GB2033677A

GB2033677A - Switched electrical connector

Info

Publication number: GB2033677A
Application number: GB7933481A
Authority: GB
Original assignee: Langer J B
Current assignee: Langer J B
Priority date: 1978-10-11
Filing date: 1979-09-27
Publication date: 1980-05-21
Also published as: GB2033677B

Abstract

A switched connector, preferably a b.c. lampholder, has an input contact 18 and an output contact 14 for each pole. Each output contact 14 is biased outwardly by a spring 30 which also biases a common cam follower 28 against a cam surface 24 on a common actuating member 20. The input and output contacts are bridgeable by a rod 26 of a length such that the bridging connection can only be established when the output contacts are retracted, e.g. by the presence of a bulb. The connector automatically switches "off" if the output contacts extend. <IMAGE>

Description

SPECIFICATION Switched electrical connector This invention relates to switched electrical connectors, and is particularly, but not exclusively, of use with switched lampholders as used in table lamps and the like.

In known lampholders, the switch has fixed "on" and "off' positions. In the "on" position voltage is applied to one of the terminals intended for contact with a lamp, whether a lamp is present or not. There is thus a danger of a person receiving a shock if the fingers are inserted into the lampholder when no lamp is present. This danger is all the more present because there is a tendency when a lamp fails to remove it from the lampholder without switching off the supply.

An object of the present invention is therefore to provide a switched electrical connector which receives a lamp or other item of electrical equipment and in which the switch assumes an "off' condition when the lamp or other item is removed.

The invention accordingly provides a switched electrical connector having one or more poles comprising an input contact, an output contact movable along an axis and biased outwardly of the connector, the input contact and output contact being spaced from each other substantially in the direction of said axis, a switch actuating member, and a bridge member movable transversely to said axis by the switch actuating member, the bridge member being arranged such that if (and only if) the output contact is in its depressed condition the transverse movement of the bridge member brings it into and out of a position bridging the input and output contacts.

Preferably the bridge member is pivotally mounted on one or other of the contacts and is of a length greater than the spacing between the contacts when the output contact is depressed and less than such spacing when the output contact is extended.

Preferably also, the output contact is biased by a spring which also forms part of an over-centre mechanism interconnecting the actuating member and the bridge member.

In a preferred form, the connector is a lampholder with two poles, and a common actuating member is arranged to move the bridge members of both poles.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional front view of a lampholder forming one embodiment of the invention; Figure 2 is a side view corresponding to Figure 1 with the lampholder in an "on" condition; Figure 3 is a similar side view but showing the lampholder in an "off" condition; Figure 4 is another side view showing the effect on the lampholder of removing the lamp; Figures 5a to 5e schematically illustrate the operation of the above embodiment; and Figures 6a and 6b schematically illustrate an alternative embodiment.

Referring first to Figures 1 and 2, the lampholder comprises a body 10 which may be of moulded plastics construction. A transverse partition 12 has bores in which are slidably received contact members 14 supplying current to the terminals of a lamp 16. It should be noted that Figures 1 to 3 show the condition of the lampholder with the lamp in place, but the lamp 16 is omitted from Figures 2 and 3 for simplicity. Each of the contact members 14 has an associated plate-shaped input contact 18; these may be electrically connected to conventional pillar-type terminals (not shown) in the upper part of the lampholder for connection to supply wires.

A switch actuating member 20 is slidably mounted in the body 10 for movement at right angles to the sliding axis of the contact members 14. Movement of the actuating member 20 is delimited by lugs 22 thereon. The actuating member 20 is formed on its underside with a V-shaped cam surface 24.

Each of the contact members 14 can be connected to and disconnected from its associated input contact 18 by a bridging member in the form of a rod 26, as will become apparent below. The rods 26 pass through respective bores in a cylindrical cam follower 28. The rods are encircled by and act as guides for compression springs 30 which serve the dual function of urging the cam follower 28 against the cam surface 24 and of biasing the contact members 14 outwardly of the body 10. In Figures 1 to 3, the contact members 14 are held against the force of the springs 30 bythe lamp 16; in Figure 4, the lamp being removed, outward movement of the contact members 14 is limited by lips 14a at the upper ends thereof.

As seen in Figures 1 to 4, the contact members 14 are suitably of hollow cup shape and hold metal slugs 32 of lesser length to form a pocket in which the rods 26 and springs 30 are received. This is a simple and convenient manner of providing a pivotal mounting for the rods on the contact members.

In the "on" condition as seen in Figure 2, the rods 26 are held against the input contacts 18 by the leftward cam force arising from the force of the springs 30 urging the cam follower 28 against the left-hand flank of the cam surface 24. To switch off, the actuating member 20 is moved in the direction indicated.

As the cam follower 28 reaches the apex of the "V", the rods 26 move in a snap-action, over-centre manner to the position shown in Figure 3, where further movement in the "off" direction is prevented by an abutment (not shown) on the body 10, thus breaking the electrical path to the contact members 14. The lamp can again be switched "on" by reversing this movement.

Considering now the case where the lampholder has a lamp in position and is "on" as seen in Figure 2 and then the lamp is removed, the contact members 14 move downwardly under the action of the springs 30 and this movement brings the tops of the rods 26 below the lower edges of the input contacts 18; at The drawing(s) originally filed were informal and the print here reproduced is taken from a later filed formal copy.

this moment the camming force urges the rods 26 into an "off" position on the opposite side of the input contacts 18. This condition is seen in Figure 4.

In this condition, operation of the actuating member 20 will result only in movement of the bridging rods 26 between alternate "off" positions on either side. If the lampholder is in an "off' condition when the lamp is removed, the same effect is achieved without any initial sideways movement of the rods 26.

It will thus be understood that after removing and replacing a lamp the lampholder is always "off" and a switching movement will be required to restore output current.

Figure 5 summarises this mode of operation. With a lamp in position switching occurs between "off" (Figure 5a) and "on" (Figure 5b) to the right of the input contact 18. On removal of the lamp (Figure 5c) the rod 26 may move without contacting the contact 18. If the lamp is reinserted with the rod 26 to the left, then switching may proceed between "off" and "on" positions to the left of the contact 18 (Figures 5d and 5e respectively).

Modifications of the above embodiment are of course possible within the scope of the present invention. For example, as seen in Figure 6, a bridging rod 26' may be pivoted on the input contact 18, the axially movable contact 14 being provided with a plate-shaped contact 14' for contact therewith. The remainder of such an embodiment would be as described above and the operation similar, as will be readily understood. It is also possible in principle for the bridging member to move bodily in a direction at right angles to the axis of movement of the output contact rather than being pivoted, but such an arrangement would be rather complex to manufacture and is therefore not preferred.

Although described with reference to a lampholder, the invention may also be applied to other electrical connecting devices, for example a switched socket-outlet adaptor.

Claims

1. A switched electrical connector having one or more poles comprising an input contact, an output contact movable along an axis and biased outwardly of the connector, the input contact and output contact being spaced from each other substantially in the direction of said axis, a switch actuating member, and a bridge member movable transversely to said axis by the switch actuating member, the bridge member being arranged such that if (and only if) the output contact is in its depressed condition the transverse movement of the bridge member brings it into and out of a position bridging the input and output contacts.

2. A connector according to claim 1, in which the bridge member is pivotally mounted on one of the contacts and is of a length greater than the spacing between the contacts when the output contact is depressed and less than such spacing when the output contact is extended;

3. A connector according to claim t or claim 2, in which the output contact is biased by.a spring which also forms part of an over-centre mechanism interconnecting the actuating member and the bridge member.

4. A connector as claimed in any preceding claim, being a lampholder.

5. A lampholder according to claim 4, in which there are two switched poles, a common actuating member being arranged to move the bridge members of both poles.

6. A lampholder according to claim 5, in which the output contacts are pins for engagement with a bayonet cap bulb, the inner ends of said pins being dished to act as pivotal mountings for the respective bridge members.

7. A lampholder according to claim 5 or ctaim 6, in which the bridge members are metal rods.

8. A lampholder according to claim 7, in which each rod is enveloped by a respective coil compression spring trapped between the actuating member and the respective output contact.

9. A switched lampholder substantially as herein described with reference to the accompanying drawings.