GB2145577A - Lampholder having internally mounted diode - Google Patents

Abstract

A lampholder includes an internally mounted diode 11 of which one of the connecting wires 12 serves as an external terminal of the lampholder and the other 10 forms a contact 6 for direct engagement with the lamp 7. One end of a length of wire similar to the connecting wires 10, 12 of the diode serves as the second external terminal 15 of the lampholder and the other forms the second contact (6) for engagement with the lamp 7. The body 1 is formed as a moulding encapsulating the diode 10. Alternatively the diode may be removably held in position in a cavity in a previously moulded body closed by a cap. The lampholder body may be formed with a polarizing peg (18, Fig. 1 not shown). <IMAGE>

Description

SPECIFICATION Lampholder This invention relates to multiplexing circuits and is particularly concerned with lamps for use in such circuits.

Multiplexing is used in lighting circuits when relatively large numbers of small lamps are utilized.

Such lamps are typically rated at six ortwelve volts so thatthere is a need for a power supply to convert the normal domestic inputto the required voltage and for large numbers of lamps the power supply unit has to be large, leading to considerable expense, bulkand heat dissipation. Large numbers of lamps also require extensive cable runs. Such a situation arises in gaming or amusement machines and is described in moredetail in ourcopending application no. 8314986.

Multiplexing involvesthesimultaneoustransmis- sion of several signals along a single path without any lossofidentityofan individual signal. In orderto prevent the misdirection of currents in the multiplexing network, it is necessary to insert a diode in a series circuitwith each lamp so asto allow the current necessaryto give sufficient illumination to travel in a single direction onlythrough the lamp.

As a matter of convenience the diode may be attached to the holder of each individual lamp, being fitted either internally or externally, In either case expensive soldering operation is involved. Forexample, a lampholder according to Registered Design No.

991,791 may be modified bythe inclusion of an additional terminal and soldering the diode between thisterminal and one of the existing terminals.

According to the present invention an internally mounted diode is included in circuit without the need fora soldering operation by means of a construction in which one of the connecting wires ofthe diode serves as an external terminal of the lampholder and the otherforms a contact for direct engagement with the lamp. As a consequence, the circuit extends from the external terminal, directly through the diode to the lamp so that no joint at all is required and, moreover, the diode is held in position mechanically by engagementwith the interior ofthe lampholder.

The other external terminal of the lampholder may beformedfrom a length ofwiresimilartothe connecting wires of the diode, one end of this length of wire serving as the terminal and the other end forming the contactfor engagement with the lamp in the same way as the wire from the diode. If, for example, the lamp is ofthewedge base type, the ends of both wires may be flattened so as to form appropriately shaped contacts for engagement with those ofthe lamp. The other ends of the wires may serve as external terminals without any form of modification, but as they are then of similar appearance, a polarising peg may extend from the body ofthe lampholder so that an external connectorfitted to the lampholderwill be in the correct orientation.

The internal mounting of the diode within the body ofthe lampholder may be achieved either by enclosing the diodewithin the moulding tool and moulding the body round it so that the diode is encapsulated or, alternativelythe diode together with its connecting wires may be enclosed in a cavity in a previously moulded lampholder.

Examples of these two forms of construction will now be described with reference to the accompanying drawings, in which: Figure 1 is an elevation of a unitary form of construction of lampholder; Figure 2 is a plan view; Figure 3 is a sectional view on the line Ill-Ill in Figure 2; Figure 4 is a similar sectional view on the line IV-IV in Figure 2; Figure 5 is an underneath plan view illustrating the disposition of two terminals and a polarising peg; and, Figures 6to 10 are corresponding views of a similar construction moulded intwo pieces.

Referring first to the form of construction shown in Figures 1 to 5, the lampholder has a solid base portion 1 and an upper portion comprising a pair of arcuate shields 2 which enclose the lower portion of a wedge base lamp 7 (Fig. 3) and a pair of resilient hook-like portions 3for holding the lampholder in its mounting.

Within the space bounded by the arcuate shields 2 are rigid locating members for the base ofthe lamp, one opposed pairofthesemembers4being insulating and the other opposed pair 5 supporting flattened contacts 6for engagement with corresponding contacts on the base ofthe lamp.

As seen in Figure 3, one ofthe contacts 6 informed bytheflattened end of an upper connecting wire 10 extending upwardlyfrom a diode 11 which is moulded into the solid base 1. The other connecting wire 12 extends downwardly th rough the bottom of the base to form an external terminal. It will thus be seen that the circuit extends from the terminal 12 through the diode 11 to the contact 6 without any form ofjoint and thatthe diode 11 is held firmly within the moulding constituted bythe base 1 ofthe lampholder.

As seen from the sectional view of Figure 4, the other ofthe contacts 6 is formed by the flattened end of a length of wire 14 ofthe same thickness as the wires 10 and 12 and the lower end of which formsthe second terminal 15. The wire is cranked at 16 and is thus firmly embedded in the base 1 without risk of movement.

Sincethetwo terminals 12 and 15 are identical, the base 1 is formed with a polarising peg 18, the location of which is best seen from Figures, which co-operates with a female connectorfitted to the terminals 12 and 1 Sto ensurethatthe lampholder is correctly polarised.

The ends ofthewires 10 and 14 are flattened as a preliminary stage in the production ofthe lampholder and the diode 11 together with its connecting wires 10 and 12 and also the cranked wire 14 are inserted in the moulding tool priortothe moulding operation and the body ofthe lampholder is then moulded around these components so thatthey are encapsulated and thus held firmly in position. As a consequence, no electrical or mechanical connections are necessaryto holdthe components in position and once the moulding is complete, nothing more is required.

Asimilar result may be achieved by moulding the base ofthe lampholder in two separate parts and then securing these together as illustrated in Figures 6 to 10. Apart from the base itself, all the other compo nents are identical with those already described and illustrated and these are therefore indicated by the same reference numerals and are not further described. In this alternative construction the main part ofthe base is shown at21 and it will be seen, particularlyfrom the sectional view of Figure 8 that it stops short at the bottom ofthe diode 11. The diode 11 and its connecting wire 10 are a close sliding fit in the base portion 21 and are slid into position afterthe lampholderasawhole has been moulded.Similarly, the wire 14 is also fitted in position after moulding, being situation in a space 23 in the part 21. The cranked portion 16 is located rather nearerthe lower end ofthewire and engages the shoulder 24 atthe lower end of the space 23 so as to provide a location forthewire 14.

The second part ofthe base is in the form of a cap 22 which fits overthe lower end ofthe part 21 and, as seen in Figures 8 and 9, provides a positive location both forthe diode 11 and its associated wires and for the wire 14, bearing againstthe cranked portion 16. As illustrated, the cap 22 fits over a slight bead 26 on the bottom edge ofthe portion 21 so as to form a snap fit.

This enablesthe cap 22to be removed if required,for exampleto replacethediode 11. In many cases, removability is not required and the cap 22 may be held in position by adhesive. If so, the snap fit provided by the bead 26 is not necessary.

Itwill be understood that the overall effect of the two alternative constructions is the same in that the circuit extends directly through the diode 11 from the terminal 12 to the contact6 so that no soldered joint is required and the diode 11 is held firmly in position by engagement with the interior ofthe base ofthe lampholder.

Claims (7)

1. Alampholderincluding an internally mounted diode ofwhich one ofthe connecting wires serves as an external terminal ofthe lampholder and the other forms a contact for direct engagement with the lamp.

2. A lampholder according to claim 1 including a length of wire similarto the connecting wires of the diode, one end ofwhich serves as the second external terminal ofthe lampholder and the otherforms the second contactforengagementwiththe lamp.

3. Alampholderaccordingtoclaim 1 orclaim 2 in which the body adjacent the external terminals includes a projecting polarising peg.

4. A lampholderaccording to any one ofthe preceding claims in which the body informed as a moulding encapsulating the diode.

5. A lampholder according to any one of claims 1 to 3 in which the diode is removably held in position in a cavity in a previously moulded body.

6. A lampholder according to claim 5, in which the cavity containing the diode is closed by a cap.

7. A lampholder according to claim 1, in which the diode is mounted as described, and as illustrated with reference to the accompanying drawings.