In order to present the lenses properly in a pair of spectacles, it is necessary to provide an adjustable bridge which can be altered to a particular wearer's requirements. Traditionally, a bridge has been located between two lenses held in rims and secured in a frame. The bridge spans the wearer's nose to present the lenses as required. Typically, the bridge acts in association with the arms of the spectacles which either hook over respective ears or are in compressive engagement with a wearer's head.

More recently, so-called rimless spectacles have become popular due to their lighter weight and their ability to use lenses of almost any shape. Rimless spectacles are also less conspicuous and possibly have a more fashionable appearance. However, rimless spectacles are particularly susceptible to damage.

The bridge and arms are directly mounted to the lenses and deformation forces are concentrated at these mounting locations. This can crack or break the lenses.

To provide these rimless spectacles with greater robustness, it is known (see PCT/US84/02004) to use shape memory materials and particularly metals. Such shape memory materials mean that the spectacles will readily deform if accidentally bent or compressed but will thereafter return at least substantially to their normal shape.

Unfortunately, particularly with regard to spectacles bridges, although the flexibility of shape memory metals is advantageous for preventing damage, it is difficult to adjust the spectacles to a particular wearer's requirements. Any deformation adjustment would be lost as a result of the shape memory reflex.

There is a similar problem with the arms which engage the ears or side of the wearer's head and with mounting nose pads etc.

Previously, to allow adjustment, it has proven necessary to add rigid material components such as stainless steel or similar, which are joined to the memory wire by collets or tubes about the mounting points of the shape memory metal bridge arm. These rigid material components can provide mountings for the nose pads and can retain deformation for adjustment to an individual spectacle wearer's personal requirements around the nose, temple and ears.

Addition of such rigid material components can add to manufacturing costs and make a spectacles mounting look bulky. The collets or tubes and the rigid material components may retain some deformations when the shape memory material is flexed other than for adjustment. There is also a problem that the welds or solder used to secure the rigid material component to the shape memory material may fail.

It would be desirable to eliminate the necessity for such separate rigid material components for mountings and adjustment in spectacles made with shape memory materials.

In accordance with the present invention there is provided a method of forming a spectacles component, such as a spectacles bridge, comprising the steps of:- (a) configuring a single piece of material capable of having a shape memory state into a shape required for a spectacles component; (b) Carrying out a tempering step by heating the piece of material to a tempering temperature and sustaining it at that tempering temperature for such time period that the material substantially loses its flexibility; (c) after heating to the tempering temperature, cooling the piece of material so that it remains substantially without its flexibility; (d) specifically heating a predetermined portion only of the piece of material to a modifying temperature such that this portion assumes the shape memory state with a shape memory response to deformation; and (e) cooling the piece material so that the predetermined portion retains its shape memory reflex response whilst at least one other portion remains substantially without flexibility to allow retention of adjustable deformation and/or to provide mountings for other components.

Further in accordance with the present invention there is provided a spectacles component formed from a material having a shape memory state with a shape memory reflex capability, the component having been treated to substantially lose its flexibility whereby it can retain adjustment deformation and a part of the component has been subsequently treated to provide that part with the shape memory state having the shape memory reflex capability.

Spectacles embodying the invention will now be described by way of example with reference to the accompanying drawings in which:- Figure 1 is a perspective view of one of the spectacles; Figure 2 is a front view of a bridge for the spectacles of Figure 1; Figure 3 is a side view of a mounting for a bridge for the spectacles of Figure 1 ; Figure 4 is a front schematic cross-sectional view of a mounting for a spectacles bridge with a spectacles lens ; and Figure 5 is a schematic side cross-section of an alternative mounting for spectacles.

In the spectacles to be described, a spectacles component, such as a spectacles bridge, is made from a single or continuous piece of shape memory wire formed from a material capable of having a shape memory state in which it has a shape memory response to deformation. The wire may initially be in that state or may instead initially not have this state. The same piece of shape memory wire can eventually form both the rigid coupling structures to the lenses and the mountings for nose pads whilst providing a shape memory reflex response in a predetermined portion between the lenses.

Figure 1 illustrates spectacles 1. These spectacles 1 comprise two lenses 2 held together by a bridge 3. A respective side arm 4 is secured through a temporal lug 11 and a hinge 5 to each lens 2. The actual lenses 2 are determined by an optician for a particular wearer or by a requirement for sunglasses etc. The bridge 3 supports nose pads 7 via mountings 8. Each individual spectacles wearer has different facial features so the structure of the spectacles 1 must be adjustable. Spectacles 1 can be adjusted by deformation and displacement of various components and junctions. Thus, for example, the location and shape of bends 6 at the end of each side arm 4 can be adjusted to fit over a wearer's ears for firm location.

As will be explained, the bridge 3 includes a predetermined portion A of shape memory material which allows deformation in the event of accidental bending or damage but which then automatically recovers its previous shape. Wearers of spectacles will have different nose dimensions and so the relative positions of the pads 7 must be adjustable. In the event of such adjustment, it is of course necessary that the shape memory material allows the new position of the pads 7 to be retained. The bridge 3 to be described retains the desired shape memory reflex in a predetermined central portion A of the bridge 2 which substantially spans between the lenses 2 but provides other side portions which permit the making and retention of the desired adjustment deformation.

A shape memory material used in the present invention is a nickel/titanium/cobalt alloy of approximately the following composition: Ni 54.57%; Ti 43.744%; 1.61% Co; 0 0.038%; C 0.038%. This is a shape memory metal which is naturally flexible in its base state but has the potential to provide a shape memory response when appropriately treated. Shape memory metals are more commonly used in spectacle frames than plastics due to their better appearance and properties at the desired operating temperatures. However, it should be clearly understood that other shape memory metals and materials could be used in accordance with the present invention.

In order to form the spectacles bridge 3, a piece of shape memory material wire or strip, either in its base flexible state or after previous treatment to a shape memory response condition is first bent to the desired or required shape and held in that configuration. Typically, the wire will have a diameter of about 1.1 millimetres.

The length of the piece of wire will depend upon the width of spectacles bridge required and the technique used for fixing the bridge to the spectacles lenses. The bent shape is generally that required of an eventual spectacles bridge so that a single piece of shape memory material provides all the necessary structural features.

Figure 2 illustrates in front view one form of the spectacles bridge 3. The bridge 3 includes a predetermined portion A which is central with two other portions B either side of it.

The piece of wire is bent as described above to form the bridge 3. The bridge 3, whilst held by deformation forces in the desired configuration shown in Figure 2, is heated to a tempering temperature and sustained at that temperature for a time period necessary to effectively temper the bridge 3. The extent of tempering is determined by the tempering temperature and exposure time period. The tempering temperature and exposure time period are chosen to ensure that the portions B are eventually sufficiently strong to allow mounting of the nose pads 7 and to allow deformation adjustment of the bridge 3 when incorporated in a pair of spectacles.

A typical tempering temperature is 380°C for a time period of about 45 minutes but the actual temperature and the exposure time period necessary will depend upon the particular material used. Heating of the bridge 3 takes place in a temperature controlled oven and the tempering temperature maintained to + or- 5°C over the exposure time period. After tempering the bridge 3 at the chosen tempering temperature, it is cooled normally in a bath of cool water for a few seconds. The whole bridge 3 loses its flexibility as a result of the tempering process.

The next step is to heat only the predetermined portion A of the bridge 3 to a modifying temperature whereby a shape memory reflex is provided to the underlying material within this portion A. The bridge 3 is loaded into a mould so that the portions B either side of the centrally located first portion A are substantially thermally masked whilst the portion A is exposed to be heated to the modifying temperature. The exposed portion A is normally about 5 to 10mm in length. A focused flame or other heating device is directed towards the exposed portion A in order to heat it to the desired modifying temperature. At this modifying temperature there is a desired modification in the underlying material so that it achieves a shape memory reflex capability. The whole bridge 3 is then again cooled in a bath of cool water for a few seconds and subsequently allowed to naturally cool further to room temperature. The mould ensures that the portions B remain below a temperature to achieve a shape memory capability. Any heating of the portions B is by conduction from portion A and then only for a second or so until the whole bridge 3 is cooled in the bath of water.

A typical modifying temperature is 700-800°C and the portion A will be heated until it glows red for a few seconds. Actual modifying temperatures and heating times will depend upon the actual original shape memory material used.

Normally, the bridge 3 as part of a pair of spectacles will be coated or plated. By such means, any detrimental surface burnish or charring as a result of localised heating of the portion A to the modifying temperature will be hidden.

After the above described two heating steps (i. e. tempering and modifying), the bridge 3 has a predetermined central portion A with a shape memory reflex and other side portions B which have substantially lost their flexibility which allows easier coupling to nose pads 7 and to the lenses 2 of spectacles 1.

Typically, a standard bridge will be manufactured and adapted for different wearer requirements through adjusting the position of the nose pads 7. However, as the portion A has a shape memory reflex, any deformation to narrow the span will not be retained. Thus, a bridge span dimension must be set by the overall spectacles design or a range of bridges manufactured with different spans for a particular spectacles design to accommodate most, if not all, potential wearers facial features, in particular nose widths.

As indicated previously, rimless spectacles have the bridge 3 directly coupled to the lenses 2. A number of securing techniques are known and used. Spectacle bridges 3 embodying the present invention can use these known techniques.

However, the deformation-retaining portions B will not be able to achieve bends that are as tight as previously rigid material components, such as those joined by stainless steel wire or similar metal so securing arrangements with broader engagement areas are needed.

Figure 3 illustrates, one way of attaching the spectacles bridge 3 to a lens 2. The bridge 3 is secured by a bend which is hooked around a pin or bolt 14. The pin or bolt 14 is itself tightly secured by a nut 25 and washer 26. The pin or bolt 14 projects through a hole drilled in the lens 2. The pin or bolt 14 also has a decorative head 27 to hide the bend in the bridge 3 hooked around the pin or bolt 14. The head 27 may be embossed with a logo or shaped for aesthetic effect.

In Figure 4 it is shown how the bridge 3 has a substantially U-shaped bend 21 closely embracing the pin or bolt 14. The distal end of the bend 21 is then bent inward to create a notch bend 22 to engage a notch (not separately visible in the drawing) cut in the lens 2. The notch bend 22 prevents rotation about the pin or bolt 14. Thus, the bridge 3 is securely located relative to the lens 2.

In use, the bridge 3 will be secured at each end to a respective lenses 2 in order to hold those lenses 2 together as a pair of spectacles. The portion A (Figure 2) of the bridge 2 has a shape memory reflex created by the method described above. Each bend 21 in the other side portions B of the bridge 3 (see Figure 4) will be also rendered relatively rigid by the method described above. The bends 21 are able to securely grip the pin or bolt 14, particularly if locked against rotation by the notch bend 22 in a notch formed in the lens as described previously.

The piece of material at least capable of a shape memory response is initially bent to form the bridge 3 with features 8 to eventually secure nose pads 7 (Figure 1) and bends 9 (similar to bend 21 in Figure 4) to eventually engage securing pins or bolts 14. The bridge 3 will then be tempered at the tempering temperature to retain these features 8 and bends 9 in the portions B as described previously. These features 8 and bends 9 are masked from the modifying temperature used to return the portion A to its shape memory reflex response.

Figure 5 illustrates an alternative mounting arrangement for spectacles.

Essentially, a bend 31 is formed by bending an end of the spectacles component to engage holes 32,33 drilled into a spectacles lens 34. The bend 31 is formed from the portion of the component which has lost its flexibility. The mounting depends upon an interference engagement between the bend 31 and the holes 32,33 to resiliently secure the component without using bolts or pins or screws. The bend 31 is effectively spring loaded such that there are forces in the direction of the arrowheads to hold the component in engagement with the holes 32,33. Thus, the bend 31 is deformed within the elastic response limit of the material.

Figure 5 shows a spectacles bridge as the component with a bend 31 but it will be understood that the arrangement could be used for lugs 11 as seen in Figure 1.

As an alternative to holes 32,33 a single slit or slot could be cut in the lens 34 to accommodate and secure the bend 31.

The bent end 31 could be arranged, as shown in Figure 5, with the bend 31 on the outside of the lens 34 or, alternatively with the bend 31 inwardly facing dependent upon spectacles design choice.

It will be understood that there are many ways of mounting and securing components in spectacles. The present invention provides spectacles components which can be mounted and secured using most, if not all of these mounting and securing arrangements.

The spectacles 1 include arms 4. If the spectacles 1 are to be resistant to deformation or crush damage, these arms 4 can also be formed from shape memory material. Furthermore, to enable adjustment of the spectacles 1 and retention of such adjustment, the Lugs 11 and the wings 4 and/or other parts of the arms 4, may be formed as described above. Thus, whilst parts have a shape memory reflex, other parts such as the distal ends of each Lug 11 where it is secured to its lens 2 and/or its hinge 5 and the bend 6 of the arms 4 are capable of retaining deformation adjustment as required.

Normally, the lug 11 is made from 1. 2mm stainless steel or similar metal like monel or titanium. The lugs 11 are made of such materials so they can be adjusted to different angles for pantoscopic tilt and adjustment to widen or narrow the temple width to suit each wearer. Such adjustment is made by deformation of each lug 11 so at least some portions of the lugs 11 must be deformable if other portions have a shape memory responses. Most people have one ear higher than the other so spectacles needs to be adjusted to fit the wearer.

The difference in deformation response may be achieved as described previously by heating the whole lug 11 or arm 4 to the tempering temperature for the necessary time period and then cooling. Those portions of the lug 11 or arm 4 which need a shape memory reflex are heated to the modifying temperature and cooled whilst the other parts, such as distal ends of the lugs 11 or bend 6, are masked from the modifying heat so they remain rigid to provide resilient deformation for spectacles adjustment and to retain that adjustment. As seen in Figure 1, the lugs 11 are secured to their respective lenses 2 by similar mounting arrangements to those used for the bridge 3. The lens 2 includes a drilled hole through which a pin or bolt 14 projects. A bend of the lug 11 is then hooked around that pin or bolt 14. The bend and therefore the lug 11 is secured by a nut and washer on to the pin or bolt 14. The pin or bolt 14 includes a broad engagement head to ensure robust engagement with the bend to secure it. As before, a distal end of the bend in the lug 11 is bent inwardly to engage a notch cut in the lens 2 to further improve secure location by preventing rotation thereabout.

Each arm 4 can be treated as described previously so that a portion (e. g. about one third of its length) does not have a shape memory reflex capability. This portion can then be deformed in order to create the bends 6 to be hooked over a wearer's ears. Normally, a plastics material sleeve will then be secured over the bend 6 for wearer comfort and to avoid exposing any sharp points or edges.

The piece of shape memory material will normally be provided as a wire of 1.1, 1.3 and 1.5 millimetre diameter. This wire is normally presented with a substantially round cross-section. If a rectangular or oval cross-section is required then the piece of material may be stamped or otherwise shaped whilst it has lost its flexibility after the tempering stage of the above described method. Thus, with a spectacle bridge, the portions B can be shaped at any stage after tempering. The portion A can only be shaped after tempering but before being subjected to the modifying temperature to provide its shape memory reflex response. Spectacles components and the methods described enable the advantages of shape memory material (helping spectacles to regain their original shape after damage or distortion) to be retained without the disadvantages (the difficulty in adjustably bending the spectacles into a retained desired configuration). At the same time, the need for separate added bendable components is removed.