Optical: systems and elements – Lens – With support
Reexamination Certificate
2001-05-09
2002-10-29
Schwartz, Jordan (Department: 2873)
Optical: systems and elements
Lens
With support
C118S052000, C118S500000
Reexamination Certificate
active
06473247
ABSTRACT:
The present invention relates generally to optical lens supports and more particularly to ophthalmic lens supports.
It is standard practice to treat ophthalmic lenses after fabricating them to confer particular characteristics on them, for example abrasion resistance and/or antireflection properties. This is known in the art.
In the present context, and in the usual way, the expression “ophthalmic lens” refers to a blank from which an eyeglass lens to be mounted in an eyeglass frame is then obtained by trimming.
The blank usually has a circular peripheral contour but this is not necessarily always the case.
The following description must therefore be considered to apply to any contour.
Be this as it may, applying a treatment to an ophthalmic lens usually entails depositing at least one layer of material onto its surface and it is obviously important for the deposit to be very uniform.
An antireflection deposit is usually applied in a vacuum.
This is the case, for example, in U.S. Pat. No. 2,532,971, in which ophthalmic lenses to be treated are each disposed in an individual support for holding them throughout their treatment.
The treatment in practice entails rotating the ophthalmic lenses at a relatively moderate speed, which is of the order of 50 rpm, about the rotation axis of a collective support to which the combination of the lens and its support is attached.
The individual support for each ophthalmic lens includes a base and three bearing studs carried by the base for holding an ophthalmic lens by its edge, one of which studs is fixed relative to the base, although its position relative thereto may be adjustable, and the other two of which are individually carried by elastically deformable arms carried by the base.
In practice the base takes the general form of a globally circular contour ring whose radial dimension, i.e. whose dimension in the direction of its thickness, and therefore in the plane of its edges, is very much less than its height, i.e. its dimension perpendicular to that plane.
In practice, the individual support in the general form of a ring, which itself has to be fixed into a ring, is never operative through the edge of its base.
More recent implementations are substantially the same, for example that described in U.S. Pat. No. 5,325,812, in which an individual ophthalmic lens support of the above kind is in practice reduced to a simple elastically deformable ring adapted to be fixed into a rigid support ring.
Another technique for depositing a layer of material, usually referred to as spin coating, has been developed for other types of substrate, namely silicon wafers used in the field of microelectronics, whereby the substrate is rotated and a small quantity of material is deposited on its surface.
The rotation speed of the substrate during the spreading of the material is relatively high, and higher than its speed of rotation during deposition of the material, and is in practice always greater than 1500 rpm, in order to spread the material correctly over the whole of the surface of the substrate.
Because of the high rotation speed used, it is obviously important for the individual supports of the substrates to be treated to be properly seated inside the corresponding apparatus.
For applying a treatment to an ophthalmic lens by spin coating, a support in the general form of a ring of the kind which is usually employed at present for holding an ophthalmic lens, as outlined above, would obviously not be suitable, because of its poor seating.
German patent application No. 38 38 012 describes a support for applying a treatment by spin coating to an ophthalmic lens, including three clamping members each of which consists of a support finger which receives the ophthalmic lens and a clamping finger which clamps the lens, with a flyweight system that varies the pressure applied to the lens according to the rotation speed.
The overall result is a particularly complex implementation.
A general object of the present invention is an optical lens support which, in contrast, provides a simple way of holding an optical lens correctly, even within apparatus using the spin coating deposition technique.
That optical lens support, which is of the kind including at least one first base and, carried thereby, for holding an optical lens by its edge, at least three bearing studs, is generally characterized in that, the base including, for its own seating, a plane bearing surface whose peripheral contour is globally circular, its radial dimension along any radius of that bearing surface is at least equal to its axial dimension perpendicular to the plane thereof.
There is obtained in this way a seating surface sufficient to enable use of the support in apparatus implementing the spin coating technique. The support can in particular be fixed by its single bearing surface on a turntable of the spin coating apparatus forming a pneumatic sucker, i.e. incorporating a plurality of suction orifices holding the base against said turntable by applying suction to its bearing surface.
It is even advantageously possible, thanks to the optical lens support according to the invention, to use existing apparatus, without any significant adaptation thereof, so obtaining the benefit in the field of optical lenses of a technology already proven in another field.
Generally speaking, it is advantageously possible, thanks to the optical lens support in accordance with the invention, to accommodate relatively high rotation speeds.
From this point of view, another object of the present invention is a method of using the support characterized in that it involves rotating the support and the optical lens it is carrying at a rotation speed greater than 500 rpm.
In a first embodiment, at least one of the three bearing studs is fixed relative to the base and at least one other is carried by an elastically deformable member itself carried by the base.
For at least some applications two of the bearing studs of the optical lens support in accordance with the invention are preferably fixed, only the third of the bearing studs being carried by an elastically deformable member.
It is therefore advantageously possible to control better the elastic force to which the optical lens is subjected even though, given the temperature to which it is subjected, which can be as high as 100° C., and the fact that the elastic force is applied to its edge, which can be very thin, for some prescriptions at least, the optical lens can be made dangerously more fragile, so that it is desirable to protect it.
The bearing studs of the optical lens support in accordance with the invention are preferably operative along a circumference that is eccentric to the periphery of the base, i.e. relative to the periphery of the bearing surface thereof, the center of this circumference being nearer the fixed bearing stud or studs than the center of that periphery.
Good results have been obtained with the optical lens in its support off-centered in this way.
The base of the optical lens support according to the invention preferably has a central opening and the fixed bearing stud or studs are preferably on its border whereas the bearing stud or studs carried by an elastically deformable member are preferably inside the contour of the central opening.
It is therefore advantageously possible to treat both faces of the optical lens continuously, merely by turning over the combination of the lens and its support.
Furthermore, when two fixed bearing studs are used in this way, unwanted vibration in use is advantageously reduced, which has the benefit of improving the stability of the combination during the corresponding rotation.
Finally, the relatively small thickness of the base of the optical lens support according to the invention is also advantageous and beneficial in that it enables the support to be stored on edge in a storage rack having regularly spaced grooves into each of which a support can be inserted.
In a second embodiment the three bearing studs are fixed to the base and each has a radial bearing face and an axial bearing face,
Duon Jean-Claude
Keller Gerhard
Lametairie Patrick
Mace Michel
Menges Gilles
Choi William
Essilor International
Schwartz Jordan
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