GB2168860A

GB2168860A - Lampholder

Info

Publication number: GB2168860A
Application number: GB08530567A
Authority: GB
Inventors: David Partridge
Original assignee: Starpoint Electrics Ltd
Current assignee: Starpoint Electrics Ltd
Priority date: 1984-12-20
Filing date: 1985-12-12
Publication date: 1986-06-25
Also published as: GB8432238D0; GB8530567D0

Abstract

The external terminals of a lampholder are each constituted by a twin-jaw insulation displacement connector 3, 4 each arranged with its jaws in a line at opposite sides of base 1 which has walls shaped to define entrance slots 20 to the jaws. A cover 30, which may be integrally hinged to the base 1, is formed with projections 40 co-operating with the jaws 3, 4 of the connectors to force a conductor into the jaws when the cover is fitted in position where it is held by latches 34, 35, 36. A diode 13 is connected between the terminal 4 and one of the lamp contacts by means of insulation displacement connectors 11, 12 gripping the wires of the diode. <IMAGE>

Description

SPECIFICATION Lampholder This invention relates to lampholders, particularly those for use with wedge-based lamps, for exam ply in amusement machines and automotive circuits. Amusement machines in particular include relatively large numbers of such lamps which have to be connected in circuit, usually in a multiplexing arrangement which involves the inclusion of a diode in series circuit with each lamp. In order to avoid the need for a soldered connection at each terminal of the lampholder, separate connectors may be used, but when relatively large numbers of lampholders are involved, this adds materially to the overall cost.The situation is aggravated if a series of lampholders needs to be connected together by a loop of wire between each pair of lampholders in an amusement machine (commonly known as "daisy-chaining") since this involves two connections to each terminal of each lampholder.

According to the present invention, the two terminals of a lampholder are each constituted by a twin-jaw insulation displacement connector arranged with its jaws in line with one another at opposite sides of the base so that a conductor to be connected may be laid across the base and forced into the metal jaws of the connector.

In making a connection to such a lamp holder, or, more generally, making two such connections simultaneously, the cables merely need to be held in alignment with the jaws of the connector and then, when in position, forced fully into the jaws.

In order to hold the cables in alignment with the jaws of the connectors, the base of the lampholder preferably has walls which are so shaped in the vicinity of the jaws of the connectors as to define entrance slots to the jaws, opposite sides of which are formed with projections defining a restricted entrance to the slot. The width of this entrance is selected so that the insulation of the cable cannot pass freely through it, and the first stage in the operation is for the insulated cables to be forced past the projections so as to rest on the jaws of the connectors. The second stage consists of forcing the cables fully home into the jaws which will cut the insulation (displace it) and effect an electrical connection with the conductor.

In many cases, the frictional grip of the jaws will be sufficient to hold each conductor in position, particularly if the lampholder is already installed in position before the connections are made. In some cases, however, connections may be made to a relatively large number of lampholders before installation, e.g. to produce a "daisy-chain" of lampholders and this sub-assembly may be handled on various occasions prior to installation so that there may be a risk of the conductors being pulled from the connectors.

To overcome this risk, each connector may include means for retaining a conductor within its jaws, so as to supplement the normal frictional grip. The retaining means may be provided by appropriate shaping of the jaws, so as to constitute a form of non-return action when a conductor is inserted, but preferably a cover is provided which is removably fitted over the base of the lampholder.

This cover extends over the entrance to the jaws of the connectors and positively holds each conductor in position.

When forcing conductors into the jaws of the connectors, it is convenient to use a specially-designed tool which engages the conductors in the region of each jaw and is, for example, pneumatically operated so as to force each conductor into position. When using a cover to hold the conduc- tors in position, this cover is preferably formed with projections co-operating with the jaws of the connectors, so as to take the place of the tool just mentioned. In other words, it is then only necessary to hold the conductors in alignment with the jaws of the connectors and to press the cover into its operative position.As the projections on the cover enter the jaws of the connectors, they force the conductors into the jaws, thus making the connections to the conductors in the normal way, and when the operative position is reached, then serving to hold the conductors firmly in position.

Although a tight frictional fit may be sufficient to hold the cover in position, a latch or latches are preferably included for this purpose. These latches may be on the cover itself, and may snap into engagement with corresponding surfaces on the lampholder when the cover reaches its operative position. The latches may conveniently operate in two stages, the first stage holding the cover in a preliminary position with the conductors in alignment with the jaws of the connectors as already described, and the second stage holding the cover in its fully operative position.

For any particular lampholder, the cover may be regarded as optional in that it may not be required if the electrical connections are made after the lampholder has been installed in position and there is no subsequent risk of the connections becoming loose. Under these circumstances, covers may be supplied separately from the lampholders so that they can be fitted as and when required.

On the other hand, if the connections are made in advance and may be subjected to handling before installation, a cover may be regarded as essential.

Under these circumstances, it is convenient for each lampholder to have its cover integrally hinged to the main body of the lampholder so that it is automatically available when required and there is no risk of its subsequently becoming lost.

As so far described, a lampholder in accordance with the invention can be used in any circumstances where the ease and certainty of the connection-making is of advantage. As mentioned originally, a typical use for such lampholders is in automative circuits, but its use in an amusement machine is even more advantageous since such large numbers of lampholders are involved. When the lampholders are connected in a multiplexing arrangement, it is advantageous for the associated diode to be included within the body of the lampholder. The diode needs to be connected between one of the terminals and one of the lamp contacts and this is preferably achieved by means of respective insulation displacement connectors gripping the wires of the diode. The other lamp contact is connected directly to the second external terminal.The diode is inserted in position during the manufacture of the lampholder and since it merely has to be thrust into position with its wires in register with the jaws of the two connectors, the operation can very simply be automated and, owing to the lack of any need for very accurate registration, the components can be bandolier- mounted, leading to an extremely simple operation.

An example of a lampholder in accordance with the invention will now be described with reference to the accompanying drawing, which is a perspective view, partly sectioned to illustrate the connectors more clearly, showing the base of the lampholder facing upwardly with a hinged cover in an open or inoperative position.

The main body of the lampholder is shown at 1 with the lamp-receiving socket facing downwardly at 2. The lamp contacts are not illustrated, but one is connected directly to an external terminal constituted by an insulation displacement connector (commonly referred to as an IDC), which is indicated generally as 3 and has a pair of spaced metal jaws, while the other contact is connected to one jaw 11 of an internally-mounted IDC, of which the other jaw is shown as 12, a diode 13 being mounted directly between these two jaws. The jaw 12 is connected to the second output terminal shown generally as 4 which is also constituted by an IDC and has a pair of spaced jaws, effectively identical to those of the connector 3. The diode 13 is thus connected in series between one of the lamp contacts and the external terminal 4.

The jaws of the IDCs 3 and 4 lie immediately within the outer wall of the housing 1, which is formed with a slot 20 in register with each of the jaws. Each slot 20 is formed with a restricted entrance defined by a pair of projections 21, the spacing between which is slightly less than the diameter of an insulated cable to be used with the connector. As a consequence, a length of cable extending between the pair of jaws of each connector is supported by the projections 21 in approximate register with the two jaws and with a minimum amount of pressure the cable can be forced past the projections 21 to align with the jaws ready for the connections to be made.

A cover for the lampholder is shown as 30 and may or may not be required according to the circumstances of use. If the lampholder is intended to be used with the cover 30, the latter can be hinged to the body 1 by an integral web or strap 31 which is shown in dotted lines to indicate its optionality.

The cover is of hollow construction, designed to fit over the body 1 and is formed within its hollow interior with a pair of projections indicated generally at 32 which, when the cover is fitted to the body 1, register with cables 33 which as already described, initially rest between the projections 21 at the mouth of each slot and the jaws of the connectors.

The cover 30 also has three protruding latches; two on opposite faces 34 and one at one end 35 which are for the first stage latching. Four further latches are provided within the hollow of the cover, two on opposite sides 36 and two at one end 37 for the second stage of latching when the connections are made.

When the cover 30 is fitted in position, e.g. by turning about the hinge constituted by the strap 31, the faces of the projections 32 engage the cables 33 and relatively slight pressure on the cover 30 latches it to the main body 1 into accurate register with the jaws of the connectors 3 and 4. The cover 30 is held in this preliminary position by engagement of the latches 34 and 35 with corresponding projections on the exterior of the body 1.

In this position, the operator can check that the conductors 33 are correctly positioned in readiness for the making of the final connection. For this purpose, rather more force must bye exerted on the cover 30 which may need some assistance of a mechanical advantage, for example a vice-like hand clamp. This causes the projections 32 to force the conductors 33 into the jaws of the connectors, the cover then being held in its operative position by engagement of the latches 36 and 37 with further projections on the body 1.

It will be seen that each projection 32 has a relatively broad central concave portion 40 which will engage the corresponding portion of the cable 33 even though this does not lie in a directly straight line between the jaws of the connectors. The ends of each projection, shown as 41, are also concave and form a more accurate fit with the cable in the slots 20 and are separated from the respective surface 40 by a relatively narrow neck 42 which, in operation, registers with the gap in the respective jaw of the connector. Accordingly, when pressure is applied to the cover 30 to move it to its operative position, pressure is exerted on each cable on opposite sides of each jaw by the surfaces 40 and 41 and as the conductor enters the jaw it is followed by the neck portion 42 which, in the final position, rests against the portion of cable actually held within the jaw.

If the cover 30 is not used, the operation just described is carried out by a pressure tool as described previously.

Claims

1. A lampholder having a pair of terminals for external connections each constituted by a twinjaw insulation displacement connector arranged with its jaws in line with one another at opposite sides of the base so that a conductor to be connected may be laid across the base and forced into the jaws of the connector.

2. A lampholder according to claim 1 in which the base has walls which are so shaped in the vicinity of the jaws of the connectors as to define entrance slots to the jaws, opposite sides of which are formed with projections defining a restricted entrance to the slot.

3. A lampholder according to claim 1 or claim 2, and including means for retaining a conductor within the jaws of the insulation displacement connectors.

4. A lampholder according to claim 3 in which the retaining means is in the form of a cover removably fitted over the base of the lampholder.

5. A lampholder according to claim 4, in which the cover is formed with projections co-operating with the jaws of the connectors to force a conductor into the jaws when the cover is fitted in position.

6. A lampholder according to claim 4 or claim 5, including a latch or latches for holding the cover in position on the base.

7. A lampholder according to claim 6, in which the latches operate in two stages, the first stage holding the cover in a preliminary position prior to forcing the conductors into the jaws of the connectors and the second stage holding the cover in its fully operative position.

8. A lampholder according to any one of claims 4 to 7 in which the cover is integrally hinged to the main body of the lampholder.

9. A lampholder according to any one of the preceding claims and including a diode connected between one of the terminals and one of the lamp contacts by means of insulation displacement connectors gripping the wires of the diode.

10. A lampholder substantially as described and as illustrated with reference to the accompanying drawing.