GB2170040A

GB2170040A - Improved light bulbs

Info

Publication number: GB2170040A
Application number: GB08600459A
Authority: GB
Inventors: Walter Anderson
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-01-23
Filing date: 1986-01-09
Publication date: 1986-07-23
Also published as: GB8600459D0

Abstract

An incandescent lamp which comprises a glass bulb, which is either evacuated or filled with a neutral gas or gas mixture, a lamp base, capable of effecting engagement with an electrical lamp socket, and means within the bulbs for supporting a filament and connecting it to the base, characterised in that there are provided two or more filaments connected in parallel with one another. The bulb will not be extinguished completely on the failure of either of the filaments and may be used in rear light warning systems on motor vehicles, especially a system comprising an in-motion warning light and, preferably, a stationary warning light of a contrasting colour.

Description

SPECIFICATION Improved light bulbs This invention relates to light bulbs in particular for systems in which the continued operation of a light is important in the event of filament failure.

An incandescent lamp comprises an electrical conductor through which an electrical current is passed causing it to glow at white heat and emit light energy.

The conductor is usually a wire, or filament, which is carried on a glass mount and whose ends are welded to thicker support wires (leads) through which the current is supplied to the filament. In order to prevent oxidation of the filament, by exposure to air, it is enclosed in a glass bulb, which is sealed together with the mount. The lead in wires are sealed into the glass and the bulb is either evacuated, or it is filled with a neutral gas or gas mixture (e.g. nitrogen and argon). The early filaments were made of carbon but it was not possible to raise the temperature of these to white heat without substantially reducing the life of the filament. A much more suitable material for light bulb filaments is found to be tungsten, which can be heated to 3000".c.

However, even a light bulb having a tungsten filament only has a finite lifetime and it is impossible to predict when the filament will 'burn out'. This presents a problem especially in systems where the continued operation of a light is important, such as in the invention disclosed hereinafter.

The invention seeks to provide a simple and effective form of light bulb intended for use in many types of lighting systems which overcomes or reduces the above disadvantages.

According to the present invention there is provided an incandescent lamp which comprises a glass bulb, which is either evacuated or filled with a neutral gas or gas mixture, a lamp base, capable of effecting engagement with an electrical lamp socket, and means within the bulbs for supporting a filament and connecting it to the base, characterised in that there are provided two or more filaments connected in parallel with one another.

Preferably the filaments are inserted into the lamp base in parallel so that additional terminal connections in the lamp socket are not required.

This enables the bulb to be used interchangeably with ordinary bulbs.

In use of the bulb of the invention, should one of the filaments burn out, the light will not be extinguished completely, but will merely be reduced to half of its original intensity. This will indicate that the bulb should be replaced in the near future.

The bulb of the invention would be very suitable in applications wherein the continued operation of a light or lighting system is important since it is highly unlikely that both filaments will burn out or otherwise fail at the same time.

A particular important application of the bulbs of the invention relates to safety lights, in particular for forms of transport such as motor vehicles.

Nowadays, motor vehicles are fitted with brake lights of high intensity which help to reduce the number of rear end shunts which occur. However, should a vehicle be brought to a sudden halt, for example if it was involved in a crash, then said brake lights are usually not on while the vehicle is stationary. Therefore if the visibility is impaired, for example by darkness and/or fog, it is quite possible that oncoming motorists may not see such vehicles, or realise that they are stationary, until it is too late to take effective avoiding action. Thus, it is easy to perceive how multiple pile-ups occur in bad weather. Much preferred is a lighting system which will indicate to other motorists whether a vehicle is stationary or in motion.

Thus a second aspect of the invention seeks to provide a simple and effective form of rear lighting system for use with all types of vehicles which overcomes or reduces the above disadvantages.

According to the second aspect of the present invention there is provided a rear lighting system for vehicles comprising a light indicating that the vehicle is in motion.

Accordingly, the absence of the light of the invention indicates that the vehicle is stationary. Ideally, switching means and lights of two contrasting colours are provided such that when the vehicle ceases moving the 'in motion' light switches off and a 'stationary' light switches on. Preferably the 'stationary" light is a red light, and conveniently comprises the existing brake lights fitted to most vehicles. The 'in motion' light is preferably of a contrasting colour, most desirably green.

The lighting system may be actuated by being coupled, via a relay, to the ignition and the speedometer drive; but it may also be used in conjunction with other motion detecting devices such as a sensor on the drive transmission, a sensor connected to one of the wheels, or any moving part.

The relay operates to actuate the 'in motion' light when motion is detected and conversely to actuate the 'stationary' light when motion is not detected.

Preferably the lights will have the double filament bulbs of the first aspect of the invention so that if one filament burns out the light will not be extinguished completely, but will merely be reduced to half of its original intensity. For example, two filaments can be inserted in parallel (so as not to require additional terminal connections in the bulb holder socket, enabling the bulb to be used interchangeably with ordinary bulbs and not just with the system of the invention).

A principal advantage of the system of the invention is that when motorists observe vehicle lights without the 'in-motion' light, particularly if the system includes high intensity 'stationary' lights, they know that there is a hazard ahead and can therefore act accordingly.

1. An incandescent lamp which comprises a glass bulb, which is either evacuated or filled with a neutral gas or gas mixture, a lamp base, capable of effecting engagement with an electrical lamp socket, and means within the bulbs for supporting

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improved light bulbs This invention relates to light bulbs in particular for systems in which the continued operation of a light is important in the event of filament failure. An incandescent lamp comprises an electrical conductor through which an electrical current is passed causing it to glow at white heat and emit light energy. The conductor is usually a wire, or filament, which is carried on a glass mount and whose ends are welded to thicker support wires (leads) through which the current is supplied to the filament. In order to prevent oxidation of the filament, by exposure to air, it is enclosed in a glass bulb, which is sealed together with the mount. The lead in wires are sealed into the glass and the bulb is either evacuated, or it is filled with a neutral gas or gas mixture (e.g. nitrogen and argon). The early filaments were made of carbon but it was not possible to raise the temperature of these to white heat without substantially reducing the life of the filament. A much more suitable material for light bulb filaments is found to be tungsten, which can be heated to 3000".c. However, even a light bulb having a tungsten filament only has a finite lifetime and it is impossible to predict when the filament will 'burn out'. This presents a problem especially in systems where the continued operation of a light is important, such as in the invention disclosed hereinafter. The invention seeks to provide a simple and effective form of light bulb intended for use in many types of lighting systems which overcomes or reduces the above disadvantages. According to the present invention there is provided an incandescent lamp which comprises a glass bulb, which is either evacuated or filled with a neutral gas or gas mixture, a lamp base, capable of effecting engagement with an electrical lamp socket, and means within the bulbs for supporting a filament and connecting it to the base, characterised in that there are provided two or more filaments connected in parallel with one another. Preferably the filaments are inserted into the lamp base in parallel so that additional terminal connections in the lamp socket are not required. This enables the bulb to be used interchangeably with ordinary bulbs. In use of the bulb of the invention, should one of the filaments burn out, the light will not be extinguished completely, but will merely be reduced to half of its original intensity. This will indicate that the bulb should be replaced in the near future. The bulb of the invention would be very suitable in applications wherein the continued operation of a light or lighting system is important since it is highly unlikely that both filaments will burn out or otherwise fail at the same time. A particular important application of the bulbs of the invention relates to safety lights, in particular for forms of transport such as motor vehicles. Nowadays, motor vehicles are fitted with brake lights of high intensity which help to reduce the number of rear end shunts which occur. However, should a vehicle be brought to a sudden halt, for example if it was involved in a crash, then said brake lights are usually not on while the vehicle is stationary. Therefore if the visibility is impaired, for example by darkness and/or fog, it is quite possible that oncoming motorists may not see such vehicles, or realise that they are stationary, until it is too late to take effective avoiding action. Thus, it is easy to perceive how multiple pile-ups occur in bad weather. Much preferred is a lighting system which will indicate to other motorists whether a vehicle is stationary or in motion. Thus a second aspect of the invention seeks to provide a simple and effective form of rear lighting system for use with all types of vehicles which overcomes or reduces the above disadvantages. According to the second aspect of the present invention there is provided a rear lighting system for vehicles comprising a light indicating that the vehicle is in motion. Accordingly, the absence of the light of the invention indicates that the vehicle is stationary. Ideally, switching means and lights of two contrasting colours are provided such that when the vehicle ceases moving the 'in motion' light switches off and a 'stationary' light switches on. Preferably the 'stationary" light is a red light, and conveniently comprises the existing brake lights fitted to most vehicles. The 'in motion' light is preferably of a contrasting colour, most desirably green. The lighting system may be actuated by being coupled, via a relay, to the ignition and the speedometer drive; but it may also be used in conjunction with other motion detecting devices such as a sensor on the drive transmission, a sensor connected to one of the wheels, or any moving part. The relay operates to actuate the 'in motion' light when motion is detected and conversely to actuate the 'stationary' light when motion is not detected. Preferably the lights will have the double filament bulbs of the first aspect of the invention so that if one filament burns out the light will not be extinguished completely, but will merely be reduced to half of its original intensity. For example, two filaments can be inserted in parallel (so as not to require additional terminal connections in the bulb holder socket, enabling the bulb to be used interchangeably with ordinary bulbs and not just with the system of the invention). A principal advantage of the system of the invention is that when motorists observe vehicle lights without the 'in-motion' light, particularly if the system includes high intensity 'stationary' lights, they know that there is a hazard ahead and can therefore act accordingly. CLAIMS

1. An incandescent lamp which comprises a glass bulb, which is either evacuated or filled with a neutral gas or gas mixture, a lamp base, capable of effecting engagement with an electrical lamp socket, and means within the bulbs for supporting a filament and connecting it to the base, characterised in that there are provided two or more filaments connected in parallel with one another.

2. A bulb as claimed in claim 1 in which the filaments are inserted into the lamp base in parallel so that additional terminal connections in the lamp socket are not required.

3. A bulb as claimed in either of claims 1 or 2 in which there are two filaments in parallel.

4. A lamp bulb substantially as hereinbefore particularly described.

5. A rear lighting system for vehicles comprising a light indicating that the vehicle is in motion.

6. A system as claimed in claim 5 actuated by being coupled, via a relay, to the ignition and the speedometer drive, a sensor on the drive transmission, a sensor connected to one of the wheels, or any moving part.

7. A system as claimed in either of claims 5 or 6 in which a relay operates to actuate an 'in-motion' light when motion is detected and conversely to actuate a 'stationary' light when motion is not detected.

8. A system as claimed in any of claims 5 to 7 in which the light is a light according to any of claims 1 to 4.