Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Continuous rim mounting
Patent
1993-04-26
1995-11-28
Sikes, William L.
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Continuous rim mounting
351 83, 351103, 351110, G02C 108
Patent
active
054712572
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to spectacles having two lenses made of a plastic material and each connected to a temple by means of a temple mounting member, and a bridge interconnecting the lenses, the temples, the temple mounting members and the bridge being made of wire material.
DESCRIPTION OF THE RELATED ART
Spectacles having rim parts made of wire material have per se been known for generations, both rimmed and in rimless design. This type of spectacles has, however, had a limited distribution particularly due to its fragility as concerns breaking or splitting of the lenses.
In a known design of rimless spectacles the temples are fastened to the lenses either by means of spring clamps placed on the circumference of the lenses as disclosed in U.S. Pat. No. 718,363, or by means of metal screws which are passed through holes in the lenses and are retained on the front side of the lenses either by nuts as disclosed in U.S. Pat. Nos. 906,360, 967,292 and 2,256,846 or in eylets formed by the interconnecting nose bridge as disclosed in DE patent No. 343622. However, these fastening methods all have the inherent disadvantage that even a minor deformation of the wire parts of the rim easily causes splits in the lenses at the spring clamps or around the screws passing through the lenses.
For spectacles with lenses of a thermoplastic material it has been proposed in French patent No. 1068345 to fasten a wire rim to a lens by pressing a heated profiled metal pin into the lens material. This fastening method is, however, not applicable for spectacles with lenses made of modern optical plastic materials.
Correspondingly, GB patent No. 760025 discloses a fastening method by which a pin of a yielding plastic material is passed through a pre-drilled bore in the lens and fastened by thermal expansion by heating or by pressing on the front side of the lenses. Besides the fact that this method in practice does not ensure a sufficiently firm fastening to prevent the lenses from working loose, the heat treatment requirement entails a considerable risk of damaging the surface treatment of the lenses.
During recent years the appearance of new and stronger wire materials such as, e.g. titanium alloys, has given rise to a renewed interest in wire-rimmed spectacles which can be produced with a considerably lower weight than conventional types of spectacles. EP-A-256098 proposes a different form of fastening, whereby the temple mounting members and the bridge serving to connect the lenses are shaped to form a resilient metal strap inserted with spring effect into rectangular slits in the lenses.
In practice it has appeared, however, that the arrangement of the resilient strap in the underdimensioned slits will easily cause the lens to break. If, in order to counteract this risk, the spring tension is reduced, the strap will tend to work itself loose and fall out.
SUMMARY OF THE INVENTION
The object of the invention is to provide an improved design of spectacles with wire temples and bridge, while fully preserving the advantages of this type of spectacles as concerns simplicity of structure and reduced weight, at the same time ensuring that the lenses and rim parts are held firmly together with a considerably reduced risk of breaking or splitting.
This can be achieved according to the invention by forming the temple mounting members and the bridge by at least one piece of wire material curved or bent to provide eyelets underlying the head of a screw, comprising a shaft of a yielding plastic material adapted for form-fit engagement with a threaded bore drilled directly in the lens between the front and back of same.
Fastening by means of screws adapted for engagement with threaded bores drilled directly in the lens entails a considerably reduced risk of local tensions around the fastening point, while at the same time the elastic deformability of the screw shafts contribute to absorb deformations and ensure a stable fixation. As compared to the above-mentioned embodiment which has a resilient strap, manufact
REFERENCES:
patent: 2458963 (1949-01-01), Stevens
patent: 2880649 (1959-04-01), Eisler
patent: 5177510 (1993-01-01), Peters et al.
Dang Hung Xuan
Sikes William L.
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