GB2346268A

GB2346268A - Power converter with cigarette lighter socket

Info

Publication number: GB2346268A
Application number: GB9901021A
Authority: GB
Inventors: Mark Loughborough; Saul Manashe
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-01-18
Filing date: 1999-01-18
Publication date: 2000-08-02
Anticipated expiration: 2019-01-18
Also published as: GB2346268B; GB9901021D0

Abstract

A low voltage electricity supply unit has inlet 2 means for connecting the unit to a domestic electricity supply and an outlet 3 in the form of a cigarette/cigar lighter socket. A switched mode power converter is connected between the inlet 2 and the outlet 3, and can be housed in a cubic case 1. The inlet 2 can be in the form of an IEC plug and both inlet 2 and outlet 3 can be integral with the case 1.

Description

Power Supplies This invention concerns power supplies and more particularly power supplies which provide a low voltage from a high voltage domestic electricity supply.

Many items of domestic electronic and electrical equipment, and particularly portable items, for example laptop personal computers, mobile telephones, computer accessories/peripherals and the like, use external low voltage power supplies either as the sole supply to the equipment itself, or as a substitute for or to recharge one or more internal batteries, the relatively high domestic alternating voltage being converted into a suitable low, direct current voltage.

Transformer based power supplies are widely used for the purpose, the AC voltage from the domestic supply being suitably reduced by the transformer before being converted into a desired DC voltage. The problem with such supplies is that the transformers are large and heavy, particularly as the power output from the power supply is increased. This is a distinct disadvantage when the equipment being supplied is light weight and portable, because the power supply can be heavier and/or larger than the equipment itself.

There has been an increasing use of portable electrical equipment which can be supplied from the low voltage electrical supply of a motor vehicle through its cigar/cigarette lighter.

Such connections are usually made by a special connecting lead which at one end has a plug which fits into the cigar/cigarette lighter and the other end has a small connector socket or plug which fits into a corresponding power input connector or socket.

When the equipment is removed from the vehicle it either has to rely on its internal power source, which can become exhausted rapidly, especially if it is not fully charged, or it has to be connected to a low voltage supply powered by the domestic electricity supply. As explained above, transformer based supplies have typically been used for the purpose, but they have the disadvantages outlined above.

According to the present invention there is provided a low voltage electrical supply unit comprising inlet means for connecting the unit to a domestic electricity supply, outlet means in the form of a cigarette/cigar lighter socket, and a switched mode power converter connected between the inlet means and the outlet means.

Power supplies in accordance with the present invention have the advantage that high output powers can be achieved through the use of switched mode voltage converters of relatively small weight and volume, particularly when compared with transformer based systems. Furthermore, whereas the outlet plugs of traditional transformer based power supplies typically have a maximum current capacity of 1 Ampere, cigarette/cigar lighters can usually satisfactorily carry currents in excess of 5 Amperes.

An embodiment of low voltage power supply in accordance with the present invention will now be described with reference to the accompanying diagrammatic drawings in which: Fig. 1 shows a plan view of a first embodiment; Fig. 2 shows a view of the embodiment of Fig. 1 from one end; Fig. 3 shows the view of the embodiment of Fig. 1 from the other end from that of Fig. 2; Fig. 4 shows a plan view of a second embodiment; Fig. 5 shows a view of the embodiment of Fig. 4 from one end; and Fig. 6 shows the view of the embodiment of Fig. 4 from the other end from that of Fig. 5.

The embodiment shown in Figs 1 to 3 consists of an essentially cubic case 1 having an inlet plug 2 for connection to the domestic mains supply, and an electrical outlet 3 in the form of a cigarette/cigar lighter socket. The inlet plug 2 is in the form of an IEC plug which enables the power supply to be connected to the domestic mains supply using leads which have an appropriate plug at one end, these being widely used as mains leads for computers and mains powered electrical devices such as electric kettles. This embodiment has the additional advantage that it is in effect universal in that it can be used in different countries which require different plugs to connect to the domestic mains supply.

Within the case 1 is a switched mode power supply which, for example, is capable of providing an output voltage of 13.6 at a current of 5 Amperes. Using switched mode power supplies, the volume occupied by the supply, and its weight, can be substantially less than that of a transformer based power supply of comparable output.

The embodiment of Figs. 4 to 6 is of substantially identical construction to that of Figs. 1 to 3 except that instead of having an IEC socket for the inlet, it has a UK 13 Ampere three pin plug. As will be appreciated, the UK 13 Ampere three pin plug can be replaced by other plug configurations which can be plugged directly into a domestic electrical mains outlet.

Power supplies in accordance with the present invention can be used to provide low voltage power supplies in substantially fixed installations, for example in a workstation or desk. The present invention can then be used in such applications with an input connected to internal wiring for the mains supply whilst using an output in the form of a cigarette/cigar lighter socket, for example installed in a panel mount or power module attached to the workstation, desk, other furniture, perimeter trunking, a ceiling distribution system or within a control cabinet, for example a commonly used 48cm rack system.

Claims

Claims 1. A low voltage electrical supply unit comprising inlet means for connecting the unit to a domestic electricity supply, outlet means in the form of a cigarette/cigar lighter socket, and a switched mode power converter connected between the inlet means and the outlet means.

2. A low voltage electrical supply unit substantially as herein described with reference to the accompanying drawings.

Amendments to the clalms have been filed as follows Claims 1. A low voltage electrical supply unit comprising inlet means for connecting the unit to a domestic electricity supply, outlet means in the form of a cigarette/cigar lighter socket, and a switched mode power converter connected between the inlet means and the outlet means.
2. An electrical supply unit according to claim 1, wherein the inlet comprises an IEC plug.
3. An electrical supply unit according to either of the preceding claims, wherein the inlet and outlet are integral with the case for the switched more power converter.
4. A low voltage electrical supply unit substantially as herein described with reference to the accompanying drawings.