GB2501672A

GB2501672A - Two-part power plug

Info

Publication number: GB2501672A
Application number: GB1204404.6A
Authority: GB
Inventors: Myran Ausch
Original assignee: NETBIT ELECTRONICS Ltd
Current assignee: NETBIT ELECTRONICS Ltd
Priority date: 2012-03-13
Filing date: 2012-03-13
Publication date: 2013-11-06
Also published as: GB201204404D0

Abstract

A three-pin power plug 10 for connection to an electrical socket comprises: a first body-part 20 with two pins 1 (e.g. live pin and neutral pin); and a second body-part 30 with the third pin 2 (e.g. earth or ground pin). The second body-part 30 is configured to connect to the first body-part 20. The first or second body-part may comprise a transformer. The second body-part 30 may connect to the first body-part 20 by means of a protrusion 3 on one of the body-parts that slides into a complimentary-shaped recess 4 in the other body-part. The protrusion 3 and recess 4 may be T-shaped. The protrusion 3 and recess 4 may each include an electrical contact 6, one of which is electrically connected to the third pin, whereby the first and second body-parts 20, 30 are electrically connected when the first body-part 20 and the second body-parts 30 are physically connected. When the body-parts 20, 30 are disconnected, the plug 10 has the advantage that its reduced dimensions, relative to a standard plug, enable it to be packaged and posted by mail more cheaply and easily.

Description

Power Plug or Adaptor

Field of the invention

The present invention relates to a plug for connection to an electrical socket. In particular, it relates to a plug comprising three pins.

Background of the invention

It is common for power plugs to be posted by mail! especially with the increased purchase of products over the internet. It is useful if that posted product fits through the letterbox, saving the user from a trip to the post office.

To fit through most letterboxes, at least one dimension of the plug must be 30mm or less.

Conventional three-pinned plugs are unable to fit through a standard UK letterbox, since none of the dimensions is 30mm or less.

A conventional three-pin plug comprises two AC pins (that are connected to live and neutral wires) and a third pin that is connected to ground to protect against insulation failure of a connected device. The third pin is therefore an important component of the conventional plug. For safety, the ground pin is usually longer that the AC pins to ensure that an electrical device is earthed before power is able to flow through it. However, the arrangement of the three pins in a triangle, for example in the UK standard pin arrangement, and the longer length of the ground pin, provides a plug which is bulky and unable to fit through a 30mm slot, whichever way it is orientated.

There are a couple of available solutions to this problem. One solution has been to use a detachable part comprising the set of pins, a pin case'. The pin case is posted detached from the plug body. When received by the user, the user attaches the pin-case to the plug body to obtain a complete plug. A design for a plug with a detachable pin case is described in US patent application publication no. US 2012/0015543. A disadvantage of this design is its cost of manufacture. It is expensive to manufacture a detachable pin case and a separate plug body.

An alternative solution to reducing the dimensions of a plug is to provide a plug with a retractable ground pin, see fig. 1. In its retracted position, the ground pin is pushed in to toward the AC pins. In its extended position, the ground pin is pulled away from the AC pins to provide the standard three-pin triangular arrangement. A disadvantage of this type of plug is that it is not robust enough since the retractable pin can be easily damaged. Furthermore, such a retractable-pin may provide safety risks.

An object of the present invention is to overcome the above disadvantages, i.e. to provide a three-pinned plug which has reduced dimensions relative to a standard plug, whilst being cheap to manufacture and robust.

A further object is to provide such a power plug which has increased safety.

Summary of the invention

In accordance with the present invention there is provided a three-pin plug for connection to an electrical socket, the plug comprising: a first body-pad comprising two pins; a second body-pad comprising the third pin, wherein the second body-pad is configured to connect to the first body-part. A plug in accordance with the present invention is cheap to manufacture. It is also relatively robust, because there are no moving components in either body-part. By removing one of the pins from the main plug body, via the modular plug design, the plug width can be reduced to 30mm or less.

The second body-pad may be configured to connect detachably or non-detachably to the first body-pad. It may be beneficial to provide a non-detachable connection of the body-parts in instances where the supplier is concerned that continued attachment and reattachment of the first and second body-parts may cause malfunction, and also to prevent tampering by the user once the body-parts have been attached. However, detachable connection may be advantageous since it reduces the storage space of the plug when not in use.

In a preferred embodiment, the third pin is a ground pin. For safety, the ground pin may be longer than the two pins of the first body-part. In this embodiment, the longer length pin is detachable, enabling the depth of the plug to be reduced when the two parts are separated.

In one embodiment, the first or second body-part comprises an electrical lead extending therefrom for connection to an electrical device. The one of the first or second body-pad may fudher comprise a transformer. In a preferred embodiment, the one of the first or second body-part is the first body-part. Thus, the main plug body is associated with two pins, such that the second body-part is smaller than the first body-part, comprising the third pin only.

In a preferred embodiment of the invention, the second body-part connects to the first body-part by means of a protrusion on the first or second body-part that slides into a complimentarily-shaped recess on the second or first body-part. The protrusion and recess may be T-shaped. The plug preferably further comprises an electrical contact on each of the recess and protrusion, one of the contacts being electrically connected to the third pin, to electrically connect the first and second body-parts upon physical connection of the first and second body-parts. This provides an electrical connection between the two body-parts and, in particular, electrically connects the third pin to the first body part.

In one embodiment, the plug further comprises a snap-fit feature which engages when the first and second body-parts are connected together to prevent detachment of the body-parts. This snap-fit feature may be releasable to allow the body-parts to be disconnected. Alternatively, the snap-fit feature is not releasable, preventing disconnection of the body-parts.

In one embodiment, the first body-pad comprises a safety means which is configured such that, when the plug is connected to an electrical socket, electricity is prevented from flowing from the plug to an electrical device attached thereto, unless the second body-part is attached to the first body-pad. The safety means may comprise a switch which is configured to remain in an open state until the second body-part is attached to the first body-pad, thereby closing the switch and allowing electricity to flow when the plug is in use.

In the embodiment where the first and second body-parts are connected via a protrusion and corresponding recess, the safety means can be located between the protrusion and recess. In the embodiment where there are electrical contacts provided at the protrusion and recess, the switch can be configured to close when the electrical contacts are electrically connected. Alternatively, or in addition! a switch can be located at the snap-fit feature and is configured to close when the snap-fit feature is engaged.

Detailed description of the invention

The present invention will now be described in detail with reference to the accompanying drawings, in which: Fig. 1 shows a plug with a retractable ground pin, not forming part of the present invention; Fig. 2 shows a side-perspective view of a plug in accordance with a preferred embodiment of the present invention, with the first and second body-parts separated; Fig. 3 shows a perspective view of the plug of fig. 2 from above, wherein the first and second body-pads are connected; Fig. 4 shows a side view of the plug of fig. 2, wherein the first and second body-pads are connected; Fig. 5 shows a front view facing the pins of the plug of fig. 2, wherein the first and second body-pads are connected; Fig. 6 shows a perspective view of the plug of fig. 2, wherein the first and second body-parts are connected.

The power plug or adaptor of the present invention is preferably a power plug or adapter for a mobile phone. However, the invention is applicable to any power plug or adaptor. A specific embodiment will now be discussed with reference to figs. 2-6.

With reference to tig. 2, the plug 10 of the present invention comprises a first-body part 20 and a second body-part 30. The first body-part 20 comprises the main body 40 of the plug which houses a transformer and has an electrical lead 50 extending therefrom for connection to an electrical device.

The first body-part 20 comprises two AC pins 1 fixed to the body-part 20 and connected to live and neutral wires. The second body-part 30 comprises the ground pin 2, which for safety reasons is longer than the two AC pins 1.

The second body-pad 30 is connectable to the first body-pad 20 to provide a complete three-pinned plug 10 (as shown in figs. 3-6). When posted, the first body-pad 20 is sent separated from the second body-part 30, as shown in fig. 2. The user then assembles the plug by connecting the second body-pad 30 to the first body part 20.

The connection between the two body-parts 20, 30 may be achieved by a protrusion 3 and correspondingly shaped recess 4, as shown in figs. 2 and 5-6. In the connection illustrated, the protrusion 3 is T-shaped and formed on the second body-part 30. The T-shaped protrusion 3 is configured to slide into a corresponding T-shaped recess 4 in the first body-part 30.

To electrically connect the two body-parts 20, 30 together and, in particular, to electrically connect the ground pin 2 of the second body-pad 30. to ground an electrical device connected to the electric lead 50 extending from the first body-pad 20, electrical contacts 6 are provided on the mating surfaces of the recess 4 and protrusion 3. When the first and second body-parts 20, 30 are fully connected, the electrical contacts 6 meet and provide an electrical connection. Alternatively, if an electrical connection to ground is not required, a dummy ground pin 2 can be provided, where there is no electrical connection between the body-pads 20. 30, and thus no electrical connection between the third pin 2 and the first body-pad 20.

The plug 10 may also be provided with a snap-fit feature 5. The snap-fit feature is shown for the second body-pad 30 in fig. 2. The first-body pad 20 will have a corresponding shape to provide engagement. The snap-fit feature ensures that the first and second body-parts 20, 30 remain fully connected during use. Furthermore, it may be used to provide an indication, via an audible click, to the user that the connection of the body-parts 20, 30 is complete.

The snap-fit connection may be releasable to allow the user to disconnect the first and second body-parts 20, 30. Alternatively, the snap-fit feature is not releasable, preventing the user from disconnecting the body-parts 20, 30 once they have been connected.

By providing a modular plug 10 comprising the two AC pins 1 as part of the main body 40 of the plug 50 and a detachable ground pin 2 plug-part 30, there is the potential risk that a user may plug in the first plug-part 20 without the second plug-part comprising the ground-pin 2. To avoid such a risk, in a preferred embodiment, the plug 10 comprises a safety means (not shown) which prevents electricity flowing from a power socket through the plug to a connected electrical device, unless the first and second body-parts 20, 30 are fully connected. The safety means can be achieved in a variety of ways. For example, a switch may be provided which is configured to remain in an open state until the second body-part 30 is attached to the first body-part 20. Once fully connected, the switch is closed allowing electricity to flow when the plug 10 is in use.

The switch may be located between the protrusion 3 and recess 4. Alternatively, a switch may be configured to close when the electrical contacts 6 are electrically connected, i.e. when the first and second body-parts 20, 30 are fully connected. Alternatively, the switch can be located at the snap-fit feature 5 and configured to close when the snap-fit feature is engaged. The switch may be, for example, a mechanical switch, an electrical switch, or an electro-mechanical switch.

The present invention provides a plug that is cheap to manufacture, is robust and can fit through a standard UK letterbox.

It will be appreciated that this description is by way of example only; alterations and modifications may be made to the described embodiment without departing from the scope of the invention as defined in the claims. For example, the protrusion can be provided on the first body-part and the recess on the second body-part, the connection means can be means other than a protrusion and recess, and the snap-fit feature may be any snap4it feature suitable for the purpose or may not be present at all.

Claims

Claims 1. A three-pin plug for connection to an electrical socket, the plug comprising: a first body-part comprising two pins; a second body-pad comprising the third pin, wherein the second body-part is configured to connect to the first body-pad.
2. The plug according to claim 1, wherein the second body-part is configured to connect detachably or non-detachably to the first body-part.
3. The plug according to claim 1 or 2, wherein the third pin is a ground pin.
4. The plug according to claim 3, wherein the ground pin is longer than the two pins of the first body-pad.
5. The plug according to any preceding claim, wherein one of the first or second body-part comprises an electrical lead extending therefrom for connection to an electrical device.
6. The plug according to claim 5, wherein the one of the first or second body-part further comprises a transformer.
7. The plug according to claim 5 or 6, wherein the one of the first or second body-part is the first body-part.
8. The plug according to any preceding claim, wherein the second body-part connects to the first body-part by means of a protrusion on the first or second body-part that slides into a complimentarily-shaped recess on the second or first body-pad.
9. The plug according to claim 8, wherein the protrusion and recess are T-shaped.
10. The plug of claim 8 or 9, wherein the plug further comprises an electrical contact on each of the recess and protrusion, one of the contacts being electrically connected to the third pin, to electrically connect the first and second body-pads upon physical connection of the first and second body-parts.
11. The plug according to any one of claims 1 and 3-10, further comprising a snap-fit feature which engages when the first and second body-parts are connected together to prevent detachment of the body-parts.
12. The plug according to claim 11, wherein the snap-fit feature is releasable to allow the body-parts to be disconnected.
13. The plug according to claim 11, wherein the snap-fit feature is not releasable, preventing disconnection of the body-parts.
14. The plug according to any preceding claim, wherein the first body-part comprises a safety means which is configured such that, when the plug is connected to an electrical socket, electricity is prevented from flowing from the plug to an electrical device attached thereto, unless the second body-pad is attached to the first body-part.
15. The plug according to claim 14, wherein the safety means comprises a switch which is configured to remain in an open state until the second body-part is attached to the first body-part, thereby closing the switch and allowing electricity to flow when the plug is in use.
16. The plug of claim 14 or 15, when dependent on any one of claims 8-10, wherein the safety means is located between the protrusion and recess.
17. The plug of claim 15 when dependent on claim 10, wherein the switch is configured to close when the electrical contacts are electrically connected.
18. The plug of claim 15, when dependent on any one of claims 11-13, wherein the switch is located at the snap-fit feature and is configured to close when the snap-fit feature is engaged.
19. The plug according to claim 1, wherein there is an electrical connection between the two connected body-pads.
20. A power plug substantially as hereinbefore described with reference to and as shown in figs. 2 to 6.