Indian Patents. 252341:METHOD FOR OPERATING A LUMINARY AND CORRESPONDING LUMINARY

Title of Invention	METHOD FOR OPERATING A LUMINARY AND CORRESPONDING LUMINARY
Abstract	A ballast for fluorescent tubes and the use thereof for producing fluorescent tube lighting fixtures using a novel gas excitation mode in which light is generated by means of controlled poulses leading to an increased power efficiency, with a data collection and transmission functionality, are disclosed.

Full Text	This invention relates in general to fluorescent lighting luminaries and more particularly to a new operating mode of fluorescent tubes in a luminary. A fluorescent tube is a discharge glass bulb whose inner side is covered with fluorescent layer that reacts by emitting visible light when excited by ultraviolet radiation sourced from the gas medium that fills the bulb. Such a gas contains very low pressure mercury vapor. Generally, a ballast is serial impedance that stabilizes the current in the fluorescent tube, Usually, as mentioned above, simple inductors are used as ballasts because they operate as reactances with small losses when serial coupled to the tube. Some magnetic ballasts provide more features than serial impedance for the tube like for instance transformers for increasing voltage levels. In the goal of energy saving, other types of ballast have been developed applying solutions that use semiconductors. This more sophisticated design brought also possibilities to use operating frequencies higher than conventional 50/60 Hz from main electric supply. Frequency in the range of 25 kHz has been employed. Examples of electronic Ballast design are described in patents WO 00/21342 published April 2000, WO 99/05889 published February 1999, WO 97/33454 published September 1997, WO 99/60825 published November 1999, WO 98/34438 published August 1998 and EP-0-955794-A2 published November 1999. Exposed solutions relate mainly to current savings and life time improvement of fluorescent tubes by optimizing different parameters such as waveform, voltage amplitude...etc. American patent N°6,262,542 discloses an electronic Ballast including a lamp driving circuit having a pulse width modulated signal generator to control the duty cycle of the square wave form current flowing through the lamp. What is interesting to point out is not the current flowing through the lamp but moreover a control signal that is included into the circuitry for monitoring the lamp operation. It is also to note that lamp coupling method as described in patent N°6,262,542 forces the current to flow through the cathode's filaments. American patent N°4,902,939 discloses a driving circuitry dedicated to avoid light flickering when witching on and off the power from minimum to maximum variable lighting intensity. Obviously the objective is not to increase the power efficiency of fluorescent lamps. The major difference with the invention is that the driving voltage described in patent N°4,902,939 consists of sinusoidal waveforms directly derived from main power supply. Although existing electronic ballasts intend to bring energy savings through their operating modes of fluorescent tubes as well as to extend life time of fluorescent lamps, considerable research and development remain to be done in this domain. The invention discloses a particular brand new operating mode for fluorescent tubes that reduces current drawn by the lamp for 40% to 50% regarding to conventional magnetic ballasts mostly installed in fluorescent lighting fixtures. In addition, life time of tubes driven by the invention increases for up to 3 times and light emitted does not flicker or suffer stroboscopic effect. Above benefits are obtained by operating fluorescent luminaries the way disclosed in the invention, such luminaries including one or more standard fluorescent tubes that contain mercury vapor gas and heating filament cathodes at ends, a fixture that integers proper holding and connection devices for fluorescent tubes and one ballast for driving the fluorescent tubes. Ballast operating mode differs from existing systems by the fact that it uses voltage pulses applied to the electrodes for exciting the fluorescent gas, such pulses consisting of short time non periodic voltage levels separated by variable duration dead times. In a preferred implementation, the ballast generates pulses composed of perfectly alternate voltage amplitudes. The ballast is also able to control the timing of pulses as well as the dead times by using programmed algorithms. Another benefit can result in monitoring dead times between pulses from real time samplings of the current in the tube. Special coupling installed in tube's connections are controlled by the ballast to short cut cathode's filaments on right time, in order to cancel any current flow through it and so avoid losses of voltage. Ignition of conduction in the tube can profit of temporarily connecting a capacitor that seriously increases voltage at ends of every fluorescent tube and is disconnected as soon as the conduction establishes. The ballast modifies the current in the tube after the conduction happens in order to reduce the current in the capacitor to the minimum before disconnecting it. In a preferred implementation, the ballast can communicate with an control unit through a wired or wireless link for performance monitoring and remote failure detection. In another aspect, the invention also relates to luminaries that fit in with multiple standard fluorescent tubes containing mercury vapor gas and heating cathodes located at both ends, and consisting of a fixture including tube connection/holding devices and a ballast for operating fluorescent tubes. The luminary according to the invention differs from existing systems by the fact that it uses voltage pulses applied to the electrodes for exciting the fluorescent gas, such pulses consisting of short time non periodic voltage levels separated by variable duration dead times. In a particularly preferred implementation form of the invention, the ballast can be advantageously adapted to generate pulses composed of alternate voltage amplitude. The ballast is also able to control the timing of pulses as well as the dead times by using programmed algorithms. In an even more preferred implementation form, the ballast is adapted to monitor dead time between pulses from real time samplings of the current that crosses gas in the fluorescent tubes. Fluorescent tube's connectors include special couplings that can be activated by the ballast to short cut the cathode's filaments on right time, in order to cancel any current flow through it and so avoid losses of voltage. A capacitor can be connected to increase the voltage at ends of every fluorescent tube allowing to ignite the conduction through the gas, and can be disconnected as soon as the conduction establishes. In this case, the ballast can be adapted further to modify the current in the tube after the conduction happens in order to reduce the current in the capacitor to the minimum before disconnecting it. It is particularly appropriate when many luminaries are used in a single place that the ballasts have on line or wireless link with a central control unit, for performance monitoring and remote failure detection. In some implementation, the ballast includes two parts, the first being a standard ballast operating at normal main power supply voltage, and the second being specifically designed to operate with the non periodic short pulses as described in the invention. The invention is also presented under a third form, namely as a voltage supply signal for the fluorescent tubes in normal operating condition, which signal being formed of pulses characterized by including non periodic short time voltage levels separated by variable length dead times. Preferably, the signal pulses are of alternative nature i.e. the signal includes equal amplitudes of positive and negative polarity. The invention will be developed more in detail below, by means of examples of implementation form, and it will refers to the diagrams attached, where: - figure 1 represents a simplified traditional diagram of a fluorescent tube with a magneto-inductive ballast and a starter, - figure 2 represents a comparison between a conventional magneto-inductive ballast and the new ballast according to the present invention, - figure 3 shows schematically how the new ballast according to the present invention is installed in an existing luminary, - figure 4 shows schematically how a set of luminaries can interconnect in a network for remote monitoring. Figure 1 in appendix represents the simplest shape of a magneto-inductive type ballast in series with a fluorescent tube, in which the electric main voltage supplies the tube with a frequency of 50 or 60 Hz. This kind of ballast with possibly some minor evolutions, are mostly used in today luminaries. Although some manufacturers are seeking to market new electronic ballasts since a while, luminaries equipped with such electronic ballasts have higher costs that significantly restrain a broad diffusion of these technologies. The present invention characterizes a new kind of electronic ballast different from existing systems by the fact that it is intended to replace the conventional magnetic ballast in existing luminaries without need of removing the original magnetic ballast when installing the ballast from the invention. Figure 2 schematically represents the action of the new ballast designed with the invention. The operation of a fluorescent tube equipped with conventional magnetic ballast is illustrated in the upper part of figure 2. It shows that the excitation of mercury atoms by the collision of an electron flowing between the pre-heating electrodes occurs randomly and relatively seldom (cf the only collision represented inducing light radiation). At the opposite, the bottom of figure 2 represents the action of the new ballast working with voltage levels of a very different nature. The latter induces much more collisions and consequently excites more mercury atoms. This phenomenon is illustrated on the figure by three collisions leading to higher ultraviolet radiation. The efficiency increases from the standard level of 65 lumens per unit of power (Watt) for the conventional magnetic ballast to a value of 120 lumens per Watt by using the new ballast from the invention. The main point concerning the impact of the new ballast on the lighting efficiency is that the ignition voltage applied to a fluorescent tube, i.e. from one electrode to the other, is a high frequency alternative voltage consisting in short time non periodic pulses separated by variable duration dead times. This special voltage waveform is generated so that every dead time (time of no voltage) is monitored from real time samplings of the current flow crossing the tube. The current intensity depends on a resonance effect in the gas that significantly increases the number of collisions between electrons and mercury atoms. By using this resonance phenomenon, the power consumption can be considerably reduced. The high frequency voltage is used to be just sufficient to maintain the resonance and the voltage level is void as long as the resonance phenomenon maintains the light emission. The current measurement reveals instantaneously the resonance effect, allowing the microprocessor included in the ballast to monitor the voltage waveform in real time. The voltage pulses are preferably of completely alternative form, i.e. using voltages of same amplitudes and opposite polarity, and are non periodic events. The waveform is real time controlled through programmed algorithms, embedded in the ballast's microprocessor. These algorithms refer preferably to measurements of the current crossing the plasma in the tube for controlling particularly the dead time duration between pulses according to the value of the current level. The current is continuous real time sampling. As appearing in figure 3, an existing luminary is equipped with a new kit of components, especially designed to fit the luminary. This new kit includes in addition to the electronic ballast from the invention, new tube connectors that are inserted in place of the original plugs. The old components are left in place (i.e. magnetic ballast and starter) and the new ballast is connected to the main power supply bus by using quick coupling devices. The new connectors include preferably special coupling devices the new ballast can activated to short cut the filaments of the cathodes in order to void any current flow through them and thus cancel losses of voltage. To ignite conduction in the fluorescent tube, a capacitor is briefly connected in parallel with the tube in order to increase the voltage between the electrodes. As soon as conduction is produced through the mercury vapor, the capacitor is disconnected. The ballast adapts the current through the mercury vapor once conduction occurs, in a way that current crossing the capacitor is reduced to the minimum before removing the capacitor. The new operating mode of fluorescent tube as described is based on the principle aiming to increasing the number of collisions between electrons and mercury atoms in molecular excitation of plasma medium where a new voltage waveform improves the lighting energy efficiency. The high frequency alternate signal that is used comprises accurate monitored dead time phases that contribute to reduce energy consumption to the minimum. The process is optimized by constant monitoring of the current flowing through the tube and continuous regulation of the dead time, according to the programmed functions that supervise the conditions and physical parameters coupling voltage variations and collision rate between electrons and mercury atoms. The program is included in an electronic device placed in the new ballast that is installed in luminaries. This electronic device looks like a "macrochip" electronic component including all processes of controlling and monitoring functions. The electronic device consists of a controller (central processing unit) which integrates the software in a secured and protected chip also containing coded functions which make it available only under precise conditions, in order to avoid any undesired access to the operation and program. It should be noted that frequencies and voltage waveforms are in a much higher range of frequency than the main supply. In addition, it should be underlined that the variations of voltage are non sinusoidal and not periodic. The voltage variation includes dead time phases in which current in the tube is void. Because of this particular operating mode, it is not necessary that some current crosses the filaments of electrodes for maintaining the flow of electrons in the tube. Because of appearance of a resonance phenomenon increasing the number of collisions between electrons generated by cathodes and mercury atoms in the gas, the operating mode according to the invention as stated above, reduces the operating temperature and improves electronic ballast reliability. Optimal operation thanks to control pre-heating of cathodes and specific excitation mode during ignition of conduction of the vapor whatever the temperature in the tube. The nominal running mode is thus reached gradually, as the resonance phenomenon maintained by the process stabilizes. During this phase of progressive transformation which requires a few minutes, the current crossing the tube increases, as well as the emission of light, by successive steps. At the end of this phase, the phenomenon of resonance is stable according to the specific environmental conditions. Current decreases gradually and reaches a minimum average value after approximately 15 minutes. Thanks to the use of the procedure according to the invention, the temperature of the electrodes can be lowered by more than 40° C, which has a significant incidence over the lifespan of the tube. Figure 4 shows how a greater number of luminaries, each of them integrating the new ballast, is connected via a special communication bus to a central control unit. This unit can be local or remote, as shown on figure 4. In this example, a wireless connection in the form of SMS messages using GSM is used. In this type of control unit, the performance of the lighting system of a site can be recorded and the operation be permanently and remotely monitored in case of a breakdown. This makes it possible to provide to the users statistics and reports of precise operations statistics and reports stating amongst other things the energy consumption while making it possible to intervene more quickly when maintenance is necessary. FIG1 is a diagram describing the principle of construction and operation of a single fluorescent tube luminary. A flux of electrons, crossing the tube between the two electrodes placed at each end, excites mercury atoms and produces ultraviolet radiation. These electrodes consist of electron thermo-emissive filaments (called pre heating Cathodes) that must heat to incandescent. The alternative main current voltage is used to supply power to the cathodes through a high inductive coil (called Ballast) included to the circuit, that limits the current drawn by the low impedance ionized gas to an acceptable value. Igniting the conduction through the gas requires a special device (called Starter) connecting the heating filaments directly one to the other, in parallel with the gas medium (see Fig.1, low section). The starter may consist of a filament bulb including a switch reacting to temperature opened at normal temperature. When the power is applied to the circuit, the current starter bulb lights on and internal temperature goes up rapidly while the cathodes of the fluorescent tube are incandescent. When the temperature is high enough, the switch closes, short cutting the starter which rapidly decreases in temperature and thus opens again the switch. Interrupting suddenly the current induces a high voltage surge at coil's outputs (self induction effect) igniting conduction between the two cathodes, through the mercury vapor heated by the incandescent filaments. From this point, the starter is no more activated as long as the conduction of the vapor remains. The filaments of the cathodes stay incandescent due to their construction and position that drive a part of the current crossing the tube to flow through their surface also hit by mercury ions that help to maintain temperature by dissipating collision energy. As conduction is ignited and current stabilizes, tube's impedance decreases significantly. Due to its value of impedance at operating frequency of the main power, the ballast coil ensures proper current limitation. Such a system is defined as "magneto-inductive ballast". However, some evolutions exist in ballast technology that improve the simple description above, and stated in figure 1. WE CLAIM: 1. Method for operating a luminary for fluorescent tubes, said luminary adapted to receive a number of standard fluorescent tubes that comprise mercury vapor gas and pre-heating electrodes at ends, comprising a fixture that comprises proper holding and connection devices for the fluorescent tubes and one ballast (New Ballast) for driving the fluorescent tubes, characterized in that the ballast applies a voltage to the electrodes for exciting the fluorescent tubes, which is composed solely of non periodic voltage pulses separated by non-voltage intervals of variable duration. 2. Operating method according to claim 1, characterized in that the ballast (New Ballast) produces voltage pulses of alternative form. 3. Operating method according to claim 1, characterized in that the ballast (New Ballast) controls the voltage signals as well as the non-voltage intervals by means of a programmed algorithm. 4. Operating method according to claim 1, characterized in that the ballast (New Ballast) controls each non-voltage interval duration according to real time samplings of the current crossing the gas in the fluorescent tubes. 5. Operating method according to claim 1, characterized in that the special couplings (Special Couplings) of connection/fixation of the fluorescent tubes are activated by the ballast (New Ballast) in order to short cut the filaments of the electrodes of the fluorescent tubes in such a way as to cancel the current crossing through them and to thus avoid voltage losses. 6. Operating method according to claim 1, characterized in that conduction through the gas of the fluorescent tubes is ignited by the temporary connection of a capacitor (Capacitor) making it possible to increase the voltage between the electrodes of each fluorescent tube and that this capacitor is disconnected as soon as the conduction is obtained. 7. Operating method according to claim 6, characterized in that the ballast (New Ballast) modifies the current level crossing the gas in such way that the current level crossing the capacitor is reduced to a minimum before the disconnection of the capacitor (Capacitor). 8. Operating method according to claim 1, characterized in that the ballast communicates with a remote control unit (Operator Headquarter) through a wired or wireless link for performance monitoring of the ballast and for remote failure detection. 9. Luminary for fluorescent tubes, said luminary adapted to receive a number of standard fluorescent tubes that contain mercury vapor gas and electrodes at ends, comprising fixture that comprises proper holding and connection devices for fluorescent tubes and one ballast for driving the fluorescent tubes characterized in that the ballast (New Ballast) comprises circuits for controlling a voltage applied to the ends of the fluorescent tubes, in the form of non-periodic voltage pulses separated by non-voltage intervals of variable duration. 10. Luminary for fluorescent tubes according to claim 9, characterized in that the ballast (New Ballast) is adapted to produce voltage pulses in an alternative form. 11. Luminary for fluorescent tubes according to claim 9, characterized in that the ballast (New Ballast) produces the voltage signals as well as the non-voltage intervals by means of programmed algorithms. 12. Luminary for fluorescent tubes according to claim 9, characterized in that the ballast (New Ballast) is adapted for controlling each non-voltage interval duration according to real time samplings of the current crossing through the gas of the fluorescent tubes. 13. Luminary for fluorescent tubes according to claim 9, characterized in that the holdings of connection/fixings of the fluorescent tubes comprise special couplings (Special Couplings) is able to be activated by the ballast (New Ballast) to short cut the electrodes filaments of the fluorescent tubes in order to cancel the crossing current. 14. Luminary for fluorescent tubes according to claim 9, characterized in that a capacitor (Capacitor) can be connected in order to increase the voltage between the electrodes of each fluorescent tube in order to start conduction through the gas, said capacitor (Capacitor) is disconnected as soon as the conduction is obtained. 15. Luminary for fluorescent tubes according to the claim 14, characterized in that the ballast (New Ballast) is adapted to modify the current crossing through the gas of the fluorescent tube when conduction is obtained, in such a way that the current in the capacitor (Capacitor) is reduced to the minimum before the disconnection of said capacitor. 16. Luminary for fluorescent tubes according to claim 9, characterized in that the ballast has a wire or wireless connection enabling him to communicate with a remote control unit (Operator Headquarter) for performance monitoring of the ballast and for remote failure detection. 17. Luminary for fluorescent tubes according to claim 9, characterized in that the ballast includes two parts; the first (Conventional magnetic Ballast) is a standard ballast working with the main sector voltage and the second (New Ballast) is a specifically assembled part to work with the non-periodic pulses.

Full Text

This invention relates in general to fluorescent lighting luminaries and more
particularly to a new operating mode of fluorescent tubes in a luminary.
A fluorescent tube is a discharge glass bulb whose inner side is covered with
fluorescent layer that reacts by emitting visible light when excited by ultraviolet
radiation sourced from the gas medium that fills the bulb. Such a gas contains very
low pressure mercury vapor.
Generally, a ballast is serial impedance that stabilizes the current in the fluorescent
tube, Usually, as mentioned above, simple inductors are used as ballasts because
they operate as reactances with small losses when serial coupled to the tube. Some
magnetic ballasts provide more features than serial impedance for the tube like for
instance transformers for increasing voltage levels.
In the goal of energy saving, other types of ballast have been developed applying
solutions that use semiconductors. This more sophisticated design brought also
possibilities to use operating frequencies higher than conventional 50/60 Hz from
main electric supply. Frequency in the range of 25 kHz has been employed.
Examples of electronic Ballast design are described in patents WO 00/21342
published April 2000, WO 99/05889 published February 1999, WO 97/33454
published September 1997, WO 99/60825 published November 1999, WO 98/34438
published August 1998 and EP-0-955794-A2 published November 1999. Exposed
solutions relate mainly to current savings and life time improvement of fluorescent
tubes by optimizing different parameters such as waveform, voltage amplitude...etc.
American patent N°6,262,542 discloses an electronic Ballast including a lamp driving
circuit having a pulse width modulated signal generator to control the duty cycle of
the square wave form current flowing through the lamp. What is interesting to point
out is not the current flowing through the lamp but moreover a control signal that is
included into the circuitry for monitoring the lamp operation. It is also to note that

lamp coupling method as described in patent N°6,262,542 forces the current to flow
through the cathode's filaments.
American patent N°4,902,939 discloses a driving circuitry dedicated to avoid light
flickering when witching on and off the power from minimum to maximum variable
lighting intensity. Obviously the objective is not to increase the power efficiency of
fluorescent lamps. The major difference with the invention is that the driving voltage
described in patent N°4,902,939 consists of sinusoidal waveforms directly derived
from main power supply.
Although existing electronic ballasts intend to bring energy savings through their
operating modes of fluorescent tubes as well as to extend life time of fluorescent
lamps, considerable research and development remain to be done in this domain.
The invention discloses a particular brand new operating mode for fluorescent tubes
that reduces current drawn by the lamp for 40% to 50% regarding to conventional
magnetic ballasts mostly installed in fluorescent lighting fixtures.
In addition, life time of tubes driven by the invention increases for up to 3 times and
light emitted does not flicker or suffer stroboscopic effect.
Above benefits are obtained by operating fluorescent luminaries the way disclosed in
the invention, such luminaries including one or more standard fluorescent tubes that
contain mercury vapor gas and heating filament cathodes at ends, a fixture that
integers proper holding and connection devices for fluorescent tubes and one ballast
for driving the fluorescent tubes. Ballast operating mode differs from existing
systems by the fact that it uses voltage pulses applied to the electrodes for exciting
the fluorescent gas, such pulses consisting of short time non periodic voltage levels
separated by variable duration dead times.
In a preferred implementation, the ballast generates pulses composed of perfectly
alternate voltage amplitudes. The ballast is also able to control the timing of pulses
as well as the dead times by using programmed algorithms. Another benefit can
result in monitoring dead times between pulses from real time samplings of the
current in the tube. Special coupling installed in tube's connections are controlled by
the ballast to short cut cathode's filaments on right time, in order to cancel any
current flow through it and so avoid losses of voltage. Ignition of conduction in the
tube can profit of temporarily connecting a capacitor that seriously increases voltage
at ends of every fluorescent tube and is disconnected as soon as the conduction
establishes. The ballast modifies the current in the tube after the conduction
happens in order to reduce the current in the capacitor to the minimum before
disconnecting it.
In a preferred implementation, the ballast can communicate with an control unit
through a wired or wireless link for performance monitoring and remote failure
detection.
In another aspect, the invention also relates to luminaries that fit in with multiple
standard fluorescent tubes containing mercury vapor gas and heating cathodes
located at both ends, and consisting of a fixture including tube connection/holding
devices and a ballast for operating fluorescent tubes.
The luminary according to the invention differs from existing systems by the fact that
it uses voltage pulses applied to the electrodes for exciting the fluorescent gas, such
pulses consisting of short time non periodic voltage levels separated by variable
duration dead times.
In a particularly preferred implementation form of the invention, the ballast can be
advantageously adapted to generate pulses composed of alternate voltage
amplitude. The ballast is also able to control the timing of pulses as well as the dead
times by using programmed algorithms.
In an even more preferred implementation form, the ballast is adapted to monitor

dead time between pulses from real time samplings of the current that crosses gas
in the fluorescent tubes.
Fluorescent tube's connectors include special couplings that can be activated by the
ballast to short cut the cathode's filaments on right time, in order to cancel any
current flow through it and so avoid losses of voltage.
A capacitor can be connected to increase the voltage at ends of every fluorescent
tube allowing to ignite the conduction through the gas, and can be disconnected as
soon as the conduction establishes. In this case, the ballast can be adapted further
to modify the current in the tube after the conduction happens in order to reduce the
current in the capacitor to the minimum before disconnecting it.
It is particularly appropriate when many luminaries are used in a single place that the
ballasts have on line or wireless link with a central control unit, for performance
monitoring and remote failure detection.
In some implementation, the ballast includes two parts, the first being a standard
ballast operating at normal main power supply voltage, and the second being
specifically designed to operate with the non periodic short pulses as described in
the invention.
The invention is also presented under a third form, namely as a voltage supply
signal for the fluorescent tubes in normal operating condition, which signal being
formed of pulses characterized by including non periodic short time voltage levels
separated by variable length dead times. Preferably, the signal pulses are of
alternative nature i.e. the signal includes equal amplitudes of positive and negative
polarity.
The invention will be developed more in detail below, by means of examples of
implementation form, and it will refers to the diagrams attached, where:
- figure 1 represents a simplified traditional diagram of a fluorescent tube with a
magneto-inductive ballast and a starter,
- figure 2 represents a comparison between a conventional magneto-inductive
ballast and the new ballast according to the present invention,
- figure 3 shows schematically how the new ballast according to the present
invention is installed in an existing luminary,
- figure 4 shows schematically how a set of luminaries can interconnect in a network
for remote monitoring.
Figure 1 in appendix represents the simplest shape of a magneto-inductive type
ballast in series with a fluorescent tube, in which the electric main voltage supplies
the tube with a frequency of 50 or 60 Hz. This kind of ballast with possibly some
minor evolutions, are mostly used in today luminaries. Although some manufacturers
are seeking to market new electronic ballasts since a while, luminaries equipped
with such electronic ballasts have higher costs that significantly restrain a broad
diffusion of these technologies.
The present invention characterizes a new kind of electronic ballast different from
existing systems by the fact that it is intended to replace the conventional magnetic
ballast in existing luminaries without need of removing the original magnetic ballast
when installing the ballast from the invention.
Figure 2 schematically represents the action of the new ballast designed with the
invention. The operation of a fluorescent tube equipped with conventional magnetic
ballast is illustrated in the upper part of figure 2. It shows that the excitation of
mercury atoms by the collision of an electron flowing between the pre-heating
electrodes occurs randomly and relatively seldom (cf the only collision represented

inducing light radiation).
At the opposite, the bottom of figure 2 represents the action of the new ballast
working with voltage levels of a very different nature. The latter induces much more
collisions and consequently excites more mercury atoms. This phenomenon is
illustrated on the figure by three collisions leading to higher ultraviolet radiation. The
efficiency increases from the standard level of 65 lumens per unit of power (Watt) for
the conventional magnetic ballast to a value of 120 lumens per Watt by using the
new ballast from the invention.
The main point concerning the impact of the new ballast on the lighting efficiency is
that the ignition voltage applied to a fluorescent tube, i.e. from one electrode to the
other, is a high frequency alternative voltage consisting in short time non periodic
pulses separated by variable duration dead times.
This special voltage waveform is generated so that every dead time (time of no
voltage) is monitored from real time samplings of the current flow crossing the tube.
The current intensity depends on a resonance effect in the gas that significantly
increases the number of collisions between electrons and mercury atoms. By using
this resonance phenomenon, the power consumption can be considerably reduced.
The high frequency voltage is used to be just sufficient to maintain the resonance
and the voltage level is void as long as the resonance phenomenon maintains the
light emission. The current measurement reveals instantaneously the resonance
effect, allowing the microprocessor included in the ballast to monitor the voltage
waveform in real time.
The voltage pulses are preferably of completely alternative form, i.e. using voltages
of same amplitudes and opposite polarity, and are non periodic events. The
waveform is real time controlled through programmed algorithms, embedded in the
ballast's microprocessor.

These algorithms refer preferably to measurements of the current crossing the
plasma in the tube for controlling particularly the dead time duration between pulses
according to the value of the current level. The current is continuous real time
sampling.
As appearing in figure 3, an existing luminary is equipped with a new kit of
components, especially designed to fit the luminary. This new kit includes in addition
to the electronic ballast from the invention, new tube connectors that are inserted in
place of the original plugs. The old components are left in place (i.e. magnetic ballast
and starter) and the new ballast is connected to the main power supply bus by using
quick coupling devices.
The new connectors include preferably special coupling devices the new ballast can
activated to short cut the filaments of the cathodes in order to void any current flow
through them and thus cancel losses of voltage.
To ignite conduction in the fluorescent tube, a capacitor is briefly connected in
parallel with the tube in order to increase the voltage between the electrodes. As
soon as conduction is produced through the mercury vapor, the capacitor is
disconnected. The ballast adapts the current through the mercury vapor once
conduction occurs, in a way that current crossing the capacitor is reduced to the
minimum before removing the capacitor.
The new operating mode of fluorescent tube as described is based on the principle
aiming to increasing the number of collisions between electrons and mercury atoms
in molecular excitation of plasma medium where a new voltage waveform improves
the lighting energy efficiency. The high frequency alternate signal that is used
comprises accurate monitored dead time phases that contribute to reduce energy
consumption to the minimum.

The process is optimized by constant monitoring of the current flowing through the
tube and continuous regulation of the dead time, according to the programmed
functions that supervise the conditions and physical parameters coupling voltage
variations and collision rate between electrons and mercury atoms.
The program is included in an electronic device placed in the new ballast that is
installed in luminaries. This electronic device looks like a "macrochip" electronic
component including all processes of controlling and monitoring functions. The
electronic device consists of a controller (central processing unit) which integrates
the software in a secured and protected chip also containing coded functions which
make it available only under precise conditions, in order to avoid any undesired
access to the operation and program.
It should be noted that frequencies and voltage waveforms are in a much higher
range of frequency than the main supply. In addition, it should be underlined that the
variations of voltage are non sinusoidal and not periodic. The voltage variation
includes dead time phases in which current in the tube is void. Because of this
particular operating mode, it is not necessary that some current crosses the
filaments of electrodes for maintaining the flow of electrons in the tube.
Because of appearance of a resonance phenomenon increasing the number of
collisions between electrons generated by cathodes and mercury atoms in the gas,
the operating mode according to the invention as stated above, reduces the
operating temperature and improves electronic ballast reliability.
Optimal operation thanks to control pre-heating of cathodes and specific excitation
mode during ignition of conduction of the vapor whatever the temperature in the
tube. The nominal running mode is thus reached gradually, as the resonance
phenomenon maintained by the process stabilizes. During this phase of progressive
transformation which requires a few minutes, the current crossing the tube
increases, as well as the emission of light, by successive steps. At the end of this

phase, the phenomenon of resonance is stable according to the specific
environmental conditions. Current decreases gradually and reaches a minimum
average value after approximately 15 minutes.
Thanks to the use of the procedure according to the invention, the temperature of
the electrodes can be lowered by more than 40° C, which has a significant incidence
over the lifespan of the tube.
Figure 4 shows how a greater number of luminaries, each of them integrating the
new ballast, is connected via a special communication bus to a central control unit.
This unit can be local or remote, as shown on figure 4. In this example, a wireless
connection in the form of SMS messages using GSM is used. In this type of control
unit, the performance of the lighting system of a site can be recorded and the
operation be permanently and remotely monitored in case of a breakdown. This
makes it possible to provide to the users statistics and reports of precise operations
statistics and reports stating amongst other things the energy consumption while
making it possible to intervene more quickly when maintenance is necessary.
FIG1 is a diagram describing the principle of construction and operation of a single
fluorescent tube luminary. A flux of electrons, crossing the tube between the two
electrodes placed at each end, excites mercury atoms and produces ultraviolet
radiation. These electrodes consist of electron thermo-emissive filaments (called pre
heating Cathodes) that must heat to incandescent. The alternative main current
voltage is used to supply power to the cathodes through a high inductive coil (called
Ballast) included to the circuit, that limits the current drawn by the low impedance
ionized gas to an acceptable value.
Igniting the conduction through the gas requires a special device (called Starter)
connecting the heating filaments directly one to the other, in parallel with the gas
medium (see Fig.1, low section). The starter may consist of a filament bulb including
a switch reacting to temperature opened at normal temperature. When the power is
applied to the circuit, the current starter bulb lights on and internal temperature goes
up rapidly while the cathodes of the fluorescent tube are incandescent. When the
temperature is high enough, the switch closes, short cutting the starter which rapidly
decreases in temperature and thus opens again the switch. Interrupting suddenly the
current induces a high voltage surge at coil's outputs (self induction effect) igniting
conduction between the two cathodes, through the mercury vapor heated by the
incandescent filaments. From this point, the starter is no more activated as long as
the conduction of the vapor remains. The filaments of the cathodes stay
incandescent due to their construction and position that drive a part of the current
crossing the tube to flow through their surface also hit by mercury ions that help to
maintain temperature by dissipating collision energy.
As conduction is ignited and current stabilizes, tube's impedance decreases
significantly. Due to its value of impedance at operating frequency of the main
power, the ballast coil ensures proper current limitation. Such a system is defined as
"magneto-inductive ballast".
However, some evolutions exist in ballast technology that improve the simple
description above, and stated in figure 1.
WE CLAIM:
1. Method for operating a luminary for fluorescent tubes, said luminary adapted to receive a number of
standard fluorescent tubes that comprise mercury vapor gas and pre-heating electrodes at ends,
comprising a fixture that comprises proper holding and connection devices for the fluorescent tubes
and one ballast (New Ballast) for driving the fluorescent tubes, characterized in that the ballast applies
a voltage to the electrodes for exciting the fluorescent tubes, which is composed solely of non periodic
voltage pulses separated by non-voltage intervals of variable duration.
2. Operating method according to claim 1, characterized in that the ballast (New Ballast) produces
voltage pulses of alternative form.
3. Operating method according to claim 1, characterized in that the ballast (New Ballast) controls the
voltage signals as well as the non-voltage intervals by means of a programmed algorithm.
4. Operating method according to claim 1, characterized in that the ballast (New Ballast) controls each
non-voltage interval duration according to real time samplings of the current crossing the gas in the
fluorescent tubes.
5. Operating method according to claim 1, characterized in that the special couplings (Special
Couplings) of connection/fixation of the fluorescent tubes are activated by the ballast (New Ballast) in
order to short cut the filaments of the electrodes of the fluorescent tubes in such a way as to cancel the
current crossing through them and to thus avoid voltage losses.
6. Operating method according to claim 1, characterized in that conduction through the gas of the
fluorescent tubes is ignited by the temporary connection of a capacitor (Capacitor) making it possible
to increase the voltage between the electrodes of each fluorescent tube and that this capacitor is
disconnected as soon as the conduction is obtained.
7. Operating method according to claim 6, characterized in that the ballast (New Ballast) modifies the
current level crossing the gas in such way that the current level crossing the capacitor is reduced to a
minimum before the disconnection of the capacitor (Capacitor).
8. Operating method according to claim 1, characterized in that the ballast communicates with a
remote control unit (Operator Headquarter) through a wired or wireless link for performance
monitoring of the ballast and for remote failure detection.
9. Luminary for fluorescent tubes, said luminary adapted to receive a number of standard fluorescent
tubes that contain mercury vapor gas and electrodes at ends, comprising fixture that comprises proper
holding and connection devices for fluorescent tubes and one ballast for driving the fluorescent tubes
characterized in that the ballast (New Ballast) comprises circuits for controlling a voltage applied to
the ends of the fluorescent tubes, in the form of non-periodic voltage pulses separated by non-voltage
intervals of variable duration.
10. Luminary for fluorescent tubes according to claim 9, characterized in that the ballast (New Ballast)
is adapted to produce voltage pulses in an alternative form.
11. Luminary for fluorescent tubes according to claim 9, characterized in that the ballast (New Ballast)
produces the voltage signals as well as the non-voltage intervals by means of programmed algorithms.
12. Luminary for fluorescent tubes according to claim 9, characterized in that the ballast (New Ballast)
is adapted for controlling each non-voltage interval duration according to real time samplings of the
current crossing through the gas of the fluorescent tubes.
13. Luminary for fluorescent tubes according to claim 9, characterized in that the holdings of
connection/fixings of the fluorescent tubes comprise special couplings (Special Couplings) is able to
be activated by the ballast (New Ballast) to short cut the electrodes filaments of the fluorescent tubes
in order to cancel the crossing current.
14. Luminary for fluorescent tubes according to claim 9, characterized in that a capacitor (Capacitor)
can be connected in order to increase the voltage between the electrodes of each fluorescent tube in
order to start conduction through the gas, said capacitor (Capacitor) is disconnected as soon as the
conduction is obtained.
15. Luminary for fluorescent tubes according to the claim 14, characterized in that the ballast (New
Ballast) is adapted to modify the current crossing through the gas of the fluorescent tube when
conduction is obtained, in such a way that the current in the capacitor (Capacitor) is reduced to the
minimum before the disconnection of said capacitor.
16. Luminary for fluorescent tubes according to claim 9, characterized in that the ballast has a wire or
wireless connection enabling him to communicate with a remote control unit (Operator Headquarter)
for performance monitoring of the ballast and for remote failure detection.
17. Luminary for fluorescent tubes according to claim 9, characterized in that the ballast includes two
parts; the first (Conventional magnetic Ballast) is a standard ballast working with the main sector
voltage and the second (New Ballast) is a specifically assembled part to work with the non-periodic
pulses.