all figures are schematical and not necessarily to scale and illustrate only details essential to the understanding of the invention while other details have been omitted . in all figures the same reference numerals are used for identical or corresponding details . reference is first made to fig1 that illustrates a pair of spectacles 1 comprising a frame 2 holding two lenses 4 . in a usual manner the frame comprises a connecting bridge or a nose bridge 3 and hinges 5 for the temple bars . the pair of spectacles is symmetrical about a plane of symmetry indicated by the dash - dotted line 15 . the pair of spectacles is shown exclusively to illustrate how the clip - on shield is attached and it is not a part of this invention . the clip - on shield for spectacles as a unit is designated by the reference numeral 6 and it comprises two shield lenses 7 and a connecting bridge or nose bridge 8 that secures the shield lenses relative to each other . preferably the clip - on shield is symmetrical about an axis of symmetry which , in the intended position , coincides with the plane of symmetry 15 of the spectacles . the shield lenses may be made of glass or -- more commonly -- a plastics material which has been coloured or coated to provide the desired optical properties . at their laterally outermost rim parts , the shield lenses 7 are provided with guide pins arranged opposite the hinges 5 for the temple bars . the connecting bridge of the clip - on shield consists of a piece of wire 11 which , as depicted in fig1 extends horizontally from one lens to the other and being at its extremities angled substantially vertically downwards , the downwardly extending sections forming spacer elements 10 . fig2 is a sectional plan view of the clip - on shield and it will appear that the shield lenses 7 extend arcuately and how the wire 11 that forms the connecting bridge follows a wavy course wherein the central portion forms an angle whose apex is forwardly oriented , i . e . downwardly oriented in fig2 . this apex constitutes the engagement tongue 12 of the clip - on shield . at a further distance from the plane of symmetry 15 , the wire 11 passes through a substantially u - shaped bend wherein the concave portion of the u inclines forwards and towards the centre . this bending will be designated the straddle 13 in the following , since it serves the purpose of defining an area which may straddle the connecting bridge 3 of the spectacles as indicated by the dotted line in fig2 . the wire continues by inclining forwardly in an oppositely oriented u - shaped bend from where it continues by inclining backwards and outwards . this bend , the convex part of which faces forwards and into the plane of symmetry , is designated the finger bend 14 , as it serves the purpose of providing a support for the fingers when the clip - on shield is to be fitted or taken off , or the spectacles are to be pushed upwards . from the finger bend 14 the wire continues to a point beyond the respective shield lens 7 slightly within its rim . here , as mentioned above , the wire is angularly bent whereby the extremity becomes downwardly oriented . the wire is secured to the shield lens 7 by its vertical section that constitutes a spacer element 10 defining the minimum distance of the shield lens relative to the lens of the spectacles at this point . the wire may be secured to the shield lens by any of the known methods without departing from the scope of the invention . according to one embodiment a hollow sleeve is glued to the back of the lens and the wire is taken through the sleeve and secured e . g . by folding of a protruding extremity . according to a second embodiment a hollow sleeve is secured to the shield lens with pins or protrusions that are taken through recesses in the shield lens . according to a third embodiment the wire is folded and taken through suitable bores in the shield lens , optionally back and forth . other arrangements and attachments may also be suitable . a friction surface may be realised by manufacturing the sleeve from a friction material or by providing sections of the wire with a frictional coating or by providing portions of the shield lens with a frictional coating . as will appear from studying fig2 and 1 , the spacer element is located fairly closely to the innermost rim of the respective shield lens while the remainder of the lens surface has no spacer elements which means that it is possible to establish contact in points or in sections between shield lenses and frame or lenses . according to a preferred embodiment the wire comprises a resilient material which may be folded to the shape described . suitable materials include alloys of titanium , aluminium , gold , etc . other suitable materials may be suggested by a person skilled in the art . fig3 is a front view of the case according to the invention with a fitted clip - on shield , said shield being outlined with dotted lines as regards the components that are invisible from the outside of the case . fig3 illustrates how the case 30 comprises a retainer guide 31 which is symmetrical about the plane of symmetry 32 and two identical compartments or housings 35 located at either side of the retainer guide 31 whereby a unit is provided which is inverted symmetrically about the plane of symmetry 32 . reference now being made to fig4 and 7 , it will appear how the retainer guide comprises grooves 34 at either side while the housings 35 comprises corresponding beads 42 , as will appear from fig4 and 10 , which beads are shaped to match the grooves 34 to provide attachment of the housings . the left housing is illustrated in fig6 and it is seen in a vertical sectional view in fig5 and study thereof will reveal that the housing is open upwardly and downwardly , the upwardly facing edges having bevels 40 that form a funnel - like entry opening 41 . reference now being made to fig8 and 10 , it will appear that the case 35 forms a cavity delimited by the front 36 , the back 37 , the inner housing fillet 38 , and the outer housing fillet 39 . the designations front and back refer to the intended fitting position of the clip - on shield , viz . with its lens front facing towards the front . the term ` inner housing fillet ` is used to describe that the internal rim of the shield lens faces towards the rounded inner fillet whereas the outer rim faces towards the rounded outer fillet . the width of the cavity to the shield lens is increased in the vicinity of the outer fillet whereby only a clip - on shield with backwardly oriented pins 9 can be received at the outer rims , as will appear from fig4 . as will appear from fig3 in principle the case consists of two separate cavities that each receives the respective shield lenses of the clip - on shield . the retainer guide 31 has a planar top surface 33 which is perpendicular to the plane of symmetry 32 . this top surface constitutes a solid abutment for a correspondingly configured connecting bridge 11 in the clip - on shield . when the clip - on shield is fitted in firm abutment with the planar top surface 33 , the location of the clip - on shield is consequently controlled by the abutment on the top surface 33 and by the lens inner rims supporting on the inner fillet 38 . the retainer guide 31 is made of a dimensionally stable material , preferably a profile which may be extruded of aluminium or mould cast in aluminium or a plastics material . the thickness of the retainer guide may be e . g . 9 mm . preferably the housings 35 are made of a soft material , such as rubber with a shore - a hardness of 60 . the wall thickness of the front and the rear may be 2 - 2 . 5 mm . according to the invention the housings are so configured that in its empty state the case extends substantially rectilinearly or describes a very flattened arch , while the case must be curved into increased curvature in order to conform the clip - on shield , once introduced . the radii of curvature in its empty state may be e . g . 200 and 220 mm , respectively , for the back and the front , respectively , while the radius of curvature of the clip - on shield is about 150 mm , both in their relaxed state . the resilience of the housings and the friction on the insides serve to ensure adequate retention of the clip - on shield . hereby advantage is taken of the resilience of the clip - on shield and in particular of the connecting bridge 11 of the clip - on shield . according to one embodiment the housings and in particular their inner fillets are adapted to ensure that the inner rims of the shield lenses have a certain abutment pressure in a direction towards the plane of symmetry 32 . hereby advantage is taken of the resilience of the clip - on shield &# 39 ; s connecting wire to ensure retention . the case containing the clip - on shield may tolerate a very high degree of deformation without this engagement tending to loosen . in its storage position the clip - on shield is so arranged , as shown in fig3 that the shield lenses are completely protected by the housings whereas the connecting bridge is shielded , but yet readily accessible whereby it is easy to seize the clip - on shield to remove it from the case . handling is particularly convenient in case of a clip - on shield which may be fitted onto a pair of spectacles by seizure of the connecting bridge between two of one &# 39 ; s fingers as is the case with the clip - on shield featured in the above identified patent application ser . no . 08 / 947 , 623 . although specific embodiments will have become apparent from the above disclosure , it will be understood that they have been described exclusively to exemplify the invention and not to limit same , and that the invention may be widely modified by the person skilled in the art without departing from the scope defined by the appended claims .
the present invention relates to a case for a clip - on spectacle shield comprising a retainer guide and two housings arranged for receiving respective shield lenses of the clip - on shield where the connecting bridge of the clip - on shield extends from one housing to the other , said case being characterised in that the retainer guide is made of a dimensionally stable material , that the retainer guide is made to secure the housings and to support the connecting bridge of the clip - on shield in a well - defined orientation , that the housings are made of a resilient material and are configured to tightly enclose the shield lenses so as to ensure that the case is deformed elastically for an increased curvature when the clip - on shield is contained therein whereby the clip - on shield is secured elastically .