GB2480601A

GB2480601A - Electrical plug with retractable pins

Info

Publication number: GB2480601A
Application number: GB1008353A
Authority: GB
Inventors: Nigel Philip Valentine Fitzhugh
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-05-19
Filing date: 2010-05-19
Publication date: 2011-11-30
Also published as: GB201008353D0

Abstract

An electrical plug includes a plug housing 1 with a pair of contact pins 4, 5 and an earth pin 16 which project from the plug housing 1 in an operative condition of the plug. The pins 4, 5, 16 can all be retracted into a recess 11 to place the plug in a stowed condition. A component housing 30 is pivotally connected to the plug housing 1 via a rotatable hinge connection 31 which incorporates electrical connections joining the contact pins 4, 5 to electrical components within the component housing 30. In a separate embodiment, the contact pins 4, 5 are mechanically interconnected by a U-shaped bridging piece 6 such that they move together on a common plane. A free end of the earth pin 16 is received within the bridging piece 6 in the stowed condition and the bridging piece 16 has a cross-web which causes the earth pin 16 to be ejected from the recess 11 when the contact pins 4, 5 are moved towards an operative position. One part of the rotatable hinge connection 31 may be provided with a spigot which is rotatably received in a socket formed in a second part of the hinge connection 31, and an electrically conductive element (e.g. metal pin) passes through the spigot.

Description

ELECTRICAL PLUGS WITH RETRACTABLE PINS

TECHNICAL FIELD OF THE INVENTION

This invention relates to electrical plugs of the kind having retractable pins which project from a housing for insertion into an electrical socket.

BACKGROUND

Electrical plugs in which the pins can be retracted by pivoting or folding have previously been proposed. GB 2 458 318 A discloses an electrical plug in which a pair of contact pins and an earth pin can all be rotated into a recess to place the plug in a stowed condition. The contact pins are mechanically interconnected such that they move together on a common plane. The plug is provided with a hinged flap which, in an operative condition of the plug, engages the contact pins and the earth pin to prevent them from rotating into the recess. The flap also covers the pins in the stowed condition. Such an arrangement provides an extremely compact, simple and reliable way of holding the pins in both conditions. However, additional areas have been identified in which this earlier proposal can be improved still further.

The arrangement disclosed in GB 2 458 318 A enables the housing to be extremely thin, which is a great advantage in the case of items which are carried on the person or which are designed to fit into a storage compartment for example.

However, the overall size of the housing is limited by the need to fit into a wall socket without obstruction, and in conventional plugs this requirement usually results in items such as transformers being located in a separate package which is connected to the plug via a trailing lead. This is considered to be inconvenient, unsightly and potentially dangerous since trailing leads and power supplies can present a potential tripping hazard.

A second area addressed by the present invention also relates to safety considerations. In some circumstances the contact pins could be inserted into an electrical socket while the earth pin is still retracted, so that the equipment supplied by the plug could become live without being earthed.

The present invention seeks to provide a new and inventive form of electrical plug with retractable pins which addresses the above-identified issues.

SUMMARY OF THE INVENTION

The present invention firstly proposes an electrical plug comprising a plug housing, a pair of contact pins and an earth pin which project from a front face of the plug housing in an operative condition of the plug and which can all be retracted into a recess to place the plug in a stowed condition, in which the plug is provided with a component housing which is pivotally connected to the plug housing via a rotatable hinge connection which incorporates electrical connections joining the contact pins to electrical components within the component housing.

One part of the rotatable hinge connection is preferably provided with a spigot which is rotatably received in a socket formed in a second part of the rotatable hinge connection, and an electrically conductive element passes through the spigot.

The contact pins, the earth pin and the component housing are preferably rotatable about substantially parallel axes. Preferably the plug housing and the component housing are of substantially the same thickness and the hinge connection allows the two housings to lie substantially co-planar.

The invention also provides an electrical plug comprising a housing having front and rear faces, a pair of contact pins and an earth pin which project from the front face of the housing in an operative condition of the plug and which can all be rotated into a recess at the front face of the housing to place the plug in a stowed condition, in which the contact pins are mechanically interconnected by a generally U-shaped bridging piece such that they move together on a common plane, a free end of the earth pin is received within the U-shaped bridging piece in the stowed condition, and the U-shaped bridging piece is provided with a cross-web which causes the earth pin to be ejected from the recess when the contact pins are moved towards the operative position.

One of the bridging piece and the housing is preferably provided with a spigot which is rotatably received in a socket formed in the other part, and an electrically conductive element passes through the spigot.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice.

In the drawings: FiQure 1 is a general view of a mobile phone charger in accordance with the invention as viewed from its front face; FiQure 2 is a further general view of the charger as viewed from its rear face; FiQure 3 is a further general view of the charger, shown in a normal operative condition; FiQure 4 is a cross-sectional view of a part of a rotational connection as used in the charger; Ficiure 5 is a general view of the rotational connection, shown in a separated condition; Ficiure 6 is a general view of the pins of the charger shown in a stowed condition; Ficiure 7 is a general view of the pins in the process of being moved into the operative condition; and Ficiure 8 is another general view of the pins shown from the opposite side to Fig. 7.

DETAILED DESCRIPTION OF THE DRAWINGS

It will be appreciated that although the following description refers particularly to a mobile phone charger the invention is potentially applicable to mains adapters and other devices for operating portable electronic equipment such as laptop computers.

Referring firstly to Fig. 1, the mobile phone charger comprises a plug housing 1 and a component housing 30 for containing the electronic components of an AC to DC adapter.

The plug housing 1 is of planar form, being very thin with relatively close spacing between its front and rear faces 2 and 3.

The plug housing is provided with a pair of metal contact pins 4 and 5 joined by an insulating bridging piece 6. The bridging piece is mounted in a recess 11 to rotate about a first axis A. In their operative position, as shown, the contact pins 4 and 5 both project substantially perpendicularly from the front face 2, but rotation of the bridging piece 6 allows the contact pins 4 and 5 to rotate into stowed position in which they lie fully within the recess 11. As can be seen in Fig. 2, the recess 11 also opens at the rear face 3 so that when the contact pins are in the operative position the bridging piece 6 projects beyond the rear face of the housing 1 and provides a convenient lever for manually rotating the contact pins.

Continuing to refer to Fig.s 1 and 2, an earth pin 16 is mounted at the opposite end of the recess 11 from the bridging piece 6.

The earth pin is longer than the pins 4 and 5 and also rotatably mounted in the recess 11 SO that the earth pin can rotate about a second axis B which is parallel to the first axis A. In the operative position, as shown, the earth pin 16 projects perpendicularly from the front face 2, but the earth pin can be rotated and stowed within the recess 11 between the contact pins 4 and 5.

When the contact pins 4 and 5 are stowed within the recess 11 the pins 4 and 5 are slightly recessed below the front face 2, and when the earth pin 16 is in the stowed position it too is recessed below the front face 2, lying flush with the pins 4 and 5. A retaining flap 23 is pivotally hinged to one side of the housing 1 to pivot about a third axis C which extends perpendicular to the axes A and B. The flap 23 may be received in shallow recesses on opposite sides of the recess 11 to lie flush with the front face 2. When the pins 4, 5 and 16 are in their stowed positions the flap 23 extends across the pins to hold them in the recess 11. In order to reconfigure the plug to its operative condition, as shown, the flap 23 is pivoted away from the front face 2 allowing the pins 4, 5 and 16 to be rotated out of the recess 11. When the pins project perpendicularly from the front face 2 the flap 23 can be re-seated in the recess. In this condition the opposite side edges of the flap abut the earth pin 16 and the bridging piece 6, thereby locking the pins in the projecting position.

The area of the plug housing 1 is similar to that of a conventional electrical plug, but being exceptionally thin, the internal volume of the plug housing is even less than in a conventional plug. The transformer and other main power supply components of the charger are housed within the component housing 30, which is joined to an edge of the plug housing 1 via a hinge connection 31, preferably at the bottom edge nearest the contact pins 4 and 5, to pivot about a fourth axis D which extends parallel to the axes A and B. The component housing 30 is preferably, but not necessarily, substantially planar, and of the same width and thickness as the plug housing 1. Thus, the two housings 1 and 30 can be arranged to lie substantially co-planar, e.g. during storage, but when the plug housing is inserted into an electrical socket the component housing can be pivoted to extend angularly away from the socket as shown in Fig. 3.

A mobile phone may be charged by plugging it into a conventional charger socket 32 which is mounted in the bottom edge of the component housing 30 farthest from the plug housing 1. Electrical power passes from the contact pins 4 and through the bridging piece 6 and internal connections within the plug housing, travelling via the hinge connection 31 to the power supply components within the housing 30. Fig.s 4 and 5 show one way in which the electrical connections can be arranged to pass unobtrusively and safely through the pivotal connections of the bridging piece 6 and the hinge connection 31 without exposing the electrical connections. One part 40 of the pivotal connection is provided with a cylindrical spigot 41 which is rotatably received in a corresponding recess 42 in the other part 43 of the pivotal connection. The electrical connection is made via a conducting metal pin 44 which passes axially through both the spigot 41 and the recess 42. With such an arrangement, a good electrical connection can be made without risk of unintended contact, e.g by sliding a knife blade between the two parts.

With the present plug, movement of the contact pins 4 and 5 into the operative position automatically causes ejection of the earth pin 16 by an amount which is sufficient to prevent insertion of the contact pins into engagement with the live parts of the socket. As shown in Fig.s 6 to 8, this is achieved by a bridging piece 6 which is generally U-shaped, incorporating a cross-member 7 and a pair of arms 8 and 9 from which the contact pins 4 and 5 project in a substantially parallel relationship. It will also be noted that the conducting metal pins 44 are shown projecting from the contact pins 4 and 5. In the stowed position, shown in Fig. 6, the free end of the earth pin 16 is received between the arms 8 and 9 overlying a web 10 which integrally spans the arms 8 and 9. When the pins 4 and 5 are rotated into the operative position, shown in Fig.s 7 and 8, the web 10 acts to lift the earth pin 16 sO that it now projects angularly above the front face 2 of the housing (not shown). In order to insert the plug into a socket the earth pin must be manually rotated into the perpendicular position, accompanied by closure of the flap 23 to lock the pins in position.

Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.

* * * * * * * *

Claims

CLAIMS1. An electrical plug comprising a plug housing, a pair of contact pins and an earth pin which project from a front face of the plug housing in an operative condition of the plug and which can all be retracted into a recess to place the plug in a stowed condition, in which the plug is provided with a component housing which is pivotally connected to the plug housing via a rotatable hinge connection which incorporates electrical connections joining the contact pins to electrical components within the component housing.
2. An electrical plug according to Claim 1 in which one part of the rotatable hinge connection is provided with a spigot which is rotatably received in a socket formed in a second part of the rotatable hinge connection, and an electrically conductive element passes through the spigot.
3. An electrical plug according to Claim 1 or 2 in which the contact pins, the earth pin and the component housing are rotatable about substantially parallel axes.
4. An electrical plug according to any preceding claim in which the plug housing and the component housing are of substantially the same thickness and the hinge connection allows the two housings to lie substantially co-planar.
5. An electrical plug comprising a housing having front and rear faces, a pair of contact pins and an earth pin which project from the front face of the housing in an operative condition of the plug and which can all be rotated into a recess at the front face of the housing to place the plug in a stowed condition, in which the contact pins are mechanically interconnected by a generally U-shaped bridging piece such that they move together on a common plane, a free end of the earth pin is received within the U-shaped bridging piece in the stowed condition, and the U-shaped bridging piece is provided with a cross-web which causes the earth pin to be ejected from the recess when the contact pins are moved towards the operative position.
6. An electrical plug according to Claim 5 in which one of the bridging piece and the housing is provided with a spigot which is rotatably received in a socket formed in the other part, and an electrically conductive element passes through the spigot.
7. An electrical plug according to Claim 5 or 6 in which the plug is provided with a retaining member which is manually rotatable about an axis which is substantially perpendicular to the rotational axes of the pins such that, in said operative condition, the retaining member engages the contact pins and the earth pin to prevent them from rotating towards the recess.
8. An electrical plug according to Claim 7 in which, in the operative condition, the retaining member is disposed between the contact pins and the earth pin, and in the stowed condition, the retaining member overlies the contact pins and the earth pins.
9. An electrical plug which is substantially as described with reference to the drawings.* * * * * * * *