GB2200475A

GB2200475A - Mount for an eyepiece lens

Info

Publication number: GB2200475A
Application number: GB08801988A
Authority: GB
Inventors: Cyril Nelson Edward Angell
Original assignee: Avon Industrial Polymers Melksham Ltd
Current assignee: Avon Industrial Polymers Melksham Ltd
Priority date: 1987-01-30
Filing date: 1988-01-29
Publication date: 1988-08-03
Also published as: GB8801988D0; GB8702146D0

Abstract

A mount used to mount a lens (19) adjacent an eyepiece, e.g. of a respirator, has a frame (10) which surrounds the lens (19). A retaining collar, formed from a closed band (20) of a material more rigid than that of the frame (10), surrounds the frame. The frame has tabs (13, 14) which extend from the frame for securing the mount adjacent to the eyepiece. These pass respectively through an aperture and slot present in the retaining collar to secure the collar in position relative to the frame (10). <IMAGE>

Description

MOUNT FOR AN EYEPIECE LENS.

This invention relates to means for mounting a lens in an eyepiece of e.g. a respirator or sporting goggles.

It is known to mount an eyepiece lens, which may or may not be a sight-corrective lens, in a frame of elastic material having an inwardly-facing groove that engages the edge of the lens. One such use of an elastic frame is described in our published European Patent Application No. 184 929, wherein a sight-corrective lens is attached between the plain eyepiece lens of a respirator and the eye of a wearer by a monocular mount of thermoplastic or thermosetting material comprising a frame to hold the lens. Tabs extending from the frame are provided for attaching it to the surround of the plain eyepiece.

The use of resilient material in the lens frame is advantageous in that it facilitates changing of the lens and helps to protect it from shocks and stresses, as well as being convenient for provision of attachment means such as described in European Patent Application No. 184 929. However with the rough handling and/or violent conditions to which the eyepieces may be subjected the frame is sometimes deformed sufficiently to allow the lens to fall out, and clearly it would be desirable to avoid this without losing the abovementioned advantages.

In the present invention the eyepiece lens mount includes a retaining collar having a closed band of material substantially more rigid than the frame, the retaining collar being fittable around the outside of the frame to restrict outward expansion thereof but removable for e.g. changing of lenses. The collar need not touch the mounted lens, so the shock-protection afforded by resilient mounting may be retained.

In one version, so as to provide definite relative orientation of frame and collar and avoid distortion of the former, the removable collar when fitted on the frame engages attachment or support means extending from the frame; these might be for example the ear-pieces of a pair of goggles, or tabs used to mount the frame in a respirator. The collar may have an aperture through which one of the support or attachment means passes when the collar is fitted. For additional security the collar may have an inturned flange to engage a front or rear surface of the frame and prevent slipping of the collar axially relative to the lens and frame.

By way of example, an embodiment of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a partial median section of a respirator facepiece showing an eyepiece; Figure 2 is a face view of the frame of a mounting for securing a sight-corrective lens inside the eyepiece; Figures 3, 4 and 5 are respectively rear elevational, vertical sectional and front perspective views of a retaining collar of the mounting; and Figure 6 is a front perspective view of the mounting with the collar fitted onto the frame.

Figure 1 shows the facepiece 1 of a respirator which has been sectioned so that in the upper half of the facepiece we can look into its right hand side. A circular surround 2 is formed in the rubber material of the facepiece into which is fitted an eyepiece 3, the eyepiece 3 having a configuration whereby a concaveconvex portion 4 of which the radii of curvature on both sides are equal and which therefore has no optical corrective effect, is presented at an advantageous angle to the eye by the provision of an angled, crescent-like wall 5 linking it to a planar rim of the eyepiece which is held in the surround.Attachment means 6,7 for a mount containing a monocular sight-corrective lens are provided diametrically opposed to each other on the circular surround 2 but are asymmetric; attachment means 6 being a comparatively wide arch and attachment means 7 being exactly the same except that the arch of its aperture is wider i.e. the aperture is of greater tangential extent.

Figure 2 shows a mount for mounting a sightcorrective lens 19 inside the eyepiece of the respirator.

The frame 10 of the mount is a one-piece moulding of a suitable thermoplastic or thermosetting material, for example EPDM or EPT, which is quite soft and flexible.

The frame is of a standard shape for receiving a prescription sight-corrective lens 19 the edge of which fits into a continuous groove 12 around the opening of the frame in just the same manner as into a normal spectacle frame. Opposed across the frame are tabs 13,14 which fit snugly through the respective apertures of the attachment means 6,7 in a manner described in more detail in European Patent Application 184 929.

The soft resilient frame 10 provides a mounting from which the lens 19 may easily be removed, e.g. for replacement, simply by pressing it out with corresponding deformation of the frame.

Referring now to Figures 3, 4 and 5 a retaining collar for the mounting comprises a closed band 20 of hard plastics material shaped and dimensioned so as to be a snug fit around the outside of the lens frame 10, as seen in Figure 6. The closed band 20 is a short tubular sleeve portion 21 to fit around the frame 10 with an inwardly projecting flange 22 all around its rear edge 23; the rear opening of the closed band 20 within the flange 22 is thus smaller than the frame 10 so that the latter cannot fall out rearwardly.

At one of the lateral sides of the sleeve portion 21 there is a substantially square aperture 24 through which the root of the tab 13 of the frame 10 fits closely when the mount is assembled. Opposing aperture 24, in the rear edge of the opposite lateral side of the sleeve portion 21, is a wide shallow slot 25 in which the wider attachment tab 14 of the frame 10 rests when assembled, again as seen in Figure 6.

It will be seen that when the frame 10 and collar are assembled as in Figure 6 the mount can still be attached by the tabs 13,14 into the respirator facepiece 1 by means of the attachment arches 6,7 as described in European Patent Application 184 929. The narrow tab 13 projects through the aperture 24 in the collar and this, combined with the inward rear flange 22 and the close fit of the frame 10 in the collar, keeps the latter uniquely positioned and retained on the frame. The rigidity of the collar prevents outward expansion or flexing of the more flexible frame 10, and consequently the lens 19 is not dislodged even by rough handling of the mount. When however it is desired to remove the lens 19, the frame 10 holding the lens is conveniently pulled out from the front of the collar by pulling on the tab 14; the lens may then be changed easily and the frame re-inserted by first sliding the tab 13 through the hole 24 in the collar and then pressing in the rest of the frame.

It will also be apparent that this invention is by no means restricted to respirators or to sightcorrective lenses, but could be applied in other fields, e.g. combat goggles or sports goggles,.in which lenses are retained in flexible frames.

Claims

CLAIMS:

1. A mount for mounting a lens adjacent an eyepiece, a frame of the mount surrounding the lens and the mount having a retaining collar removably located outside the frame, the retaining collar having a closed band of material more rigid than the frame and acting to restrain movement of the frame away from the lens.

2. A mount for mounting a lens adjacent an eyepiece according to claim 1 wherein the retaining collar is provided with at least one closed aperture through which an attachment means extending from the frame may pass thereby providing means for attaching the collar to the frame.

3. A mount for mounting a lens adjacent an eyepiece according to claim 1 or claim 2 wherein the retaining collar is provided with at least one open slot into which an attachment means extending from the frame may pass thereby providing means for engaging the collar and frame.

4. A mount for mounting a lens adjacent an eyepiece according to one of the preceding claims wherein a flange extends at right angles from one edge of the closed band of material comprising the retaining collar, the flange extending for a short distance towards the central opening enclosed by the band such that when the collar is located outside the frame the flange engages a front or rear surface of the frame.

5. A mount for mounting a lens adjacent an eyepiece substantially as described herein and with reference to the drawings.

6. A respirator having an eyepiece mounted within a surround and a second lens located behind the eyepiece so as to be between the eyepiece and the eye of a wearer of the respirator, the second lens being mounted in a mount according to any one of the preceding claims wherein mutually engageable attachment means are provided to secure the mount of the second lens to the surround of the eyepiece.