GB2169756A - Adaptor for miniature fluorescent lamp - Google Patents

Abstract

An electrical socket adapter for a compact fluorescent lamp assembly comprises a housing (25), a connector (26) projecting from the housing for coupling the adapter with an electrical socket, an adapter socket connected electrically to the connector (26) and arranged to receive the connector (27) of a lamp (18), and a ballast (28) which interconnects the connector (26) and the adapter socket for providing a stabilised voltage supply for the lamp. The ballast (28) and the adapter socket are mounted within the housing (25), and the ballast defines a mounting recess (29) which receives the adapter socket. There is a uniform weight distribution of the ballast about a central axis of the adapter socket. In an alternative configuration, the connector (26) may be mounted in the ballast recess (29), and the socket at the other end of the adaptor. <IMAGE>

Description

SPECIFICATION Adapter for use with an electric lamp This invention relates to an electrical socket adapter for use with an electric lamp.

The majority of standard lamp-holders in use in existing luminaires are for use with lamps that terminate with either B.C. (Bayonet Cap) or E.S. (Edison Screw) fixing.

The present invention has been developed to provide, by means of an adapter, a quick and cheap method of using a non-standard terminating electric lamp, requiring control gear to operate it, in a standard B.C. or E.S. lamp holder, without the need for rewiring or complicated or expensive conversion.

This invention was developed primarily, though not exclusively, for use with the new energy saving lamps currently manufactured or marketed by Philips Lighting in Europe and North American Philips Lighting Corporation in North America under the trade names of 'PL' and 'PLC' lamps, respectively, and by Osram in Europe under the trade name of 'Dulux' lamps. Similar lamps are also marketed by other established manufacturers under different trade names. Because of their energy saving characteristics these lamps, which are available in different lengths and wattages, are beginning to be sold in large numbers. These new lamps have been made without the standard B.C. or E.S. lamp-cap and consequently none of these lamps can be used directly in existing luminaires having B.C. or E.S. lamp holders without an adapter or conversion.

Also, unlike the normal tungsten type household lamps, which are 'pear' shaped, these 'new type' lamps are generally longer and slimmer (see Fig.1). The position is further complicated in that these lamps are miniature fluorescent type lamps and as such require a ballast to operate the lamp. It is therefore necessary that any quick fitting adapter developed for use with lamps of this type in luminaires with B.C. or E.S. lamp-holders must incorporate: a) a lamp-cap, either E.S. or B.C. for insertion into an existing lamp-holder.

b) appropriate control gear i.e. a ballast.

c) a 'new type' lamp holder to accept the new type non-standard lamp-cap.

A number of specialist lamp-holder manufacturers are currently producing these 'new type' lamp-holders to accept these new energy saving lamps with 'new type' lamp-caps.

Some of these new lamp-holders have been given the trade identification numbers of G23, GX23 and G32O. Similarly, there are many specialist ballast manufacturing companies manufacturing ballasts of different rectangular sections and lengths to operate the various different wattage lamps available.

However, existing designs of lamp socket adapters are unable to mount the ballast and the adapter socket (for the 'new type' lamp) in a stable manner in a common housing.

Thus, in a first existing arrangement (shown in Figure 7) the ballast (which is a standard rectangular ballast) is mounted in a housing from one side of which projects a B.C. or E.S.

connector or lamp-cap, and the adapter socket is mounted externally on an opposite side of the housing. Although stable, this provides a lengthy, cumbersome and unwieldy arrangement, which will be of excessive length in certain lamp conversion situations.

In a second existing arrangement, the overall length is reduced as compared with the first arrangement, in that a ballast has been designed which clips onto one side of the housing. However, this has the very significant disadvantage of being relatively unstable, in view of the (usual) substantial weight of the ballast which is mounted off-centre (with respect to the adapter socket) on the housing. Therefore, with table lamps with small bases, and other situations such as pendant mountings, the unstable arrangement of the ballast is highly undesirable and may even be dangerous.

The present invention has therefore been developed with a view to provide an electrical socket adapter which can provide a stable assembly of ballast and adapter socket within a common housing, thereby overcoming the unwieldiness of the first existing arrangement and the instability of the second existing arrangement, this being achieved by cooperative designing of the ballast and the adapter socket.

Accordingly, the present invention provides an electrical socket adapter which comprises: a housing; a connector projecting from the housing for coupling the adapter with an existing electrical socket of a particular type, the connector being formed so as to be suitable to be received by the particular type of socket; an adapter socket connected electrically to the connector and arranged to receive the connector of a lamp of the type which requires a ballast for its operation; and a ballast interconnecting the connector and the adapter socket for providing a stabilised voltage supply for the lamp; in which: the ballast and the adapter socket are mounted within the housing; the ballast is arranged in the housing so as to define a mounting recess which receives the adapter socket; and there is a substantially stable weight distribution of the portions of the ballast about a central axis of the adapter socket.

Alternatively, the invention may provide an electrical socket adapter as defined above, but in which the positions of the connector and the adapter socket are reversed i.e. the connector is located within the housing, surrounded by the ballast and the adapter socket projects from one side of the housing.

Any arrangement of the ballast and the adapter socket will suffice, provided that it meets the three criteria set out above.

Insofar as the ballast and the adapter socket are mounted within the housing, the controlling factor, as far as the depth or thickness of the housing is concerned, will be the depth or length of the adapter socket. Conveniently, the adapter socket will be a proprietory component which is readily available. By mounting the adapter socket within the housing, this provides a much shorter assembly than the first existing arrangement referred to above.

The ballast will be designed with two factors in mind : firstly, it must have an electrical specification to meet the demand of the lamp or lamps with which it is to be used; and secondly, beyond having to define a mounting recess for the adapter socket, it can occupy all or any desired proportion of the space available within the housing which is not occupied by the adapter socket.

One preferred arrangement comprises an annular ballast which defines a central circular recess in which the adapter socket is received. However, other arrangements are possible, such as splitting the ballast into separate component portions e.g. square, rectangular, or part annular, which are distributed about the central axis of the adapter socket in such a way as to achieve the three essential criteria referred to above.

When, as is provided by a preferred embodiment of the invention, the adapter socket is applied to convert existing B.C. or E.S.

lamp caps for use with 'new type' energy saving lamps, it is possible to combine a B.C.

or E.S. lamp-cap (the connector), control gear for the energy saving lamp (the ballast) and a lamp holder (the adapter socket) in the smallest possible overall dimensions to give maximum possible commercial application.

The invention will now be described in detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 illustrates three recently available designs of energy saving lamp; Figure 2 illustrates a lamp-holder or socket for use with any one of the lamps shown in Figure 1; Figure 3a is a side view of a table lamp with a conventional lamp holder arrangement for a tungsten filament lamp; Figure 3b is a side view of the same table lamp, but having an electrical socket adapter according to the invention fitted thereon in place of the standard tungsten lamp; Figure 4a is a side view of a conventional ceiling lamp with a tungsten filament lamp; Figure 4b is a side view of the same lamp, but having an electrical socket adapter of the invention fitted thereon in place of the standard tungsten lamp;; Figure 5 illustrates a standard construction of ballast for use with a fluorescent lamp; Figure 6 illustrates a ballast for use in an electrical socket adapter according to the invention; Figure 7 illustrates one known construction of electrical socket adapter; Figure 8 illustrates in more detail an embodiment of electrical socket adapter according to the invention; and Figure 9 illustrates a modification of the socket adapter of Figure 8 to function as a lamp holder.

Referring to Figures 1 and 2, there are shown a range of energy saving lamps 10, 11 and 12 and a lamp socket 13 for use therewith. The lamps and the socket are commercially available components, and the lamps 10 to 12, as illustrated, comprise energy saving lamps manufactured and marketed by Philips Lighting in Europe under the trade names 'PL'.

These energy saving lamps are miniature fluorescent tubes , which provide very efficient conversion of electrical energy to light, but require appropriate control gear i.e. ballasts therefor.

A typical construction of ballast 14 for an energy saving lamp is shown in Figure 5. As is well known a ballast is used as a stabiliser to the electrical characteristics of a discharge lamp.

Figures 3a and 4a illustrate two lamp arrangements in which a standard tungsten lamp 15 is mounted in a conventional B.C. socket or lamp-holder 16.

Figures 3b and 4b illustrate conversion of the lamps shown in Figures 3a and 3b, using an embodiment 17 of electrical socket adapter according to the invention, to enable the lamp to operate with an energy saving lamp 18.

While Figures 3 and 4 illustrate conversion of an existing B.C. lamp holder to be suitable for use with an energy saving lamp, it should be understood that an adapter according to the invention can also be used readily to convert a standard E.S. lamp holder in the same way.

Referring now to Figure 7 of the drawings, there is shown one existing construction of electrical socket adapter which is designated generally by reference numeral 19. The adapter 19 comprises an adapter housing 20, a connector 21 in the form of a B.C. or E.S.

lamp-cap which projects from one side of the housing 20, and an adapter socket (similar to socket 13 shown in Figure 2) in the form of a lamp-holder 22 which projects from the opposite side of the housing 20. A rectangular ballast 23 is mounted within the housing 20, and provides a stabilised voltage supply from the connector 21 to the socket 22.

Referring again to Figures 3a and 4a, it will be evident that replacement of the tungsten lamp 15 by the adapter 19 and energy saving lamp 18 will result in a quite substantial increase in the axial extent of fitting in the re gion of the attachment to the lamp holder 16.

Thus, apart from the inevitable increase in length of the energy saving lamp 18, over the length of the lamp 15, the socket attachment will be increased in length by the depth of the housing 20, plus the length of the socket 22 which is mounted externally of and projects from the housing 20. Therefore, this provides a lengthy, cumbersome and somewhat unwieldy adapter attachment.

However, referring now to the embodiment of the invention illustrated in detail in Figure 8, there is shown an electrical socket adapter 24 which comprises a common housing 25, a connector 26 projecting from one side of the housing 25 to be received by a conventional lamp holder (16 in Figures 3 and 4), and a socket 27 which has been designed to receive the energy saving lamp 18. There is also a ballast 28 which is designed to operate the energy saving lamp.

However, in the embodiment 24 shown in Figure 8, both the socket 27 and also the ballast 28 are mounted in a stable manner within the housing 25. Clearly, this reduces the axial extent of the adapter attachment, as compared with the existing arrangement shown in Figure 7, thereby providing a much less cumbersome arrangement. Furthermore, and as will be described in more detail below, a stable arrangement is provided, despite the inevitable weight penalty involved when a ballast is provided in the fitting.

Thus, the ballast 28 and socket 27 meet three essential criteria, as follows: 1. The ballast 28 and the adapter socket 27 are mounted within the common housing 25; 2. The ballast 28 is arranged in the housing 25 so as to define a mounting recess 29 which receives the adapter socket 27; and 3. There is a substantially stable weight distribution of the component portions of the ballast 28 about a central axis 30 of the adapter socket 27.

In the preferred arrangement of ballast, as shown in more detail in Figure 6, the ballast 28 is an annular arrangement which defines a central circular recess 29 in which the adapter socket 27 is readily mounted. Clearly, this provides a stable arrangement, despite the weight of the ballast, since the weight of the ballast is distributed at a uniform distance from the central axis 30.

Although not shown, other arrangements of ballast may be provided if desired, provided that they meet the three criteria set out above. By way of example only, the ballast may be formed by splitting it into a number of component portions, electrically connected together, e.g. square, rectangular or part annular, and distributed uniformly about the central axis 30.

The embodiment of the invention, described above with reference to the drawings, therefore provides an arrangement of ballast and adapter socket which is much shorter than the construction known from Figure 7, while providing the advantage of an entirely stable weight distribution about the central axis of the adapter socket.

Other features and advantages of the electrical socket adapter according to the invention are set out in the following description: The preferred adapter's extreme compactness is achieved by designing a new circular ballast instead of using any of the current rectangular shaped ballasts available, and such that the circular ballast has a central hole of sufficient diameter so that a 'new type' lamp-holder can be fully incorporated into the recess of the central hole.

For example consider a typical example of the new type lamp-holder (see Figure 2), in which the length of the lamp-holder is approximately 34 mm long and has an overall diameter of approximately 34.6 mm. Therefore to accommodate such a lamp-holder in as compact an adapter as possible, without shielding the translucent envelope of the lamp, the ballast must have a central hole of a little over 34.6 mm diameter and a depth of no more than 34 mm.

With these two parameters in mind the outside diameter of the specially designed circular ballast must be as small as possible, bearing in mind also that the ballast must reach the required technical specifications to operate the lamp concerned. By designing a circular ballast with a central hole and taking the forementioned two parameters into consideration it is possible to make a ballast for PL, PLC, Dulux and similar lamps with an overall outside diameter of no more than 72 mm (see Figure 6).

It is therefore possible to manufacture a housing to include ballast and lamp-holder that is preferably no more than 38 mm deep and 76 mm in diameter (allowing say 2 mm for wall thickness of housing). This housing, which could be made of plastics by injection moulding, onto which a B.C. or E.S. lamp-cap can be attached, with all electrical parts and connecting wires hidden internally, will make a compact adapter (see Figure 8) for simple insertion into a standard B.C. or E.S. lamp-holder in the normal manner. It would be possible to incorporate on the adapter housing (see Figure 8), which would be an integral part of the housing if made in plastic by means of injection moulding, either threaded or simple snap-on arrangements to accept a shade ring for attaching lamp shades such as those illustrated in Figure 3 and Figure 4.Similarly further projections on or grooves into the adapter housing could be made to clip on or attach various purpose-made shades or light reflectors.

The ballast, being made of iron with copper windings, is relatively heavy and therefore it is essential that an equilibrium around the central hole be maintained otherwise the adapter could not be used in Figure 4 applications where the luminaire would not hang straight, and in many Figure 3 applications where the luminaire would topple over, which together is a major part of the potential commerical market.

The smallest commercially available existing ballast at the present time which could be incorporated into an adapter for general applications for the 7, 9 and 11 Watt PL, Dulux and similar type lamps is approximately 84.5 mm long, 41 mm wide and 32 mm high (see Figure 5). Bearing the equilibrium factor in mind and discarding all unnecessary support brackets and casing from the ballast as shown in Figure 5, one practical way to make an adapter of any generally commercially acceptable dimensions using a compact rectangular ballast is the known arrangement illustrated in Figure 7. At least one manufacturer makes such an adapter. It will be seen that the overall length of this existing adapter is longer than the preferred adapter by approximately the length of the 'new type' lamp-holder (see Figure 7 and Figure 8).With rapid advances in the manufacture of electronic control gear, it may be possible to replace the present iron and copper ballast with electronic ballast but the same principle could be applied, by constructing a circular electronic ballast around a central hole to allow the lamp-holder to be recessed therein.

Although Figure 8 shows the existing B.C.

or E.S. lamp-cap in an outward projected position on the adapter with the 'new type' lampholder recessed in the centre hole of the housing, the position could be reversed with the existing lamp-cap being recessed (with sufficient clearance diametrically around the B.C.

or E.S. lamp-cap to enable insertion into existing lamp-holder) and the 'new type' lamp-holder in an outward projected position.

The preferred adapter has the following distinct advantages: (1) The ballast, being by far the heaviest part of the whole adapter, has its weight evenly distributed around the lamp-holder and lamp-cap. Hence when inserted into flex hanging luminaries, the luminaire will hang straight.

Similarly, when inserted in free standing luminaires, once again because the weight is evenly distributed around the centre, the luminaire will not topple over.

(2) The overall length of the adapter is the bare minimum physically possible i.e. length of B.C. orE.S. lamp-cap plus length of 'new type' lamp-holder (allowing a few millimetres for housing). Therefore, when the adapter is inserted in luminaires with narrow translucent shades with lamp switched on, less unsightly shadow will be noticeable near the lamp-holder end as a result of an overly long adapter.

(3) The minimum diameter adapter possible is used bearing in mind the other necessary parameters, and therefore the adapter is capable of being inserted into the maximum number of narrow diameter luminaires.

(4) The extra 30 mm or so saved in overall length in many applications is critical, and therefore the lamp could be accommodated in far many more small luminaires and where the lamp would otherwise protrude above or below the shade and prove unsightly and unusable.

While there has been described and illustrated herein an embodiment of electrical socket adapter for converting one existing type of socket (for a B.C. or E.S. fitting) to be suitable to operate with a different type of fitting e.g. an energy saving lamp cap, it should be understood that the invention has wider applications and can be employed to convert existing sockets for operation between other types of fittings. Also, the features of the ballast and adapter socket (in a common housing) may be provided in other fittings than "adapters". For example, if the connector (26) is omitted, the housing may form a lamp holder for use as original or replacement equipment in a luminaire, and particularly as an integral base for a table or ceiling mounted luminaire (see Figure 9), having a shade 31.

Claims (11)

1. A compact fluorescent lamp comprising a housing, a connector projecting from the housing for coupling the lamp with an electrical socket, a miniature fluorescent tube which is mounted at one end in the housing, and a ballast interconnecting the connector and the fluorescent tube to provide a stabilised voltage supply therefor, in which: the ballast is arranged in the housing so as to define a mounting recess which receives said one end of the fluorescent tube; and there is a substantially stable weight distribution of the portions of the ballast about a central axis of the housing.

2. A lamp according to claim 1, in which the connector is a B.C. or E.S. lamp cap.

3. A lamp according to claim 1 or 2, in which the miniature fluorescent tube is an energy saving lamp.

4. An electrical socket adapter which comprises: a housing; a connector projecting from the housing for coupling the adapter with an existing electrical socket of a particular type, the connector being formed so as to be suitable to be received by the particular type of socket; an adapter socket connected electrically to the connector and arranged to receive the connector of a lamp of the type which requires a ballast for its operation; and a ballast interconnecting the connector and the adapter socket for providing a stabilised voltage supply for the lamp; in which: the ballast and the adapter socket are mounted within the housing; the ballast is arranged in the housing so as to define a mounting recess which receives the adapter socket; and there is a substantially stable weight distribution of the portions of the ballast about a central axis of the adapter socket.

5. A socket adapter according to claim 4, in which the positions of the connector and the adapter socket are reversed, whereby the connector is located within the housing, surrounded by the ballast, and the adapter socket projects from one side of the housing.

6. A socket adapter according to claim 4 or 5, in which the ballast comprises an annular ballast which defines a central circular recess in which the adapter socket is received.

7. A socket adapter according to claim 4 or 5, in which the ballast is split into separate component portions which are distributed substantially uniformly about the central axis of the adapter socket.

8. A socket adapter according to claim 7, in which the component portions of the ballast are square, rectangular or part annular.

9. A socket adapter according to any one of claims 4 to 8, including a miniature fluorescent lamp coupled therewith.

10. A compact fluorescent lamp according to claim 1 and substantially as hereinbefore described with reference to, and as shown in Figure 8 or 9 of the accompanying drawings.

11. A socket adapter according to claim 4 and substantially as hereinbefore described with reference to, and as shown in any one of the embodiments illustrated in the accompanying drawings.