EP0491534B1

EP0491534B1 - An illuminating electric light switch

Info

Publication number: EP0491534B1
Application number: EP91311645A
Authority: EP
Inventors: Andreas Charalambous Georgiou
Original assignee: CHARALAMBOUS GEORGIOU ANDREAS
Current assignee: CHARALAMBOUS GEORGIOU ANDREAS
Priority date: 1990-12-17
Filing date: 1991-12-16
Publication date: 1995-09-27
Anticipated expiration: 2011-12-16
Also published as: GB9027260D0; GB2251060B; GB2251060A; DE69113419D1; EP0491534A1

Description

THIS INVENTION relates to improvements in or relating to electric light switches.
It is well known to provide a wall-mounted electric light switch in a room for remotely operating an associated remote source of illumination elsewhere in the room. Such light switches are usually mounted on a wall of the room adjacent an entrance, so that the associated source of illumination can be switched on or off upon entering or leaving the room.
Known electric light wall switches are commonly simple on/off switches, but it is known to incorporate a dimmer circuit into such switches, so that the level of illumination provided by the associated source in the room can be controlled from the switch.
To enable a light switch to be seen and located in the darkness, particularly in dark halls and passage, it is also known to provide an electric light wall switch with a very dim continuously illuminated indicator light. GB-A-1 001 951 and DE-A-29 17 367 disclose such light switches having constantly illuminated surrounds. In both cases a light source is located within the housing of the light switch.
The present invention addresses the problem of providing a low level of illumination in a room for children and others of a nervous disposition who do not wish to sleep in total darkness. Whilst such low level illumination can be achieved using an existing dimmer type of switch or by exchanging the lamp which is used to provide a high level of illumination for normal activity in the room for a lamp of lower power, neither of these solutions is totally satisfactory or convenient.
The present invention aims to provide a convenient means of providing low level illumination in a room and, to this end, the invention provides an electric light switch for mounting in a room to control a primary source of illumination providing a high level of illumination required for normal activity within the room, which switch includes: a housing incorporating a secondary source of illumination providing a low level of illumination enabling fearless repose within the room; and means for selecting the secondary source as the source of illumination with the room, which selecting means enables either the primary source or the secondary source or neither of the primary and secondary sources to be selected as the source of illumination within the room.
Conveniently, the selecting means comprises a common movable electrical contact member controlling the supply of power to both the primary source and the secondary source of illumination.
In one embodiment of the invention, the common contact member has a first position in which the primary source is illuminated and the secondary source is extinguished, a second position in which both the primary and secondary sources are extinguished and a third position in which the primary source is extinguished and the secondary source is illuminated.
Advantageously, the secondary source of illumination comprises an array of light-emitting diodes.
Desirably, the array of light-emitting diodes is composed of pairs of light-emitting diodes connected in series, each pair of diodes being connected in parallel with opposite polarities.
Preferably, a capacitor is connected in series with the light-emitting diode array reactively to limit the electrical current through the diodes to a safe operating level.
According to another preferred feature, a protective resistor is connected in series with the current-limiting capacitor and the diode array to limit current surge and to act as a safety fuse.
Expediently, the secondary source constitutes a lighting panel in a wall of the switch housing.
Conveniently the lighting panel is an elongated panel extending along a side wall of the switch housing.
In order that the invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a front view of a wall-mounted electric light switch embodying the present invention;
Figure 2 is a side view of the Figure 1 light switch;
Figure 3 is a schematic diagram of an internal electrical circuit arrangement of the switch.
Figure 4 is a schematic diagram of another circuit arrangement for the switch; and
Figure 5 is a schematic diagram of a further circuit arrangement for the switch.

Referring firstly to Figures 1 and 2, a wall-mounted electric light switch 1 comprises an electrically insulating housing 2 for mounting on the wall of a room to control a primary source of illumination (not shown) elsewhere in the room. The housing 2 may be made of a suitable electrically insulating plastics material. A lighting panel 3 comprising an array of light emitting diodes is incorporated in a side wall 4A of the housing 2 and extends around at least a portion of the perimeter of a front wall 4B of the housing 2 to constitute a secondary source of illumination.
An electrically insulating operating portion of a three-position movable contact member 5 of an electrical switch mechanism in the housing 2 projects from the interior of the housing 2 through a rectangular opening 6 in the front wall 4B of the housing 2 to enable operation of the switch mechanism by a user. The housing 2 is formed with mounting apertures, such as the apertures 7, for the passage of fixing screws used to fix the switch 1 to a switch box on the wall.
As shown in Figure 3, the light switch 1 has first and second electrical terminals 10 and 11 within the housing 1 for connection to respective common and live terminals 12 and 13 of a remote primary source of illumination 14 having a lamp 24 connected between live terminal 13 and neutral terminal 15. The light switch 1 also has an earth terminal 25.
Terminal 10 of switch 1 is connected to a stationary contact 16 of movable contact member 5, which has a movable switch contact 17 selectively engageable with first, second and third fixed switch contacts 18, 19 and 20. The first fixed contact 18 is connected to the second light switch terminal 11. The second fixed contact 19 is an isolated contact. The third fixed contact 20 is connected to the first terminal 11 of the switch via a series arrangement of a capacitor 21, a resistor 22 and n light emitting diode pairs 23a to 23n, n being an integer which depends upon the level of illumination required, the value of the electrical supply voltage available (eg 110 or 240 volts) and the type of light-emitting diode used.
Each light emitting diode pair 23 comprises first and second light emitting diodes 26 and 27 connected in parallel but with opposite polarities.
Capacitor 21 is a class X2 capacitor which serves reactively to limit the current through the series path between contact 20 and terminal 11 to a safe operating level, typically 20mA, required by the light emitting diodes. Resistor 22 acts to limit current surges which can occur on closing contacts 17 and 20 and acts as a safety fuse should capacitor 21 fail.
With the movable contact member 5 in its first position interconnecting stationary contact 16 and fixed contact 18, electrical power is supplied directly from switch terminal 10 to switch terminal 11 and the primary source 14 is illuminated to provide a high level of illumination for normal activity in the room.
With the movable contact member 5 in its second position interconnecting contacts 16 and 19, electrical power is supplied neither to the primary source 14 of illumination nor to the secondary source 3 of illumination, so that neither source is illuminated.
With the switch in its third position connecting contacts 16 and 20, a restricted current limited by capacitor 21 flows between terminals 10 and 11 through the light emitting diode pairs 23 of the secondary source 3, which is thereby illuminated to provide a low level of illumination enabling fearless repose within the room. This restricted current also flows through the lamp 24 of the primary source 14 but is insufficient to cause the primary source to emit any light.
It is envisaged that an illuminating light switch embodying the invention may be shaped and dimensioned to enable it to replace a conventional light switch in an existing installation or could be more freely designed for new installations.
Whilst the above described embodiment of the invention has a secondary source of illumination employing light emitting diodes, it is envisaged that the secondary source could equally employ any other suitable low power light sources, such as miniature neon tubes or incandescent bulbs.
For example, Figure 4 illustrates a circuit arrangement for the light switch 1 in which the secondary source of illumination in the form of a plurality of neon light sources 30a to 30n connected in parallel between the terminal 11 and the contact 20. Each secondary light source 30 comprises a miniature neon tube 29 connected in series with a current-limiting resistor 28.
By way of further example, Figure 5 illustrates a circuit arrangement for the light switch 1 in which the secondary source of illumination comprises a plurality of low voltage incandescent bulbs 32a to 32n. In this case, the primary winding 33 of a transformer 31 is connected between the terminal 11 and the contact 20 and the bulbs 32a to 32n are connected in parallel across the secondary winding 34 of the transformer, a suitable low voltage being applied to the bulbs by the secondary winding when the mains supply voltage is applied across the primary winding 33.
In the described embodiment, the secondary source of illumination is switched on and off by means of the common three position movable contact member 5 which also controls the primary light source 14. However, it is envisaged that, if desired, separate movable contact members could be provided on the light switch for respectively operating the primary and secondary sources.
In the described embodiment, the secondary source of illumination takes the form of a strip like lighting panel extending along the side wall of the housing of the light switch. The secondary source could, of course, take any other geometrical form and be positioned at any desired location on the switch housing.

Claims

An electric light switch (1) for mounting in a room to control a primary source (14) of illumination providing the high level of illumination required for normal activity within the room, which switch (1) includes: a housing (2) incorporating a secondary source (3) of illumination providing a low level of illumination enabling fearless repose within the room; and means (5,16,17,18,19,20) for selecting the secondary source (3) as the source of illumination within the room, which selecting means (5,16,17,18,19,20) enables either the primary source (14) or the secondary source (3) or neither of the primary and secondary sources (14,3) to be selected as the source of illumination within the room.
A light switch (1) according to claim 1, wherein the selecting means (5,16,17,18,19,20) comprises a common movable electrical contact member (5) controlling the supply of power to both the primary source (14) and the secondary source (3) of illumination.
A light switch (1) according to claim 2, wherein the common contact member (5) has a first position in which the primary source (14) is illuminated and the secondary source (3) is extinguished, a second position in which both the primary and secondary sources (14, 3) are extinguished and a third position in which the primary source (14) is extinguished and the secondary source (3) is illuminated.
A light switch (1) according to any preceding claim, wherein the secondary source (3) of illumination comprises an array of light-emitting diodes (23a, 23b...n).
A light switch (1) according to claim 4, wherein the array of light-emitting diodes (23a,23b..n) is composed of pairs of light-emitting diodes (23) connected in series, each pair of diodes (23) being connected in parallel with opposite polarities.
A light switch (1) according to claim 5, wherein a capacitor (21) is connected in series with the light-emitting diode array (23) reactively to limit the electrical current through the diodes (23) to a safe operating level.
A light switch (1) according to claim 6, wherein a protective resistor (22) is connected in series with the current-limiting capacitor (21) and the diode array (23) to limit current surges and to act as a safety fuse.
A light switch (1) according to any one of claims 1 to 3, wherein the secondary source (3) of illumination comprises a plurality of neon light sources (30a,30b...n).
A light switch (1) according to claim 8, wherein the neon light sources (30a,30b...n) are connected in parallel, each light source comprising a miniature neon tube (30a, 3Ob...n) connected in series with a resistor (28).
A light switch (1) according to any one of claims 1 to 3, wherein the secondary source (3) of illumination comprises a plurality of incandescent light sources (32a, 32b...n).
A light switch (1) according to claim 10, wherein the incandescent light sources (32a,32b...n) are low voltage incandescent bulbs connected in parallel across a low voltage secondary winding (34) of a transformer the primary winding (33) of which is energised to illuminate the incandescent bulbs.
A light switch (1) according to any preceding claim, wherein the secondary source (3) constitutes a lighting panel (3) in a wall of the switch housing (2).
A light switch according to claim 12, wherein the lighting panel (3) is an elongated panel extending along a side wall (4a) of the switch housing.