Method for manufacturing an optical element with a functional film

Abstract

Disclosed is a method for manufacturing an optical lens including the following successive steps: a step of providing an optical lens attached to a blocking piece; a step of laminating a functional film on a surface of the optical lens; a step of obtaining an assembly constituted by the blocking piece, the optical lens and the functional laminated film; a step of cutting the excess film directly on the assembly, so as to reduce the film shape; and a step of deblocking the optical lens with the film, and the blocking piece.

Claims

1. A method for manufacturing an optical lens, the method comprising the following successive steps: a step of providing an optical lens attached to a blocking piece at a convex surface of the optical lens, the blocking piece acting as a receptacle to receive the optical lens; a step of laminating a functional film on a concave surface of said optical lens opposite the convex surface to obtain a laminated lens surface; a step of obtaining an assembly constituted by the blocking piece, the optical lens and the functional laminated film, the optical lens with the functional laminated film being fastened to the blocking piece by a bonding material; a step of cutting a film excess directly on said assembly to reduce the film shape, the film excess comprising parts of the functional laminated film which extend beyond an edge of the optical lens and thus overhang the edge; and a step of deblocking the optical lens with the functional laminated film, and the blocking piece, the deblocking step being carried out with at least a pressurized fluid jet configured to separate the optical lens with the functional laminated film from the bonding material.

2. The method according to claim 1, wherein the step of cutting the film excess allows that the entire film surface is completely adhered on the laminated lens surface, without any part of the film which overhangs the edge of the lens.

3. The method according to claim 2, wherein the step of cutting the film excess is determined to obtain a minimum radial distance in a plan view between an edge of the cut film and an edge of the laminated lens surface, the minimum radial distance being between 0.05 mm and 10 mm, the cut film edge being closer to a center of the lens than the laminated lens surface edge.

4. The method according to claim 1, wherein the step of cutting the film excess is carried out with one cutting element chosen from a sharp edge and a laser cutter.

5. The method according to claim 1, further comprising the following steps: a step of providing an assembly support; a step of placing the assembly in said assembly support, so that the film constitutes the upper part of said assembly; a step of providing an arm equipped with a cutting element in a fixed position relatively to a center of the assembly support, at least one element to be chosen from the arm and the assembly support being configured to rotate around a central axis of the assembly support; and a step of rotating the at least one element relative to the central axis of the assembly support to allow the cutting element to cut the film excess.

6. The method according to claim 1, wherein the functional laminated film comprises a main film made of one of cellulose triacetate (TAC), polyethylene terephthalate (PET), polycarbonate (PC), polyvinyl alcohol (PVA), and cyclic olefin copolymer (COC).

7. The method according to claim 1, wherein the functional laminated film provides at least one feature to the lens chosen from one or more of a hard coat, an anti-reflective coating, a polarizing film, anti-shock properties, a tint, a mirror, a filter for specific wavelength, anti-smudge, anti-fog or antistatic properties, and self-healing or self-cleaning properties.

8. The method according to claim 2, wherein the step cutting the film excess is determined to obtain a minimum radial distance in a plan view between an edge of the cut film and an edge of the laminated lens surface, the minimum radial distance being between 0.05 mm and 5 mm, the cut film edge being closer to a center of the lens than the laminated lens surface edge.

9. The method according to claim 2, wherein the step of cutting the film excess is determined to obtain a minimum radial distance in a plan view between an edge of the cut film and an edge of the laminated lens surface, the minimum radial distance being between 1 mm and 3 mm, the cut film edge being closer to a center of the lens than the laminated lens surface edge.

10. The method according to claim 2, wherein the step of cutting the film excess is carried out with one cutting element chosen from a sharp edge and a laser cutter.

11. The method according to claim 3, wherein the step of cutting the film excess is carried out with one cutting element chosen from a sharp edge and a laser cutter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) We give hereafter a detailed description of a preferred embodiment of a method pursuant to the invention, by referring to the following figures:

(2) FIG. 1 is a perspective view of a first assembly constituted by a blocking piece, an optical element with a functional film and a carrier,

(3) FIG. 2 is a perspective view of a second assembly which corresponds to the first assembly of FIG. 1 without the carrier,

(4) FIG. 3 is a perspective view of the second assembly of the FIG. 2 after a cutting step of the functional film,

(5) FIG. 4 is a perspective view of an apparatus pursuant to the invention and intended to cut the excess film which overhang the optical lens,

(6) FIG. 5 is a perspective view of a specific area of the apparatus of FIG. 4 and showing an interaction between a cutting element of said apparatus and the film deposited on an optical lens,

(7) FIG. 6 is a perspective view of a specific area of the apparatus of FIG. 4 and showing a step of withdrawal manually the functional film excess on the optical element after having been cut.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) Referring to FIG. 1, when a lamination method is used to deposit a functional film 1 on an optical element which is generally constituted by an optical lens 2, a final first assembly 3 comprising said optical lens 2 with said film 1, a carrier 4 and a blocking piece 5 is obtained. To sum up a lamination method, a multilayers assembly comprising the functional film 1, the carrier 4 and different layers placed therebetween, is beforehand thermoformed in order to adapt the form of the functional film 1 to the surface of the optical lens 2 intended to receive said functional film 1.

(9) Then, this multilayers assembly is laminated on the surface of the optical lens 2, and once said multilayers assembly has been deposited on said optical lens 2, we obtain the first assembly 3 showed in FIG. 1.

(10) It is important to point out that the functional laminated film 1 provides at least one feature to the optical lens 2 to be chosen among a hard coat, an anti-reflective coating or a polarizing film, anti-shock properties, a tint, a mirror or a filter for specific wavelength, self-healing or self-cleaning properties, a surface modifier having anti-smudge, anti-fog or antistatic properties, alone or in combination. In a more general manner, such a functional film has a protection function in regard to the optical lens 2 on which it is deposited, or a supplemental optical function intended to improve the optical properties and/or characteristics of the optical lens 2. The functions of said functional film 1 are thus non-limited to the examples listed before, which are only illustrative and not limitative.

(11) The functional laminated film 1 comprises a main film made of Cellulose Triacetate (TAC), polyethylene terephthalate (PET), polycarbonate (PC), Polyvinyl Alcohol (PVA), or Cyclic Olefin Copolymer (COC). These are only illustrative examples which are not limitative in the framework of a method pursuant to the invention.

(12) The blocking piece 5 acts as a receptacle to receive the optical lens 2 just before the film lamination step occurs. Such a blocking piece 5 is designed to maintain the optical lens 2 in a stable manner before the film lamination step is achieved. On that subject the optical lens 2 is fixed in the blocking piece 5 by means of an adhesive material.

(13) Referring to FIG. 2, once the first assembly 3 has been formed after the film lamination step, the carrier 4 which is a rigid and transparent plastic film is manually removed from the first assembly 3. We finally obtain a second assembly 6 made of the optical lens 2 with the functional laminated film 1 and the blocking piece 5, said second assembly constituting an independent resulting piece which can be easily handled and/or transported to finally obtain the suitable optical lens 2 with a functional film 1 having a homogeneous adherence on said optical lens 2, and having the required size with respect to the lens 2 dimensions.

(14) In the example showed in the different figures, it is supposed that the optical lens 2 and the blocking piece 5 have a circular contour and each have a symmetry of revolution.

(15) Referring to FIGS. 2 and 4, it can therefore happen that some parts 20 of the functional film 1 extend beyond the circular edge 7 of the optical lens 2 so that they overhang over said edge.

(16) An inventory of film patches with varying dimensions can be maintained. However, such an inventory increases complexity and cost in manufacturing. Further, while it should be possible, even if more expensive, to plan an inventory of film patches when the overhang of the film is due to choosing, prior to the surfacing step a semi-finished lens with a diameter smaller than a larger dimension of the film, such is not always the case.

(17) However, during the manufacturing of some type of lenses, the surfacing step happens to reduce the diameter of the optical lens as compared to the initial dimension of the semi-finished lens. Such reduction of diameter may lead to the maximum dimension of the film being larger than the surfaced lens diameter, or more precisely having part of the film overhanging above the surface lens edge, when the film is oriented and centered with the optical center of the lens.

(18) The final diameter after such reduction of diameter during the surfacing step depends on the prescription desired for the optical lens, ie the optical power. Accordingly, a multiplicity of such diameters may be produced. Further such reduction of diameter may lead to lens contour that do not have symmetry of revolution anymore. Accordingly, in such cases, if one desire films that mostly cover most of the surface of the lens, at least in one dimension, but do not have any overhang, the construction of an inventory of films patches of various dimensions becomes highly complicated.

(19) Such a configuration, involving a functional film 1 which extends in any direction beyond the optical lens edge 7, is not acceptable, because it may negatively influence the deblocking step which enable to separate the optical lens 2 with the film 1 from the blocking piece 5. Indeed, said separating step is generally achieved by means of pressurized fluid jet and thus, it is possible and even probable, that said pressurized fluid jet generates a film delamination which can lead to a film 2 removal. Consequently, the film lamination step must be restarted, greatly increasing the optical lens manufacturing costs.

(20) In order to prevent delamination, a method of manufacturing an optical lens 2 pursuant to the invention, comprises a step of cutting the film 1 excess 20, directly on the second assembly 6 obtained.

(21) Referring to FIG. 3, the aim of this cutting step is to limit the film size so that the film dimensions be completely included in the optical lens dimensions. In other words, the film size is to be equal or less than the size of the optical lens 2. Advantageously, this cutting step allows obtaining a minimum radial distance d in a plan view between the film 1 edge and the laminated lens surface edge which is comprised between 0.05 mm and 10 mm, preferably comprised between 0.1 mm and 5 mm, for example between 0.5 mm and 3 mm with the film edge being closer to a center of the lens than the laminated lens surface edge.

(22) Such a configuration enables a smoother deblocking. Indeed, during the further deblocking step, which is configured to separate the lens from the blocking piece, stress is applied on the film, the lens and the blocker. In particular, the separating step may be achieved by means of pressurized fluid jet. Due to cutting the film so that the film edge is closer to a center of the lens than the laminated lens surface edge, the edges of the film provide less drag to the pressurized fluid jet. This is even truer when the laminated lens surface is concave. In such case if the edge of the film is closer to the center of the lens than the edge of the lens, the edge of the film are protected from the pressurized fluid jet by the edges of the lens. Indeed, the edges of the film are inside the concavity formed by the concave laminated lens surface.

(23) Referring to FIGS. 4, 5 and 6, the cutting step is carried out with an apparatus 10 comprising an arm 11 equipped with a cutting element 12, and an assembly support 13 intended to receive the second assembly 6. The cutting element 12 may for example be chosen among a sharp edge, a laser cutter, and a blade. In a general manner, any type of cutting means works, if it is capable of cleanly cutting the functional film 1 with a certain accuracy. The arm 11 extends in a horizontal direction and have a first extremity which is linked to a vertical cylindrical rod 14 and a second extremity where the cutting element 12 is placed. Preferably, the arm distance from a center of the assembly support 13 is adjustable so as to adapt the arm position, or dimension, to a specific optical lens 2 size. The assembly support 13 is cylindrical-shaped and is positioned on a cylindrical platform 15 of the apparatus 10, so that its axis of revolution extends in a vertical direction perpendicularly to the platform surface 15. This assembly support 13 is delimited by a circular bottom and by a cylindrical lateral wall 16 and is rotatably mounted on the platform 15 about its axis of revolution. The assembly support 13 may be rotated, either manually, or automatically by means of a motor and a control device. When the assembly support 13 is handled manually by an operator, said operator can adjust the rotation direction in function of his need. In this configuration, it is supposed that the assembly support 13 is freely mounted in rotation in the two possible directions of rotation about its revolution axis. In a same way, when a motor makes rotated the assembly support 13, said motor is designed to allow a rotation movement of the assembly support 13 in the two possible directions of rotation about its revolution axis. An electrical motor is particularly suitable to perform such assembly support 13 rotary movements.

(24) Referring to FIG. 4, the second assembly 6 is placed inside the assembly support 13 so that the optical lens 2 and the functional film 13 protrude above said assembly support 13, the functional film 1 corresponding to the upper part of said second assembly 6. In this configuration, the functional film 1 extend in a plan which is approximately horizontal (the term approximately is used because the functional film is not rigorously plan).

(25) Referring to FIG. 5, the arm is then positioned with respect to the vertical rod, and its position or length is eventually adjusted so as to lead the cutting element 12 above the functional film 1 at a given radial distance d from the peripheral edge of the optical lens 2, inside said optical lens 2. Preferably, the cutting element 12 is then above the lens surface so as to have a radial distance d which is directed toward the center of the lens, and having a part of the surface of the optical lens uncovered from the film on the whole contour of the optical lens. A sensor/feeler enables to automatically adapt the position of the cutting element 12 to the position of the edge of the optical lens.

(26) The cutting element 12 is then activated to contact the functional film 1 and to begin the cutting step. In order to cut the suitable portions of the functional laminated film 20 which extend beyond the optical lens edge, the assembly support 13 is rotated, manually or automatically with a motor.

(27) Referring to FIG. 6, once the functional film parts 20 overhanging the optical lens 2 edge 7 have been cut, they have then removed manually from the rest of the functional film 1 which adheres homogeneously and firmly to the optical lens 2. This operation may be simply carried out with two fingers of the hand.

(28) When the laminated functional film sizes have been reduced by the cutting step, the deblocking step can begin to separate the optical lens 2 with the film 1 and the blocking piece 5 without any risk of film delamination, because the film 1 is completely included in the optical lens 2 without any part which extends beyond the optical lens edge 7.