GB2269062A - Emergency lighting; Battery charging - Google Patents
Emergency lighting; Battery charging Download PDFInfo
- Publication number
- GB2269062A GB2269062A GB9315257A GB9315257A GB2269062A GB 2269062 A GB2269062 A GB 2269062A GB 9315257 A GB9315257 A GB 9315257A GB 9315257 A GB9315257 A GB 9315257A GB 2269062 A GB2269062 A GB 2269062A
- Authority
- GB
- United Kingdom
- Prior art keywords
- power
- lamp
- battery
- power supply
- transistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
- H02J9/062—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads
- H02J9/065—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads for lighting purposes
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/36—Controlling
- H05B41/38—Controlling the intensity of light
- H05B41/39—Controlling the intensity of light continuously
- H05B41/392—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Business, Economics & Management (AREA)
- Emergency Management (AREA)
- Circuit Arrangements For Discharge Lamps (AREA)
Abstract
The emergency lighting system has a fluorescent lamp connected to output terminals 36, 38 of an inverter 30 which is powered from a battery via a DC-DC converter 12, 14, and in order to reduce the warm-up time before the lamp becomes fully effective, the DC-DC converter initially boosts the input power to the inverter for a predetermined time to a level greater than that normally required to operate the lamp at normal brightness. The power boost is achieved by controlling the ON period duration of a switching transistor 12 by means including an R-C circuit 39, 40, 42, 40 in which a transistor 54 effectively gradually removes a capacitor 42 from the circuit so that the operating frequency of transistor 12 changes from 18 KHz to 36 KHz over an initial two minute period. The ON period duration of transistor 12 is also controlled to maintain light output as the battery voltage decreases. A battery charger has a switching converter in which an FET (76), (Fig 2), is turned on for a period inversely proportional to the main supply voltage so that the charging rate is independent of mains voltage fluctuations. An inductor (84) in series with the battery (72) sets the desired charge current. <IMAGE>
Description
LAMP CONTROL APPARATUS AND METHOD OF CONTROL
This invention relates to a lamp control apparatus and method of control, and especially to a lamp circuit for an emergency lamp fitting.
Emergency light fittings wherein battery power is provided for use in the event of mains power supply failure are known and are often provided in industrial or commercial premises, particularly for the illumination of escape routes. If mains power supply should be interrupted, for example due to a fire or other similar problems, safe routes out of the premises need to be adequately indicated for people therein.
Because such emergency lamp fittings need to operate independently of mains power supply they are normally powered by their own internal battery packs, with the fitting being provided with means operative to actuate the battery pack in the event of interruption of the mains power supply. Such battery packs may be rechargeable - drawing charging power from the mains supply when it is available.
Known emergency lamp circuits suffer from several disadvantages, namely that it may take a noticeable period of time (possibly up to 10-20 seconds) for the emergency lighting to become fully effective, and that when the battery packs are reaching the end of their life the effectiveness of the emergency lighting may be reduced.
The present invention aims to reduce some or all of the above problems.
Accordingly, in a first aspect the present invention provides a control circuit for an emergency lamp including power supply means for supplying electrical power from a battery to a lamp, the power supply means including first power control means operable to supply power to the lamp for a predetermined time period at a rate greater than the minimum
required by the lamp.
Preferably the predetermined time period is commencable
when the first power control means are activated so that power
is initially suppliable to the lamp at a rate greater than the
minimum required.
In this way a "boost" start period is provided and the
emergency lamp may have a minimum start up time between initial
operation and peak effectiveness, and it may be assured that
the lighting reaches adequate luminescence within the shortest
possible time.
The term lamp includes all forms of lighting e.g., inter
alia, fluorescent lamps and other lamps having a warm-up
characteristic.
Preferably, the first power control means includes a
switching transistor usable to control the power supplied to
the lamp, and the on-time of the transistor is adjustable to
adjust the rate of power supply. In a practical embodiment,
the switching transistor is controlled by one or more timing
capacitors and the timing capacitance is reducible at the end
of said predetermined time period so as to reduce the on-time
of the transistor.
Advantageously, the circuit includes a magnetic core
connectable between the battery and the first power control
means wherein the magnetic core is usable to store energy from
the power supply means and to subsequently transfer the stored
energy to the lamp. Thus, the power supply means, which may
include a converter section, can be considered to be that of a - "discontinuous boost converter". That is to say that all the
energy stored in the magnetic element is transferred to the
load before the magnetic element is allowed to store energy
once more.
The main switching transistor can be turned on for a fixed
period of time which may be determined by the battery terminal voltage. During this time energy is being stored in the magnetic core, with the amount of energy being determined by the on-time of the main switching transistor whose on-time may be inversely proportional to battery voltage (see below). Thus constant throughput power to the load and hence constant lamp brightness may be maintained.
At start up it may be desirable to double the power going into a lamp inverter part of the circuit. In the circuit this may be achieved by doubling the on-time of the main switching transistor, thereby doubling the amount of energy stored in the magnetic element. This double power at start up "boost" helps the lamp e.g. a fluorescent lamp, to strike and warms the lamp up quicker thus increasing lamp brightness. This is very desirable because in an emergency this would be the time when maximum illumination would be required for safe passage from a building etc.
Advantageously the converter comprises means to cause operation thereof at a predetermined frequency, and the circuit may further include a delay capacitor connected to a booster transistor operatively connected by a second capacitor to a timing circuit so that switching off the second capacitor has the effect of doubling the operational frequency of the converter.
After this initial boost period the lamp power may be reduced to normal running power and stabilised over the remaining battery discharge time by means of its control circuit.
The lamp output transformer may be optimised by impedance matching it to the expected group of fluorescent lamps, and this may greatly reduce the number of transformers otherwise required. The characteristic impedance of the groups of lamps may be determined by their struck voltage/current components. Therefore for maximum power transfer this gives the inverter transformer output impedance required.
In a second aspect the present invention provides a
control circuit including power supply means for supplying
electrical power from a battery to a lamp, the power supply
means including second power control means operable to control
the rate of power supply, wherein the duty cycle of the second
power control means is adjustable to compensate for variations
in the terminal voltage of the battery.
Thus as the battery approaches its end point i.e., becomes
close to discharged, the circuit compensates for the drop in
battery terminal voltage by means of its control circuit,
thereby extending the end point of the battery and maintaining
constant lamp brightness.
The second power control means may include or be included
in the first power control means of the first aspect of the
present invention.
Preferably the circuit includes a switching transistor usable to control the power supplied to the lamp, and the on
time of the transistor is adjustable to adjust the rate of
power supply.
In a practical embodiment the on-time of the switching
transistor is controlled by at least one timing capacitor and
the time taken for the timing capacitor(s) to charge is
adjustable according to the terminal voltage of
the battery, so that the on-time of the transistor is
adjustable to compensate for variations in said terminal
voltage.
In a third aspect, the present invention provides a
battery charging circuit for supplying power from a power
supply to a rechargeable battery, including third power control
means for controlling the rate of power supply, wherein the
duty cycle of the third power control means is adjustable to
compensate for variations in the voltage of the power supply.
Thus the battery charger may maintain the same charge current into the battery irrespective of mains input voltage range or fluctuations therein.
To accomplish this the battery charger is preferably arranged to include a transformer for storing energy from the power supply wherein the duty cycle of the third power control means is adjustable to maintain a substantially constant rate of energy storage in the transformer. The amount of energy stored may be held constant by allowing the supply current to flow for a time which is inversely proportional to the value of the supply voltage. In this way the time-current product remains constant.
Preferably the circuit includes current control means to supply a substantially constant current from the transformer to the battery.
In a preferred embodiment this is achieved by allowing a power transistor to conduct charge for a predetermined period, determined by the charging time of a capacitor which is fed via a resistor from a supply voltage. The result of this arrangement is that the charge received by the battery means is independent of the supply voltage and thus the battery charger is adaptable to any variation or fluctuation in input voltage range. This minimises power consumption, internal luminaire temperature and battery temperature. It also maximises battery life.
The constant current charger means that at high mains excursions (all nominal mains vary by +/- tolerance) the battery is still charged with the optimum amount, thereby minimising power dissipated in the circuit and minimising battery temperature and maximising battery life. i.e., The charger circuit only draws from the power supply the actual power that is required. Similarly the maintained circuit only applies the minimum power necessary to the lamp, whatever the mains. Therefore the temperature is minimised, again keeping battery life at a maximum.
The battery charger may further include a resistor which
defines a predetermined threshold value such that a voltage
preference circuit is established causing selective operation
of the lamp via the battery when the mains voltage falls below
a predetermined low threshold value. It may also restore mains
voltage supply to the lamp when a second higher threshold is
exceeded by the mains supply.
The invention may also provide an improved lamp circuit
which can be easily adapted to a range of battery voltages,
thereby allowing the flexibility of using many lamp sizes and
powers.
To accomplish this the charge circuit is arranged to give
a constant charge current irrespective of nominal battery
voltage. Additionally, during emergency operation, the
combined converter/inverter circuits demand a constant current
from the battery, again irrespective of normal battery voltage.
The invention will be described further by way of example
with reference to the accompanying drawings in which:
Fig. 1 is a circuit diagram of a first embodiment of the
invention including timing and inverting sections;
Fig. 2 is a circuit diagram of a charger circuit according
to-on aspect of the invention; and
Fig. 3 is a circuit diagram of modified charger circuit.
- Referring firstly to Fig. 1, a battery (not shown) is connected to the circuit at terminal 10 and to a mains
switching transistor 12 (Q3) via a magnetic core 14 having two
windings 16,18. In this condition the transistor 12 is held in
an "off" condition as no base current can flow. The
transistor's collector consequently rises to the battery
voltage level biasing a diode 20 in a forward direction. An
output capacitor 22 is hence charged up to the battery's
voltage minus the voltage drop due to diode 20.
This voltage is applied to an inverter section referred to generally by the reference 30 and including two transistors 32,34. The voltage applied is however too low to allow the invertor 30 to start up and the circuit is dormant and a fluorescent lamp (not shown) connected between terminals 36,38 is not energised.
Alternatively, when terminals 24 and 26 are connected to the battery a base current flows into the switching transistor 12 allowing a current to build up in a linear fashion in the first winding 16. This commences the charge period of a switching cycle during which energy is being stored in the magnetic core 14.
After a period of time determined by the product of R multiplied by C, being the Resistance and the Capacitance respectively of resistors 39,40 and time capacitors 42,44, the voltage on the base of a timing transistor 42,44, is turned on (0.65 volts nominal). At that time the transistor 46 is turned on which clamps the base voltage of the switching transistor 12 to zero volts thus turning the main switching transistor off again.
The voltage on the first winding 16 is therefore reversed and the voltage at the collector of the switching transistor rises to a high voltage. As this voltage collapses, the voltage on the second winding 18 reverses direction and a further diode 48 conducts thereby discharging the timing capacitors 42,44. This causes the timing transistor 46 to turn off allowing base current to flow into the mains switching transistor 12 via an inductor 50. This turns the switching transistor 12 "on" once more, which cycle is repeated in a self-oscillating manner at a frequency of approximately 18kHz.
In this embodiment the timing circuit 60 is set such that after approximately two minutes, the charge on boost capacitor 52 reduces to a point where a boost transistor 54 begins to turn off. This effectively removes one of the two timing capacitors 42 from the timing circuit 60 and halves the
capacitance thereof.
This removal happens gradually over a period of time and
is not visibly detectable. The effect of halving the timing
capacitance is to double the operating frequency of the
converter to approximately 36kHz. Thereby, the main switching
transistor 12 is turned "on" for only half its former period,
i.e. half of that the aforementioned 2 minute boost period.
The energy thus stored in the first winding 16 is halved
and therefore the energy passed to the inverter section 30 is
also halved resulting in the fluorescent lamp attached to the
terminals 36,38 running at a normal brightness.
This circuit further has the capacity to maintain lamp
brightness even when the battery is operating at a reduced
voltage. In this mode the time taken for the second timing
capacitor 44 to reach a base threshold of the timing transistor
46 is increased. This has the effect of increasing the "on" time of the main switching transistor 12 thereby increasing
energy stored in the first winding 16. A closed loop control
is formed compensating for reduced battery voltage across the
lamp terminals 36,38.
Turning now to Fig. 2, a charger circuit 70 according to a
further aspect of the invention delivers charge into a battery 7by storing energy in a transformer 74 and transferring its
energy to the battery in its second phase of operation. The
amount of energy stored is held constant by allowing a supply
current to flow for a time which is inversely proportional to
the value of the supply voltage. In this way, the time ~ current product will remain constant, thereby determining the
amount of energy stored in the transformer 74.
This operating characteristic is achieved by allowing a
power transistor 76 to conduct for a period determined by the
charging time of a capacitor 78. This capacitor is fed via a
resistor 80 from a supply equal to the peak value of supply
voltage and the conduction time of the power transistor 76 is again inversely proportional to the value of the supply voltage.
As the peak current value that flows in the power transistor 76 after a given conduction time, assuming a fixed value of transformer inductance, is proportional to the value of the supply voltage, both these effects cancel each other.
Therefore, the peak current in the power transistor 76, and therefore the energy stored in the transformer, remains the same. The result of this arrangement is that the charge received by the battery is independent of the actual supply voltage.
The batteries are fed with charge current from a secondary winding 82 on the transformer 74 which produces sufficient voltage to make battery voltage changes insignificant in comparison therewith. The same charge current is therefore maintained. Preferably a wattless dropper in a form of an inductor 84 is used to set the charge current to the desired value.
Due to the relatively long period of time taken to adjust to supply voltage variations, the charge remains fixed at a particular duty cycle across the sinusoidal variation of the income unsmoothed supply. Peak rectification of the supply by a diode 86 and a capacitor 88 ensure that the regulating circuit is fed from a source that changes with supply voltage yet remains constant during the short duration of a supply cycle.
This results in the charge drawing current proportional to the instantaneous value of the supply, and the average current taken by the charger remains sinusoidal so that the harmonic content of the supply amount is acceptable.
In Fig. 3 the charger circuit is modified to provide for self selection of mains failure changeover voltage threshold.
In this modification, a changeover and maintained control circuit 90 is altered such that capacitor 92 is charged to a negative value proportional to the mains supply voltage. The relative values of a resistor 77 in the inverter and further resistor 94 in the changeover control 90 determines at what specific voltage the mains switching transistor 12 switches and changes from battery to mains operation.
This switching operation is enhanced by a latch formed by a triac 96, which, once set in its conducting state by operation of the luminaire in the high range of 180-275 v AC, causes the changeover switch to operate at an elevated point appropriate to the nominal supply voltage in use. Operation of the luminaire from a mains supply voltage in the low range (99134 v AC) means the triac 96 is not set and the changeover switch remains at its default low operating points. The latch formed by the triac can be reset by disconnection of the batteries should it be desirable to clear the current changeover state.
The invention is not confined to foregoing details and variations being made thereto within the scope are with the invention.
Claims (15)
1. A control circuit for an emergency lamp, including power supply means for supplying electrical power from a battery to a lamp, the power supply means including first power control means operable to supply power to the lamp for a predetermined time period at a rate greater than the minimum required by the lamp.
2. A control circuit according to claim 1 wherein the predetermined time period is commencable when the first power control means are activated so that power is initially suppliable to the lamp at a rate greater than the minimum required.
3. A control circuit according to claim 1 or claim 2, wherein the first power control means include a switching transistor usable to control the power supplied to the lamp and the ontime of the transistor is adjustable to adjust the rate of power supply.
4. A control circuit according to claim 3 wherein the on-time of the switching transistor is controlled by one or more timing capacitors and timing capacitance is reducible at the end of said predetermined time period so as to reduce the on-time of the transistor.
5. A control circuit according to any one of the above claims including a magnetic core connectable between the battery and the first power control means wherein the magnetic core is usable to store energy from the power supply means and subsequently transfer the stored energy to the lamp.
6. A control circuit for an emergency lamp, including power supply means for supplying electrical power from a battery to a lamp, the power supply means including second power control means operable to control the rate of power supply; wherein the duty cycle of the second power control means is adjustable to compensate for variations in the terminal voltage of the battery.
7. A control circuit according to claim 6 wherein the second power control means includes a switching transistor usable to control the power supplied to the lamp and the on-time of the transistor is adjustable to adjust the rate of power supply.
8. A control circuit according to claim 7 wherein the on-time of the switching transistor is controlled by at least one timing capacitor and the time taken for the timing capacitor(s) to charge is adjustable according to the terminal voltage of the battery, so that the on-time of the transistor is adjustable to compensate for variations in said terminal voltage.
9. A control circuit substantially as any one embodiment herein described with reference to figure 1 of the accompanying drawings.
10. An emergency lamp fitting including a control circuit according to any one of the above claims operatively connected to a lamp.
11. A battery charging circuit for supplying power from a power supply to a rechargeable battery, including third power control means for controlling the rate of power supply, wherein the duty cycle of the third power control means is adjustable to compensate for variations in the voltage of the power supply.
12.- A battery charging circuit according to claim 11 including a a transformer for storing energy from the power supply wherein the duty cycle of the third power control means is adjustable to maintain a substantially constant rate of energy storage in the transformer.
13. A battery charging circuit according to claim 12 including current control means to supply a substantially constant current from the transformer to the battery.
14. A battery charging circuit substantially as herein described with reference to figures 2 and 3 of the accompanying drawings.
15. An emergency lamp fitting including a battery charging circuit according to any one of claims 11 to 14, a control circuit according to any one of claims 1 to 9 , and a lamp.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB929215808A GB9215808D0 (en) | 1992-07-24 | 1992-07-24 | An improved lamp fitting |
Publications (3)
Publication Number | Publication Date |
---|---|
GB9315257D0 GB9315257D0 (en) | 1993-09-08 |
GB2269062A true GB2269062A (en) | 1994-01-26 |
GB2269062B GB2269062B (en) | 1996-05-22 |
Family
ID=10719271
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB929215808A Pending GB9215808D0 (en) | 1992-07-24 | 1992-07-24 | An improved lamp fitting |
GB9315257A Expired - Lifetime GB2269062B (en) | 1992-07-24 | 1993-07-23 | Lamp control apparatus and method of control |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB929215808A Pending GB9215808D0 (en) | 1992-07-24 | 1992-07-24 | An improved lamp fitting |
Country Status (1)
Country | Link |
---|---|
GB (2) | GB9215808D0 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0813285A2 (en) * | 1996-06-12 | 1997-12-17 | GEWISS S.p.A. | Emergency lighting device with optimized energy consumption |
GB2337644A (en) * | 1998-05-22 | 1999-11-24 | Mackwell Electronics Limited | Starting and warming up of fluorescent lamps |
WO2013179134A1 (en) | 2012-05-30 | 2013-12-05 | Fulham Co., Ltd. | Ballast with battery backup |
EP2141967A3 (en) * | 2008-06-30 | 2014-12-17 | Osram-Sylvania Inc. | False failure prevention circuit in emergency ballast |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4029993A (en) * | 1975-12-18 | 1977-06-14 | General Electric Company | Two level inverter circuit |
GB1508130A (en) * | 1975-07-22 | 1978-04-19 | Thorn Electrical Ind Ltd | Emergency lighting systems |
GB2197760A (en) * | 1986-10-31 | 1988-05-25 | Fano Int Ltd | Emergency lighting unit |
US5004953A (en) * | 1989-06-30 | 1991-04-02 | The Bodine Company | Emergency lighting ballast for compact fluorescent lamps with integral starters |
GB2243503A (en) * | 1990-04-28 | 1991-10-30 | Koito Mfg Co Ltd | Lighting circuit for vehicular discharge lamp |
GB2245436A (en) * | 1990-05-30 | 1992-01-02 | Solar Wide Ind Ltd | Solar-powered fluorescent lamp-drive circuit |
-
1992
- 1992-07-24 GB GB929215808A patent/GB9215808D0/en active Pending
-
1993
- 1993-07-23 GB GB9315257A patent/GB2269062B/en not_active Expired - Lifetime
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1508130A (en) * | 1975-07-22 | 1978-04-19 | Thorn Electrical Ind Ltd | Emergency lighting systems |
US4029993A (en) * | 1975-12-18 | 1977-06-14 | General Electric Company | Two level inverter circuit |
GB2197760A (en) * | 1986-10-31 | 1988-05-25 | Fano Int Ltd | Emergency lighting unit |
US5004953A (en) * | 1989-06-30 | 1991-04-02 | The Bodine Company | Emergency lighting ballast for compact fluorescent lamps with integral starters |
GB2243503A (en) * | 1990-04-28 | 1991-10-30 | Koito Mfg Co Ltd | Lighting circuit for vehicular discharge lamp |
GB2245436A (en) * | 1990-05-30 | 1992-01-02 | Solar Wide Ind Ltd | Solar-powered fluorescent lamp-drive circuit |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0813285A2 (en) * | 1996-06-12 | 1997-12-17 | GEWISS S.p.A. | Emergency lighting device with optimized energy consumption |
EP0813285A3 (en) * | 1996-06-12 | 1999-05-06 | GEWISS S.p.A. | Emergency lighting device with optimized energy consumption |
GB2337644A (en) * | 1998-05-22 | 1999-11-24 | Mackwell Electronics Limited | Starting and warming up of fluorescent lamps |
GB2337644B (en) * | 1998-05-22 | 2002-07-17 | Mackwell Electronics Ltd | Fluorescent Lamps for Emergency Lighting Applications |
EP2141967A3 (en) * | 2008-06-30 | 2014-12-17 | Osram-Sylvania Inc. | False failure prevention circuit in emergency ballast |
WO2013179134A1 (en) | 2012-05-30 | 2013-12-05 | Fulham Co., Ltd. | Ballast with battery backup |
EP2856846A4 (en) * | 2012-05-30 | 2016-04-20 | Fulham Co Ltd | Ballast with battery backup |
US9954390B2 (en) | 2012-05-30 | 2018-04-24 | Fulham Co., Ltd. | Ballast with battery backup |
Also Published As
Publication number | Publication date |
---|---|
GB2269062B (en) | 1996-05-22 |
GB9315257D0 (en) | 1993-09-08 |
GB9215808D0 (en) | 1992-09-09 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
PE20 | Patent expired after termination of 20 years |
Expiry date: 20130722 |