at least the upper surface of the fluid-permeable blank contact element being made of an elastic material, the vacuum blocking piece comprising a support element having an upper and a lower part, the lower part being made to engage with a clamping device for fixing the blocking piece, and the upper part supporting the fluid-permeable blank contact element. The method further comprises positioning 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. Furthermore, the method comprises creating a vacuum within the vacuum blocking piece to provide an attractive force through the fluid-permeable elastic blank contact element, causing the lens blank to adhere to the entire upper surface of the fluid-permeable elastic 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 another aspect, a method of manufacturing an eyeglass lens is provided. The method includes providing a vacuum blocking piece according to the present disclosure. The method further includes disposing a lens blank on the upper surface of a 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 elastic blank contact element and adsorbing the front surface of the lens blank to the entire upper surface of the fluid-permeable elastic blank contact element, and mechanically processing at least a portion of the rear surface of the lens blank while the front surface of the lens blank is vacuum blocked by the vacuum blocking piece.

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

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

[0025] According to common understanding and the definition in ISO 13666:2019(E) Section 3.5.2, an eyeglass lens can be an ophthalmic lens as defined in ISO 13666:2019(E) Section 3.5.1 that is worn in front of the eye without contacting it.

[0026] The blocking piece relates to an adapter piece for attaching 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 performing bevel machining of an ophthalmic lens according to provided bevel machining 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 released from the blocking in such a way as to maintain the integrity of the front surface of the lens blank, in particular of the lens blank, which can optionally be protected by a protective foil or coating. The blocking piece can 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 mainly or exclusively uses vacuum force, i.e., the pressure due to the suction force inside the vacuum blocking piece, to fix the lens blank to the vacuum blocking piece, which is described, for example, in European Patent Application Publication No. 4035832 A1. Therefore, vacuum-blocking a lens blank means fixing the lens blank to the blocking piece mainly or exclusively using vacuum force, i.e., the pressure due to the suction force inside the vacuum blocking piece.

[0027] That the blank contact element has fluid permeability means that a fluid stream of gas, in particular a stream of air, can occur through the blank contact element. In particular, the 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 should be understood as a material having 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 initial shape.

[0029] When we say that at least the upper surface of the blank contact element is made of an elastic material, we mean that at least the surface that comes into contact with the lens blank when blocking the lens blank is made of an elastic material. Optionally, the entire blank contact element may be made of an elastic material. The blank contact element may be made as a single piece of elastic material.

[0030] The blank contact element may be supplied as a separate component from the vacuum blocking piece. However, according to some optional embodiments, the blank contact element may form an integral part with the vacuum blocking piece. When the blank contact element is made to be used with the vacuum blocking piece, it means that the blank contact element and the vacuum blocking piece may be supplied as an assembly for vacuum blocking a 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] The suction force throughout the “essentially entire upper surface” of the blank contact element means that the suction force and the airflow that may result from it are not limited to specific small areas on the upper surface of the blank contact element, such as recesses or holes provided only within a small area on the upper surface of the blank contact element. Rather, “essentially the entire upper surface” means that the suction force is provided over most of the upper surface, particularly over more than 90% of the usable portion of the upper surface, preferably over the entire usable upper surface. The usability of a portion of the upper surface means that the said portion of the upper surface is not covered by the lens blank but is usable for contact with it. This can be achieved by providing a porous elastic material and / or by providing holes distributed throughout the entire upper surface of the blank contact element.

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

[0033] This disclosure provides the advantage 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, as it eliminates the need to apply protection to the front surface of the lens bank that comes into contact with the blank contact element during vacuum blocking, because the risk of mechanical damage to the front surface of the lens blank resulting from contact with the blank contact element is nonexistent or negligible. As a result, additional costs for applying and removing protective measures to the lens blank can be eliminated, and therefore, the manufacturing cost of spectacle lenses can be reduced. Furthermore, there is no need to provide and maintain machinery for applying and removing protective measures, which can further reduce costs.

[0034] Furthermore, the risk of damaging the lens blank during the application and / or removal process of protective measures, such as protective foil, can also be reduced. Conventional processes for applying and / or removing protective foil often subject the lens blank to mechanical stress, which can result in edge damage to the lens blank. Such damage can be avoided according to this disclosure, as the application and / or removal of protective foil is unnecessary.

[0035] Furthermore, since the application of protective coatings and / or protective foils to the front surface of the lens blank may be omitted, the amount of waste generated during the manufacture of spectacle lenses may also be reduced. This can further improve the environmental sustainability of the spectacle lens manufacturing process.

[0036] In addition, this disclosure offers the advantage that the elastic material can provide suitable 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 machining of the rear surface of the blocked lens blank, and further eliminates the necessity of bonding or fixing. The provided static friction can be suitable for transmitting torques of up to 12 Nm, and even 15 Nm, which corresponds to typical values ​​achievable with conventional blocking pieces based on alloy blocking of spectacle lens blanks, and is therefore well suitable for mechanical machining of blocked lens blanks. However, optionally, an adhesive may be applied between the blank contact element and the lens blank, thereby increasing the transmittable torque. The adhesive may be a two-component adhesive. One or more adhesive spots may be applied to the front surface of the lens blank and / or the upper surface of the blank contact element.

[0037] In particular, elastic materials can provide significantly higher static friction than rigid porous materials such as porous ceramic materials as described in European Patent Application Publication No. 4035832A1.

[0038] The blank contact element may be made entirely of an elastic material. This may allow the blank contact element to be formed as a single part made from a single material, thus facilitating the 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 from one or more of these materials. Optionally, the polyurethane-based material may include or consist of polyurethane foam. These materials may offer 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 a support element, which may be made of, for example, ceramic material, SiC, Al2O3, or porous aluminum. Furthermore, rubber-based materials and / or polyurethane-based materials, such as polyurethane foils, may offer suitable permeability to fluids such as air, suitable for applying an attractive force to vacuum-block the lens blank through the blank contact elements. Furthermore, these materials may offer 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 3 N / mm² as specified by ISO 1827:2022. 2 It can provide a stiffness modulus exceeding [a certain value]. The vacuum blocking piece may be constructed to provide static friction between the blank contact element and the support element with a coefficient of friction of up to 2.5. This can 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 modulus of elasticity of porous polyurethane foil is approximately 3 N / mm². 2 ~Approx. 10N / mm 2 It could be within the range.

[0041] The blank contact element may 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 may be manufactured separately from the vacuum blocking piece. For example, the blank contact element may be manufactured by a sulfidation process. Furthermore, the manufacturing process for the blank contact element may include drilling holes in the sulfidated 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 can ensure that the lens blank is adequately protected from mechanical scratches caused by the vacuum blocking piece. Furthermore, this can absorb and / or attenuate the mechanical shock transmitted from the vacuum blocking piece to the blocked lens blank, especially during machining of the lens blank. In addition, the blank contact device can absorb and / or attenuate the shock to the lens blank, ensuring that the blocking of the lens blank is not jeopardized by the shock.

[0043] The elastic material may be at least partially porous, and the fluid permeability of the blank contact element is at least partially obtained by the porosity of the elastic material. This can optionally be achieved by forming the blank contact element at least partially from a foamed material, such as polyurethane foam. The elastic material may exhibit open porosity, allowing fluid streams to pass through the porous material. Such fluid streams passing through holes can be used to provide an attractive force that generates pressure to fix the lens blank to the blank contact element and the blank contact element to the blocking piece during the blocking process. This can ensure that the fluid stream is evenly distributed across the entire surface of the blank contact element.

[0044] Alternatively or additionally, the fluid permeability of the blank contact element is obtained, at least in part, by one or more holes formed within the blank contact element. The blank contact element may include a plurality of holes dispersed on the upper surface of the blank contact element. These holes may be through holes extending throughout the entire thickness of the blank contact element. The through holes may extend straight into the blank contact element, i.e., along the direction of the pressure acting on the lens blank to secure it to the blank contact element. Alternatively or additionally, one or more holes may extend in directions other than straight within the blank contact element. This may allow the use of elastic materials that are 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 fabricated from a porous material and exhibit one or more holes. This allows the fluid permeability of the blank contact element to be achieved partly by the porosity of the elastic material and partly by one or more holes. This may allow for a combination of the aforementioned advantages of both approaches.

[0046] The shape and size of the top 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 position may reduce the risk of mechanical impact on the blank contact element on parts of its top surface other than those in contact with the lens blank, which could otherwise break the vacuum seal formed between the lens blank and the blocked blank contact element, potentially causing the blocked lens blank to detach unintentionally. Alternatively, if a sealing lip is provided, the size and / or shape of the sealing lip may be adjusted to match the size and / or shape of the lens blank. For example, the difference in diameter between the blank contact element and / or sealing lip compared to the lens blank may, at will, deviate by 0.5 mm or less. This may facilitate the machining process of the lens blank edges.

[0047] The blank contact element may further include a sealing lip positioned around the blank contact element, which is designed to help provide a vacuum within the blocking piece and between the lens blank and the upper surface of the blank contact element. The sealing lip may be advantageous in allowing the blank contact element to fit snugly against the curved front surface of the lens blank. Optionally, the sealing lip may provide lower porosity or no porosity at all, unlike the inner portion of the blank contact element. This can prevent or reduce the intrusion of fluid streams from the periphery to 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 component that does not form part of the blank contact element and / or the support element.

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

[0050] The sealing lip may extend radially outward from the vacuum blocking piece around the blank contact element.

[0051] The sealing lip may be made of an elastic material, such as a polyurethane-based material and / or a rubber-based material. This can improve the sealing lip's ability to conform its shape to the front surface of the blocked lens blank that faces the blank contact element.

[0052] The blank contact element may further include a lower surface made to contact the vacuum blocking piece, and the blank contact element may include one or more projections extending from the lower surface of the blank contact element. The one or more projections may be made to engage with the blocking piece when the blank contact element is mounted on the vacuum blocking piece. Therefore, 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 projections made to mechanically engage with one or more recesses on the upper surface of the support element when the blank contact element is mounted on the support element. This may allow the blank contact element and the blocking piece to fit together, and may increase the stability of the connection between the blank contact element and the vacuum blocking element, in particular, during rotational motion that occurs 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 made to avoid rotational motion relative to each other by coupling with each other. Alternatively or additionally, the blank contact element and the support element may be made to mechanically couple with each other at the outer peripheral portion of the blank contact element.

[0053] A fluid-permeable blank contact element may be configured to fit with the interface of a support element that forms an interface with the blank contact element. This can hinder or eliminate the relative motion between the blank contact element and the lens blank, and thus improve the mechanical stability of the assembly, which includes the blocking piece, the blank contact element, and ultimately the blocked lens blank.

[0054] The upper part of the support element may be made to support a fluid-permeable blank contact element and may be formed of a rigid fluid-permeable material. The rigid fluid-permeable material of the support element may include or consist of one or more of the following materials: ceramic materials, carbide materials, in particular silicon carbide, oxide materials, in particular aluminum oxide, and aluminum foam. These materials may have the advantage of being inherently open-porous or being manufactured to be open-porous. In addition, these materials may have the advantage of exhibiting high rigidity and therefore high stability under pressure. Thus, these materials provide a suitable combination of fluid permeability and mechanical stability, thereby making them suitable materials for use in blank contact elements. For example, porous materials with certain (open) porosity that have been conventionally used in grinding or cutting processes may be used. For example, such a material may be silicon carbide (called 10C) having a moderate hardness of value "M" and a moderate grain size of numerical value 60 according to the specification of DIN 69100. A support element having a top surface made of such a material can provide suitable support for a fluid-permeable blank contact element made of an elastic material, and in particular can enable the suction of fluid for vacuum blocking of the lens blank through the blank contact element and the support element.

[0055] The vacuum blocking piece may contain an adhesive that secures the underside of the blank contact element to the upper surface of the support element. This further enhances the fixation of the blank contact element to the vacuum blocking piece, and thus the stability of the assembly, which includes the blank contact element, the vacuum blocking piece, and the lens blank blocked thereto, can be further improved.

[0056] The vacuum blocking piece may further include a sealing lip formed separately from the blank contact element. This may allow for a secure seal of the vacuum area to the outside. To assist in achieving this objective, a rubber circumferential sealing lip may be provided on the upper outer edge. Furthermore, since the sealing lip may be separate from the blank contact element, mechanical impact on 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 upper surface of the blank contact elements may be plasma-treated in a vacuum chamber before blocking the lens blank. Alternatively or additionally, a polishing step may be performed on the front surface of the lens blank and / or the upper surface of the blank contact elements. This may remove contaminants from the surface, increase the surface energy, and / or increase the adhesion between the lens blank and the blank contact elements.

[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 edges of the blank contact element may be higher than the center of the upper surface of the blank contact element. This may facilitate contact with the front surface of a convex spectacle lens blank. The concave shape of the blank contact element may be adapted to the convex shape of the lens blank that will be blocked by the vacuum blocking piece containing the blank contact element.

[0059] All disclosures and features shown with respect to the blank contact element are also disclosed with respect to the vacuum blocking piece, and vice versa. All disclosures and features shown with respect to the blank contact element and / or vacuum blocking piece are also disclosed with respect to the manufacturing method of spectacle lenses, and vice versa.

[0060] Those skilled in the art will understand that the features described above and those shown in the following description and figures are not only disclosed in the expressly disclosed embodiments and combinations, but also include individual features as well as other technically feasible combinations. Several optional embodiments and specific examples are described below with reference to the drawings illustrating the disclosure, and the disclosure is not limited to the embodiments described.

[0061] Optional embodiments of this disclosure are illustrated below with reference to the drawings. The drawings show: [Brief explanation of the drawing]

[0062] [Figure 1A-1E] Vacuum blocking piece according to various optional embodiments. [Figure 2A-2B] A schematic diagram of a blank contact element according to an optional embodiment. [Figure 3] A schematic diagram of a blank contact element according to another optional embodiment. [Figure 4] A method for manufacturing eyeglass lenses, according to an optional embodiment. [Modes for carrying out the invention]

[0063] In the drawings, the same reference number is used for corresponding or similar features between different drawings.

[0064] Figure 1A shows a vacuum blocking piece 10 according to an optional embodiment for vacuum blocking a lens blank 12 (see Figure 1C). The vacuum blocking piece 10 includes a support element 14 having an upper part 16 and a lower part 18, the lower part 18 being configured to engage with 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, which is configured to contact the lens blank 12 and is made of an elastic material. Furthermore, the blank contact element has a lower surface 24 that contacts the upper part of the support element 16. The blocking piece 10 is configured to fix the lens blank 12 by applying a vacuum within the vacuum blocking piece 10 to provide an attractive force over essentially the entire upper surface 22 of the blank contact element 20, thereby causing the lens blank 12 to adhere to the upper surface 22 of the blank contact element 20 and causing the blank contact element 20 to adhere to the upper part 16 of the support element 14.

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

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

[0067] The blank contact element 20 and / or support element 14 of the vacuum blocking piece 10 may further include a sealing lip 26 positioned around the blank contact element 20, the sealing lip 26 being configured to help provide 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 separate parts. In addition, the parts forming the blank contact element 20 and the sealing lip 26 may have an extension 28 extending outward from the upper part of the support unit and be fixed to the support element 14 of the vacuum blocking piece. This allows the blank contact element 20 and the sealing lip 26 to be fixed to the support element 14 in a particularly robust configuration. Optionally, the extension 28 may be sandwiched between the upper part 16 and the lower part 18 of the support element 14.

[0068] Therefore, according to the optional embodiment shown in Figure 1A, the sealing lip 26 and the blank contact element are formed together as a single component. 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 the operating principle of a vacuum blocking device described in European Patent Application Publication No. 4035832A1.

[0070] The fluid-permeable blank contact element 20 may be configured to fit with the interface of the support element 14, which forms the interface with the blank contact element. The upper part 16 of the support element 14 may be configured to support the fluid-permeable blank contact element 20 and may be made of a rigid fluid-permeable material.

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

[0072] Figure 1B is a perspective view showing the blank contact element 20 attached to the support element 14 of the vacuum blocking piece 10. As demonstrated here, the upper surface 22 and sealing lip 26 of the blank contact element 20 are formed as a single unit.

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

[0074] Figure 1D is a perspective view showing a lens blank 12 vacuum-blocked by a vacuum blocking device according to an optional embodiment of Figure 1B.

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

[0076] Figure 2A schematically shows a top view of a blank contact element 20 having a plurality of holes 30, indicated as dots, provided throughout its entire thickness across the top surface of the blank contact element 20. The holes may be distributed across the entire top surface of the blank contact element to enable 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. The fluid flow may be generated solely by the holes 30, or additionally by the 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 they may differ in size and / or shape.

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

[0078] Figure 3 shows a schematic diagram of the 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 made to contact the vacuum blocking piece 10, includes a plurality of projections 32 extending from the lower surface 24 of the blank contact element 20. One or more projections are made to engage with the blocking piece 10 and, in particular, with the upper part 16 of the support element 14 when the blank contact element 10 is attached to the vacuum blocking piece 10. The upper part 16 of the support element 14 may include a plurality of recesses having arrangement, size, and shape such that the projections 32 can engage with the support element 14. This increases mechanical stability and can prevent relative movement of the blank contact element 20 with respect to the support element 14 when machining the vacuum-blocked lens blank 12 on the vacuum blocking piece 10.

[0079] Figure 4 schematically shows method 400 for manufacturing eyeglass lenses.

[0080] Method 400 includes, in step 402, providing a vacuum blocking piece 10 for vacuum blocking a lens blank 12, the vacuum blocking piece 10 comprising a fluid-permeable blank contact element 20 having an upper surface 22 made to contact the lens blank 12, the upper surface 22 of the fluid-permeable blank contact element 12 being made of an elastic material. Furthermore, the blank contact element 20 comprises a support element 14 having an upper part 16 and a lower part 18, the lower part 18 being made to engage with a clamping device for securing the vacuum blocking piece 10, and the upper part 16 supporting the fluid-permeable blank contact element 20.

[0081] Method 400 includes, in step 404, positioning the lens blank 12 on the upper surface 22 of the blank contact element 20 such that the front surface of the lens blank 12 completely covers the upper surface 22.

[0082] In step 406, method 400 includes applying a vacuum within the vacuum blocking piece 10 to provide an attractive force through the fluid permeable elastic 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 elastic blank contact element 20.

[0083] In step 408, 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 Support elements 16. Upper part of the support element 18 Lower part of the support element 20 Blank Contact Elements 22 Blank upper surface of contact element 24 Blank lower surface of contact element 26 Sealing Lip 28 Extension of blank contact element 30 holes 32 Protrusion 400 ways 402-408 Method Steps

Claims

1. In 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), wherein the lower part (18) is configured to engage with a clamping device for fixing the vacuum blocking piece (10), - A fluid-permeable blank contact element (20) having fluid permeability, wherein at least the upper surface (22) of the blank contact element (20) that is made to contact the lens blank (12) is made of an elastic material, and the blank contact element (20) further has a lower surface (24) for contacting the upper part (16) of the support element (14), Includes, - The lens blank (12) is fixed by applying a vacuum inside the blocking piece (10) to the upper surface (22) of the blank contact element (20), thereby providing an attractive force throughout basically the entire upper surface (22) of the blank contact element (20), causing the lens blank (12) to adhere to the upper surface (22) of the blank contact element (20), and the blank contact element (20) to adhere to the upper part (16) of the support element (14). - Includes a sealing lip (26) positioned around the blank contact element (20), the sealing lip (26) being configured to help provide 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), - The sealing lip (26) and the blank contact element (20) are integrally molded. A vacuum blocking piece (10) characterized by the above.

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

3. The vacuum blocking piece (10) according to 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. The vacuum blocking piece (10) according to claim 1 or 2, wherein the elastic material is at least partially porous, and the fluid permeability of the blank contact element is obtained at least in part by the porosity of the elastic material.

5. The fluid permeability of the blank contact element is obtained by one or more holes (30) formed in at least a portion of the blank contact element (20), as described in claim 1 or 2, for the vacuum blocking piece (10).

6. The vacuum blocking piece (10) according to claim 1 or 2, wherein the shape and size of the upper surface (22) of the blank contact element (20) match the shape and size of the lens blank (12) to be blocked.

7. The vacuum blocking piece (10) according to claim 1 or 2, wherein the blank contact element further includes a lower surface (24) made to contact the support element (14), and the blank contact element (20) includes one or more projections (32) extending from the lower surface (24) of the blank contact element (20), the one or more projections (32) being made to engage with the support element (14) when the blank contact element (20) is attached to the support element (14).

8. The vacuum blocking (10) piece according to claim 1 or 2, wherein the fluid-permeable blank contact element (20) is configured to fit with the interface of the support element (14) that forms an interface with the blank contact element (20).

9. The upper part (16) 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, the vacuum blocking piece (10) according to claim 1 or 2.

10. The vacuum blocking piece (10) according to claim 1 or 2, wherein the vacuum blocking piece (10) is configured to provide static friction between the blank contact element (20) and the support element (14) having a coefficient of friction of 2.5 or more.

11. The vacuum blocking piece (10) according to claim 1 or 2, wherein the upper surface of the support element (14) includes one or more recesses, and the blank contact element (20) includes one or more projections (32) that are made to mechanically engage with the one or more recesses on the upper surface of the support element (14) when the blank contact element (20) is attached to the support element (14).

12. The vacuum blocking piece (10) according to claim 1 or 2, wherein the vacuum blocking piece (10) includes an adhesive for fixing the lower surface (24) of the blank contact element (20) to the upper surface of the support element (14).

13. In the method for manufacturing eyeglass lenses (400), - Step (402) of providing the vacuum blocking piece (10) according to claim 1 or 2, - Step (404) of positioning the lens blank (12) on the upper surface (22) of the blank contact element (20) such that the front surface of the lens blank (12) completely covers the upper surface (22), - Step (406) of applying a vacuum to the vacuum blocking piece (10) and providing an attractive force through the fluid permeable elastic blank contact element (20) to cause the front surface of the lens blank (12) to be attracted to the entire upper surface (22) of the fluid permeable elastic blank contact element (20), - A step of mechanically (408) machining at least a portion of the rear surface of the lens blank (12) while the front surface of the lens blank (12) is vacuum-blocked by the vacuum blocking piece (10), A method that includes this.

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