GB2171858A - Improvements in lighting systems - Google Patents

Abstract

An AC Mains operated electrical circuit including means (2) eg. transverter for converting the domestic supply frequency at the distribution board to a higher frequency of the order of 750HZ to 5kHZ and a fluorescent lamp operative at that frequency. The lamp per se embodies a conventional bayonnet or screw fitting and incorporates a capacitor ballast (5) and rectifying voltage multiplier starter (7). <IMAGE>

Description

SPECIFICATION Improvements in lighting systems This invention relates to electrical supply systems for lighting circuits and lamps for use therein.

It is well known that fluorescent lamps are much more energy efficient than tungsten filament lamps, and simple plug-in replacements for such tungsten lamps tend to be large, heavy and expensive because they need to contain ballast and starting equipment, much of which, furthermore, is discarded at the end of the life of the lamp.

It is an object of this invention to mitigate this drawback.

In accordance with the present invention from one aspect there is provided an a.c.

mains operated electrical circuit including means for converting the domestic supply frequency to a higher frequency of the order of 750HZ to 5kHZ and a fluorescent lamp operative at that frequency.

From another aspect there is provided a fluorescent lamp operative at a frequency of the order of 750HZ to 5kHZ, the lamp embodying a conventional bayonet or screw fitting and incorporating a capacitor ballast and rectifying voltage multiplier starter.

The means by which the domestic supply frequency is increased is preferably a transverter, in which the mains supply is converted to D.C. and then inverted, eg. by a transistor invertor, to manifest the higher frequency referred to. Typically the higher frequency referred to will be 1kHZ. At 1kHZ a capacitor ballast is small and lightweight and the ionisation characteristic of gas tubes is such that a good waveform is retained. The voltage multiplier employed may be of the Cockroft-Walton design utilizing small lightweight capacitors and diodes, thus the lamp itself is small, lightweight and inexpensive-the lamp unit contains no iron, as with a choke starter.

It will be appreciated that significant savings in energy costs can be achieved by the use of this invention, the pay-back time for the cost of the inversion equipment at the distribution board being very short even with normal domestic consumption, indeed the luminous efficiency of gas tubes is better at 1kHZ than at 50HZ. The system is furthermore hazard free, since if a conventional tungsten lamp is plugged into a 'converted' circuit it works normally and if a capacitor ballast lamp in accordance with this invention is plugged into a conventional 50HZ supply socket it simply fails to light, it is not hazardous. In order that the invention may be fully understood one embodiment thereof will now be described, by way of example, with reference to the accompanying drawing.The drawing (Fig. 1) schematically illustrates a distribution board having a transverter 2 for converting the 50HZ mains supply into a 1kHZ output for supplying a number of lamp socket outlets only one (3) is shown. The lamp unit 4 includes a capacitor ballast 5 in series with a fluorescent tube 6, to maintain a degree of consistency in the current through the tube, with a rectifying voltage multiplier 7 of the Cockroft-Walton type connected, with a high value resistor 8, across the tube as a starter.

The voyage multiplier 7 is essentiaily poor in regulation which in the event of failure of the capacitator 5 is an advantage since the poor regulation of the d.c. supply limits direct current flow through the mains supply and the high current flow through the lamp due to capacitor failure results in protective fuse failure. Normally this capacitor 5 restrains the flow of direct current from the unit 7 through the mains supply.

Although the invention has been described with reference to the particular embodiment illustrated, it is to be understood that various modifications may readily be made without departing from the scope of this invention. For example, the values of the components given are only illustrative for the particular embodiment and of course other supply and distribution frequencies may readily be accommodated; however, frequencies higher than the range quoted might tend to interfere with other equipment in the vicinity and frequencies below the range will adversely affect the size and value of the ballast capacitor thus destroying the size and weight advantage of the lamp.

1. An a.c. mains operated electrical circuit comprising means for converting the domestic supply frequency to a higher frequency of the order of 750HZ to 5KHZ, and a fluorescent lamp operative at that frequency.

2. A circuit according to claim 1, in which the supply frequency is converted by a transverter.

3. A circuit according to claim 1 or claim 2, in which the higher frequency is of the order of 1KHZ.

4. A circuit according to any one of claims 1 to 3, in which the lamp embodies a capacitor ballast and rectifying voltage multiplier starter and incorporates a conventional bayonet or screw fitting.

5. An a.c. mains operated electrical circuit substantially as herein described and illustrated.

6. A domestic fluorescent lamp operative in a circuit as claimed in any one of claims 1 to 5.

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

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in lighting systems This invention relates to electrical supply systems for lighting circuits and lamps for use therein. It is well known that fluorescent lamps are much more energy efficient than tungsten filament lamps, and simple plug-in replacements for such tungsten lamps tend to be large, heavy and expensive because they need to contain ballast and starting equipment, much of which, furthermore, is discarded at the end of the life of the lamp. It is an object of this invention to mitigate this drawback. In accordance with the present invention from one aspect there is provided an a.c. mains operated electrical circuit including means for converting the domestic supply frequency to a higher frequency of the order of 750HZ to 5kHZ and a fluorescent lamp operative at that frequency. From another aspect there is provided a fluorescent lamp operative at a frequency of the order of 750HZ to 5kHZ, the lamp embodying a conventional bayonet or screw fitting and incorporating a capacitor ballast and rectifying voltage multiplier starter. The means by which the domestic supply frequency is increased is preferably a transverter, in which the mains supply is converted to D.C. and then inverted, eg. by a transistor invertor, to manifest the higher frequency referred to. Typically the higher frequency referred to will be 1kHZ. At 1kHZ a capacitor ballast is small and lightweight and the ionisation characteristic of gas tubes is such that a good waveform is retained. The voltage multiplier employed may be of the Cockroft-Walton design utilizing small lightweight capacitors and diodes, thus the lamp itself is small, lightweight and inexpensive-the lamp unit contains no iron, as with a choke starter. It will be appreciated that significant savings in energy costs can be achieved by the use of this invention, the pay-back time for the cost of the inversion equipment at the distribution board being very short even with normal domestic consumption, indeed the luminous efficiency of gas tubes is better at 1kHZ than at 50HZ. The system is furthermore hazard free, since if a conventional tungsten lamp is plugged into a 'converted' circuit it works normally and if a capacitor ballast lamp in accordance with this invention is plugged into a conventional 50HZ supply socket it simply fails to light, it is not hazardous. In order that the invention may be fully understood one embodiment thereof will now be described, by way of example, with reference to the accompanying drawing.The drawing (Fig. 1) schematically illustrates a distribution board having a transverter 2 for converting the 50HZ mains supply into a 1kHZ output for supplying a number of lamp socket outlets only one (3) is shown. The lamp unit 4 includes a capacitor ballast 5 in series with a fluorescent tube 6, to maintain a degree of consistency in the current through the tube, with a rectifying voltage multiplier 7 of the Cockroft-Walton type connected, with a high value resistor 8, across the tube as a starter. The voyage multiplier 7 is essentiaily poor in regulation which in the event of failure of the capacitator 5 is an advantage since the poor regulation of the d.c. supply limits direct current flow through the mains supply and the high current flow through the lamp due to capacitor failure results in protective fuse failure. Normally this capacitor 5 restrains the flow of direct current from the unit 7 through the mains supply. Although the invention has been described with reference to the particular embodiment illustrated, it is to be understood that various modifications may readily be made without departing from the scope of this invention. For example, the values of the components given are only illustrative for the particular embodiment and of course other supply and distribution frequencies may readily be accommodated; however, frequencies higher than the range quoted might tend to interfere with other equipment in the vicinity and frequencies below the range will adversely affect the size and value of the ballast capacitor thus destroying the size and weight advantage of the lamp. CLAIMS

1. An a.c. mains operated electrical circuit comprising means for converting the domestic supply frequency to a higher frequency of the order of 750HZ to 5KHZ, and a fluorescent lamp operative at that frequency.

2. A circuit according to claim 1, in which the supply frequency is converted by a transverter.

3. A circuit according to claim 1 or claim 2, in which the higher frequency is of the order of 1KHZ.

4. A circuit according to any one of claims 1 to 3, in which the lamp embodies a capacitor ballast and rectifying voltage multiplier starter and incorporates a conventional bayonet or screw fitting.

5. An a.c. mains operated electrical circuit substantially as herein described and illustrated.

6. A domestic fluorescent lamp operative in a circuit as claimed in any one of claims 1 to 5.