EP0231325A1 - Light fitting - Google Patents

Abstract

In a closed electric lighting wall lamp, the bulb holders are in a light transmission envelope, the envelope being releasably sealed to allow access to a selected bulb holder.

Description

LIGHT FITTING

This invention relates to a light fitting and in particular to an enclosed light fitting in which a plurality of bulb holders are located axially spaced apart, each in a tubular envelope. Enclosed light fittings find use for both display and for safety applications. Display applications, such as the outlining of building fascia at night, require light fittings which can be left in situ exposed to the elements and yet protected against rain ingress. Safety applications, such as the temporary illumination of helicopter landing pads and road obstructions require a light fitting which is flexible so that it can be stored in compact form whilst awaiting use and yet which will prove fully operative when required for use. In order to provide an enclosed light fitting which is more suitable for both d-isplay and safety applications, there is a requirement for simple bulb replacement without the need for the light fitting as a whole to be dismantled and perhaps returned to the manu- facturers. Thus, according to one feature of our invention we provide an enclosed light fitting comprising a plurality of bulb holders and electric supply means to each of the bulb holders, each of the bulb holders being located in a protective envelope, the envelope being light transmitting, characterised in that the envelope includes releasable sealing means permitting access to a selected bulb holder.

According to a further feature of our invention we provide an enclosed light fitting comprising a tubular envelope, a plurality of bulb holders located axially spaced one from the other in the tubular envelope, electric supply means to the bulb holders and releasable sealing means for the envelope, said releasable sealing means permitting the envelope to be opened for access to a selected bulb holder. Thus, a failed bulb can be simply replaced in situ. Conveniently the electric supply means is positioned within the envelope and does not pass through the walls of the envelope so that sealing of the envelope along its length is made more certain. However in an alternative embodiment the electric supply means can be carried within the walls of the envelope.

For display applications, ^"such as the outlining of building features at night, the light fitting supplied by the manufacturers may not satisfy the user. Thus, the light fitting may have too few lights or they may be incorrectly spaced apart. By providing means to open and close the envelope, with selected access to particular bulb holders, the user can alter the positions of the bulb holders and thus of the lights. It is a feature of our invention that we provide a method of making an enclosed light fitting which includes the steps of connecting a plurality of bulb holders to an electric supply, positioning the bulb holders so that they are spaced one from another, and wrapping a protective tubular envelope around the bulb holders . Thus according to a further feature of our invention we provide a method of making an enclosed light fitting which includes the steps of positioning a plurality of the bulb holders so that" they are spaced one from another, connecting the bulb holders to an electric supply, n wrapping a protective tubular envelope around the bulb holders, the envelope being releasable to permit access to selected bulb holders.

Preferably the envelope is made from flexible lay- flat tubing having releasable sealing means along its- longitudinal edges; but in an alternative embodiment the tube can be of a pre-formed tubular construction of flexible plastics material. Thus in accordance with yet a further feature of my invention I provide a method of making an enclosed light fitting which includes the steps of selectively parting a releasable section of an envelope which surrounds a plurality of bulb holders connected to electric supply means, and positioning a bulb holder within said section. By positioning in this context I include connecting an additional bulb holder to the electric supply means, re-spacing a bulb holder already present, or removing an existing bulb holder. The bulb holder will include bulb mounting means. In one embodiment the bulb mounting means will include a screw threaded part; and in another embodiment the bulb mounting means will include a coil spring resiliently receiving a bulb shank. In both embodiments, usefully the outer periphery of the bulb holder is slotted long¬ itudinally, with the electric supply means in the form of live and neutral wires non-slidably received in the slots. The bulb holders are thus located at selected positions along the wires. Means are provided electric¬ ally to connect the wires and the bulb mounting means, and whilst this may be a soldered conductor such as a copper or aluminium wire, preferably it is a contact plate which can be slid into radial locating slot in the bulb holder so as also to position the bulb mounting means in the bulb holder.

The envelope, whilst flexible, preferably has sufficient longitudinal strength to carry predetermined weights, for instance double the human body weight. Thus in a particularly advantageous arrangement we provide a life-jacket including a flexible light fitting, the light fitting having a loop portion engagable by a hook. Thus a person wearing the life-jacket can both be sighted at night because of the light fitting, and can there- after be lifted aboard a rescue vessel or vehicle. If preferred, the loop can be closed to form an eye engagable by a claw hook. j r _

The light fitting can display a continuous light or an intermittently flashing light.

We have also devised a method of making an envelope, for an enclosed light fitting, the envelope being of two identical parts coupled by at least one hook and boss, each hook and boss extending longitudinally between opposite ends of the part but not reaching said ends, each part being an injection moulding, the mould including a fixture aligned with said hook which fixture has a width and length at least equal to that of the hook whereby the part can be withdrawn from the mould, leaving the fixture in situ.

The invention will be further described by way of example with reference to the accompanying drawings, in which :

Fig. 1 is a cross-section, partly in section, of one embodiment of bulb holder for-use in the invention;

Fig. 2 is an exploded view of the bulb holder of Fig. 1; Fig. 3 is a cross-section, partly in section, of a second embodiment of the invention;

Fig. 4 is a cross-section of one embodiment of tubular envelope;

Fig. 5 is a cross section of a second embodiment of tubular envelope;

Fig. 6 is a side elevation of a light fitting according to the invention; Fig. 7 is a view of life jacket including a light fitting;

Fig. 8 is a side view of another embodiment, in which individual spaced envelopes are provided for each bulb holder assembly;

Fig. 9 is a sectional view of one embodiment of envelope for a pair of bulb holders;

Fig. 10 is a view along the line X - X of Fig. 9;

Fig. 11 is a side section through another embodi- ment of bulb envelope;

Fig. 12 is a view along the line XII - XII of Fig. 11;

Fig. 13 is an enlarged view of the circles portion of Fig. 11; . and Fig. 14 is a section of an injection moulding - assembly.

Bulb 2 is mounted in bulb holder 3, being screw- threaded into bulb mounting means 4 located in housing 6. Housing 6 is of a rigid transparent plastics material such as PVC or nylon, and has two longitudinal slots 8 in its outer periphery shaped and sized to grip the positive and neutral electric wires 10,12 respectively, so that slipping of the housing 6 and thus of bulb holder 3 along the wires 10,12 is prevented and so that bulb holder 3 can be located at a predetermined axial position along the wires 10,12. It will be understood that a plurality of bulb holders 3 will be located at pre¬ determined spacings one to another along the length of the wires; and that the bulbs will be connected in parallel across the wires 10,12 so that failure of_. one bulb will not cut off the electric supply from the remaining bulbs. Bulb shank 14 is connected to wire 10, whilst bulb tip lό is connected to wire 12, the respective contact clips 18,20 being separated by insulation 22. Each contact clip 18,20 has an aperture 21 in which is received peg 26 of bridging member 23. Each bridging member 23 has a generally planar mid-portion 24 to which is attached the upstanding peg 26, and cranked arms 28 having a first portion 30 in the plane of mid-portion 24, a second portion 3 transverse thereto and extending in the same direction as peg 26, and a third portion 33 parallel to the first portion and directed away from the central plane of the arm.

The outer surfaces of the second portions 32 in use engage the inner surfaces of lugs 36 of contact member 38• Thus when the right hand contact member 38 as seen in Fig. 2 is inserted into a radial opening 40 in housing 6, from right to left as seen in Fig. 2, toes 42 of contact member 38 first slide over second portions 3 and then spring there-behind whilst concurrent¬ ly recess 44 engages around wire 12 and then cuts through or pierces the wire insulation 46 to engage conductors 48. Electrical connection is thereby made from conductors 48 by way of contact member 38 and bridging member 23 through peg 26 to tip 16. Similarly a connection from wire 10 can be made to shank 14•

Piercing of wire insulation 46 acts to locate contact member 38 at a predetermined position along the wires 10,12. The piercing can be effected by any convenient method, including in one embodiment a spike protruding into recess 44•

In the embodiment of Fig. 3, the bulb holder 3 is in two sections 50,52, section 50 being electrically connected to and axially located along wire 10, whilst section 52 is electrically connected to and axially located along wire 12. Sections 50,52 each have a cylindrical recess 54 in which is received a coil spring 56. A bulb 2a of the type having its electrical contacts 57 at opposite ends is resiliently hung between the sections 50,52, with contacts 57 within the end turns of coil spring 56. The coil spring 56 acts as an electrical conductor between the wire and the respective bulb contact. Contact member 38 is a pin driven through one wire and received in a socket 59, and is positioned between coils of spring 56 to both provide the electrical connection and to locate the coil axially relative to the corresponding wire. In an alternative embodiment, contact member 38 is of similar shape to that shown in Fig. 2, but the bridging member is of a different construction comprising a first pair of shoulders between which two or more coils of the spring 56 are tightly held to make a good electrical contact and to connect the spring and bridging member firmly together, and with a second pair of shoulders separated by a planar surface around which the arms of the bridging member engage.

Bulb holder section 52, which is identical to bulb holder section 50 , has its cylindrical recess 54 communi¬ cating with a radially directed open-ended hole or slot 66. To assemble the coil spring 56, and the bridging member sub-assembly where provided in the above alternative embodiment, into bulb holder section 52, the sub-assembly is fed into recess 54 with the bridging member first, such that the bridging member can pass through slot 66, whereafter the sub-assembly is turned through 90° so that the sides of the slot are received between shoulders of the bridging member. Thus orientated, contact member 38, either a pin, or a plate with the projection for the bridging member alternative can be pushed into position, with its toes 42 first sliding over and then springing behind the planar surface whilst concurrently the recess 44 first engages around wire 12 and then cuts or pierces insulation 46 to engage conductors 48.

To avoid contact members 38 severing conductors 48, ends 68 of the contact member 38 abut the closed end of slot 66.

In an alternative embodiment, again for use with a bulb 2a having its electrical contacts at opposite ends, the sections 50,52 can be joined to form a single replacable unit.

For one form of display, the bulb holders 3 and wires 10,12 are positioned within a tubular envelope 70. Envelope 70 includes a releasable connection in the form of ball 72 and socket 74, the connection extending longitudinally of the envelope. Preferably the envelope is extruded as a tube of plastics material in the "almost closed" condition so as to assist subsequent tight mating to limit water ingress. The ball and socket connection can be selectively released to allow access to specific bulb holde^'rs 3, for instance to change a bulb. Alterna¬ tively, one or more of the existing bulb holders 3 may need to be repositioned, for a better light effect or to allow the light fitting more easily to be assembled for instance around a fascia protuberance.

Whilst I prefer the electrical supply means to be in the form of separate positive and neutral wires within and separate from the envelope, in an alternative embodi¬ ment the electrical supply means could be by wires secured to the inner surface of the envelope or within the wall of the envelope with the supply carried to the bulb holder by spiders or equivalent spacer members. In an alternative embodiment, to secure a better seal and more rigid fitting of the releasable connection, a modified profile as indicated by the dotted line 76 could be used.

Integral flange 78 is attached to the tubular envelope to allow the light fitting to be secured as by nailing to a building fascia.

Preferably the envelope is of PVC, and of a thick¬ ness selected to withstand extended wear and tear, but also to be of sufficient flexibility so that it can be bent around corners, as would be required when fitting to a building fascia. For certain applications, such as delineating at night a helicopter landing pad, the light fitting needs to withstand considerable weights without being crushed or splitting, ^'so that the light fitting and particularly the envelope needs sufficient flexibility to be flattened without permanent damage.

For yet another application the envelope should be of a material and of a thickness to have a substantial tensile strength, for instance able to lift double the human body weight. Thus for an improved life jacket 80, I loop the envelope as at 82 so that a night rescue team can lift the wearer aboard a rescue vessel or vehicle by gripping or passing a claw or hook through the loop 82. In certain embodiments I may close the loop to form' an eye. Thus the light fitting could be permanently secured, as by being sewn in, to life jackets and to similar specialised outer clothing such as that used by mountaineers and yachtsmen; for such applications a separate battery 84, switched in either manually or automatically as by contact with salt water, could.be used. Warnings of unexpected hazards, such as a road accident, could similarly be signalled at night. For certain warning applications, particularly those involving sea or water rescue, a fully sealed light fitting may be preferred, since a wearer of a life-jacket including a light fitting according to my invention may be in the sea for severalhours before being rescued, and therefore it is extremely important to take every precaution against sea-water ingress.

The light fitting may display a constant light¬ ing or flashing lighting. For warning signals, I have found that a light fitting flashing five, times a second each of duration 0.1 seconds will provide a useful warning signal; though for air-sea rescue at night a light illuminated for 0.1 seconds once a second may be preferred.

The envelope closure of Fig. 7 may provide adequate protection against water ingress for most applications. Envelope 70 has a releasable connection comprising a male part 90 of width 1.5 mm and length 2 mm extending the length of the envelope and mating with a female part having a recess 92 preferably sized closely to grip the male part. A water resistant grease or a silicon sealing material may be injected between the parts 90,92, both during initial assembly and upon any subsequent re-assembly, as after releasing the connection to replace a bulb. Though the parts may mate tightly, for additional security and water tightness they include tangentially-extending outer portions 94 having arcuate ends 96 around which a longitudinally-extending clip 98 is a snap-fit. Preferably one side edge of clip 98 will first be placed around one of the outer portions 94 and then the other side edge will be pressed over the other of the outer portions 94_' In use, the light fitting must retain its sealed integrity and its generally cylindrical inner cross- section, whilst yet being flexible about its. longitudinal axis. I have found that this combination of contra¬ dictory requirements can be obtained by for instance using an envelope 70 of flexible PVC (ultra violet stabil¬ ised grade); and a clip 98 of cellulose acetate butylate, preferably moulded around an alumium foil section, the aluminium giving additional tensile strength with flexibility about the longitudinal axis. The aluminium foil conveniently has a thickness between 0.3 mm and

0.1 mm, and is preferably of thickness 0.05 mm. The clip 98 has a thickness in the range 0.5 mm to 1.0 mm, prefer¬ ably 0.75 mm. In alternative embodiments, the clip can be made of acrylonitrile butadiene styrene or rigid PVC with a section thickness selected to maintain the sealing at outer portions 94 during bending of the light fitting about the longitudinal axis of envelope 70.

The annular envelope 70 may conveniently have an inner diameter of 20 mm and an outer diameter of 25 mm. The flange 78 can extend 25 mm from the transverse radial plane and include mounting holes 100. The envelope is of the polyvinyl chloride (PVC) finish known as "crystal", (rather than of the more opaque "MASTERBATCH" ) such as is obtainable from ICI pic of England under their grade 1-2, and having a British Standard softness between 10 (hard) and 20 (soft) points; the PVC preferably is selected from that known as "migration resistant". Such PVC has been^found to withstand a surface temperature of 120°C+, whereas with the light fitting horizontal, the area immediately above the bulb has been measured at 50°C maximum. Furthermore, PVC is an electrical insulator, so that should there be an electrical fault anyone inadvert¬ ently touching the envelope should not receive an electrical shock.

For additional protection against water ingress, outer portions 94 will be located uppermost when the light fitting is mounted other than vertically. Thus in an alternative embodiment, portions 94 can be formed adjacent flange 78.

If required the bulbs 2 can emit light of different colours, the bulb holders 3 having a plurality of pairs of longitudinal slots 8 in its outer periphery, with the number of pairs equal for instance to the number of different colours. Thus selected pairs of wires in the slots 8 will be electrically connected to the appropriate bulb holders, so that the lights can be "chased" i.e. switched on in sequence to form pre-arranged messages or other lighting pattern.

As compared to the embodiment of Fig. 6 in which the individual bulb holders of the Fig. l/2 embodiment and the complementary pairs of bulb holders of the Fig. 3 embodiment are located in a common tubular transparent or translucent envelope 70, in the embodiment of Fig. 8 each individual bulb holder or complementary pair of bulb holders is located in a separate tubular envelope 100.

Preferably the separate tubular envelopes 100 are formed from two identical sections 102, 104, abutting" at faces 105- Each section 102, 104 includes a pair of hooks 106 releasably engagable with a boss 108, the hooks being at the free end of a flexible stem 109 so that the hook can be radially disengaged from its boss. Each hook has a 120° rib and each boss a complementary 120° groove, so that relative longitudinal movement of the sections can be prevented, when coupled. In addition, each end of each section 102, 104 has part-circular end section 110 of reduced diameter, providing an internal circumfer¬ ential groove 112. At each axial end of groove 112 is an annular retaining rib 114 (Fig. 13) whereby the coupled sections 102, 104 can grip the wires 10,12 by way of ribs 114 to permit individual placement of the envelopes 100 at selected positions along the wires, and thereafter to prevent movement of the envelope along the wires. Groove 112 is filled with a silicone sealing medium to provide a weather seal, as can be faces 105 and the engaging surfaces of hooks 106 and bosses 108. In an alternative embodiment to that of Fig. 10 it will be understood that if the wires 10,12 are supplied in a_. circular PVC outer covering, then the sections 102, 104 at each end would have only one semi-circular groove. To permit ejection e.g. of section 104 from the mould 120 (upwardly as viewed in Fig. 10), I provide a ^' rectangular plate 122 under the full length of the hook 106. The movable half 126 of the mould 120 can then be withdrawn downwardly, so removing the rectangular plate 122 with mould half 126, whereupon the mould section 104 can be ejected upwardly by a standard arrangement of ejector pins 128. It will be understood by those knowledgeable in injection moulding that the conventional "Z" pin pulls on the screw and runner so that the screw is "broken" during withdrawal of mould half 126 at the nozzle. After a predetermined movement of mould half 126, together with the moulding (section 104) and screw and runner 129 the Z pin and ejector pins are held stationary whilst the mould half 126 continues to move on its opening stroke.

Plate 122 has a tapered section 130, so that shrinkage of the moulded section 104 onto the plate 122 tend to "brake" the opening stroke, with potential damage to the moulded section.

Figs. 11 and 12 show an alternative form, for the internal surface 140 of envelope 100. The envelope 100 has a bulbous form 142 which provides a lens configura¬ tion, with a number of lens surfaces 140 disposed circum- ferentially around the bulbous form 142. Thus the illumination from bulb 2 is magnified in certain planes, giving a pleasing effect. Thus, viewed around the circumference of the envelope 100, the light intensity will increase and diminish, and a similar effect will also be obser-ved when the envelope is viewed from different axial positions. The bulbous form 142, and the surfaces 140, can in alternative embodiments be of any selected arrangement to give a required effect. As in the previously described embodiments, the bulb holder or complementary pair of bulb holders in a single envelope can be joined to different sets of wires so that the envelopes can be illuminated in unison, in programmed sequence, and if required with bulb lighting of different colours.

The wire receiving slot or groove can be of keyhole form, as shown number 8 on Fig. 5, or other suitable form e.g. 8a. If a permanent affixing is required, the slot and enclosed wire can be enclosed e.g. by a quickly-solid¬ ifying plaster across the radially outer opening of the keyhole.

Claims

CLAIMS ;

1. An enclosed light fitting comprising a plurality of bulb holders and electric supply means to each of the bulb holders, each of the bulb holders being located in a protective envelope, the envelope being light transmitt- ing, characterised in that the envelope includes releas¬ able sealing means permitting access to a selected bulb holder.

2. A light fitting according to Claim 1 characterised in that the protective envelope is tubular and in that the releasable sealing means extends longitudinally, parallel to the major axis of the envelope.

3. A light fitting according to Claim 1 characterised^' in that the electric supply means is- a first electrically conducting wire and a second electrically conducting wire and in that the bulb holder has an electrical connection to at least one of the wires, the electrical connection locating the bulb holder axially relative to the wire.

4» A light fitting according to claim 3 characterised in that the bulb holders are arranged in co-operating pairs, with one of the pair electrically connected to the first wire and the other of the pair electrically connected to the second wire, each of said pairs being within a separate envelope.

5- A light fitting according to Claim 3 characterised in that the bulb holders are all within a single tubular envelope, the envelope being flexible so that, adjacent bulb holders are axially located along the wires but are not all axially aligned.

6. A light fitting according to Claim 2 characterised in that the envelope has a first part terminating in a ball and a second part terminating in a socket, the ball and socket providing the said releasable sealing means.

7. ^" A light fitting according to Claim 2 characterised in that the envelope has a first part terminating in a hook and a second part terminating in a boss engagable by the hook, the hook and boss providing the said releas¬ able sealing means.

8. A method of making an enclosed light fitting which includes the steps of positioning a plurality of' bulb holders so that they are spaced one from another, connecting the bulb holders to an electric supply, and wrapping a protective tubular envelope around the bulb holders, the envelope being releasable to permit access to pre-selected bulb holders.

9 . A method of making an enclosed light fitting which includes the steps of parting a releasable section of an envelope which surrounds a plurality of bulb holders connected to electric supply means, and positioning as herein defined a bulb holder within said section.

10. A method of making an envelope for an enclosed light fitting, the envelope being of two identical parts coupled by at least one hook and boss, each hook and boss extending lontitudinally between opposite ends of the part but not reaching said ends, each part being an injection moulding, the mould including a fixture aligned with said hook which fixture has a width and length at least equal to that of the hook whereby the part can be withdrawn from the mould leaving the fixture in situ.

11. - A life jacket including an outer surface, an enclosed light fitting as claimed in Claim 1, the electric supply means being powered by a battery.