GB2224608A

GB2224608A - Discharge lamp operating circuit; revitalising dry batteries

Info

Publication number: GB2224608A
Application number: GB8824998A
Authority: GB
Inventors: Kenneth Alan Morecroft
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-10-25
Filing date: 1988-10-25
Publication date: 1990-05-09
Also published as: GB8824998D0

Abstract

An integrated circuit oscillator 1 operating at 3 to 20 KHz drives a power switching stage 3 connected to the primary winding of an output transformer 5, a secondary winding of the transformer being connected to one terminal only at each end of a gas discharge lamp 9. A resistor 2 between the oscillator 1 and switching stage 3 is adjustable for lamp dimming. The switching stage 3 may be a transistor, a Darlington transistor configuration, or a thyristor such as a triac. A push-pull switching stage may alternatively be provided. The circuit may also be used to revitalise a dry battery by connecting the battery to the transformer secondary in association with a diode and a neon bulb. <IMAGE>

Description

LIGHTING POTTER SOURCE This invention relates to apparatus used in operating a gas discharge tube from a D.C. source.

Gas discharge tubes otherwise known as "neon lamps" and flourescent tubes, are used in domestic and industrial lighting.

The present flourescent lighting tubes consist of a glass tube sealed at both ends having previously been filled ith neon, argon or other suitable gas and having two electrical connections on both ends and includes heating filaments at each end to heat the gas so an electrical arc is struc between the two electrodes of the tube.

A ballast is provided to limit the current consumption of the tube.

A starter which is a type of capacitor is used in conjunction with the ballast to provide sufficient discharge to strike an arc in the tube to allow electrons to floral between the electrodes thus producing light.

The ballast dissipates a large amount of heat and the power used in making this heat is wasted and the weight of the ballast is disadvantagous.

Ose of the objects of the invention is to provide improved apparatus for operating a gas discharge tube; and extending the life of the tube.

On the face of it the invention is an apparatus to run a gas discharge tube or bulb from a .C. C. source.

The apparatus consists of an adapted oscillator circuit with a high frequency output, the high frequency output being connected to a transistor circuit stage, which amplifies current and/or voltage which is fed to one end of the low tension winding of a suitable transformer, the other end of the low tension winding of the transformer being connected to the anode of the D.C.

power source. The high tension terminal(s) of the transformer is(are) connected to the terminals of the gas discharge tube.

A D.C. source voltage of between 6 volts and 24 volts is used to power the apparatus I2v or 24 volts being the preferred voltage.The gas discharge tube operating voltage bein ideally 240 volts A.C.

A suitable battery provides the source voltage although a transformer, rectifier and smoothing capacitor can supply the source voltage converting an A.C. mains input (typically 240 volts) to a 6 volt to 240 volt D.C. supply Discharge tubes commonly used are "flourescent lighting tubes" and "neon lights".

To light the flourescent tube a satisfactory trarzsformer having a low tension winding rated Ov to I5 volts and a high tension winding of 240 volts is driven by an amplifier and an oscillator outputting a frequency of between 3 kilohertz and 20 kilohertz and can be a sweeping frequency. However by choosing transformer and components other frequencies may be found suitable.

entailed description of the apparatus incorporating the invention follows 8(til reference to be made with the drawings. This apparatus has been chosen as an example to illustrate the invention.

The drawings are as follos:- Fig I is a circuit diagram incorporating the invention Fig 2 is a circuit diagram of a suitable D.C. source.

Fig I is a circuit diagram of apparatus suitable for operating a gas discharge tube from a D,C. supply,notably from the mains supply by using the power supply circuit in Fig 2, although a battery may be used as the D.C. supply for the apparatus.

The apparatus consists of an adapted oscillator circuit(I) which is designed to give an output signal of between 3 kilohertz and 20 kilohertz, the oscillator circuit being based on a 555 timer Integrated Circuit which is wired in an astable mode.

In the oscillator circuit(I) RI,R2 andCi are connected between the terminals of the integrated circuit as shown in Fig I to produce the frequency output required. Suitable values have been found to be < 1= 15 kilohm 2= I5 kilohm and CI= IO nanofarads.

The output of the oscillator circuit(I)is connected to a transistor circuit (3) by way of a variable resistor (2) and resistor R3. The purpose of --VkI (2) being to dim the light output of the gas discharge tube, a suitable value for VRI being 22 kilohms.

The resistor R3 is connected between the terminals of VRI (2) and TRI (3) to control the current and/or voltage to be output by the transistor (3).

The resistor R3 in the preferred circuit has a value of I00 ohms.

The emitter of the transistor (3) is connected to the negative or Ov terminal (I2) of the D.C. source. The collector of transistor (3) is connected to a terminal (4) -of a transformer 5)the connection (7) of the transformer (5) being connected to a positive D.C. source.When using the power supply in Fig 2 terminal (7) on the L.T. winding of the transformer (5) is connected to (28) V2+ D.C. supply. Shewn a battery is used as a D.C. source terminals (6) and(7) are both connected to the positive or anode of the battery (not shown) and terminals (I2) to the negative or cathode of the battery.

The low tension windings of the transformer (5) in the preferred circuit are rated at 6 volts and the high tension winding is rated 240 volts.

One of the 2 terminals of the high tension winding (IO) is connected to one terminal of the gas discharge tube (9) the remaining terminal of the high tension winding (IO) is connected to a capacitor (8) which is connected to the rezaining terminal of the gas discharge tube (9). The value of the capacitor (8) in the preferred circuit is I00 nanofarads.

The flourescent tube is rated at an operating voltage of between 80 volts and I80 volts A.C. depending on size, and may suitably be a commercially available flourescent tube of e.g. 80 watts (or as low as 8 watts).

Flease note that capacitor (8) may have to be omitted when using certain flourescent lamps with the apparatus.

single connection only is required at either end of the tube (9) and there no need for heater elements to be provided in the flourescent tube to help in starting the tube and no ballast is needed so eliminating heat loss.

It is also found that the tube may be driven into illumination by connecting one of the high tension outputs (IO) of the transformer (5) to one end of the tube (9) providing that the glass envelope or the other end of the tube is contacted by a person.

In an alternative configuration the output of the oscillator circuit (I) may be connected by suitable components to a thyristor or triac to drive the transformer.

R.F.I. suppression may be applied as necessary.

A push pull output may also be used in the apparatus.

An alternative to a battery D.C. source is the preferred mains power supply unit as shown in fig 2 as an example to illustrate a suitable supply. A preferred voltage of 240 volts A.C. is applied to the high tension terminals of a second transformer (20). With low tension outputs of between 6 and I2 volts for each winding (there being 2 winnings each of 6 volts to I2 volts) and are terminated thus:- terminals (22) and t23) are connected to a full wave bridge rectifier (24) rated 50 volts to 200 volts, the positive rail (27) being the first output D.C.source terminal (27). The negative rail (26) is the Ovolt D.C. source terminal. The second positive terminal (2I) is the second D.C. source (28).A smoothing capacitor (25) is connected between terminals (26) and (27). A smoothing capacitor (25) rated at 500 microfarad has been found to be satisfactory in the preferred circuit.

;leo connect the power supply in Fig 2 to the apparatus in Fig I the negative terminal (26) in Fig 2 is connected to terminals (I2) in Fig I. The positive terminal (27) in Fig 2 is connected to terminal (6) in Fig I.

The positive terinal (28) in Fig 2 is connected to terminal (7) in Fig I.

Where the D.C. source is derived from a mains supply as shown in Fig 2 the circuit in Fig I may be modified by replacing transistor TRI by a number of transistors in a darlington formation.

It has also been found that the apparatus shown in Fig I may be of use in revitalising dry batteries. In this format a rectifying diode is connected to one of the terminals from the high tension winding of the output transformer with a neon bulb connected to the other terminal on the high tension winding of the output transformer.

Claims

I. Apparatus for lighting a gas discharge tube from a D.C.

supply or suitable power supply wherein a variable resistor is used to allow dinr.inO of gas discharge tubes, and the output connections from the traasformer are connected to one terninal only on each end of the gas discharge tube.
2. Apparatus as claimed in claim I when a remote control receiver output is used to allow dimming.
3. Apparatus as claimed in claim I wherein a light dependent resistor is used to allow dimming.
4. Apparatus as claimed in claim I wherein a voltage dependent resistor is used to allow dimming.
5. Apparatus as claimed in claim I wherein a battery back up circuit is used to allow for mains failure.
6. Apparatus as claimed in claim I wherein a pulse detector circuit is used to allow mains control of dimming.

Amendments to the claims have been filed as follows CLAIM I A high frequency ballast unit for the ionization of the gas of fluorescent lamps and gas discharge tubes of 30 inches length and ore te normal illumination using only one electrode at each end of the tube. The high frequency ballast unit consists of a D.C. driven oscillator with a square wave cutout, the output having a fixed mark/ space ratio. The oscillator output is applied via a variable resistor to a transistor(s) which in turn is connected to the L.T. terminals of an inverter transformer of which the H.T. terminals are connected in series with a capacitor to the gas discharge tube.The D.C. supply to the high frequency ballast is in the form of an A.C. to D.C. converter.The inverter output transformer is driven at a higher voltage than the rating for the L.T. windings of the inverter transformer which causes magnetic fields in the transformer to give a more efficient output of the transformer to the tube.

CLAIM 2 Claim. as in claims I but where the value of the variable resistor is altered to allov; dimming of different size and ratings of tubes.

CLAIM 3 Claim as in claim I and 2 but where the output transistor(S) have built in current and voltage sensors which can be used to sense any adverse current or voltage conditions in the high frequency ballast unit.

CLAIM 4 Claim as in claim I but where the high frequency ballast has the AC mains to .C. power supply as an integral part of the circuit.

CLAIM 5 Claim as claimed in claims I ard 3 but where the output transistor(s) are replace by thyristors or triacs.