GB2315338A - Lens frame including a retaining ring - Google Patents

Abstract

A frame for a lens has a rim 1 and a retaining ring 2. The rim has a channel 3 on its inner surface 8 for holding a lens 7 and the ring has a lip 4 extending around the ring and into the channel when assembled. The rim 1 and ring 2 may be made from a resilient material to provide a snap fit and cushioning for delicate lenses such as liquid crystal devices.

Description

A FRAME FOR A LENS This invention relates to a frame for a lens. It relates particularly, though not exclusively, to a frame for use in eye wear such as, for example, spectacles.

Lenses are usually inserted into spectacle frames by heating the frame rims (thus causing the rims to expand) and/or by snapping the lenses into place using force or pressure. This makes replacing lenses difficult because either the lens or the frame may be damaged by repeated applications of heat or pressure.

A known frame which attempts to solve such problems is disclosed in GB 2 199 155. This known frame has split rims to enable easy manual replacement of lenses. The rims are cut vertically into two parts having surfaces in the plane of the lens which are superimposed and provided with protrusions on one part and cavities on the other part to enable the split rims to be snapped together to retain the lens. A resilient washer is provided to minimise damage to the lens during insertion and removal.

Although this known frame can reduce damage during lens replacement, the split frames are complex to manufacture and require very good alignment to assemble. The protrusions only provide attachment at specific points, so that the split rims can warp and collect dirt and debris therebetween. The separate washer is easy to lose.

According to the present invention there is provided a frame for a lens, comprising a rim and a retaining means, the rim having a channel on an inner surface for holding the perimeter of the lens, characterised in that the retaining means comprises a ring having a lip extending into the channel and extending around the periphery of the ring. This can provide the advantage of having the rim securely fixed to the retaining ring all the way round the lens, thereby simplifying manufacture and minimising gaps between the two constituent parts.

The rim and/or ring preferably comprises a resilient material and can provide cushioning to minimise shock to delicate lenses in use. Very preferably the lip and channel are a snap fit. This makes assembly possible without special tools or skill. The channel wall adjacent the lip is advantageously inclined at an angle to the insertion direction of the lip such that in use the lip is secured releasably in the channel.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying diagramatic drawing, in which Figure 1 shows a cross section of part of a frame according to the invention before assembly.

Figure 1 shows an exploded view of a frame for a lens according to the present invention. The frame comprises a rim part (1) having a channel (3) on the inner surface (8) for holding the perimeter of the lens (7), and a retaining means part (2) which comprises a ring having a lip (4) which extends around the periphery of the ring and which when assembled extends into the channel (3).

In the present example the rim (1) and ring (2) are circular, as is the lens.

However the rim and ring may take different shapes such as square, oval, egg shaped etc., depending upon the shape of the lens and the design of spectacles required. Although in the present example Figure 1 shows a cross section of a single lens, there may be one or more lenses mounted in the frame.. For example ski goggles and other eye wear often only have one lens, whereas spectacles commonly have two lenses with a nose piece in between. The channel (3) in the present example is dimensioned to accommodate the circumferential perimeter of the lens (7). The frame is assembled by urging the ring (2) in the insertion direction (9) towards the rim (1) until it snaps into place.

Preferably one or both the rim and ring parts are made from resilient material such as a thermoplastic plastics material. This can provide protection for the lenses from external shocks to the frame.

The frame is convenient for use in eye wear, for example sunglasses or ski goggles. The frame is especially advantageous when using delicate lenses such as lenses containing liquid crystal material which require stress free or low stress insertion into the frame.

The shape of the channel in the rim is important. As shown in Figure 1 the external channel wall (5) tapers away from the lens and the lip of the ring when assembled. This allows easy assembly and disassembly. If the same channel wall had a reentrant profile (or a vertical wall) disassembly would be very difficult.

This would be especially true if the lip had a matching profile at the edge (6) where it abuts the rim when assembled.

In summary a frame for a lens comprises a rim (1) and a retaining ring (2).

The rim has a channel (3) on the inner surface for holding a lens (7) and the ring has a lip (4) extending around the ring and extending into the channel when assembled. The rim and ring preferably comprise a resilient material to provide a snap fit and cushioning for delicate lenses such as for example liquid crystal devices.

Claims (7)

1. A frame for a lens, comprising a rim and a retaining means, the rim having a channel on an inner surface for holding the perimeter of the lens, characterised in that the retaining means comprises a ring having a lip extending into the channel and extending around the periphery of the ring.

2. A frame as claimed in claim 1 in which the rim and/or ring comprise a resilient material.

3. A frame as claimed in any preceding claim in which the lip and channel are a snap fit.

4. A frame as claimed in any preceding daim in which the channel wall adjacent the lip is inclined at an angle to the insertion direction of the lip such that in use the lip is secured releasably in the channel.

5. A frame as claimed in any preceding claim in which the rim and ring are not circular in outline.

6. A frame as claimed in any preceding claim carrying a lens containing a liquid crystal material.

7. A frame for a lens substantially as herein described.