Method of applying multi-layer structure onto a curved substrate
AssigneeEssilor International (Compagnie Generale d'Optique)
InventorRomain Fayolle
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Abstract
A curved multi-layer structure (10) is formed from individual films (1, 2) that are initially flat. The films are firmly bonded to each other along respective facing surfaces. A heat treatment is applied to one or both of the films (1, 2) of the structure so as to cause respective contractions or elongations that are different for the two films at standard use temperatures. A difference between said contractions or elongations causes the curvature of the multi-layer structure. The structure thus has a permanent curved shape, without contact between compression-forming instruments and a useful part of the multi-layer structure being necessary. The multi-layer structure can then be applied onto a curved substrate without causing any tears or ripples.
Claims11
Method of applying a multi-layer structure onto a substrate, the multi-layer structure being obtained from at least two initially flat individual films, said method comprising the following steps:
- /1/ providing the multi-layer structure configured so that said films remain firmly bonded to each other along respective facing surfaces (Σ1, Σ2), as long as a temperature of the structure is below a failure temperature;
- /2/ applying a heat treatment to at least part of the multi-layer structure, with a maximum temperature of the heat treatment that is below the failure temperature, so that due to the particular application of the heat treatment the two films have different respective contractions or elongations after cooling of the structure to a use temperature, and a difference between said respective contractions or elongations of the films producing a curvature of the multi-layer structure, whereby the heat treatment of step /2/ itself produces the curvature of the structure, then
- /3/ applying the multi-layer structure onto a curved face (S1) of the substrate, the substrate comprising an ophthalmic lens,
- the multi-layer structure is formed during step /1/ at an initial temperature that is higher than the use temperature;
- and
- the heat treatment in step /2/ comprises the cooling of said multi-layer structure to below said initial temperature, and at least one of the films has, after said heat treatment, a contraction resulting at least partly from the thermoelastic behaviour of said film.
Dependencies are inferred from the claim text.