Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Rimless mounting
Reexamination Certificate
2002-05-03
2003-02-25
Dang, Hung Xuan (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Rimless mounting
C351S086000, C351S092000, C351S106000
Reexamination Certificate
active
06523952
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an eyeglass assembly which comprises a lens and a frame member, and to a method of assembling an eyeglass.
An eyeglass will comprise frame components and lens components. It will generally include two lenses (although it might include just one). An eyeglass which includes two lenses will generally include, as frame components, a nose bridge by which the two lenses are connected to one another, and temples which extend from the lenses to fit against the user's ears. The present invention is concerned with fastening frame components and lens components together.
It is known from U.S. Pat. No. 6,164,775 to fasten frame components to the lens of an eyeglass using lugs which are formed on the edge of the lens. The frame components are formed with a gripping portion which includes a pair of gripping arms. The configuration of the gripping portion can change between an open configuration in which the arms are spaced apart, and a closed configuration in which the arms grip the lug. The gripping portion can be formed from a shape memory alloy. Articles formed from shape memory alloys can exhibit shape memory properties associated with transformations between martensite and austenite phases of the alloys. These properties include thermally induced changes in configuration in which an article is first deformed from a heat-stable configuration to a heat-unstable configuration while the alloy is in its martensite phase. Subsequent exposure to increased temperature results in a change in configuration from the heat-unstable configuration towards the original heat-stable configuration as the alloy reverts from its martensite phase to its austenite phase. The transformation from austenite to martensite on cooling begins at a temperature known as the M
s
temperature, and is completed at a temperature known as the M
f
temperature. The transformation of martensite to austenite upon heating begins at a temperature known as the A
s
temperature and is complete at or above a temperature known as the A
f
temperature. Shape memory alloys are discussed in an article by L McDonald Schetky in the Encyclopedia of Chemical Technology (edited by Kirk-Othmer), volume 20 pages 726 to 736.
SUMMARY OF THE INVENTION
The present invention provides an eyeglass assembly in which a frame component is attached to a lens using a connector having a hoop configuration which is formed from a shape memory alloy.
Accordingly, in one aspect, the invention provides an eyeglass assembly which comprises a lens and a frame member, in which the lens has a lug at one edge, and which includes a connector by which the frame member is fastened to the lug, the connector comprising a hoop formed from a shape memory alloy which has (a) been treated so that the hoop shrinks inwardly when it is heated to a temperature at which the alloy transforms from martensite phase to austenite phase, and (b) been exposed to an increase in temperature so that the phase of the alloy changes from the martensite phase to the austenite phase and so that the connector hoop shrinks inwardly to grip the lens lug.
In another aspect, the invention provides a method of assembling an eyeglass which comprises a frame member and a lens in which the lens has a lug at an edge thereof and in which the frame member is fastened to the lens by means of a connector which comprises a hoop formed from a shape memory alloy which has been treated so that the hoop shrinks inwardly when it is heated to a temperature at which the alloy transforms from martensite phase to austenite phase, in which the method comprises the steps of:
a. positioning the connector in relation to the lens lug so that the lug is located within the connector hoop, and
b. causing the temperature of the alloy to increase so that the phase of the alloy changes from the martensite phase to the austenite phase and so that the connector hoop shrinks inwardly to grip the lens lug.
The present invention provides a technique for assembling an eyeglass frame which can be secure. The use of a connector with a hoop configuration has the advantage of providing a generally uniform distribution of stress across the cross-section of the connector. The stress in the connector primarily involves the connector being in tension. The stress distribution is more uniform than can be obtained with a connector which makes use of a pair of gripping arms which bend relative to one another between open and closed configurations; in this form of connector, the stress in the connector arises primarily from bending of the arms. The strength of the connection between the frame and lens of the eyeglass is dependent on the stress that is imposed by the connector on the lens lug. The hoop connector that is used in the present invention facilitates the imposition of higher stresses on the lens lug compared with the stresses which can be imposed using a connector comprising a pair of gripping arms. The use of a hoop connector therefore facilitates the formation of secure connections between the lens and a frame component of an eyeglass using connectors of small size.
The frame member and the connector can be connected to one another prior to the connector hoop is made to shrink inwardly. For example, the frame member and the connector can be formed from a common substrate, or the frame member and the connector can be connected to one another by bonding, for example by welding or soldering or brazing or by means of an adhesive. Use of a connector and frame member which are connected to one another (whether as a result of connection prior to shrinkage of the connector or by being formed from a common substrate) has the advantage that the number of components to be manipulated during assembly is reduced.
The connector and the frame member can be assembled with the lens as separate components. The frame member and the lug on the lens can then be fastened together by locating them within the connector hoop before it is heated to cause it to shrink inwardly. The lug on the lens can be configured so that it and the end of the frame member can fit together within the connector hoop. For example, the lug can be rounded with a convex shape at one end, and include a concave recessed portion at its other end in which the end of the frame member can be received.
Providing the connector and the frame member as separate components, whether or not they are fastened together prior to assembly of the eyeglass, has the advantage of allowing different materials to be used for the connector and the frame member, and use of components with different shapes or configurations etc. For example, it might be preferred for the connector to be made from a piece of extruded tube and for the frame member to be made from a piece of wire or rod.
It can be preferred for the frame member to be formed, at least in part, from a piece of tube. The tube might be extruded as such, or machined from a solid piece of the alloy. When the frame member is formed from a piece of tube, the connector hoop can be provided by an end portion of the tube.
When the frame member is formed from a piece of tube, the assembly can include a reinforcing insert for location within the tube of the frame member to reinforce it against bending. The insert can also control the shape of the frame member, for example in terms of its cross-sectional shape and also the overall shape (for example as to whether it is curved or straight). For example, an insert with a rectangular cross-section can be used within a tube whose cross-section is not rectangular so that, when the tube shrinks inwardly, on to the insert, the tube adopts a rectangular cross-section. An insert which is curved, for example arched, can cause a tubular frame member to adopt an arched configuration.
The insert can be located within the tube before the tube is exposed to an increase in temperature to cause it to shrink inwardly, so that the insert is a loose fit in the tube when placed inside the tube, and is then held snugly within the tube after the tube has been made to s
Dang Hung Xuan
Madson & Metcalf
The Beta Group Inc.
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