Title: "Improvements in or relating to spectacles"

THIS INVENTION relates to spectacles.

Spectacles are known, as so-called "sun glasses" which have lenses (normally plain lenses) provided with a partially reflective and partially light transmissive layer or coating, whereby the intensity of light passing to the wearer's eyes through said layer is attenuated without otherwise interfering with the wearer's vision, whereas, due to the relatively high level of light reflected outwardly from the partially reflective, partially transmissive layer, as compared with the inten¬ sity of light reflected from the wearer's skin and eyes through the partially reflective and partially trans¬ missive layer, the lenses present the appearance, to a person viewing the wearer, of totally reflective metallic surfaces.

It is an object of one aspect of the present invention to provide spectacles which are similar to these known spectacles in the sense that to the wearer they serve simply to attenuate the intensity of light reaching the eye, but which are capable of presenting a striking or unusual appearance to a person viewing the wearer.

According to this aspect of the invention spec¬ tacles are provided having lenses (as herein defined) each provided with a partially reflective and partially light transmissive layer which incorporates a hologram, whereby a holographic image within the area of the lens

may be viewed by a person looking at the wearer of the spectacles.

It is another object of the present invention to provide an improved means of providing spectacle frames with a metallic appearance, for example, the appearance of polished metal, whilst retaining the freedom to use for such frames materials which may be more preferred from a structural or manufacturing viewpoint.

According to this aspect of the present invention there is provided a spectacle frame provided with a light reflective coating by sputtering with metal.

The term "lens" as used herein is intended to com¬ prehend a transparent body without any converging or diverging power, as well as a body which acts as a con¬ verging or diverging lens. The term "spectacles" as used herein is also intended to include, in addition to spec- tacles of conventional construction, Items such as "clip on" attachments intended as an ancillary to normal spec¬ tacles and which may be clipped over the frames of the latter in known manner to cover the normal lenses with additional "lenses". Furthermore, the term is also intended to include variants where, for example, a single unitary transparent body extends across both eyes and thus serves as the "lenses".

In a preferred embodiment of the invention, a pair of "sun glasses" has lenses of transparent material hav¬ ing a layer or coating which is partially reflective and partially light transmissive, with the optical density of said layer or coating being varied locally in accordance with the patterning of a hologram in a manner known per s_e, so that a person viewing the lenses of the spectacles whilst worn by another person will be able to view, with¬ in the areas of the lenses, a corresponding holographic

image. The image concerned may be, for example, that of a large caricatured eye-ball winking, that of a flag such as the Union Jack, or advertising material, for example pertaining to a product in the promotion of which the spectacles in question may be sold or given away.

The said layer, when provided, may comprise a plastics material film which has been sputtered with metal. Ideally reflective metals which are silver or gold in appearance may be used. In practice, silver, gold or aluminium metals are likely to be used.

The lenses, with the hologram-incorporating, reflective/transmissive layer may be arranged to be interchangeable in the spectacle frame so that the wearer can present to onlookers selected hologram images from a plurality of available images and may change the lenses, and thus the images, from time to time, as desired.

It will be appreciated that, provided that the normal optical quality of the lenses is otherwise correct, the provision of the hologram images thereon will be non-injurious to the eyesight of the wearer but will provide the wearer with a harmless means of present- ing a striking or spectacular effect. Indeed, the sputtering technique referred to above, particularly in conjunction with the use of relief image holograms, as set out below, allows the production of sunglasses such that it will not be apparent to the person wearing the sunglasses that there is a hologram incorporated in or on the lenses, nor will there be any other impediment to clear vision.

Furthermore the invention provides a medium of sub- stantial potential for advertising and the like, as it is likely that members of the public will be willing to pay at least as much for such spectacles incorporating holo-

-I -

graphic advertising material as will cover the production and distribution costs of such spectacles, whilst the potential coverage is, of course, very great.

In another embodiment of the invention, the spectacle lenses are of glass, the hologram is provided thereon in the form of a relief image hologram on one surface of the glass, formed by ion bombardment and acid etching of the glass, with the subsequent application of a part-transmissive, part-reflective coating on the re¬ sultant undulating surface. The coating may be formed by sputtering with an appropriate metal, such as gold, silver or aluminium.

The spectacle lenses may, however, be made from plastics by injection moulding or by pressing, the holo¬ gram taking the form of a relief image hologram impressed upon the respective lens surface by nickel press master, the lenses thereafter having a part-transmissive, part- reflective coating applied thereto, for example by metallic sputtering as set out above. In this case, in the production of such a master, a photo-polymer is used, to which the hologram pattern is applied photo¬ graphically, and which is subjected to "developing" pro- cedures, known per se, to form the relief image hologram thereon and which thereafter forms a basis for the pro¬ duction, in manner also known per se, such as by an electrolyte process, for the production of the nickel master.

The arrangement, in any of the above embodiments, is such that the person wearing the spectacles does not perceive the holographic image, but has the same view as he would if he were wearing ordinary "sun-glasses". That is to say, the sunglasses, apart from the desired reduction in light intensity, present no impediment to the vision of the wearer.

In spectacles embodying the invention, the sur¬ faces of the lenses are preferably curved, in the con¬ ventional manner, but may, of course, be plane if pre¬ ferred.

It will be appreciated, of course, that the tech¬ niques and concepts disclosed above are not confined to spectacles, and that the invention also extends to the application of such technique and concepts to, for example, window panes, visors, windscreens and so forth.

In the above, and further embodiments of the invention, spectacle frames may be made of plastics, in a manner known per se and may subsequently, before being fitted with lenses, be metallised by sputtering with metal. Alternatively, lenses already fitted may be appropriately masked off during sputtering the frames. Ideally, reflective metals which are silver or gold in appearance may be used, for example silver, gold or aluminium metals may be used.

It will be appreciated that multi-layer coating of the spectacle frames may be carried out by subjecting the frames to successive coating steps, and that sputtered metal layers may be utilised in conjunction with non- metallic layers, for example a transparent layer, such as a tin oxide layer may be applied over a sputtered metal layer or alternate layers of various metals and tin oxide may be applied to the frames. It may be found advant- ageous to similarly multi-coat the hologram-bearing spectacle lenses.

Furthermore, it will be appreciated that the sputtering may, if desired, be confined to specific areas on the frames, to afford special visual effects. Like¬ wise, it is possible that the optical density of the metallic coating on the frames may be varied locally in

accordance with the patterning of a transmission hologram or diffraction grating in a manner known per se, so that a person viewing the frames of the spectacles will see holographic images associated therewith, or vividly coloured patterns or the like, with or without a "three- dimensional" effect.

The frames of the present invention may be used in conjunction with lenses bearing holograms, as proposed above. In the latter case, the sputtering of the frames in accordance with the present invention allows excellent visual coordination of the frames with the lenses, so that the frames can be made to merge visually with the lenses or can be contrasted therewith according to the wish of the designer, rather than by necessity.

However, the present invention is equally applic¬ able to spectacles having conventional lenses.

Where the spectacle frames are made of plastics the holograms thereon may be provided as relief image holo¬ grams in moulding the spectacle frames, by the technique referred to above for producing lenses bearing such holo¬ grams, with subsequent application of a reflective coat- ing, for example, by metallic sputtering.