GB2191634A - Means for locating the position of a switch in the dark - Google Patents

Abstract

Means for locating a pull switch in the dark. So that the location of a pull switch can very easily be detected in the dark even when the electric power which it switches is off, a battery operated device hanging down from the switch on a cord (14) comprises an outer casing (16) for containing a battery (26) and a light emitting diode (30) connected to an integrated circuit (28). At least a part (18) of the casing is made of light transmitting material to enable the LED to be seen. The LED may flash on and off. <IMAGE>

Description

SPECIFICATION Means for locating the position of a switch in the dark The invention relates to means for locating a pull switch in the dark.

Pull switches, which are used to operate lights in rooms, or pull switches used for switching on eiec- tronic alarms, usually possess no means for locating their position when the room is in darkness and can therefore be extremely difficult to locate in complete darkness. A person wishing to illuminate a room which is in darkness can sometimes be completely disorientated and may have great difficulty in locating the pull switch. This can be particularly distressing to an older person orto a person needing to illuminate a room quicklyfor any reason, or indeed to a very small child.

Various attempts have been made in the pastto solve this problem. For example, there has been provided a light switch having a partofitssurfacecoated with a luminous substance so that its location can be detected in the dark, but the luminosity of such a coating is usually very limited so that an older person in particular may find such switches of very little assistance. There has also been provided an el ectricswitch having in-built illumination using the electric power being switched to illuminate a part of the switch when the switch is in the ON condition, such a switch being used, for example, to indicate that electric power is available at a power point or for example to indicate to the driver of a vehiclethat hazard lights or rear window heating is switched ON.

The invention has for its object to provide a sol ution to the problem of howto locate a pull switch when the power is OFF.

According to the invention, there is provided means for locating a pull switch in the dark, said means being constituted by a device which is arranged to hang down from the switch on a cord so that by grasping the device a user can turn the switch on or off, the device having an outer casing forcontain- ing a battery and illuminating means connected to an integrated circuit and said battery, at least a part of said casing being made of lighttransmitting material so that the il lu m inating means may be observed through said lighttransmitting material. The illuminating means will preferably be constituted by a light emitting diode and in this case the integrated circuit may be connected to a flasher oscillator capable of causing the light emitting diode to flash.The pulse duration of the flasher will preferably be so very short that battery life will be extended, that isto say, for example, of about 35 milli seconds at intervals of about one second.

The device arranged to hang down from the switch may be constituted by a casing adapted to contain a battery and an integrated circuit, a generally cylindrical portion made of a transparent material and for ming an extended part of the casing within which the illuminating means may be observed. The device may include a conical upper portion to which a lower end ofthe cord can be connected. On the other hand, the device arranged to hang down from the switch may include a plastics body part of open sided cylindrical shape and a plastics sleeve, the arrangement being such that when the plastics sleeve has been displaced axially of the body part a battery can be entered into the latter, the return of the sleeve to a position in which it surrounds said body partthen hiding the battery from view.A variable resistance may be located in series with the battery in the device arranged to hang down from the switch, the arrangement being such that it is possible to vary the degree of brightness of the light emitting diode. In this case, the variable resistance may be constituted by an adjustable control element which takes the form of a rotatable disc of an electrically insulating material, the disc having a central metallic rivet which bears against the positive battery contact, the back face of the disc having an electrically conducting track which radiates outwards from the rivet and then describes partofa ring around a peripheral partofthe disc, a further contact touching said electrically conducting track at an adjustable position around the periphery ofthe disc so that there is thereby obtained a variable electrical resistance of said track in series with the battery.

In orderthatthe invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which : Figure lisa view of a pull switch embodying the invention, Figure2 is an exploded view of a part of the switch which can be grasped by the user to operate the switch, Figure 3 is a diagram of an electrical circuit which will be referred to, Figure4is a viewsimilarto Figure 2which illust- rates an alternative construction of that part of the switch, Figure 5 is a circuit diagram similarto that of Figure 3 but incorporating a possible modification which will be referred to, Figure 6 is a scrap view of a battery mounting to give such a modification, and Figure 7is a view looking in the direction of arrow 7 in Figure 6.

Referring now to Figure 1 ofthe drawings, the pull switch there indicated is in two main parts and comprises the switch proper 10fixed to a ceiling and a device 12 which hangs down from the switch 10 on a cord 14. The arrangement is such that by means of repeated 'pulls' on the cord 14, applied thereto by grasping the device 12, a user can switch the lighton and off in the room inwhichalightfittingconcerned is wired by way oftheswitch 10.

In Figure 2, is can be seen that the device 12 comprises an outercasing 16, a generally cylindrical portion 18, and a conical upper portion 20. The casing part 16 and the upper part 20 are made of an opaque synthetic plastics material. The generally cylindrical portion 18 however is made from a transparent synthetic plastics material. The generally cylindrical portion 18 is provided with upper and lpwerscrewthrea- ded stub portions 22 and 24 and these can be received within screwthreaded portions of the conical upper portion 20 and ofthe casing 16 re spectively.

The cord 14 is shown to have been secured to the conical upper portion 20 of the device by the simple expedient of passing the cord through a small hole in the portion 20 and knotting the end of the cord so that the know is captive within the upper end ofthe device.

The outercasing ofthe device is adapted to contain a battery 26 and illuminating means connected to an integrated circuit generally indicated 28, the illuminating means being a light emitting diode 30 which when the device is assembled will be located within a cavity 32 in the generally cylindrical portion 18 of the device. As shown, in Figure 2, when the device is assembled, the battery is connected to the integrated circuit by means of connectors 34 and 36.

Referring now to Figure 3, the electrical circuit of the device includes the battery 26, integrated circuit 28 and light emitting diode 30 referred to above. The integrated circuit includes a flasher oscillator 38.

The flasher oscillator 38 is a monolithic oscillator specifically designed to flash light emitting diodes and is sold underthe trade identification No. LM 3909. In operation of the device, the integrated circuit acts to causethe light emitting diodeto flash on and off. Thus when the switch is disposed in a dark room it is possible to locate the device without difficulty.

An important feature of the device is the fact that the light emitting diode is caused to flash only approximately once per second and that each pulse duration is only 35 milli seconds. The result of this is that although the batters is relatively small and of light weight it can be expected to last for at least one year withoutrenewal,flashing continuously so thatthe location ofthe device during the hours of darkness can always be seen.

In Figure 4 there is illustrated an alternative construction of the device 12. As shown, the casing part 16 ofthe original construction has been replaced by a plastics body part 160 and a plastics sleeve 162. The body part 160 is of open sided cylindrical shape so that, when the sleeve 162 has been displaced to the position in which it is shown in full lines in the drawing, a battery can be entered into it as shown. When the sleeve has been returned to a lowered position, it rests on an annular rim portion at the lower end of the body part and hides the battery from view.

Referring now to FigureS, which is a circuitdiagram similarto that previouslydescribed with reference to Figure 3, it will be seen that a variable resist- ance 40 has been added in series with the battery 26.

Bythis simple modification it is possible to vary the degree of brightness of the light emitting diode.

In Figures 6 and 7 there is illustrated one simple means whereby the modification referred to can be brought about, this entailing the addition of an adjustable control element 42 in the mounting forthe battery 26. As shown, the adjustable control element is in the form of a rotatable disc of an electrically insulating material, the disc having a central metallic rivet 44 which bears againstthe positive battery contact. As illustrated in Figure 7, the backfaceofthe disc has a carbon track46 which radiates outwards from the rivet44 and then describes an almost complete ring around a peripheral part ofthe disc. A further contact 48 touches the carbon track at an adjustable position around the periphery of the disc and thus there is obtained a variable electrical resistance of the carbon track located in series with the battery.

Various other modifications may be made. For example, the physical construction of the device can be varied. It may for example be preferred to form the device in an inverted fashion, that isto sayforthe light emitting diode to be arranged at the underside of the device. Furthermore, the entire outer casing could be made of a transport plastics material and in this case could be made in only two parts fitted together. The parts ofthe outer casing need not necessarily befitted together by screwthreaded connections. They could be snap fitted together provided the snap fittings were so secure that they were not in danger of being disconnected by normal use ofthe device.

Claims (11)

1. Meansforlocating a pull switch inthedark, said means being constituted buy a device which is arranged to hang down from the switch on a cord so that by grasping the device a user can turn the switch on or off, the device having an outer casing for containing a battery and illuminating means connected to an integrated circuit and said battery, at least a part of said casing being made of light transmitting material so that the illuminating means may be obse rved through said light transmitting material.

2. Means according to claim 1, in which the illuminating means are constituted buy a light emitting diode.

3. Means according to claim 2, in which the in tegrated circuit is connected to a flasher oscillator capable of causing the light emitting diode to flash.

4. Means according to claim 3, in which the pulse duration of the flasher is so very short that battery life will be extended.

5. Means according to claim 4, in which the pulse duration ofthe flasher oscillator is of about 35 milli seconds at intervals of about one second.

6. Means according to any one of the preceding claims, in which the device arranged to hang down from the switch is constituted by a casing adapted to contain a battery and an integrated circuit, a generally cylindrical portion made of a transparent material and forming an extended part of the casing within which the illuminating means may be observed.

7. Means according to claim 6, in which the device includes a conical upper portion to which a lower end ofthe cord can be connected.

8. Means according to any one of claims 1 to 5, in which the device arranged to hang down from the switch includes a plastics body part of open sided cylindrical shape and a plastics sleeve, the arrangement being such that when the plastics sleeve has been displaced axialiy of the body part a battery can be entered into the latter, the return of the sleeve to a position in which it surrounds said body partthen hiding the battery from view.

9. Means according to any one of the preceding claims, in which a variable resistance is located in series with the battery in the device arranged to hang down from the switch, the arrangement being such that it is possible to vary the degree of brightness of the light emitting diode.

10. Means according to claim 9, in whichthevariable resistance located in series with the battery is constituted by an adjustable control element which takes the form of a rotatable disco an electrically insulating material, the disc having a central metallic rivet which bears against the positive battery con tact, the backface of the dise having an electrically conductingtrackwhich radiates outwards from the rivet and then describes part of a ring around a peripheral part of the disc, a further contact touching said electrically conducting track at an adjustable position around the periphery of the disc so that there is thereby obtained a variable electrical resist anceofsaidtrackin series with the battery.

11. Means for locating a pull switch inthedark, said means being constituted, arranged and adapted to operate substantially as herein before described with reference to and as illustrated by Figures 1 to 3 or Figure 4 or Figures 5to 7 ofthe accompanying drawings.