GB2136552A - Light fittings - Google Patents

Abstract

A fitting (2,4) comprises a pair of holders (9) are for each end of a tube or bulb (7), a pair of switches (17,19) for one of the holders (9) wherein both switches (17,19) have two electrical contacts (20 and 8, 14 and 16) which form part of a double pole circuit, and a switch operating means in the form of a plunger (22) which when engaged brings into contact the two contacts of each switch to complete the circuit, the plunger (22) being biassed to a switch "open" position when not so engaged and when the end of the tube/bulb is removed from the holder. <IMAGE>

Description

SPECIFICATION Improvements in or relating to light fittings.

This invention relates to fittings for double-ended electric light bulbs or tubes.

It is desirable for both end contacts of a doubleended electric light bulb ortubeto be isolated when either one contact is accessible.

A fitting for a double-ended electric lighttube or bulb in accordance with this invention comprises a pair of holders one for each end ofthe tube or bulb, a pair of switches for at least one ofthe holders each switch having two electrical contacts which form part of a double pole circuit which is arranged so that in use currentcan be supplied to both endsof a tube or bulb in the fitting, and a switch operating means which is engaged either bythe end of a tube or bulb mounted in a holder or by a removable end capfora holder,the switch means when so engaged bringing into contact with each otherthetwo contacts of each switch to complete the circuit,the switch means being biassed to a switch "open" position so that when the end of the tube/bulb is removed from the holder, the switch is opened.

The holder and its associated switch may be manufactured and sold separately or it mayform an integral part of a fitting in accordance with this invention which is adapted to receive a double-ended electric lighttube or bulb.

Preferably, the switch means is deactivated before or as, any end ofthe lamp tube or bulb is exposed, the two contacts of each switch disengaging from each otherto completely interruptthe double pole circuit and thus isolate both ends of the tube or bulb.

If only one end of the tube or bulb was isolated when a single end ofthe tube or bulb was exposed, the other end ofthetube or bulb would be live and provide a hazard.

Such an arrangementwhich isolates both ends of the tube or bulb prevents electrical shocks and provides safety and protectionfortheuserofsuch a holder orfitting during removal ofthe tube or bulb as the electrical source is isolated from both ends of the tube or bulb and consequently from the user's hand(s).

The switch means may be in the form of a plunger which is actuable, for example by being engaged by the glass envelope of a double ended lamp tu be, to engage the two contacts of each switch simultaneously.

Preferably, one or more ofthe electrical contacts have inturned terminal ends which actto "grab" and hold wire connections.

Thecontactswhich are engaged by the ends of the lamptubeorbulb preferablytaketheform of small coil or S-shaped springs such thatthetube or bulb is resiliently held in place by the spring whilst atthe same time, maintaining a good contact therewith.

The invention will now be described, by way of example, with reference to the accompanying draw ings, in which: Figure 1 is a part sectioned side view of one embodiment of a fitting in accordance with the invention with the switch in the "closed" position; Figure 2 is a cross-section of the fitting of Figure 1 without a tube or bulb therein taken along line Il-Il, the figure also indicating the line I-I along which the part section of Figure 1 is taken; Figure 3 is a cross-section of the fitting of Figure 1 taken along line Ill-Ill; Figure 4 is a part section side view ofthe fitting shown in Figure2taken along line IV-IV; Figure5 is a part section side view of a fitting in accordance with a further embodiment ofthe present invention;; Figure 6 is a cross-section ofthe fitting of Figure 5 taken along line VI-VI, and Figure 7 is a wiring diagramfora fitting in accordance with the present invention.

Referring to the drawings, the light fitting comprises a base portion 2 having an upstanding socket 4 at each end to receive an end contact 5 of a double ended tubular lamp 7. The lamp 7 extends in use along the length ofthe fitting with each end contact 5 engaged by a spring 6 mounted within each socket 4. Each socket acts as a holder 9 to position, surround and shield each end portion ofthe lamp. Atransparent cover diffuser or shade 8, which in use covers the rest ofthe lamp, is positioned between the two sockets 4 (see arrow B) to extend therebetween.

One contact 5 of the lamp 7 is connected to the "live" terminal of an electrical source (see Figure 1), e.g. a main supply, via the spring 6 (eithera S or small coil spring), an electrical contact8 in the base portion ofthe socket4 and a wire 10 connected to the "live" terminal of the electrical source.

The other contact ofthe lamp 7 is connected to the "neutral" terminal of an electrical source (see Figure 14) via a wire connection 12, two electrical contacts 14 and 16 in the base portion of the socket 4 and a wire 18 connected to the "neutral" terminal of the electrical source.

The contacts 8,14 and 16 and lower portion 20 ofthe spring 6areso positioned in the baseofthesocket4to form two switches 17 and 19 side by side, each having two electrical contacts, in a double pole interruptor circuit.

In particular, the "lamp" switch 17 (see Figure 1) comprises the lower portion 20 of the spring 6 and the contact8 positionedtherebelow, and the "mains" switch 19 (see Figure 4) comprises the contact 16 and the contact 14 positioned therebelow. The switches 17 and 19 are positioned side by side in the base ofthe socket 4 and are separated from each other by an insulating wall 21.

The lower portion 20 ofthe spring 6 and the contact 16 are biassed away from the contacts 8 and 14 respectively such that when the switches 17 and 19 are The drawing(s) originally filed was (were) informal and the print here reproduced is taken from a later filed formal copy.

The claims were filed later than the filing date within the period prescribed by Rule 25(1) of the Patent Rules 1982.

open (see Figure 4), the contacts are isolated from each other. To close the switches (see Figure 1) and complete the circuit, switch means in the form of a plunger 22 is provided which on actuation pushes down both the spring 6 and contact 16 into simul taneous engagementwith the contacts 8 and 14 respectively. Current is fed to the element only when both pairs of contacts are closed.

In thefitting shown in Figures 1 to 4, the plunger is actuated by the lower edge 23 of the lamp 7, as the lamp is forced down into position by a person placing the lamp into the sockets 4, from the switch "open" position shown in Figure 4to the switch "close" position shown in Figure 1.

In the fitting shown in Figures 5 and 6, the plunger 22 is actuated by the cam surface 24, provided on an interior ridge 25 of an end cap 26, which acts on a corresponding cam surface 28, provided on the upper end ofthe plunger, as the end cap 26 is slid over the holder9 (see arrow C). The switch mechanism and arrangementforthefitting shown in Figures 5 and 6 is identical to that ofthefitting shown in Figures 1 to 4 apartfromthe means to actuatethe plunger.

The arrangement in both embodiments disclosed is such that before any end of the tube/bulb 7 is exposed, the contacts of each switch 17 and 19 disengage from each other and completely interruptthe double pole ci rcuit thus isolating both ends of the tube/bolt 7 from the electrical source. Clearly, such an arrangement provides safety and protection for a user of the fitting when a tube/bulb is being replaced as the electrical source is isolated from the user's hand.

In the drawings and description, only one socket4 at one end of the fittings is shown and described in detail having the pair of switches and plunger arrangement.

However, if necessary each socket 4 at both ends of the fittings may be provided with the pair of switches and plungerarrangementforadded safety and protection forthe user. A circuit diagram for such an arrangement is shown in Figure 7.

The sockets4 have a number of openings 28, 30 provided on the lamp side of each of the sockets 4, through which wire connections 10 and 12 respective ly pass (see Figure 2). An opening 32 is provided in the socket 4a for the wire connection 18which is connected to the "neutral" terminal ofthe electrical source, while an opening 34 is provided in the socket 4bforthe wire connection 10 or36 (see Figure 7) which is connected to the "live" terminal of the electrical source.

The contacts 8, 14 and 16 all have inturned terminal ends which act to "grab" and hold the wire connec tions securelywhen these are merely pushed through the respective openings.

The particularwiring used inthefittings described is simple as the electrical source connections are made atthe ends ofthefitting and the inter-socketconnec tions are made on the lamp side of the sockets.

Claims (11)

1. Afitting for a double-ended electric light tube or bulb comprising a pair of holders one for each end of the tube or bulb, a pairofswitchesforat least one of the holders, each switch having two electrical contacts which form part of a double pole circuit which is arranged so that in use current can be supplied to both ends of a tube or bulb in the fitting, and a switch operating means which when engaged brings into contact with each other the two contacts of each switch to complete the circuit, the switch means being biassed to a switch "open" position so that when the endofthetube/bulb is removed from the holder,the switch is opened.

2. Afitting as claimed in Claim 1 wherein the switch operating means is deactivated before or as, any end ofthe lamptube or bulb is exposed,thetwo contacts of each switch disengaging from each other to completely interruptthe double pole circuit and thus isolate both ends of the tube or bulb.

3. AfittingasclaimedineitherClaim 1 or2 wherein the switch operating means is intheform of a plungerwhich is actuable to engage the two contacts of each switch simultaneously.

4. Afitting as claimed in any preceding claims wherein theswitch operating means is engaged by the end ofthetube or bulb as it is placed within the holder.

5. Afitting as claimed in any one of Claims 1 to 3 wherein the switch operating means is engaged by a removable end cap ofthe holder as it is moved over the end ofthe tube or bulb to position said tube/bulb in the fitting.

6. Afitting as claimed in any preceding claim wherein the pair of switches are arranged side by side in the holder, the two contacts of each switch being placed one abovethe other.

7. Afitting as claimed in Claim 6wherein the pair of switches are insulated from one another.

8. Afitting as claimed in any preceding claim wherein one or more ofthe electrical contacts have inturned terminal ends which act to "grab" and hold wire connections.

9. Afitting as claimed in any preceding claim having two end contactsforengagementwith the ends ofthe lamp tube or bulb, one contact being wired to one switch and the other end contact being wired to the other switch.

10. Afitting as claimed in Claim 9 wherein the end contacts, are in the form of small coil or S-shaped springs such thatthe tube or bulb is resiliently held in place by the spring whilst atthe sametime, maintaining a good contact therewith.

11. Afitting substantially as described herein with reference to Figures 1 to 4,5 and 6, and 7 of the accompanying drawings.