Vacuum barrier and method for manufacturing ophthalmic lens

Abstract

A vacuum barrier for vacuum blocking a lens blank is provided. The vacuum barrier includes a support element having an upper portion and a lower portion wherein the lower portion is adapted to engage with a gripping device for gripping the vacuum barrier. The vacuum barrier further comprises a fluid permeable blank contact element wherein the blank contact element is fluid permeable and at least an upper surface of the blank contact element adapted to contact the lens blank is 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 barrier is adapted to secure the lens blank to the upper surface of the blank contact element by applying a vacuum within the barrier to provide a suction force through substantially the entire upper surface of the blank contact element, thus, the lens blank is sucked to the upper surface of the blank contact element and the blank contact element is sucked to the upper part of the support element.

Description

[0001] A blank contact element, a vacuum barrier and a method for manufacturing an ophthalmic lens are provided.Accordingly, the present disclosure relates to the manufacture of ophthalmic lenses.

[0002] Thus, the embodiments relate to systems, devices, and methods for blocking lens blanks and for manufacturing ophthalmic lenses, in particular spectacle lenses.

[0003] For the industrial mass production of ophthalmic lenses made of plastic or mineral glass, in particular ophthalmic lenses with free-form surfaces, a device, which can be referred to as a blocking device and is separate from the machining device for grinding or cutting the lens blank, is used to block the lens blank against a blocking element. Blocking the lens blank is necessary to secure the lens blank in a defined position and to mechanically resiliently fix it, thereby supporting the milling or grinding process for individualizing the refractive power of the lens blank. The blocking element against which the lens blank is blocked allows the lens blank to be clamped to the grinding or cutting machine via the blocking element in a form-fitting and / or force-fitting manner.

[0004] According to the prior art, a lens blank is attached to a blocking member using a metal alloy having a low melting temperature. The lens blank is positioned relative to the blocking member, with the finished front surface of the lens blank facing the blocking member, such that the surface normal of the lens blank and the surface normal of the blocking member are positioned at a predetermined angle relative to each other, and the space between the blocking member and the front surface of the lens blank is filled with liquid metal alloy. The blocking member is then cooled by a cooling device integrated into the blocking device to harden the metal alloy, thereby securing the lens blank to the blocking member. This blocking method can be performed manually or automatically. After the metal alloy has hardened, the blocking member and the lens blank attached thereto 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 profile of the spectacle lens, milling the desired refractive power in the back surface of the lens blank, polishing the milled surface by means of a polishing device in which the blocked lens blank is inserted, and applying a signature mark at the optical surface, thereby allowing accurate positioning of the optical surface.

[0006] Finally, the finished eyeglass lens is removed from the barrier. In the case of a metal alloy used for the barrier, the metal alloy is heated, melted and passed through a recycling process.

[0007] The use of metal alloys to block lens blanks carries environmental disadvantages. To compensate for this, attempts have been made to avoid using metal alloys to block lens blanks for environmental reasons. An alternative blocking method is described in DE 10 2005 038 063 A1, which proposes the use of polymeric adhesives or thermoplastic materials that can be cured by irradiation with light.

[0008] In the case of barrier materials made of polymeric or thermoplastic materials, it is often uneconomical to subject the barrier material to reuse after debarring due to contamination of the barrier material during the manufacturing process and due to mechanical and / or chemical changes that occur to the material over time.

[0009] An alternative method for blocking lens blanks proposed in the prior art is described in EP 2266754 B1. The proposed method uses a blocking element having a support surface including an annular recess to secure the lens blank to the support surface by means of a vacuum. However, this method often results in undesirable deformation of the lens blank due to the recess.

[0010] JPH03121763A describes a vacuum adapter having several interlaced cylindrical sections. DE2531134A1 depicts a vacuum adapter in which the lens is contacted via a flexible sealing ring. US3134208A shows a vacuum adapter having a circular recess that can be evacuated. Further vacuum adapters are described in US4089102A and DE3924078A1.

[0011] An alternative method for blocking lens blanks known in the prior art is the vacuum block as described in EP 4 035 832 A1 , which is considered to be the most recent prior art. This technique uses a vacuum block having a lower portion corresponding to the lower portion of other conventional blocks, which is adapted to be mounted in a conventional machine for machining the back surface of a lens blank.

[0012] US 6,126,520 describes a fixture and method for attaching an optical component to a machine using vacuum. US 2015 / 0217420 A1 describes a processing machine having a lens holding device for holding a raw lens in the processing machine, wherein the raw lens is held on the holding device by an adhesive element. DE 2531134 A1 describes a device for machining ophthalmic lenses, wherein the lens holder includes an elastically deformable sleeve that connects the outer edge of the shell to the outer edge of the support collar.

[0013] The upper part of a conventional vacuum barrier has an element made of a rigid and porous material (such as ceramic) which is designed to receive a lens blank. This element, which is adapted in diameter and curvature to the convex surface of the lens blank to be vacuum blocked, is embedded in an airtight manner in a cylindrical support element and is firmly bonded to and / or screwed to the cylindrical support element. An air valve on the underside of the adapter allows the application of a vacuum to substantially evacuate the air volume of the porous material / ceramic, thereby firmly sucking the lens blank to the surface of the element. In order to seal the evacuated area robustly with respect to the outside, a circumferential sealing lip made of rubber can be provided on the outer edge of the top part. The adhesive force between the surface of the lens blank and the vacuum adapter, which is required to transmit the forces and torques occurring during the machining of the lens blank, is achieved by approximately 8.0 to 8.5 N / cm on the lens blank. 2 This is achieved by a combination of atmospheric contact pressure and the adhesive force between the protective film bonded to the surface of the lens blank and the elements of the vacuum barrier. To release the connection between the lens blank and the vacuum barrier, the interior of the vacuum barrier can be ventilated via an air valve, thereby closing the vacuum.

[0014] In conventional vacuum blocking processes, the existing final front surface of the lens blank (which faces the blocking member when blocked) is covered with a suitable protective film or varnish before blocking, so that this front surface of the lens blank remains protected from damage when in contact with the blocking member during machining. In addition, in conventional blocking techniques, the protective film or varnish may be necessary to provide sufficient adhesion between the lens blank and the blocking member through effects such as bonding or micro-serrations, thereby providing a mechanical connection between the lens blank and the blocking member that is resilient to the forces and moments occurring during machining.

[0015] In view of EP4035832A1 as the most recent prior art, the objective technical problem of the claimed subject matter may be to provide an improved vacuum barrier and an improved method for manufacturing an ophthalmic lens, and optionally to provide an improved vacuum barrier and an improved method for manufacturing an ophthalmic lens, thereby providing the ophthalmic lens with improved environmental sustainability and reduced manufacturing costs.

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

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

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

[0019] In yet another aspect, a vacuum barrier for vacuum-blocking a lens blank is provided. The vacuum barrier includes a support element having an upper portion and a lower portion, wherein the lower portion is adapted to engage with a clamping device for clamping the vacuum barrier. The vacuum barrier further includes a fluid-permeable blank contact element, wherein the blank contact element is fluid-permeable and at least an upper surface of the blank contact element adapted to contact the lens blank is formed from an elastic material, and the blank contact element further has a lower surface adapted to contact the upper portion of the support element. The vacuum barrier is adapted to secure the lens blank to the upper surface of the blank contact element by applying a vacuum within the barrier to provide suction across substantially the entire upper surface of the blank contact element, thereby drawing the lens blank to the upper surface of the blank contact element and 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 from a rigid, fluid-permeable material.

[0020] In another aspect, a vacuum barrier for vacuum blocking a lens blank is provided. The vacuum barrier includes a support element having an upper portion and a lower portion, wherein the lower portion is adapted to engage with a clamping device for clamping the barrier. The vacuum barrier 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 barrier is adapted to secure the lens blank to the upper surface of the blank contact element by applying a vacuum within the barrier to provide suction across substantially the entire upper surface of the blank contact element, thereby drawing the lens blank to the upper surface of the blank contact element and drawing the blank contact element to the upper portion of the support element.

[0021] In yet another aspect, a method for manufacturing an ophthalmic lens is provided. The method includes providing a vacuum barrier for vacuum-blocking a lens blank, wherein the vacuum barrier includes a fluid-permeable blank contact element having an upper surface adapted to contact the lens blank, wherein at least the upper surface of the fluid-permeable blank contact element is made of an elastic material, and wherein the vacuum barrier includes a support element having an upper portion and a lower portion, wherein the lower portion is adapted to engage with a clamping device for clamping the barrier, and the upper portion supports the fluid-permeable blank contact element. The method further includes placing the lens blank at the upper surface of the blank contact element such that the front surface of the lens blank completely covers the upper surface. Furthermore, the method includes applying a vacuum within the vacuum barrier to provide a suction force through the fluid-permeable elastic blank contact element, thereby drawing the front surface of the lens blank to the entire upper surface of the fluid-permeable elastic blank contact element; and machining at least a portion of the back surface of the lens blank while the front surface of the lens blank is vacuum-blocked to the vacuum barrier.

[0022] In yet another aspect, a method for manufacturing an ophthalmic lens is provided. The method includes providing a vacuum barrier according to the present disclosure. The method further includes positioning a lens blank at the upper surface of a blank contact element such that the front surface of the lens blank completely covers the upper surface. The method further includes applying a vacuum within the vacuum barrier to provide a suction force through the fluid-permeable elastic blank contact element, thereby drawing the front surface of the lens blank to the entire upper surface of the fluid-permeable elastic blank contact element; and machining at least a portion of the back surface of the lens blank while the front surface of the lens blank is vacuum-blocked to the vacuum barrier.

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

[0024] A lens blank can be an unprocessed precursor of an ophthalmic lens, such as a lens blank having an unprocessed front surface and an unprocessed back surface. A lens blank can be provided during a molding process. However, a lens blank can also be a partially processed precursor of an ophthalmic lens. For example, a lens blank can have a partially or fully processed front surface and can be covered with a protective foil or coating. As generally understood and defined in Section 3.8.1 of ISO 13666:2019(E), a lens blank can be a piece of optical material having one optically finished surface used to manufacture a lens.

[0025] As generally understood and defined in section 3.5.2 of ISO 13666:2019(E), a spectacle lens may be an ophthalmic lens that is worn in front of the eye but not in contact with the eye according to section 3.5.1 of ISO 13666:2019(E).

[0026] A barrier is an adapter for mounting a lens blank in a processing device, in particular a processing device for machining and / or grinding and / or cutting and / or polishing the rear surface of a lens blank according to prescription data and / or for edging an ophthalmic lens according to provided edging data. On one side, the barrier is adapted to contact the lens blank, while on the other side, the barrier is adapted to engage in the processing device for processing the lens blank. The barrier is adapted to allow reversible blocking of the lens blank, wherein the blocked lens blank can be unblocked in a manner that maintains the integrity of the lens blank, in particular the integrity of the front surface of the lens blank, which may optionally be protected by a protective foil or coating. The barrier may be a barrier as generally understood and defined in DIN 58766 (2017). A vacuum barrier is a barrier that primarily or exclusively uses vacuum force (i.e., pressure generated by suction within the vacuum barrier) to secure the lens blank to the vacuum barrier, as described, for example, in EP4035832A1. Accordingly, a "vacuum barrier lens blank" refers to a lens blank that is secured to the barrier primarily or exclusively through the use of vacuum forces (ie, pressure due to suction within the vacuum barrier).

[0027] The blank contact element is fluid permeable"means that a fluid flow of gas, in particular an air flow, can be generated through the blank contact element. In particular, by applying a pressure difference between the outside and the inside of the barrier, a suction force can be generated through the blank contact element.

[0028] An elastic material is understood to be a material having elastic mechanical properties. Thus, when a mechanical force is applied to the material, the elastic material can undergo mechanical deformation, wherein the deformation is at least partially reversible. Upon removal of the applied mechanical force, the elastic material can at least partially return to its original shape.

[0029] "At least the upper surface of the blank contact element is made of an elastic material" should be understood as meaning that at least the surface adapted to contact the lens blank when blocking the lens blank is made of an elastic material. Alternatively, the entire blank contact element may be made of an elastic material. The blank contact element may be made of a single piece of elastic material.

[0030] The blank contact element can be provided as a separate part from the vacuum barrier. However, according to some alternative embodiments, the blank contact element can form an integral part of the vacuum barrier. "The blank contact element is adapted for use with the vacuum barrier" means that the blank contact element and the vacuum barrier can be provided as an assembly for vacuum blocking a lens blank. The blank contact element can provide an interface between the lens blank and the vacuum barrier when blocking the lens blank.

[0031] Suction across "substantially the entire upper surface" of the blank contact element means that the suction and the possible air flow generated by the suction are not limited to certain smaller sub-areas of the upper surface of the blank contact element, such as recesses or holes provided only in a smaller area of ​​the upper surface of the blank contact element. Instead, "substantially the entire upper surface" means that the suction is provided over a substantial portion of the upper surface, in particular over an area exceeding 90% of the accessible portion of the upper surface, preferably over the entire accessible upper surface. "A portion of the upper surface is accessible" means that the portion of the upper surface is not covered but is accessible for contact by the lens blank. This can be achieved by providing the resilient material with porosity and / or by providing holes distributed over the entire upper surface of the blank contact element.

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

[0033] The present 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 mechanical softness, thereby preventing damage to the lens blank during vacuum blocking. 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, thereby preventing mechanical damage (such as scratches) to the lens blank during vacuum blocking. This further provides the advantage that applying protection to the front surface of the lens assembly that contacts the blank contact element during vacuum blocking can be omitted, as the risk of mechanical damage to the front surface of the lens blank due to contact with the blank contact device is non-existent or negligible. Therefore, additional steps for applying and removing protective measures on the lens blank can be omitted, thereby reducing the manufacturing costs of the ophthalmic lens. Furthermore, there is no need to provide and maintain machinery for applying and removing protective measures, which further reduces costs.

[0034] Furthermore, the risk of damaging the lens blank during the application and / or removal of protective measures, such as a protective foil, can be reduced. Conventional processes for applying and / or removing a protective foil typically cause mechanical stress on the lens blank, which can lead to damage around the edge of the lens blank. According to the present disclosure, such damage can be avoided because there is no need to apply and / or remove a protective foil.

[0035] Furthermore, since the application of a protective coating and / or protective foil to the front surface of the lens blank can be omitted, the amount of waste generated during the manufacture of the ophthalmic lens can be reduced. This can further improve the environmental sustainability of the ophthalmic lens manufacturing process.

[0036] Furthermore, the present disclosure can provide the advantage that the elastomeric material can provide suitable static friction between the blank contact element and the lens blank, and between the blank contact element and the vacuum block, for machining the back surface of the blocked lens blank without the need for further adhesives or fixings. The provided static friction can be suitable for transmitting torques of up to 12 Nm or even 15 Nm, which can correspond to typical values ​​achievable with conventional blocks based on alloy blocks of ophthalmic lens blanks and can therefore be well suited for machining blocked lens blanks. Optionally, however, an adhesive can also be applied between the blank contact element and the lens blank, which can increase the transmittable torque. The adhesive can be a two-component adhesive. One or more adhesive dots can 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 EP 4 035 832 A1.

[0038] The blank contact element may be made entirely of the elastic material. This may allow the blank contact element to be formed as a single piece made of a single material and may therefore facilitate the production of the blank contact element.

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

[0040] The elastic modulus of the porous polyurethane foil can be about 3N / mm 2 About 10N / mm 2 within the range.

[0041] The rough contact element can be applied to the upper portion of the support element by coating the upper surface of the support element. Alternatively or additionally, the rough contact element can be prefabricated separately from the vacuum barrier. For example, the rough contact element can be manufactured during a vulcanization process. Furthermore, the manufacturing process for the rough contact element can include perforating the vulcanized rough contact element.

[0042] The blank contact element may have a thickness in the range of 0.3 mm to 0.8 mm. This may ensure that the lens blank is adequately protected from mechanical scratches caused by the vacuum barrier. Furthermore, this may allow for the absorption and / or damping of mechanical impacts transmitted from the vacuum barrier to the blocked lens blank, in particular during machining of the lens blank. Furthermore, the blank contact device may allow for the absorption and / or damping of impacts on the lens blank and ensure that the impacts do not compromise the blocking of the lens blank.

[0043] The elastic material can be at least partially porous, wherein the fluid permeability of the blank contact element is at least partially caused by the porosity of the elastic material. This can optionally be achieved by forming the blank contact element at least partially from a foam material (such as polyurethane foam). The elastic material can exhibit open porosity that allows fluid flow through the porous material. This fluid flow through the pores can be used to provide suction during the blocking process, thereby inducing pressure for securing the lens blank to the blank contact element and securing the blank contact element to the blocking member. This can ensure uniform distribution of the fluid flow over the entire surface of the blank contact element.

[0044] Alternatively or additionally, the fluid permeability of the blank contact element is at least partially caused by one or more holes formed in the blank contact element. The blank contact element may include a plurality of holes distributed on the upper surface of the blank contact element. These holes may be through-holes extending throughout the thickness of the blank contact element. The through-holes may extend through the blank contact element in a straight manner, i.e., in the direction of the pressure acting on the lens blank for securing the lens blank to the blank contact element. Alternatively or additionally, one or more holes may extend through the blank contact element in a non-straight manner. This may allow the use of an elastic material that does not provide porosity and, therefore, does not provide fluid permeability. 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 blank contact element.

[0045] Alternatively, the blank contact element may be made of a porous material and exhibit one or more pores. This may allow the fluid permeability of the blank contact element to be partially due to the porosity of the elastic material and partially due to the one or more pores. This may allow the aforementioned advantages of both approaches to be combined.

[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 allows for a flush arrangement of the blank contact element and the blocked lens blank. This flush arrangement reduces the risk of mechanical impact on the blank contact element outside the portion of the upper surface that contacts the lens blank, which could otherwise risk disrupting the vacuum seal formed between the lens blank and the blocking blank contact element and inadvertently releasing the blocked lens blank. Alternatively, when a sealing lip is provided, the size and / or shape of the sealing lip can be adjusted to the size and / or shape of the lens blank. For example, the diameter difference between the blank contact element and / or the sealing lip and the lens blank can optionally be 0.5 mm or less. This can facilitate the process of machining the edge of the lens blank.

[0047] The blank contact element may further include a sealing lip disposed at a periphery of the blank contact element, wherein the sealing lip is adapted to assist in providing a vacuum within the barrier and between the lens blank and the upper surface of the blank contact element. The sealing lip may facilitate providing a tight fit between the blank contact element and the curved front surface of the lens blank. Optionally, the sealing lip may provide a lower porosity or no porosity compared to an inner section of the blank contact element. This may prevent or reduce fluid flow 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 which does not form part of the blank contact element and the support element.

[0049] The sealing lip can be made of a material that is different from the material of the blank contact element and the material of the support element. This allows the properties of the sealing lip to be adapted independently of the properties of the blank contact element and the support element. The porosity of the material of the sealing lip can be different from the porosity of the material of the blank contact element and the support element. The sealing lip can be made of a non-porous material. This allows a vacuum seal to be provided at the outer edge between the blank contact element and the blocked lens blank, and increases the area of ​​vacuum applied to the blocked lens blank. This can increase the area of ​​suction applied to the blocked lens blank and, therefore, increase the stability of the blockage. Alternatively or additionally, this can allow the pressure difference between ambient pressure and the applied vacuum to be reduced.

[0050] The sealing lip may extend in a radially outward direction of the vacuum barrier at a periphery of 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 may enhance the ability of the sealing lip to adapt 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 barrier, wherein 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 the barrier when the blank contact element is mounted on the vacuum barrier. Accordingly, the upper surface of the support element of the vacuum barrier 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 mounted on the support element. This may provide a form fit between the blank contact element and the barrier, thereby improving the stability of the connection between the blank contact element and the vacuum barrier, particularly during rotational movement that occurs when machining the back surface of the lens blank being machined. In other words, the upper surfaces of the blank contact element and the support element may be adapted to interlock with each other to prevent 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 section of the blank contact element.

[0053] The fluid-permeable blank contact element can be adapted to form-fit the interface of the support element that interfaces with the blank contact element. This can hinder or exclude relative movement between the blank contact element and the lens blank and thus improve the mechanical stability of the assembly comprising the barrier and the blank contact element and the resulting blocked lens blank.

[0054] The upper portion of the support element can be adapted to support a fluid-permeable blank contact element and can be formed from a rigid, fluid-permeable material. The rigid, fluid-permeable material of the support element can include one or more of the following materials or be composed of one or more of the following materials: a ceramic material; a carbide material, particularly silicon carbide; an oxide material, particularly aluminum oxide; and aluminum foam. These materials offer the advantage that they inherently exhibit open porosity or can be manufactured to exhibit open porosity. In addition, these materials offer the advantage that they exhibit high rigidity and therefore high stability under pressure. Therefore, these materials provide a suitable combination of fluid permeability and mechanical stability, making them suitable materials for blank contact elements. For example, a porous material with a certain degree of (open) porosity can be used, which is commonly used in grinding or cutting processes. For example, such a material can be silicon carbide (referred to as 10C) with a medium hardness value of "M" and a medium grain size value of 60 according to the specification of DIN 69100. A support element having an upper portion made of such a material may provide suitable support for a fluid-permeable blank contact element made of an elastic material and may in particular allow drawing fluid through the blank contact element and the support element to vacuum-block the lens blank.

[0055] The vacuum barrier may comprise an adhesive securing the lower surface of the blank contact element to the upper surface of the support element. This may further enhance the fixation of the blank contact element to the vacuum barrier and thus further enhance the stability of the assembly comprising the blank contact element, the vacuum barrier and the lens blank blocked thereon.

[0056] The vacuum barrier may further include a sealing lip formed separately from the blank contact element. This allows for robust sealing of the evacuated area from the outside. To facilitate this, a circumferential sealing lip made of rubber may be provided on the outer edge of the top portion. Furthermore, because the sealing lip is separate from the blank contact element, mechanical impacts to the sealing lip do 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 element can be treated with plasma in a vacuum chamber before blocking the lens blank. Alternatively or additionally, a polishing step can be applied to the front surface of the lens blank and / or the upper surface of the blank contact element. This can remove contaminants from the surfaces, 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 hollow portion at its center, and the edge of the blank contact element may have a raised portion that is higher than the center of the upper surface of the blank contact element. This may facilitate contact with the front surface of an ophthalmic lens blank, which may have 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 barrier including the blank contact element.

[0059] The present disclosure and all features presented with reference to a blank contact element should be considered to be disclosed also for a vacuum barrier, and vice versa. The present disclosure and all features presented with reference to a blank contact element and / or a vacuum barrier (and vice versa) should be considered to be disclosed also for a method for manufacturing an ophthalmic lens, and vice versa.

[0060] Those skilled in the art will appreciate that the features described above and in the following description and drawings are not only disclosed in the explicitly disclosed embodiments and combinations, but also that other technically feasible combinations and isolated features are encompassed by the present disclosure. Hereinafter, several alternative embodiments and specific examples are described with reference to the accompanying drawings that illustrate the present disclosure without limiting the present disclosure to the described embodiments.

[0061] The following will illustrate alternative embodiments of the present disclosure with reference to the accompanying drawings. In the drawings:

[0062] Figures 1A to 1Eshows a vacuum barrier according to various alternative embodiments;

[0063] Figure 2A and Figure 2B shows a schematic diagram of a blank contact element according to an alternative embodiment;

[0064] Figure 3 shows a schematic diagram of a blank contact element according to another alternative embodiment;

[0065] Figure 4 A method for manufacturing an ophthalmic lens according to an alternative embodiment is shown.

[0066] In the drawings, the same reference numerals are used for corresponding or similar features in different figures.

[0067] Figure 1A A vacuum barrier 10 is shown according to an alternative embodiment for vacuum blocking a lens blank 12 (see FIG. Figure 1C ). The vacuum barrier 10 includes a support element 14 having an upper portion 16 and a lower portion 18, wherein the lower portion 18 is adapted to engage with a clamping device for clamping the barrier 10. The vacuum barrier 10 includes a fluid-permeable blank contact element 20. The blank contact element includes an upper surface 22 that is adapted to contact the lens blank 12 and is made of an elastic material. In addition, the blank contact element has a lower surface 24 for contacting the upper portion 16 of the support element. The barrier 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 barrier 10 to provide suction across substantially the entire upper surface 22 of the blank contact element 20, thereby drawing the lens blank 12 to the upper surface 22 of the blank 12 contact element and drawing the blank contact element 20 to the upper portion 16 of the support element 14.

[0068] The blank contact element 20 can be made entirely of an elastomeric material. The elastomeric material can include at least one material selected from the group consisting of a polyurethane-based material and a rubber-based material. The elastomeric material can be at least partially porous, wherein the fluid permeability of the blank contact element 20 can be caused at least in part by the porosity of the elastomeric material.

[0069] 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.

[0070] The blank contact element 20 and / or the support element 14 of the vacuum barrier 10 may further include a sealing lip 26 arranged at the periphery of the blank contact element 20, wherein the sealing lip 26 is adapted to assist in providing a vacuum within the vacuum barrier 10 and between the lens blank 12 and the upper surface 22 of the blank contact element 20. According to the embodiment presented, the sealing lip 26 and the blank contact element 20 are formed as a single piece. In addition, the piece forming the blank contact element 20 and the sealing lip 26 may have an extension 28 extending outside the upper portion of the support unit and may be clamped to the support element 14 of the vacuum barrier. This may allow the blank contact element 20 and the sealing lip 26 to be fixed to the support element 14 in a particularly robust configuration. Alternatively, the extension 28 may be clamped between the upper portion 16 and the lower portion 18 of the support element 14.

[0071] Therefore, according to Figure 1A In the alternative embodiment depicted in FIG, the sealing lip 26 and the blank contact element are formed together as a single piece. However, according to other embodiments, the blank contact element 20 can be formed without the sealing lip 28, and alternatively, the sealing lip 28 can be provided separately from the blank contact element 20.

[0072] The operating principle of the vacuum barrier device 10 may correspond to the operating principle of a vacuum barrier device as described in EP 4 035 832 A1.

[0073] The fluid permeable blank contact element 20 may be adapted to form fit the interface of the support element 14 with which it interfaces. The upper portion 16 of the support element 14 may be adapted to support the fluid permeable blank contact element 20 and may be made of a rigid, fluid permeable material.

[0074] The vacuum barrier 20 can be adapted to provide a static friction force having a coefficient of friction of 2.5 or greater between the blank contact element 20 and the support element 14. The vacuum barrier can 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 can further enhance the static friction force between the blank contact element 20 and the support element 14.

[0075] Figure 1B The blank contact element 20 is depicted in perspective view attached to the support element 14 of the vacuum barrier 10. As illustrated here, the upper surface 22 and the sealing lip 26 of the blank contact element 20 are formed as a single piece.

[0076] Figure 1C The schematic sketch shows Figure 1A, which has a lens blank 12 vacuum-blocked thereto. The sealing lip 26 may have a diameter of 69 mm and the lens blank 12 may have a diameter of 70 mm.

[0077] Figure 1D The three-dimensional diagram shows the Figure 1B

[0026] An alternative embodiment of a lens blank 12 that is vacuum blocked to a vacuum blocking device.

[0078] Figure 1E The vacuum barrier 10 is depicted in perspective view with a blank contact element 20 and a sealing lip 26 attached thereto. The sealing lip 26 is provided separately from the blank contact element 20.

[0079] Figure 2A A blank contact element 20 is schematically depicted in a top view and has a plurality of holes 30 (indicated by dots) arranged through the upper surface and the entire thickness of the blank contact element 20. The holes can be distributed over the entire upper surface of the blank contact element and can allow for a uniform fluid flow through the upper surface of the blank contact element 20. The blank contact element 20 can be made of an elastic material, wherein the elastic material can be fluid permeable or impermeable. Fluid flow can be achieved solely through the holes 30 or can be achieved in addition by the optional fluid permeability of the elastic material. The holes can be uniformly or randomly distributed. The holes can have the same size and / or shape, or the holes can have different sizes and / or shapes.

[0080] Figure 2B The blank contact element 20 is schematically depicted in a cross-sectional view.

[0081] Figure 3 A schematic diagram of a blank contact element 20 according to another alternative embodiment is presented. According to this alternative embodiment, the lower surface 24 of the blank contact element 20 adapted to contact the vacuum barrier 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 with the barrier 10, in particular with the upper portion 16 of the support element 14, when the blank contact element 10 is mounted at the vacuum barrier 10. The upper portion 16 of the support element 14 may include a plurality of recesses having an arrangement, size, and shape that allow the protrusions 32 to engage with the support element 14. This may enhance mechanical stability and prevent relative movement of the blank contact element 20 with respect to the support element 14 when machining the lens blank 12 that is vacuum-blocked to the vacuum barrier 10.

[0082] Figure 4 A method 400 for manufacturing an ophthalmic lens is schematically depicted.

[0083] Method 400 includes providing, in step 402, a vacuum barrier 10 for vacuum-blocking a lens blank 12, the vacuum barrier 10 comprising a fluid-permeable blank contact element 20 having an upper surface 22 adapted to contact the lens blank 12, wherein at least the upper surface 22 of the fluid-permeable blank contact element 12 is made of an elastic material. Furthermore, the blank contact element 20 comprises a support element 14 having an upper portion 16 and a lower portion 18, wherein the lower portion 18 is adapted to engage with a clamping device for clamping the vacuum barrier 10, and the upper portion 16 supports the fluid-permeable blank contact element 20.

[0084] The method 400 comprises, in step 404 , placing the lens blank 12 at 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 .

[0085] The method 400 includes, at step 406 , applying a vacuum within the vacuum barrier 10 to provide suction throughout the fluid permeable resilient blank contact element 20 to draw the front surface of the lens blank 12 across the upper surface 22 of the fluid permeable resilient blank contact element 20 .

[0086] The method 400 includes, in step 408 , 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 barrier 10 .

[0087] List of Reference Numerals

[0088] 10 Vacuum barrier

[0089] 12 lens blanks

[0090] 14 Support elements

[0091] 16 Upper part of the support element

[0092] 18 Lower part of the support element

[0093] 20 Blank contact element

[0094] 22 Upper surface of blank contact element

[0095] 24 The lower surface of the blank contact element

[0096] 26 Sealing lip

[0097] 28 Extension of blank contact element

[0098] 30 holes

[0099] 32 protrusion

[0100] 400 Method

[0101] 402-408 method steps

Claims

1. A vacuum barrier (10) for vacuum blocking a lens blank (12), the vacuum barrier (10) comprising: a support element (14) having an upper portion (16) and a lower portion (18), wherein the lower portion (18) is adapted to engage with clamping means for clamping the vacuum barrier (10); and a fluid-permeable blank contact element (20), wherein the blank contact element (20) is fluid-permeable and at least an upper surface (22) of the blank contact element (20) adapted to contact the lens blank (12) is made of an elastic material, the blank contact element (20) further comprising a lower surface (24) for contacting the upper portion (16) of the support element (14); It is characterized by: The vacuum barrier (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 barrier (10) to provide suction across substantially the entire upper surface (22) of the blank contact element (20), thereby drawing the lens blank (12) to the upper surface (22) of the blank contact element (20) and drawing the blank contact element (20) to the upper portion (16) of the support element (14).

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

3. The vacuum barrier (10) according to claim 1 or 2, wherein: The elastic material includes at least one material selected from the group consisting of polyurethane-based materials and rubber-based materials.

4. The vacuum barrier (10) according to any one of the preceding claims, wherein The resilient material is at least partially porous, and wherein the fluid permeability of the blank contact element is at least partially caused by the porosity of the resilient material.

5. The vacuum barrier (10) according to any one of the preceding claims, wherein The fluid permeability of the blank contact element is at least partially caused by one or more holes (30) formed in the blank contact element (20).

6. The vacuum barrier (10) according to any one of the preceding claims, wherein The shape and size of the upper surface (22) of the blank contact element (20) correspond to the shape and size of the lens blank (12) to be blocked.

7. The vacuum barrier (10) according to any one of the preceding claims, further comprising a sealing lip (26) arranged at the periphery of the blank contact element (20), wherein The sealing lip (26) is adapted to assist in providing a vacuum within the vacuum barrier 10 and between the lens blank (12) and the upper surface (22) of the blank contact element (20).

8. The vacuum barrier (10) according to any one of the preceding claims, the blank contact element further comprising a lower surface (24) adapted to contact the support element (14), wherein The blank contact element (20) includes one or more protrusions (32) extending from a lower surface (24) of the blank contact element (20), the one or more protrusions (32) being adapted to engage the support element (14) when the blank contact element (20) is mounted at the support element (14).

9. The vacuum barrier (10) according to any one of the preceding claims, wherein The fluid permeable blank contact element (20) is adapted to form fit an interface of the support element (14) that interfaces with the blank contact element (20).

10. The vacuum barrier (10) according to any one of the preceding claims, wherein An upper portion 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 barrier (10) according to any one of the preceding claims, wherein The vacuum barrier (10) is adapted to provide a static friction force between the blank contact element (20) and the support element (14) having a coefficient of friction of 2.5 or greater.

12. The vacuum barrier (10) according to any one of the preceding claims, wherein The upper surface of the support element (14) includes one or more recesses, and wherein the blank contact element (20) includes one or more protrusions (32) adapted to mechanically engage the one or more recesses at the upper surface of the support element (14) when the blank contact element (20) is mounted at the support element (14).

13. The vacuum barrier (10) according to any one of the preceding claims, wherein The vacuum barrier (10) includes an adhesive that secures the lower surface (24) of the blank contact element (20) to the upper surface of the support element (14).

14. A method (400) for manufacturing an ophthalmic lens, the method (400) comprising: - providing (402) a vacuum barrier (10) according to any one of the preceding claims, and - placing (404) the lens blank (12) at 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); - applying (406) a vacuum within the vacuum barrier (10) to provide a suction force across the fluid-permeable elastic blank contact element (20) to draw the front surface of the lens blank (12) across the upper surface (22) of the fluid-permeable elastic blank contact element (20); and - machining (408) 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 barrier (10).

15. A vacuum barrier (10) for vacuum blocking a lens blank (12), the vacuum barrier (10) comprising: a support element (14) having an upper portion (16) and a lower portion (18), wherein the lower portion (18) is adapted to engage with clamping means for clamping the vacuum barrier (10); and a fluid-permeable blank contact element (20), wherein the blank contact element (20) is fluid-permeable and at least an upper surface (22) of the blank contact element (20) adapted to contact the lens blank (12) is made of an elastic material, the blank contact element (20) further comprising a lower surface (24) for contacting the upper portion (16) of the support element (14); It is characterized by: The vacuum barrier (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 barrier (10) to provide suction across substantially the entire upper surface (22) of the blank contact element (20), thereby drawing the lens blank (12) to the upper surface (22) of the blank contact element (20) and drawing 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 adapted to support the fluid permeable blank contact element (20) and is formed of a rigid fluid permeable material.

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

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

18. The vacuum barrier (10) according to any one of claims 15 to 17, wherein The resilient material is at least partially porous, and wherein the fluid permeability of the blank contact element is at least partially caused by the porosity of the resilient material.

19. The vacuum barrier (10) according to any one of claims 15 to 18, wherein The fluid permeability of the blank contact element is at least partially caused by one or more holes (30) formed in the blank contact element (20).

20. The vacuum barrier (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) correspond to the shape and size of the lens blank (12) to be blocked.

21. The vacuum barrier (10) according to any one of claims 15 to 20, further comprising a sealing lip (26) arranged at the periphery of the blank contact element (20), wherein The sealing lip (26) is adapted to assist in providing a vacuum within the vacuum barrier 10 and between the lens blank (12) and the upper surface (22) of the blank contact element (20).

22. The vacuum barrier (10) according to any one of claims 15 to 21, the blank contact element (20) further comprising a lower surface (24) adapted to contact the support element (14), wherein The blank contact element (20) includes one or more protrusions (32) extending from a lower surface (24) of the blank contact element (20), the one or more protrusions (32) being adapted to engage the support element (14) when the blank contact element (20) is mounted at the support element (14).

23. The vacuum barrier (10) according to any one of claims 15 to 22, wherein The fluid permeable blank contact element (20) is adapted to form fit an interface of the support element (14) that interfaces with the blank contact element (20).

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

25. The vacuum barrier (10) according to any one of claims 15 to 24, wherein The upper surface of the support element (14) includes one or more recesses, and wherein the blank contact element (20) includes one or more protrusions (32) adapted to mechanically engage the one or more recesses at the upper surface of the support element (14) when the blank contact element (20) is mounted at the support element (14).

26. The vacuum barrier (10) according to any one of claims 15 to 25, wherein The vacuum barrier (10) includes an adhesive that secures the lower surface (24) of the blank contact element (20) to the upper surface of the support element (14).

27. A method (400) for manufacturing an ophthalmic lens, the method (400) comprising: - providing (402) a vacuum barrier (10) according to any one of claims 15 to 26, and - placing (404) the lens blank (12) at 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); - applying (406) a vacuum within the vacuum barrier (10) to provide a suction force across the fluid-permeable elastic blank contact element (20) to draw the front surface of the lens blank (12) across the upper surface (22) of the fluid-permeable elastic blank contact element (20); and - machining (408) 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 barrier (10).

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