CA2162889A1 - System and method for distributing power to gas discharge lamps - Google Patents
System and method for distributing power to gas discharge lampsInfo
- Publication number
- CA2162889A1 CA2162889A1 CA 2162889 CA2162889A CA2162889A1 CA 2162889 A1 CA2162889 A1 CA 2162889A1 CA 2162889 CA2162889 CA 2162889 CA 2162889 A CA2162889 A CA 2162889A CA 2162889 A1 CA2162889 A1 CA 2162889A1
- Authority
- CA
- Canada
- Prior art keywords
- power
- circuit
- lighting
- gas discharge
- output
- 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.)
- Abandoned
Links
Classifications
-
- 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
-
- 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
- H05B39/00—Circuit arrangements or apparatus for operating incandescent light sources
-
- 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
- H05B41/24—Circuit arrangements in which the lamp is fed by high frequency ac, or with separate oscillator frequency
- H05B41/245—Circuit arrangements in which the lamp is fed by high frequency ac, or with separate oscillator frequency for a plurality of lamps
Landscapes
- Circuit Arrangements For Discharge Lamps (AREA)
Abstract
A system and method for reducing installation costs of gas discharge lignting provides a central AC-DC power converter (302) which is connected into an AC lighting circuit and thereafter transmits DC power through the power distribution wires (306) to individual lighting locations (305). DC-powered resonant inverter driving circuits (304) are provided and connected to the DC power where lighting is desired. The system is particularly useful in retrofitting existing buildings or individual light fixtures which use incandescent lamps with more energy-efficient fluorescent metal halide, and high pressure sodium types of gas discharge lamps.
Description
W O 94/27419 ~CTrUS94/05144 - 1 - 2 ~ 6288~
SYSTEM AND METHOD FOR DISTRIBUTING
POWER TO GAS DISCHARGE LAMPS
Field of thP ]nvention 5The present invention relates to driving circuits for gas discharge lamps and methods for constructing and inct~lling these circuits.
R~ rolln~ of thP InvPntion Gas discharge lamps, such as fluorescent lamps, high pressure sodium lamps, and metal halide lamps, require a driving circuit, or ballast, to operate properly. In rec_nt years, 10electronic ballasts have gained--popularity over m~gnP~tic ballasts because of their higher el~Pctric~l power conversion effi~iency. The effi~ iPncy improvement in using an electronic ballast rather than a m~gnPtic ballast can exceed 30% depentling on the lamp and ballast combin~tion used. An electronic ballast based on resonant inverter CilCuiLl~ has been described in U.S. Patent No. 4,933,605, ~csignp-d to the ~ccign~e of the present application.
15Electronic ballasts have typically been more expensive than m~gnetic baLlasts. To reduce overall costs, a single ballast is often wired to multiple bulbs and particularly to multiple fixtures, as shown in the prior art Py~mrle of Figure 1. A master lamp fixture 102 and a slave lamp fixture 104 share a ballast 106 located in master lamp fixture 102. L~mp 107 in slave lamp fixture 104 is driven by signals carried on connP~tion wires 108 which 20transmit high frequency driving signals from ballast 106 to lamp 107. However, such "master ballast" arrangements have not been used to drive a large number of slave fixtures. The inventor has studied this type of circuit and has determined that the sharing of ballasts between multiple fixtures is inherently limited by the following factors:
1. A single ballast can supply power only to a limited number of lamps;
252. The connP~tion wires 108 supplying current from the ballast to individual lamps in these prior art systems carry high-frequency alternating current. Long wire runs will add cignifi~nt in~uct~n- e and c~r~cit~nce between the lamp and ballast, affecting their operation and efficiPncy; and 3. High-frequency connection wires 108 must be shielded to reduce propagation of30electrom~gnPtic intelr~rence, so that inct~ tion of extensive networks of high frequency lines is made more difficult and expensive.
Often, inc~n~escent or less-efficient discharge lamp units throughout a building are replaced to obtain energy savings. Typically, as shown in Figure 2, lighting fixtures in buildingc are powered by AC current through wires 203 routed through single or multiple wo 94/27419 PcTIus94losl44 distribution boxes 202. Distribution boxes 202 connect wires 203 to fixtures 205. There are two known processes for repl ~cement of fixtures 205 with more energy-efficient lighting.
In the first process, the eYicting fixtures 205 are removed and new gas-discharge fixtures, preferably fluorescent fixtures, are directly substituted, each fixture including a ballast.
5 Re~us~ of the problems associated with high-frequency power lines, it has not been considered feasible to retrofit an existing building with centralized ballasts.
ln a second method, a gas discharge adapter, preferably a fluorescent adapter, may be inst~lled in place of each inc~ndescent bulb. A variety of these adapters are commercially available. Generally, these devices screw into a standard in~ndrscent bulb socket of a light 10 fixture or table lamp to form electrical connections with the AC power. The adapters consist of a small fluorescent ballast opeld~ g from the AC socket, and a low-wattage fluorescent lamp, typically 9 to 15 watts, which provides greater light output çffirienry than the replaced inr lndeccent bulb. The appliç~tionc of fluolescent adapters have been limited by the required size of the ballast circuit housing. In some cases these adapter are to o large to fit 15 into a given d~r~r~tive fixture. ln other cases, such dS in chAn~1rlirrs~ the protruding ballast housing at the bulb base would cignifir Intly detract from the appo~ ce of the fixture.
Another problem with these adapters is the gen~or~tion of ele.;L.o... ~gnptic il~te~ nce.
Adequate sul,l,ression of in~.~rt;nce g~onler~tçd by these devices usually ~ i~s ~ition~il col-lponents which further increases the size of the devices.
Therefore, the inventor believes that there is a need for a system which provides effirient electronic ballast circuits for a large number of gas discharge lamps at a reduced capital cost. It is further believed that there is a need for a more ly~conAhly-priced method of l~LIol;lling eYicting b~ ingc and fixtures with highly-effiçirnt ballast and lamp units.
Summary of the Invention Therefore, it is a general object of the present invention to provide an efficiçnt electronic ballast circuit which will drive a large number of gas discharge lamps.
Another general object of the present invention is to provide a novel system in which a high voltage DC front end provides DC current to a plurality of electronic inverters which drive gas discharge lamps.
It is another general object of the present invention to provide a novel method for retrofitting existing bnil~ingc with highly-efficient b~ cted gas discharge lamps.
A further object of the present invention is to provide method of l~;~lorlt~ing existing buildings with gas discharge lamps in which PYicting AC wiring is used to transmit high W O 94/27419 ~ 1 6 2 8 8 9 PCT~US94/05144 voltage DC power from a newly inct~llçd central ballast front end to a plurality of electronic inverters providing driving signals for gas discharge lamps.
Another object of the present invention is to provide new and improved gas discharge lamp ballasts with reduced physical size.
S Yet another objcct of the present invention is to provide appaldtlls and methods for refitting eYicting lighting fLxtures, such as çh~n~çliPrs, with compact fluo~escent light bulbs.
Further objects of the invention will be app~rent to those skilled in the art upon review of the specification, drawings, and claims.
These objects are achieved in the present invention by providing a central AC-DCpower converter which is conn~l-P~ into an AC lighting circuit and thereafter transmits DC
power through the power distribution wires to individual lighting locations. DC-powered resonant inverter driving circuits are provided and conn~ctPvd to the DC power where liEhting is desired. The system is particularly useful in ,cLn~r~ g eyicting b~ ingc or individual light fixtures which use int~n~psc~pnt lamps with more energy-efficient fluo,eseent lights.
The invention described herein produces signifi~nt adv~nt~gP~s~ including: (1) asavings of at least 33% in ballast cost; (2) no change in the eyicting building wiring syst~m, (3) a single front end can be used to power ballasts in mnltiple zones or rooms, (4) one f~ -jnt end can be used to operate single or multiple lamps, and (5) Plimin~tion of ele~ l~n~otic inlelr~re.lce ~c~i~tP~ with long high frequency current carrying wires.
Rrief Description of thP Drawin~c Figure 1 is a ~i~gram of a prior art m~ster-slave fLxture;
Figure 2 is a block schçm~tic diagram of a conventional AC electri~l lighting power distribution system;
Figure 3 is a block sch~Pm~tic diagram of the mot~ified lighting power distribution system according to the present invention;
Figure 4 is a s~hpm~tic diagram of the driver end used in each fixture in Figure 3;
Figure S is a schem~tic diagram of the front end provided in the distribution box as shown in Figure 3;
Figure 6 is a flowchart showing a method of retrofitting an ç~icting fixture system with the system of the present invention; and Figure 7 is a block schematic diagram showing the method according to the present invention as applied to a multibulb in~n(lescçnt lighting fixture.
DPt~ile~ Description of the Preferre~ l~mbodiments Wo 94127419 ~ l ~i 2 8 8 g PcTIuss4/05l44 The present invention will be described herein in terms of prel~ d embodiments using fluorescent lamps. However, it will be understood that the invention is not limited to the specific embo~lim~ntc ~ic~lose~ herein. The embo~imentc ~ic~ losPA may be modified by those skilled in the art within the scope of the invention, which is defined by the claims.
The present invention relates to ballast circuits for gas discharge lamps, such as fluorescent lamps. A convention~l electronic ballast, as disclosed in the inventor's U.S.
Patent Nos. 4,933,605 and 4,864,482 which are incorporated herein by reference, converts conventional AC line voltage to high voltage DC, which is then switched at high frequencies by an inverter circuit to produce an excitation signal for the associated gas discharge lamp.
In a first prcfcllcd embo~iment of the present invention, as shown in Figure 3, a new type of ballast system is constructed by providing two physically se~ dtc types of co,l,ponents: a front end 302 which produces DC power, and a plurality of driver ends 304 each inçlu~ing a l- sonant inverter circuit for prod~cing a lamp driving signal from the DC
power of the front end 302. In the e",bod;,.,Pnt shown in Figure 3, this system is provided in a building ele~ric~l distribution system, where it may be inct~lled as original equipment or as part of a rcLlofi~ g process. As shown in Figure 3, AC power from a circuit breaker panel 301 is conn~ l~ by wires 203, typically in~lu~ing a white ~neutral" wire and a black or red "hot" wire. Wires 203 run through a conduit 204 to a distribution box 202. In a convention~l AC electrical distribution system, these wires would branch from the distribution box 202 to provide AC power to various lighting fixtures in the circuit.
However, according to the present invention, wires 203 are connected as power inputs to a front end 302 located in distribution box 202.
In the front end 302 according to the present invention, 50 or 60 cycle AC power is converted into a high voltage DC power output of up to 600 volts, preferably by sPmicon~luctor rectifiers in a manner which will be described in detail with reference to Figure 5. Front end 302 is preferably made with a higher power output capability than the DC power available in a conventicn~l fluo~s~nt ballast, such as for example 2000 watts.
The front end can be conveniently built in a housing with ~imencionc of 3 inches by 4 inches x 1.5 inches. If compactly decigned, the front end 302 can easily be incPlled in a distribution box 202. The front end 302 is preferably a highly regulated power supply which active monitors and shapes the DC output. Preferably, the front end 302 may also correct power factors, shape power line harmonics, and protect against inrush ~ulren~s.
The output voltage of front end 302 may vary depending on the l~uirelllen~ of the system. Preferably, for use with a 120 volt AC system, the DC output voltage will be at W O 94/27419 2 ~ 6 2 ~ 8 9 PCTrJS94/05144 250 volts DC, and preferably 350 VDC. If 277 VAC is used as an input, 500 VDC output may be produced. Finally, if 440 VAC is provided as the power input, 580 VDC output may be produced. It is desirable to keep the output voltage less than 600 VDC to stay within the power rating of standard building wiring.
As shown in Figure 3, the DC output of front end 302 is conne~teA by wires 306 to a plurality of fixtures 305, where the DC power supplies a plurality of driver ends 304. An electronic dimmer circuit 320 may optionally be connect-P-d to driver ends 304.
Wires 306 may preferably be identic~l to wires 203, that is, conventional ins~ teA
household or office power distribution wires. F.1P~tric~l codes in the U.S., and the ratings of existing wiring, typically permit this wiring to carry up to either 600V AC or 600V DC
in a standard condllit Therefore, wires 306 may be wires design-PA for AC current, and in fact may be wires that were originally inst~llPA to carry AC current to lighting fixtures but have now been conl-~P~led to the front end 302 to carry DC current.
Thus, lamp fixtures 30S are powereA through single or multiple distribution boxes 202 which connect the single front end 302 to the plural driver ends 304 at the fixtures 305.
Each driver end 304 receives the DC output gener~tçA by front end 302. In the driver end, this DC power is converted into a high frequency (usually higher than 20 kHz) source which supplies power to one or more lamps, by any of a variety of known circuits.
The pr~rell~d 2000-watt front end 302 according to the present invention can safely drive at least 20 driver ends 304 which may be de~ign~A to operate two 40 watt, four-foot T-12 lamps.
The circuits provided in the driver end 304 are the inverter ~vilcl~ing circuits which produce an eYcit~ti~ n signal for the gas discharge lamps 107. Since no power con~itiQning or conversion circuits are provided in driver ends 304, driver ends 304 can be made in a more compact and less expensive manner as co.l.~J~ed to a convPntion~l gas discharge ballast. Preferably, the driver end circuit is a resonant inverter circuit as ~i~clos~ in U.S.
Patent Nos. 4,933,605 or 4,864,482. The cirwlit,y of driver end 304 will be discussed in greater detail with reference to Figure 4.
Driver ends 304 may take the form of conventional hard wired gas discharge ballasts having wire connectiQnc for power input, or driver ends 304 may be constructed with a bulb socket base 311 to provide power input terminals. The bulb socket base 311 threadedly connects with a standard light bulb socket 309. Driver ends 304 which are constructed with bulb socket bases 311 may also be provided with a mounting for a lamp 107, which may be W O 94/27419 ~ 89 PCTrUS94/05144 a compact, low voltage fluorescent lamp, circular fluorescent lamp, or other app,o~liate design for use in retrofitting existing lighting fixtures. Driver ends 304 of this type can be a~ro~,iately used when increased efficiency is desired in the lighting circuit but repl~cemPnt of eYisting in~ndescPnt lighting fixtures is not desired. Through the use of bulb-mount 5 driver ends, inc~ndescent lighting can be converted to fluorescent lighting using the system of the present invention while minimi7ing inct~ tion costs and avoiding replacement of the entire fixture.
While the bulb mount driver ends of this type are physically similar in appearance to known fluorescent inc~ndescent repl~cemPnt devices, they are different from these prior 10 devices in that they operate from DC current received through the bulb base, and in that the driver end circuit 304 is smaller and less obtrusive since it in~ des no AC-DC converter The driver end 304 may also be provided with a riimming circuit to control the brightnP$c of lamp 107, as rlic~losPd in the inventor's coppn~ing U.S. Patent Applic~tionc~
Serial No. 07/410,480 filed .September 21, 1989, titled "Electronic Dimming Metho~s for Solid State Electronic R~ $tcn~ and Serial No. 07/789,268 filed November 8, 1991, both inco-l ol~ted herein by ~Çe,~nce. In general, as .licclosp~ in more detail in these parent applications, a pulse width m~~ ting circuit may be provided as part of electronic dimmer circuit 320 (shown in Figure 3), with the width of the pulses produced by the pulæ width mod~ ting circuit varying with the desired bri&htnp-ss of the conmPctPd lamp 107. These pulses are then nlegl~ed and supplied to the driver end 304, and particular to terminal 409 of driver end 304 as shown in Figure 4, which is connected to the noninverting input of inverter 76. The variable width pulses genw~ed in electronic dimmer circuit 320, upon in~ on, produce a variable DC ~imming control signal which causes variation in the voltage level at pin 2 of inverter 76. This variation in voltage varies the duty cycle of the output pulses at pins 11 and 14, thus varying the brightnP,sc of the lamp 107. A separate ~imming circuit 320 may be provided for each driver end 304, or a single dimming circuit may be used with multiple driver end inverter circuits as disclosed in the above-identified copending applications.
Optionally, the electronic rlimming circuit 320 may be provided with an ambient light sensor input. In this embodiment, a photocell detects the amount of ambient light through a light collection device, and the desired blightnPcs signal of the dimming circuit is autom~tiç~lly varied inversely with the ambient light level so that less artificial light is provided at times when there is a large amount of ambient light.
wo 94n7419 216 2 8 ~ 9 PCT/USg4/05144 Further, driver ends 304 may be provided with switches 308, which may be any convention~l lighting switch. Preferably, these switches may be of the low-voltage control type which operate using relays or other means to switch high voltages without high voltages being present in the components contacted by the oper~lor of the switch.
Figure 4 is a schem~tic diagram of a preferred embodiment of the driver end 304 of the present invention, although it will be understood that the invention is not limited to the particular circuit shown.
As shown in Figure 4, driver end 304 is provided with terminals 402 and 404 for receiving DC power from a centralized source, such as front end 302 (shown in Figure 3).
Driver end 304 comprises an inverter pulse width mod~ tor 76 which provides a pulse signal on two ~dldle outputs, pins 11 and 14. Inverter pulse width mod~ tor 76 is preferably a conventic-n~l ,n~ldted circuit such as the SG 2525 ,.lanL~faclu-~;d by Motorola, U.S.A.
Inverter pulse width mod~ tor 76 has an internal osc~ tor controlled flip flop circuit and dual output NOR gates to provide dual pulse outputs at pins 11 and 14. The inttorn~l NOR gate outputs of the inverter pulse width modlll~tor 76 are co~-nect~d by intemal output transistor pairs to pins 11 and 14. The pulse outputs on pins 11 and 14 occur sequentially as the intemal flip flop circuit changes state.
A low voltage power supply is applied to the inverter pin 15. This power supply may take any desired forrn, but in the embodiment shown comprises a transformer 406 with its primary winding co~ P~I~ in series with the positive DC current input from terrninal 402.
The sp~on~ry winding is connP~t~ between terminal 404 and through a diode 408 toinverter power input pin 15. Current transferred from the primary winding to the seCo~ ry winding of transforrner 406 passes through a regulating diode 74 to charge a capacitor 75 and provide low-voltage DC power for ope~ting inverter pulse width modulator 76.The combination of capacitor 98 and resistor 100 determines the frequency of theosçill~tor 78 for the inverter pulse width m~dlll~tor, while a resistor divider formed by a resistor 410 and a variable resistor 412 determines the amount of DC voltage applied to the noninverted terminal (pin 2) of the internal error amplifier. This causes the error arnplifier to set the m~gnitude of the duty cycle of the output pulses at pins 11 and 14. These output pulses drive the inverter switches of a resol1ant inverter 413 which converts the DC signal on line 414 to high frequency AC to drive bulb 110, which in the present example is a fluolescenl bulb but may be any gas discharge lamp load.
wO 94/27419 216 2 8 8 ~ PCT/USg4/05144 The resonant inverter 413 includes switches 112 and 114 which are connP~ted to pins 14 and 11, respectively, of the inverter pulse width modulator 76. These switches are suitable solid state or mech~nic~l switches which are driven on and off in response to the pulses at the outputs of the inverter pulse width mod~ tor. Since these pulses occur at different times, the switch 112 will be on when the switch 114 is off and vice verse. During the time that the switch 112 is on or conductive, energy flows from the line 414 through the switch 112 and a resonant inductor 116 to charge a c~r~ritor 118. Then when the switch 112 is off and the switch 114 turns on, stored energy from the capacitor 118 flows back through the resonallt inductor and the switch 114. Preferably, the pulse repetitioll frequency which operates the switches is identical with the recon~ncP frequency of the LC network formed by the ~SO~ t ind~lct~lr 116 and c~p~ritor 118, so that inverter 413 olxlates effectively as a resonant inverter.
Referring now to Figure 5, the basic AC-DC conversion circuit, or front end, of the present invention is in~lic~tp~d generally at 302. Front end 302 incllldes a full wave bridge rectifier 12 having input terminals 501 and 503 conne~tPA to an AC power line. The rectifier includes outputs 18 and 20 with a negative ~ c; coPffiri~Pnt thermistor 22 connPcte~ in a series with the output 18. A storage c~r~r-itor 24 is connected to the outputs 18 and 20 of the bridge rectifier 12 via an inductor 28 and a rectifier diode 36. Full wave bridge rectifier 12 and storage c~r~citor 24, like the other co" ,l~one -l ~i of front end 302, are selP~t~Pd to have the desired current and power output capacity. In the prefell~d embodiment described previously with reference to Figure 3, the power output capacity of front end 302 is 2000 watts. Therefore, full wave bridge rectifier 12 and storage c~r~citrJr 24 are sP1e~ted to provide this power h~n-lling capacity.
The front end 302 is ~esignPd to effectively limit inrush current under all circuit o~l~ing conditions, even during a short power interruption. This is accomr~ hP~ in part by a boost switching regulator 26 which includes an inductor 28 connected in series with the thermistor 22. This inductor serves the dual purpose of providing the primary winding for a transformer 30 having a secondary winding 32, and also of storing energy during the time that a switch 34 is turned on. Switch 34 is formed by any suitable semiconductor or mPrh~nic~l switch which can be selectively rendered conductive by a control signal to complete a circuit. When the switch 34 is turned off, energy stored in the inductor 28 is transferred to the storage c~r~citor 24 through rectifier diode 36 conne~te~ in series therebetween. The output voltage from the boost switching regulator 26 is greater than the input voltage thereto.
wO 94/27419 ~ ~ 6 2 8 ~ ~ PCT/USg4/05144 g The boost switching regulator 26 also includes a pulse width modulator controller 38 to drive the switch 34. This pulse width modulator controller is a commercially available integrated circuit, such as an SG 2843 manufactured by Motorola, U.S.A.
The pulse width modulator controller 38 incl~ldes an internal oscillator which provides pulses to an internal l~t~hing pulse width modulator. The input signal on pin 4 sets the frequency of the oscill~tor and determines the pulse output frequency which is provided from the l~tching pulse width mod~ tor through an internal co,llpa,~tor to output pin 6. A current sense input for the l~s~hing pulse width modulator is provided by pin 3.
A low voltage supply is applied to pin 7 in order to provide power to the integrated circuit. Pin 7 is also connected intern~lly to an undervoltage lockout circuit and a 5 volt reference circuit. This 5 volt reference circuit is connertPd to pin 8 and also provides a 2.5 divider to a non-inverting input of an internal error amplifier. Another, inverted input of the error ~mrlifier is connected to pin 2, while an output comrenc~tion terrninal for the error ~mplifier is provided by pin 1. The refe,ence voltage is also provided by means of an internal undervoltage lockout circuit to the internal l~trhing pulse width modulator.
The start-up current for the pulse width modulator controller 38 is provided by a resistor 56 connected to the output side of thermistor 22. The pulse width modulator controller 38 r~uiles only a 1 milli~mpere start-up current, and this is provided to pin 7 by the resistor 56. The start-up current must be low so that power ~ ir~tion in the resistor 56 is in~ignific~nt With start-up power being provided to the pulse with mod~ tor controller 38, theoutput frequency of its internal oscill~tor is set by the series cc""binalion of a timing resistor 58 and a timing c~r~ritt r 60. This in turn de~""ines the pulse output frequency on pin 6 which drives the switch 34. The m~gnitll~e of the output voltage across the storage c~r~itc r 24 is set by sensing the voltage ratio between the resistors 62 and 64 conn~te~ in series across the c~r~itQr 24 at the output side of the rectifier diode 36. An i",pedance 66 is provided to ",~ l;.in loop stability of the l~sching pulse width modlll~tQr and is connect~d between the compensation and the non-inverted terminals of the error ~mplifitor (pins 1 and 2). The signal from a current sense resistor 68, which is connected in series with the switch 34, is provided to pin 3 of the pulse width modulator controller for short circuit protection and for limiting current flow through switch 34.
A start-up current through resistor 56 which builds a 1 ma level in a series c~p~cit~r 70, causes a slow start-up of the pulse width modulator controller 38. Short duration pulsating signals from the output (pin 6) then start to turn the switch 34 on and off. Inductor W O 94/27419 ~ 1 ~ 2 8 ~ 9 PCTtUS94tO5144 28 stores energy during the on period of switch 34 and transfers this energy to the storage c~r~citor 24 through rectifier diode 36 during the off period of the switch. A few turns of cecon-l~ry winding 32 now can provide energy to caraçit-r 70 through a rectifier diode 72.
This energy flowing into the c~r~citor 70 supplies the ad~ition~l power nece~ry to make S the pulse width modul~tor controller fully functional. Next, the output voltage sense signal from the resistors 62 and 64 is applied to the fee~b~ck terminal, that is, the inverting terrninal (pin 2) of the error ~mplifirr to autom~tir~lly provide the regulator for m~int~inin~
a constant output voltage from the boost switching regulator 26 irrespective of input voltage variations.
The front end 302 is provided with output terminals 502 and 504 which can be c~n~ted rc~ ely to the power input terminals 402 and 404 of a plurality of driver ends 302 (shown in Figure 3).
During normal oprr~tirJn, when power is first received at the rectifier input terminals 501 and 503, the thermistor 22 offers sl-ffiriently high re~i~t~nce to li-m-it the inrush current 15 to the storage c~r~ritor 24. However, when power if first received, it is ill)ol~nt to insure that the pulse width mod~ tor controller 38 starts operation only after the storage c~pacitor 24 becomes charged to nearly the input voltage peak. Otherwise, switch 34 might be driven on while current is still flowing to the filter c~r~r-itor through the inductor 28. Depending on the amount of current flow, the inductrlr 28 may be fully or partially saturated, and in this condition, if the switch 34 is turned on, the inductor may offer only partial or no inductance.
As a result, switch 34 will experience a virtual short circuit and possible resultant darnage.
The le~lui, ed delay in the operation of the switch 34 until the c~raritor 24 has charge is provided by the resistor 56, the c~r~çitor 70 and the internal undervoltage lockout unit of pulse width modl-l~tQr controller 38. The undervoltage lockout unit will prevent operation of the pulse width mod~ tor controller 38 until the input voltage eYce~As the undervoltage lockout value. The time that the voltage across the r~p~ritQr 70 exceeds the undervoltage lockout value depends upon the values of resistor 56 and c~r~ritor 70. These can be set to insure that the spe~ified input voltage level is not reached until storage c~r~ritor 24 is given time to charge.
As soon as the pulse width modul~tor controller 38 starts working, switch 34 will start to turn on and off. Inductor 28 will periodically store and release energy and secondary winding 32 will start to supply additional energy to c~r~r-itnr 70 through diode 72. The capacitor 70 now supplies the nçce~ry ope~ lg power to the pulse width modulatorcontroller.
W O 94/27419 ~ ¦ ~ 2 8 8 9 PCT~US94/05144 When the front end 302 experiences a short term power interruption, power may bereestablished while the r~cist~nce of the thermistor 22 is still low. In this situation, the arnount of inrush current drawn by the storage capacitor 24 depen-ls on the amount of charge retained by this c-~p~citor at the end of the power interruption. If the retained charge is low, 5 a large inrush current will occur.
To control the inrush current to a minim~l, norldam~ging level, the charge on the storage c~p~itor 24 is m~int~ineA during a short terrn power interruption by removing the lamp 107 (shown in Figure 4) as soon as the power interruption occurs. If this is done, the storage c~p~it~ r will retain its full potential with the only power drain therefiv"l being 10 caused by the resistors 62 and 64. However, the resistor divider formed by these resistors has a very high impeA~n.~e, and the energy drawn thereby is ~AL~ .cly small.
Referring again to Figure 4, lamp 107 is effectively ~licconnpcte~ from the storage c~p~ritor 24 by the removal of power from the inverter pulse width modulator 76. This removes the output signals from pins 11 and 14, and the switches 112 and 114 will remain 15 open. During a power int~upLion, the secondary winding of transformer 406 cannot supply energy to the c~p~citor 75, and the storage capacity of c~ itor 75 is s~l~te~A. to be very small so that the inverter pulse width mod~ tor 76 will almost instantly shut down. Rapid shutdown can be insured by having the internal undervoltage lockout operate at a lockout voltage close to the voltage storage capacity of the c~p~citQr 75. As soon as the voltage across the c~p~itor 75 drops below this lockout voltage, the undervoltage lockout shuts down the inverter pulse width mod~ tor 76. Thus, the front end and driver end are decignPd in conjunction with each other to produce desired OpcldLii g characteristics.
Figure 6 is a flowchart showing a method for let-~r~LL~g an ~Y~i~ting lighting in~t~ tion with a system accolding to the present invention. As noted above, a signific~nt feature of the present invention is the compatibility of the system with eYisting building wiring. In particular, the front end 302 of the present invention can be in~t~ll~ between an ~oYi~ting AC lighting circuit and an AC power source so that the wiring of the AC lighting circuit carries DC current. Then, driver ends 304 operating on DC current can be installed in lighting fixtures connected to the now-converted DC lighting circuit.
As shown in Figure 6, this conversion process begins in block 602 with the provision of an AC-DC converter, such as front end 302. In the next step, shown in block 604, the front end circuit is connP~ted to the AC input source in place of the eYisting lighting circuit, which is disconn~octed. In the p~ftlred embo~lim~nt7 as described above, the front end is g~ - 12-installed in a junction box provided for the distribution of AC power through the lighting circuit.
In block 606, the wiring of the lighting circuit, which formerly carried AC power, is connP~t~d to the DC output of the front end circuit, thus converting the exi cting conventional lighting circuit to a high voltage DC circuit.
In block 608, the eYicting convention~l AC fixtures conne~ted to the lighting circuit are replaced by DC powered circuits, such as the driver ends disclosed above. The new DC
driver ends could be inct~ll~ as part of an entirely new DC-powered lighting fixture, or the driver ends could be incPlled as a retrofit of an eYicting inç~n~lesc~nt or fluorescent fixture.
In particular, existing inc~nrlescent fixtures may be provided with screw-in DC-powered driver ends ~eCigne~ to conne~t to a standard light bulb socket.
Finally, when wiring has been compl~tP,d, the le~ufit~ed lighting circuit is operated with DC power.
This general method can also be advantageously applied to the power distributionsystem within a single li&hting fixture, as shown in Figure 7. Figure 7 shows a typical lighting fixture 702, which may be for eY~mple a decc,ldti~re ch~ndeli~r. Fixture 702 is mounted to hang from an elect~c-~l box 706 mounted in the ceiling. AC wires 703 are provided in electrical box 706 to power light fixture 702. Light fixture 702 may have a plurality of bulb sockets 704, each conn~ct~d by two wires 708 to the AC wires 703 in a convention~l inct~ tion of this type of fixture. However, as shown in Figure 7, the present invention can be advantageously applied to such a fixture in the following manner. A front end 302 according to the present invention is inct~lled in electrical box 706 and is conne~ted to receive power from AC wires 703. Front end 302 has a power output 707, which is a DC high voltage power output. According to this application of the present invention, DC
output 707 is connected to fixture wires 708 to provide DC power to bulb sockets 704. A
driver end 304 is provided with a threaded coupling which mates with bulb sockets 704 to connect the power available in bulb sockets 704 to driver end 304. Driver end 304 provides an excitation signal for a compact fluolescenl bulb 712.
Thus, lighting fixture 702 can be rell~ùfilled to operate using efficient fluorescent bulbs by inct~lling a front end 302 between AC wires 703 and fixture wires 708, and by providing special compact driver ends which can be inct~ d in bulb sockets 704 and which drive small, low voltage fluo~escent bulb 712. For this application, it will be desirable to provide these compact driver ends with various threaded bases to correspond to the sockets W O 94/27419 ~ g ~ 9 PCT~US94105144 of the fixture. For many ch~ndeliers~ a more compact base will be needed (e.g. a candelabra base).
While the front end 302 and driver end 304 in this embodiment of the invention are gen~r~lly similar to the plefe,l~d embo~limentc described previously, there are some 5 differences in accordance with the special requirements of this particular application. For ex~mrle, front end 302 will generally have a lower power output capacity than the front end 302 used in a building el~tric~l distribution system. For ex~ml)le, for a lO bulb ch~ndelier which is to be operated with nine watt compact fluorescent bulbs, a front end power output of 100 watts would be sufficient. Also, to reduce the risk of electrical shock due to the lO presence of large voltages in wires 708, the DC output of front end 302 in this application is preferably much less than 350 volts, perhaps even less than 120 volts.
Rec~llc~ the driver ends 304 in this application can be constructed in a very compact manner, a large, visually intrusive housing ~ccoci~ted with conventional screw-in fluorescent repl~cPm~nt bulbs is çlilll;n~pd. Preferably, bulbs 712 are formed in an apl,rop,iate 15 decorative manner. For use in a rh~n~elier~ these bulbs may be formed in a shape a~5,~;,..~l;,-g the shapes of conve~ltinn~l inr~ndescPnt lamps used in ch~ndPli~rs~ such as a ~flame tip" shape.
The present invention provides particular cost advantages as coll-par~d to the systems and meth~ls of the prior art. Through study of the prior art systems, the inventor has determined that the front end of the electronic ballast accounts for 20 % to 60 % of the overall cost of each electronic ballast. For example, an advanced front end which conci~tc of a highly regulated power reservoir, as descrihed by U.S. Patent No. 4,864,482, is the most expensive section of the ballast. This is shown in Figure 3.
In the prior art, the DC power supply in the ballast typically provided a relatively low power output keyed to the design of the fixture. For example, the rated power output of the ballast might be 80 watts in a popular type of ballast designe~ to drive two four-foot, 40-watt fluo~escent tubes. The power h~n~ling capability of a front end primarily depe~ c on semiconductor power ratings and filter or storage c~p~itor capacity ratings. According to the present invention, the front end, as shown in Figure 3, is constructed so that it can deliver a high power output, such as 2000 watts. Presently, a 2000-watt front end can be constructed for about $14, only $4 more than the cost of an 80-watt front end. A complete 80-watt fluorescent lamp ballast, as disclosed in U.S. Patent Nos. 4,933,605 and 4,864,482, costs approximately $17.
W O 94/27419 2 ~ ~ 2 ~ ~ 9 PCTAUS94/05144 The cost of a driver end is approximately $9. Re~cal,se 20 driver ends can be used with a single front end, the cost of the front end attributable to each fixture is less than $1 and the overall ballast cost drops from $17 to less than $10 per fixture.
In addition to the size and cost advantages rçslllting from the system according to the 5 present invention, it has been found that separating the DC power supply and the resonant inverter circuitry as ~i~çlosed in the present invention reduces electrical losses in the driver end. Also, bec~use the heat produced by the DC power supply section is not produced in the vicinity of the driver end, the circuits of the driver end operate at lower temperatures.
Longer operating colllpoQent life is obtained as a result.
An additional advantage of the system according to the present invention is that the isol~tion of the lighting circuit from the AC line produced by front end 302 protects the lighting circuit from lightning, voltage spikes, etc. Further, the filtering functi~n~ pelrolllled by the large front end 302 prevent electrom~nPtic il~lrt;l~ ce from il~lrt;ling with lighting circuit operation, and reduce overall electrom~gnPtic in~lrelence gçn~ d by the system.
SYSTEM AND METHOD FOR DISTRIBUTING
POWER TO GAS DISCHARGE LAMPS
Field of thP ]nvention 5The present invention relates to driving circuits for gas discharge lamps and methods for constructing and inct~lling these circuits.
R~ rolln~ of thP InvPntion Gas discharge lamps, such as fluorescent lamps, high pressure sodium lamps, and metal halide lamps, require a driving circuit, or ballast, to operate properly. In rec_nt years, 10electronic ballasts have gained--popularity over m~gnP~tic ballasts because of their higher el~Pctric~l power conversion effi~iency. The effi~ iPncy improvement in using an electronic ballast rather than a m~gnPtic ballast can exceed 30% depentling on the lamp and ballast combin~tion used. An electronic ballast based on resonant inverter CilCuiLl~ has been described in U.S. Patent No. 4,933,605, ~csignp-d to the ~ccign~e of the present application.
15Electronic ballasts have typically been more expensive than m~gnetic baLlasts. To reduce overall costs, a single ballast is often wired to multiple bulbs and particularly to multiple fixtures, as shown in the prior art Py~mrle of Figure 1. A master lamp fixture 102 and a slave lamp fixture 104 share a ballast 106 located in master lamp fixture 102. L~mp 107 in slave lamp fixture 104 is driven by signals carried on connP~tion wires 108 which 20transmit high frequency driving signals from ballast 106 to lamp 107. However, such "master ballast" arrangements have not been used to drive a large number of slave fixtures. The inventor has studied this type of circuit and has determined that the sharing of ballasts between multiple fixtures is inherently limited by the following factors:
1. A single ballast can supply power only to a limited number of lamps;
252. The connP~tion wires 108 supplying current from the ballast to individual lamps in these prior art systems carry high-frequency alternating current. Long wire runs will add cignifi~nt in~uct~n- e and c~r~cit~nce between the lamp and ballast, affecting their operation and efficiPncy; and 3. High-frequency connection wires 108 must be shielded to reduce propagation of30electrom~gnPtic intelr~rence, so that inct~ tion of extensive networks of high frequency lines is made more difficult and expensive.
Often, inc~n~escent or less-efficient discharge lamp units throughout a building are replaced to obtain energy savings. Typically, as shown in Figure 2, lighting fixtures in buildingc are powered by AC current through wires 203 routed through single or multiple wo 94/27419 PcTIus94losl44 distribution boxes 202. Distribution boxes 202 connect wires 203 to fixtures 205. There are two known processes for repl ~cement of fixtures 205 with more energy-efficient lighting.
In the first process, the eYicting fixtures 205 are removed and new gas-discharge fixtures, preferably fluorescent fixtures, are directly substituted, each fixture including a ballast.
5 Re~us~ of the problems associated with high-frequency power lines, it has not been considered feasible to retrofit an existing building with centralized ballasts.
ln a second method, a gas discharge adapter, preferably a fluorescent adapter, may be inst~lled in place of each inc~ndescent bulb. A variety of these adapters are commercially available. Generally, these devices screw into a standard in~ndrscent bulb socket of a light 10 fixture or table lamp to form electrical connections with the AC power. The adapters consist of a small fluorescent ballast opeld~ g from the AC socket, and a low-wattage fluorescent lamp, typically 9 to 15 watts, which provides greater light output çffirienry than the replaced inr lndeccent bulb. The appliç~tionc of fluolescent adapters have been limited by the required size of the ballast circuit housing. In some cases these adapter are to o large to fit 15 into a given d~r~r~tive fixture. ln other cases, such dS in chAn~1rlirrs~ the protruding ballast housing at the bulb base would cignifir Intly detract from the appo~ ce of the fixture.
Another problem with these adapters is the gen~or~tion of ele.;L.o... ~gnptic il~te~ nce.
Adequate sul,l,ression of in~.~rt;nce g~onler~tçd by these devices usually ~ i~s ~ition~il col-lponents which further increases the size of the devices.
Therefore, the inventor believes that there is a need for a system which provides effirient electronic ballast circuits for a large number of gas discharge lamps at a reduced capital cost. It is further believed that there is a need for a more ly~conAhly-priced method of l~LIol;lling eYicting b~ ingc and fixtures with highly-effiçirnt ballast and lamp units.
Summary of the Invention Therefore, it is a general object of the present invention to provide an efficiçnt electronic ballast circuit which will drive a large number of gas discharge lamps.
Another general object of the present invention is to provide a novel system in which a high voltage DC front end provides DC current to a plurality of electronic inverters which drive gas discharge lamps.
It is another general object of the present invention to provide a novel method for retrofitting existing bnil~ingc with highly-efficient b~ cted gas discharge lamps.
A further object of the present invention is to provide method of l~;~lorlt~ing existing buildings with gas discharge lamps in which PYicting AC wiring is used to transmit high W O 94/27419 ~ 1 6 2 8 8 9 PCT~US94/05144 voltage DC power from a newly inct~llçd central ballast front end to a plurality of electronic inverters providing driving signals for gas discharge lamps.
Another object of the present invention is to provide new and improved gas discharge lamp ballasts with reduced physical size.
S Yet another objcct of the present invention is to provide appaldtlls and methods for refitting eYicting lighting fLxtures, such as çh~n~çliPrs, with compact fluo~escent light bulbs.
Further objects of the invention will be app~rent to those skilled in the art upon review of the specification, drawings, and claims.
These objects are achieved in the present invention by providing a central AC-DCpower converter which is conn~l-P~ into an AC lighting circuit and thereafter transmits DC
power through the power distribution wires to individual lighting locations. DC-powered resonant inverter driving circuits are provided and conn~ctPvd to the DC power where liEhting is desired. The system is particularly useful in ,cLn~r~ g eyicting b~ ingc or individual light fixtures which use int~n~psc~pnt lamps with more energy-efficient fluo,eseent lights.
The invention described herein produces signifi~nt adv~nt~gP~s~ including: (1) asavings of at least 33% in ballast cost; (2) no change in the eyicting building wiring syst~m, (3) a single front end can be used to power ballasts in mnltiple zones or rooms, (4) one f~ -jnt end can be used to operate single or multiple lamps, and (5) Plimin~tion of ele~ l~n~otic inlelr~re.lce ~c~i~tP~ with long high frequency current carrying wires.
Rrief Description of thP Drawin~c Figure 1 is a ~i~gram of a prior art m~ster-slave fLxture;
Figure 2 is a block schçm~tic diagram of a conventional AC electri~l lighting power distribution system;
Figure 3 is a block sch~Pm~tic diagram of the mot~ified lighting power distribution system according to the present invention;
Figure 4 is a s~hpm~tic diagram of the driver end used in each fixture in Figure 3;
Figure S is a schem~tic diagram of the front end provided in the distribution box as shown in Figure 3;
Figure 6 is a flowchart showing a method of retrofitting an ç~icting fixture system with the system of the present invention; and Figure 7 is a block schematic diagram showing the method according to the present invention as applied to a multibulb in~n(lescçnt lighting fixture.
DPt~ile~ Description of the Preferre~ l~mbodiments Wo 94127419 ~ l ~i 2 8 8 g PcTIuss4/05l44 The present invention will be described herein in terms of prel~ d embodiments using fluorescent lamps. However, it will be understood that the invention is not limited to the specific embo~lim~ntc ~ic~lose~ herein. The embo~imentc ~ic~ losPA may be modified by those skilled in the art within the scope of the invention, which is defined by the claims.
The present invention relates to ballast circuits for gas discharge lamps, such as fluorescent lamps. A convention~l electronic ballast, as disclosed in the inventor's U.S.
Patent Nos. 4,933,605 and 4,864,482 which are incorporated herein by reference, converts conventional AC line voltage to high voltage DC, which is then switched at high frequencies by an inverter circuit to produce an excitation signal for the associated gas discharge lamp.
In a first prcfcllcd embo~iment of the present invention, as shown in Figure 3, a new type of ballast system is constructed by providing two physically se~ dtc types of co,l,ponents: a front end 302 which produces DC power, and a plurality of driver ends 304 each inçlu~ing a l- sonant inverter circuit for prod~cing a lamp driving signal from the DC
power of the front end 302. In the e",bod;,.,Pnt shown in Figure 3, this system is provided in a building ele~ric~l distribution system, where it may be inct~lled as original equipment or as part of a rcLlofi~ g process. As shown in Figure 3, AC power from a circuit breaker panel 301 is conn~ l~ by wires 203, typically in~lu~ing a white ~neutral" wire and a black or red "hot" wire. Wires 203 run through a conduit 204 to a distribution box 202. In a convention~l AC electrical distribution system, these wires would branch from the distribution box 202 to provide AC power to various lighting fixtures in the circuit.
However, according to the present invention, wires 203 are connected as power inputs to a front end 302 located in distribution box 202.
In the front end 302 according to the present invention, 50 or 60 cycle AC power is converted into a high voltage DC power output of up to 600 volts, preferably by sPmicon~luctor rectifiers in a manner which will be described in detail with reference to Figure 5. Front end 302 is preferably made with a higher power output capability than the DC power available in a conventicn~l fluo~s~nt ballast, such as for example 2000 watts.
The front end can be conveniently built in a housing with ~imencionc of 3 inches by 4 inches x 1.5 inches. If compactly decigned, the front end 302 can easily be incPlled in a distribution box 202. The front end 302 is preferably a highly regulated power supply which active monitors and shapes the DC output. Preferably, the front end 302 may also correct power factors, shape power line harmonics, and protect against inrush ~ulren~s.
The output voltage of front end 302 may vary depending on the l~uirelllen~ of the system. Preferably, for use with a 120 volt AC system, the DC output voltage will be at W O 94/27419 2 ~ 6 2 ~ 8 9 PCTrJS94/05144 250 volts DC, and preferably 350 VDC. If 277 VAC is used as an input, 500 VDC output may be produced. Finally, if 440 VAC is provided as the power input, 580 VDC output may be produced. It is desirable to keep the output voltage less than 600 VDC to stay within the power rating of standard building wiring.
As shown in Figure 3, the DC output of front end 302 is conne~teA by wires 306 to a plurality of fixtures 305, where the DC power supplies a plurality of driver ends 304. An electronic dimmer circuit 320 may optionally be connect-P-d to driver ends 304.
Wires 306 may preferably be identic~l to wires 203, that is, conventional ins~ teA
household or office power distribution wires. F.1P~tric~l codes in the U.S., and the ratings of existing wiring, typically permit this wiring to carry up to either 600V AC or 600V DC
in a standard condllit Therefore, wires 306 may be wires design-PA for AC current, and in fact may be wires that were originally inst~llPA to carry AC current to lighting fixtures but have now been conl-~P~led to the front end 302 to carry DC current.
Thus, lamp fixtures 30S are powereA through single or multiple distribution boxes 202 which connect the single front end 302 to the plural driver ends 304 at the fixtures 305.
Each driver end 304 receives the DC output gener~tçA by front end 302. In the driver end, this DC power is converted into a high frequency (usually higher than 20 kHz) source which supplies power to one or more lamps, by any of a variety of known circuits.
The pr~rell~d 2000-watt front end 302 according to the present invention can safely drive at least 20 driver ends 304 which may be de~ign~A to operate two 40 watt, four-foot T-12 lamps.
The circuits provided in the driver end 304 are the inverter ~vilcl~ing circuits which produce an eYcit~ti~ n signal for the gas discharge lamps 107. Since no power con~itiQning or conversion circuits are provided in driver ends 304, driver ends 304 can be made in a more compact and less expensive manner as co.l.~J~ed to a convPntion~l gas discharge ballast. Preferably, the driver end circuit is a resonant inverter circuit as ~i~clos~ in U.S.
Patent Nos. 4,933,605 or 4,864,482. The cirwlit,y of driver end 304 will be discussed in greater detail with reference to Figure 4.
Driver ends 304 may take the form of conventional hard wired gas discharge ballasts having wire connectiQnc for power input, or driver ends 304 may be constructed with a bulb socket base 311 to provide power input terminals. The bulb socket base 311 threadedly connects with a standard light bulb socket 309. Driver ends 304 which are constructed with bulb socket bases 311 may also be provided with a mounting for a lamp 107, which may be W O 94/27419 ~ 89 PCTrUS94/05144 a compact, low voltage fluorescent lamp, circular fluorescent lamp, or other app,o~liate design for use in retrofitting existing lighting fixtures. Driver ends 304 of this type can be a~ro~,iately used when increased efficiency is desired in the lighting circuit but repl~cemPnt of eYisting in~ndescPnt lighting fixtures is not desired. Through the use of bulb-mount 5 driver ends, inc~ndescent lighting can be converted to fluorescent lighting using the system of the present invention while minimi7ing inct~ tion costs and avoiding replacement of the entire fixture.
While the bulb mount driver ends of this type are physically similar in appearance to known fluorescent inc~ndescent repl~cemPnt devices, they are different from these prior 10 devices in that they operate from DC current received through the bulb base, and in that the driver end circuit 304 is smaller and less obtrusive since it in~ des no AC-DC converter The driver end 304 may also be provided with a riimming circuit to control the brightnP$c of lamp 107, as rlic~losPd in the inventor's coppn~ing U.S. Patent Applic~tionc~
Serial No. 07/410,480 filed .September 21, 1989, titled "Electronic Dimming Metho~s for Solid State Electronic R~ $tcn~ and Serial No. 07/789,268 filed November 8, 1991, both inco-l ol~ted herein by ~Çe,~nce. In general, as .licclosp~ in more detail in these parent applications, a pulse width m~~ ting circuit may be provided as part of electronic dimmer circuit 320 (shown in Figure 3), with the width of the pulses produced by the pulæ width mod~ ting circuit varying with the desired bri&htnp-ss of the conmPctPd lamp 107. These pulses are then nlegl~ed and supplied to the driver end 304, and particular to terminal 409 of driver end 304 as shown in Figure 4, which is connected to the noninverting input of inverter 76. The variable width pulses genw~ed in electronic dimmer circuit 320, upon in~ on, produce a variable DC ~imming control signal which causes variation in the voltage level at pin 2 of inverter 76. This variation in voltage varies the duty cycle of the output pulses at pins 11 and 14, thus varying the brightnP,sc of the lamp 107. A separate ~imming circuit 320 may be provided for each driver end 304, or a single dimming circuit may be used with multiple driver end inverter circuits as disclosed in the above-identified copending applications.
Optionally, the electronic rlimming circuit 320 may be provided with an ambient light sensor input. In this embodiment, a photocell detects the amount of ambient light through a light collection device, and the desired blightnPcs signal of the dimming circuit is autom~tiç~lly varied inversely with the ambient light level so that less artificial light is provided at times when there is a large amount of ambient light.
wo 94n7419 216 2 8 ~ 9 PCT/USg4/05144 Further, driver ends 304 may be provided with switches 308, which may be any convention~l lighting switch. Preferably, these switches may be of the low-voltage control type which operate using relays or other means to switch high voltages without high voltages being present in the components contacted by the oper~lor of the switch.
Figure 4 is a schem~tic diagram of a preferred embodiment of the driver end 304 of the present invention, although it will be understood that the invention is not limited to the particular circuit shown.
As shown in Figure 4, driver end 304 is provided with terminals 402 and 404 for receiving DC power from a centralized source, such as front end 302 (shown in Figure 3).
Driver end 304 comprises an inverter pulse width mod~ tor 76 which provides a pulse signal on two ~dldle outputs, pins 11 and 14. Inverter pulse width mod~ tor 76 is preferably a conventic-n~l ,n~ldted circuit such as the SG 2525 ,.lanL~faclu-~;d by Motorola, U.S.A.
Inverter pulse width mod~ tor 76 has an internal osc~ tor controlled flip flop circuit and dual output NOR gates to provide dual pulse outputs at pins 11 and 14. The inttorn~l NOR gate outputs of the inverter pulse width modlll~tor 76 are co~-nect~d by intemal output transistor pairs to pins 11 and 14. The pulse outputs on pins 11 and 14 occur sequentially as the intemal flip flop circuit changes state.
A low voltage power supply is applied to the inverter pin 15. This power supply may take any desired forrn, but in the embodiment shown comprises a transformer 406 with its primary winding co~ P~I~ in series with the positive DC current input from terrninal 402.
The sp~on~ry winding is connP~t~ between terminal 404 and through a diode 408 toinverter power input pin 15. Current transferred from the primary winding to the seCo~ ry winding of transforrner 406 passes through a regulating diode 74 to charge a capacitor 75 and provide low-voltage DC power for ope~ting inverter pulse width modulator 76.The combination of capacitor 98 and resistor 100 determines the frequency of theosçill~tor 78 for the inverter pulse width m~dlll~tor, while a resistor divider formed by a resistor 410 and a variable resistor 412 determines the amount of DC voltage applied to the noninverted terminal (pin 2) of the internal error amplifier. This causes the error arnplifier to set the m~gnitude of the duty cycle of the output pulses at pins 11 and 14. These output pulses drive the inverter switches of a resol1ant inverter 413 which converts the DC signal on line 414 to high frequency AC to drive bulb 110, which in the present example is a fluolescenl bulb but may be any gas discharge lamp load.
wO 94/27419 216 2 8 8 ~ PCT/USg4/05144 The resonant inverter 413 includes switches 112 and 114 which are connP~ted to pins 14 and 11, respectively, of the inverter pulse width modulator 76. These switches are suitable solid state or mech~nic~l switches which are driven on and off in response to the pulses at the outputs of the inverter pulse width mod~ tor. Since these pulses occur at different times, the switch 112 will be on when the switch 114 is off and vice verse. During the time that the switch 112 is on or conductive, energy flows from the line 414 through the switch 112 and a resonant inductor 116 to charge a c~r~ritor 118. Then when the switch 112 is off and the switch 114 turns on, stored energy from the capacitor 118 flows back through the resonallt inductor and the switch 114. Preferably, the pulse repetitioll frequency which operates the switches is identical with the recon~ncP frequency of the LC network formed by the ~SO~ t ind~lct~lr 116 and c~p~ritor 118, so that inverter 413 olxlates effectively as a resonant inverter.
Referring now to Figure 5, the basic AC-DC conversion circuit, or front end, of the present invention is in~lic~tp~d generally at 302. Front end 302 incllldes a full wave bridge rectifier 12 having input terminals 501 and 503 conne~tPA to an AC power line. The rectifier includes outputs 18 and 20 with a negative ~ c; coPffiri~Pnt thermistor 22 connPcte~ in a series with the output 18. A storage c~r~r-itor 24 is connected to the outputs 18 and 20 of the bridge rectifier 12 via an inductor 28 and a rectifier diode 36. Full wave bridge rectifier 12 and storage c~r~citor 24, like the other co" ,l~one -l ~i of front end 302, are selP~t~Pd to have the desired current and power output capacity. In the prefell~d embodiment described previously with reference to Figure 3, the power output capacity of front end 302 is 2000 watts. Therefore, full wave bridge rectifier 12 and storage c~r~citrJr 24 are sP1e~ted to provide this power h~n-lling capacity.
The front end 302 is ~esignPd to effectively limit inrush current under all circuit o~l~ing conditions, even during a short power interruption. This is accomr~ hP~ in part by a boost switching regulator 26 which includes an inductor 28 connected in series with the thermistor 22. This inductor serves the dual purpose of providing the primary winding for a transformer 30 having a secondary winding 32, and also of storing energy during the time that a switch 34 is turned on. Switch 34 is formed by any suitable semiconductor or mPrh~nic~l switch which can be selectively rendered conductive by a control signal to complete a circuit. When the switch 34 is turned off, energy stored in the inductor 28 is transferred to the storage c~r~citor 24 through rectifier diode 36 conne~te~ in series therebetween. The output voltage from the boost switching regulator 26 is greater than the input voltage thereto.
wO 94/27419 ~ ~ 6 2 8 ~ ~ PCT/USg4/05144 g The boost switching regulator 26 also includes a pulse width modulator controller 38 to drive the switch 34. This pulse width modulator controller is a commercially available integrated circuit, such as an SG 2843 manufactured by Motorola, U.S.A.
The pulse width modulator controller 38 incl~ldes an internal oscillator which provides pulses to an internal l~t~hing pulse width modulator. The input signal on pin 4 sets the frequency of the oscill~tor and determines the pulse output frequency which is provided from the l~tching pulse width mod~ tor through an internal co,llpa,~tor to output pin 6. A current sense input for the l~s~hing pulse width modulator is provided by pin 3.
A low voltage supply is applied to pin 7 in order to provide power to the integrated circuit. Pin 7 is also connected intern~lly to an undervoltage lockout circuit and a 5 volt reference circuit. This 5 volt reference circuit is connertPd to pin 8 and also provides a 2.5 divider to a non-inverting input of an internal error amplifier. Another, inverted input of the error ~mrlifier is connected to pin 2, while an output comrenc~tion terrninal for the error ~mplifier is provided by pin 1. The refe,ence voltage is also provided by means of an internal undervoltage lockout circuit to the internal l~trhing pulse width modulator.
The start-up current for the pulse width modulator controller 38 is provided by a resistor 56 connected to the output side of thermistor 22. The pulse width modulator controller 38 r~uiles only a 1 milli~mpere start-up current, and this is provided to pin 7 by the resistor 56. The start-up current must be low so that power ~ ir~tion in the resistor 56 is in~ignific~nt With start-up power being provided to the pulse with mod~ tor controller 38, theoutput frequency of its internal oscill~tor is set by the series cc""binalion of a timing resistor 58 and a timing c~r~ritt r 60. This in turn de~""ines the pulse output frequency on pin 6 which drives the switch 34. The m~gnitll~e of the output voltage across the storage c~r~itc r 24 is set by sensing the voltage ratio between the resistors 62 and 64 conn~te~ in series across the c~r~itQr 24 at the output side of the rectifier diode 36. An i",pedance 66 is provided to ",~ l;.in loop stability of the l~sching pulse width modlll~tQr and is connect~d between the compensation and the non-inverted terminals of the error ~mplifitor (pins 1 and 2). The signal from a current sense resistor 68, which is connected in series with the switch 34, is provided to pin 3 of the pulse width modulator controller for short circuit protection and for limiting current flow through switch 34.
A start-up current through resistor 56 which builds a 1 ma level in a series c~p~cit~r 70, causes a slow start-up of the pulse width modulator controller 38. Short duration pulsating signals from the output (pin 6) then start to turn the switch 34 on and off. Inductor W O 94/27419 ~ 1 ~ 2 8 ~ 9 PCTtUS94tO5144 28 stores energy during the on period of switch 34 and transfers this energy to the storage c~r~citor 24 through rectifier diode 36 during the off period of the switch. A few turns of cecon-l~ry winding 32 now can provide energy to caraçit-r 70 through a rectifier diode 72.
This energy flowing into the c~r~citor 70 supplies the ad~ition~l power nece~ry to make S the pulse width modul~tor controller fully functional. Next, the output voltage sense signal from the resistors 62 and 64 is applied to the fee~b~ck terminal, that is, the inverting terrninal (pin 2) of the error ~mplifirr to autom~tir~lly provide the regulator for m~int~inin~
a constant output voltage from the boost switching regulator 26 irrespective of input voltage variations.
The front end 302 is provided with output terminals 502 and 504 which can be c~n~ted rc~ ely to the power input terminals 402 and 404 of a plurality of driver ends 302 (shown in Figure 3).
During normal oprr~tirJn, when power is first received at the rectifier input terminals 501 and 503, the thermistor 22 offers sl-ffiriently high re~i~t~nce to li-m-it the inrush current 15 to the storage c~r~ritor 24. However, when power if first received, it is ill)ol~nt to insure that the pulse width mod~ tor controller 38 starts operation only after the storage c~pacitor 24 becomes charged to nearly the input voltage peak. Otherwise, switch 34 might be driven on while current is still flowing to the filter c~r~r-itor through the inductor 28. Depending on the amount of current flow, the inductrlr 28 may be fully or partially saturated, and in this condition, if the switch 34 is turned on, the inductor may offer only partial or no inductance.
As a result, switch 34 will experience a virtual short circuit and possible resultant darnage.
The le~lui, ed delay in the operation of the switch 34 until the c~raritor 24 has charge is provided by the resistor 56, the c~r~çitor 70 and the internal undervoltage lockout unit of pulse width modl-l~tQr controller 38. The undervoltage lockout unit will prevent operation of the pulse width mod~ tor controller 38 until the input voltage eYce~As the undervoltage lockout value. The time that the voltage across the r~p~ritQr 70 exceeds the undervoltage lockout value depends upon the values of resistor 56 and c~r~ritor 70. These can be set to insure that the spe~ified input voltage level is not reached until storage c~r~ritor 24 is given time to charge.
As soon as the pulse width modul~tor controller 38 starts working, switch 34 will start to turn on and off. Inductor 28 will periodically store and release energy and secondary winding 32 will start to supply additional energy to c~r~r-itnr 70 through diode 72. The capacitor 70 now supplies the nçce~ry ope~ lg power to the pulse width modulatorcontroller.
W O 94/27419 ~ ¦ ~ 2 8 8 9 PCT~US94/05144 When the front end 302 experiences a short term power interruption, power may bereestablished while the r~cist~nce of the thermistor 22 is still low. In this situation, the arnount of inrush current drawn by the storage capacitor 24 depen-ls on the amount of charge retained by this c-~p~citor at the end of the power interruption. If the retained charge is low, 5 a large inrush current will occur.
To control the inrush current to a minim~l, norldam~ging level, the charge on the storage c~p~itor 24 is m~int~ineA during a short terrn power interruption by removing the lamp 107 (shown in Figure 4) as soon as the power interruption occurs. If this is done, the storage c~p~it~ r will retain its full potential with the only power drain therefiv"l being 10 caused by the resistors 62 and 64. However, the resistor divider formed by these resistors has a very high impeA~n.~e, and the energy drawn thereby is ~AL~ .cly small.
Referring again to Figure 4, lamp 107 is effectively ~licconnpcte~ from the storage c~p~ritor 24 by the removal of power from the inverter pulse width modulator 76. This removes the output signals from pins 11 and 14, and the switches 112 and 114 will remain 15 open. During a power int~upLion, the secondary winding of transformer 406 cannot supply energy to the c~p~citor 75, and the storage capacity of c~ itor 75 is s~l~te~A. to be very small so that the inverter pulse width mod~ tor 76 will almost instantly shut down. Rapid shutdown can be insured by having the internal undervoltage lockout operate at a lockout voltage close to the voltage storage capacity of the c~p~citQr 75. As soon as the voltage across the c~p~itor 75 drops below this lockout voltage, the undervoltage lockout shuts down the inverter pulse width mod~ tor 76. Thus, the front end and driver end are decignPd in conjunction with each other to produce desired OpcldLii g characteristics.
Figure 6 is a flowchart showing a method for let-~r~LL~g an ~Y~i~ting lighting in~t~ tion with a system accolding to the present invention. As noted above, a signific~nt feature of the present invention is the compatibility of the system with eYisting building wiring. In particular, the front end 302 of the present invention can be in~t~ll~ between an ~oYi~ting AC lighting circuit and an AC power source so that the wiring of the AC lighting circuit carries DC current. Then, driver ends 304 operating on DC current can be installed in lighting fixtures connected to the now-converted DC lighting circuit.
As shown in Figure 6, this conversion process begins in block 602 with the provision of an AC-DC converter, such as front end 302. In the next step, shown in block 604, the front end circuit is connP~ted to the AC input source in place of the eYisting lighting circuit, which is disconn~octed. In the p~ftlred embo~lim~nt7 as described above, the front end is g~ - 12-installed in a junction box provided for the distribution of AC power through the lighting circuit.
In block 606, the wiring of the lighting circuit, which formerly carried AC power, is connP~t~d to the DC output of the front end circuit, thus converting the exi cting conventional lighting circuit to a high voltage DC circuit.
In block 608, the eYicting convention~l AC fixtures conne~ted to the lighting circuit are replaced by DC powered circuits, such as the driver ends disclosed above. The new DC
driver ends could be inct~ll~ as part of an entirely new DC-powered lighting fixture, or the driver ends could be incPlled as a retrofit of an eYicting inç~n~lesc~nt or fluorescent fixture.
In particular, existing inc~nrlescent fixtures may be provided with screw-in DC-powered driver ends ~eCigne~ to conne~t to a standard light bulb socket.
Finally, when wiring has been compl~tP,d, the le~ufit~ed lighting circuit is operated with DC power.
This general method can also be advantageously applied to the power distributionsystem within a single li&hting fixture, as shown in Figure 7. Figure 7 shows a typical lighting fixture 702, which may be for eY~mple a decc,ldti~re ch~ndeli~r. Fixture 702 is mounted to hang from an elect~c-~l box 706 mounted in the ceiling. AC wires 703 are provided in electrical box 706 to power light fixture 702. Light fixture 702 may have a plurality of bulb sockets 704, each conn~ct~d by two wires 708 to the AC wires 703 in a convention~l inct~ tion of this type of fixture. However, as shown in Figure 7, the present invention can be advantageously applied to such a fixture in the following manner. A front end 302 according to the present invention is inct~lled in electrical box 706 and is conne~ted to receive power from AC wires 703. Front end 302 has a power output 707, which is a DC high voltage power output. According to this application of the present invention, DC
output 707 is connected to fixture wires 708 to provide DC power to bulb sockets 704. A
driver end 304 is provided with a threaded coupling which mates with bulb sockets 704 to connect the power available in bulb sockets 704 to driver end 304. Driver end 304 provides an excitation signal for a compact fluolescenl bulb 712.
Thus, lighting fixture 702 can be rell~ùfilled to operate using efficient fluorescent bulbs by inct~lling a front end 302 between AC wires 703 and fixture wires 708, and by providing special compact driver ends which can be inct~ d in bulb sockets 704 and which drive small, low voltage fluo~escent bulb 712. For this application, it will be desirable to provide these compact driver ends with various threaded bases to correspond to the sockets W O 94/27419 ~ g ~ 9 PCT~US94105144 of the fixture. For many ch~ndeliers~ a more compact base will be needed (e.g. a candelabra base).
While the front end 302 and driver end 304 in this embodiment of the invention are gen~r~lly similar to the plefe,l~d embo~limentc described previously, there are some 5 differences in accordance with the special requirements of this particular application. For ex~mrle, front end 302 will generally have a lower power output capacity than the front end 302 used in a building el~tric~l distribution system. For ex~ml)le, for a lO bulb ch~ndelier which is to be operated with nine watt compact fluorescent bulbs, a front end power output of 100 watts would be sufficient. Also, to reduce the risk of electrical shock due to the lO presence of large voltages in wires 708, the DC output of front end 302 in this application is preferably much less than 350 volts, perhaps even less than 120 volts.
Rec~llc~ the driver ends 304 in this application can be constructed in a very compact manner, a large, visually intrusive housing ~ccoci~ted with conventional screw-in fluorescent repl~cPm~nt bulbs is çlilll;n~pd. Preferably, bulbs 712 are formed in an apl,rop,iate 15 decorative manner. For use in a rh~n~elier~ these bulbs may be formed in a shape a~5,~;,..~l;,-g the shapes of conve~ltinn~l inr~ndescPnt lamps used in ch~ndPli~rs~ such as a ~flame tip" shape.
The present invention provides particular cost advantages as coll-par~d to the systems and meth~ls of the prior art. Through study of the prior art systems, the inventor has determined that the front end of the electronic ballast accounts for 20 % to 60 % of the overall cost of each electronic ballast. For example, an advanced front end which conci~tc of a highly regulated power reservoir, as descrihed by U.S. Patent No. 4,864,482, is the most expensive section of the ballast. This is shown in Figure 3.
In the prior art, the DC power supply in the ballast typically provided a relatively low power output keyed to the design of the fixture. For example, the rated power output of the ballast might be 80 watts in a popular type of ballast designe~ to drive two four-foot, 40-watt fluo~escent tubes. The power h~n~ling capability of a front end primarily depe~ c on semiconductor power ratings and filter or storage c~p~itor capacity ratings. According to the present invention, the front end, as shown in Figure 3, is constructed so that it can deliver a high power output, such as 2000 watts. Presently, a 2000-watt front end can be constructed for about $14, only $4 more than the cost of an 80-watt front end. A complete 80-watt fluorescent lamp ballast, as disclosed in U.S. Patent Nos. 4,933,605 and 4,864,482, costs approximately $17.
W O 94/27419 2 ~ ~ 2 ~ ~ 9 PCTAUS94/05144 The cost of a driver end is approximately $9. Re~cal,se 20 driver ends can be used with a single front end, the cost of the front end attributable to each fixture is less than $1 and the overall ballast cost drops from $17 to less than $10 per fixture.
In addition to the size and cost advantages rçslllting from the system according to the 5 present invention, it has been found that separating the DC power supply and the resonant inverter circuitry as ~i~çlosed in the present invention reduces electrical losses in the driver end. Also, bec~use the heat produced by the DC power supply section is not produced in the vicinity of the driver end, the circuits of the driver end operate at lower temperatures.
Longer operating colllpoQent life is obtained as a result.
An additional advantage of the system according to the present invention is that the isol~tion of the lighting circuit from the AC line produced by front end 302 protects the lighting circuit from lightning, voltage spikes, etc. Further, the filtering functi~n~ pelrolllled by the large front end 302 prevent electrom~nPtic il~lrt;l~ ce from il~lrt;ling with lighting circuit operation, and reduce overall electrom~gnPtic in~lrelence gçn~ d by the system.
Claims (20)
1. A system for driving fluorescent, high pressure sodium, and metal halide type gas discharge lamps, comprising:
a centrally located AC to DC conversion circuit having a power input adapted forconnection to an AC current source and a DC power output;
a plurality of driver end means connected to said DC power output of said central conversion circuit, each for receiving DC power from said conversion circuit and converting said DC power into an excitation signal suitable for driving at least one gas discharge lamp associated with said driver end means.
a centrally located AC to DC conversion circuit having a power input adapted forconnection to an AC current source and a DC power output;
a plurality of driver end means connected to said DC power output of said central conversion circuit, each for receiving DC power from said conversion circuit and converting said DC power into an excitation signal suitable for driving at least one gas discharge lamp associated with said driver end means.
2. The system of claim 1 wherein said driver end means is a resonant inverter circuit for driving a fluorescent lamp.
3. The system of claim 1 wherein said centrally located conversion circuit is mounted in a distribution housing for an AC building circuit.
4. The system of claim 1 wherein said driver end means are mounted in DC-poweredfluorescent lighting fixtures.
5. The system of claim 3 wherein said centrally located conversion circuit is connected to said driver end means by wires of an AC building power circuit.
6. The system of claim 1 wherein at least 10 driver end means are connected receive power from a single said conversion circuit.
7. The system of claim 1 wherein the DC output voltage of said conversion circuit is at least 250 volts.
8. The system of claim 1 wherein said driver end means are provided with dimmingmeans for electronically reducing the duty cycle of the power provided to said gas discharge lamp in response to a control signal indicating a desired brightness level.
9. A system for driving gas discharge lamps, comprising:
a centrally located AC to DC conversion circuit having a power input adapted forconnection to an AC current source and a DC power output;
a plurality of resonant inverter circuits, each connected to said DC power output of said central conversion circuit and each having a lamp output connectable to at least one fluorescent lamp, each said resonant inverter circuit comprising an integrated circuit pulse width modulator and switching means, said switching means connected to said DC power output and said lamp output, said switching means controlled by said pulse width modulator to convert said DC power into a high frequency AC excitation signal at said lamp output for driving said lamp.
a centrally located AC to DC conversion circuit having a power input adapted forconnection to an AC current source and a DC power output;
a plurality of resonant inverter circuits, each connected to said DC power output of said central conversion circuit and each having a lamp output connectable to at least one fluorescent lamp, each said resonant inverter circuit comprising an integrated circuit pulse width modulator and switching means, said switching means connected to said DC power output and said lamp output, said switching means controlled by said pulse width modulator to convert said DC power into a high frequency AC excitation signal at said lamp output for driving said lamp.
10. A method for increasing the efficiency of an electrical lighting system, comprising the steps of:
identifying a lighting circuit to be upgraded, said lighting circuit having an AC power source connected by distribution wires to a plurality of existing lighting components;
providing an AC to DC converter circuit having an AC input and a DC output, and providing a plurality of gas discharge lighting drivers of a type powered by a DC power source external to said gas discharge lighting drivers;
connecting said lighting circuit from said AC power source and connecting said converter circuit to said AC power source at the point of said disconnection; connecting said lighting circuit to said DC output of said converter circuit; and replacing said existing lighting components with said gas discharge lighting drivers to form a localized DC gas discharge lighting circuit.
identifying a lighting circuit to be upgraded, said lighting circuit having an AC power source connected by distribution wires to a plurality of existing lighting components;
providing an AC to DC converter circuit having an AC input and a DC output, and providing a plurality of gas discharge lighting drivers of a type powered by a DC power source external to said gas discharge lighting drivers;
connecting said lighting circuit from said AC power source and connecting said converter circuit to said AC power source at the point of said disconnection; connecting said lighting circuit to said DC output of said converter circuit; and replacing said existing lighting components with said gas discharge lighting drivers to form a localized DC gas discharge lighting circuit.
11. The method of claim 10 wherein at least four gas discharge lighting fixtures are connected to receive power from a single converter circuit.
12. The method of claim 10 wherein said gas discharge lighting drivers comprise a resonant inverter circuit for driving a fluorescent lamp.
13. The method of claim 10 wherein said centrally located conversion circuit is mounted in a distribution box for an AC building circuit.
14. The method of claim 10 wherein said gas discharge lighting drivers are mounted in existing lighting fixtures.
15. The method of claim 14 wherein said gas discharge lighting drivers are provided with bases which mate with standard lamp sockets in the existing fixtures to provide DC
power connections of the gas discharge lighting drivers.
power connections of the gas discharge lighting drivers.
16. The method of claim 10 wherein the DC output voltage of said conversion circuit is at least 250 volts.
17. A method of increasing the efficiency of an electrical lighting fixture having a plurality of bulb sockets each connected by wires to an AC power source, comprising the steps of:
providing a compact AC to DC converter circuit having an AC input and a DC
output;
disconnecting the wires of said lighting fixture from said AC power source and connecting said converter circuit to said AC power source at the point of said disconnection;
connecting said wires to said DC output of said converter circuit; and replacing existing bulbs in said bulb sockets with compact gas discharge lighting driver circuits having bulb socket bases, said driver circuits operating to receive DC power from said conversion circuit and convert said DC power into an excitation signal suitable for driving a compact gas discharge lamp associated with said driver circuit.
providing a compact AC to DC converter circuit having an AC input and a DC
output;
disconnecting the wires of said lighting fixture from said AC power source and connecting said converter circuit to said AC power source at the point of said disconnection;
connecting said wires to said DC output of said converter circuit; and replacing existing bulbs in said bulb sockets with compact gas discharge lighting driver circuits having bulb socket bases, said driver circuits operating to receive DC power from said conversion circuit and convert said DC power into an excitation signal suitable for driving a compact gas discharge lamp associated with said driver circuit.
18. The method of claim 17 wherein the lamp associated with said driver circuit has a shape simulating the shape of an incandescent light bulb.
19. The method of claim 17 wherein the driver circuits comprise a resonant inverter of a type controlled by an integrated circuit pulse width modulator.
20. The method of claim 19 wherein said driver circuit is mounted in a compact housing in the area of the bulb socket base.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US6055993A | 1993-05-13 | 1993-05-13 | |
| US08/060,559 | 1993-05-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2162889A1 true CA2162889A1 (en) | 1994-11-24 |
Family
ID=22030278
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2162889 Abandoned CA2162889A1 (en) | 1993-05-13 | 1994-05-13 | System and method for distributing power to gas discharge lamps |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU6908894A (en) |
| CA (1) | CA2162889A1 (en) |
| WO (1) | WO1994027419A1 (en) |
Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19502772C2 (en) * | 1995-01-30 | 2002-02-28 | Walter Holzer | Electronic ballast for fluorescent lamps |
| GB2299659A (en) * | 1995-04-03 | 1996-10-09 | Solar Wide Ind Ltd | Lighting systems |
| DE19543419A1 (en) * | 1995-11-21 | 1997-05-22 | Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh | Method and circuit arrangement for operating cold cathode fluorescent lamps |
| NL1005358C2 (en) * | 1997-02-24 | 1998-09-08 | Vito | Lighting for commercial greenhouse |
| FR2761564B1 (en) * | 1997-03-27 | 2001-07-27 | Jacques Emile Boudan | SYSTEM AND APPARATUS FOR SUPPLYING THE DISCHARGE LAMPS OF A LIGHTING NETWORK |
| US6137233A (en) * | 1998-10-16 | 2000-10-24 | Electro-Mag International, Inc. | Ballast circuit with independent lamp control |
| US6222326B1 (en) * | 1998-10-16 | 2001-04-24 | Electro-Mag International, Inc. | Ballast circuit with independent lamp control |
| FR2801164B1 (en) * | 1999-11-17 | 2002-05-03 | Dev Ind Et Commercial D Aldim | DEVICE FOR PROVIDING ELECTRICAL ENERGY FOR A SET OF DISCHARGE LAMPS OF A LIGHTING NETWORK |
| FR2804571B1 (en) * | 2000-01-27 | 2004-07-23 | Eclairage Public Beep Bureau E | MODULE FORMING A BOOSTER-INVERTER FOR A DEVICE FOR SUPPLYING A DISCHARGE LAMP AND METHOD FOR MOUNTING A FLOOR LAMP OR PROJECTOR COMPRISING SUCH A MODULE |
| FR2804570B1 (en) * | 2000-01-27 | 2002-07-19 | Eclairage Public Beep Bureau E | MODULAR ELECTRONIC SUPPLY DEVICE FOR DISCHARGE LAMP |
| FR2804572B1 (en) * | 2000-02-01 | 2002-04-19 | Dev Ind Et Commercial D Aldim | MEDIUM FREQUENCY GENERATOR DEVICE FOR POWERING A DISCHARGE LAMP |
| IT1316561B1 (en) * | 2000-12-28 | 2003-04-22 | Setech S R L | FEEDING DEVICE FOR COLD CATHODE LAMPS. |
| DE10163960A1 (en) * | 2001-12-23 | 2003-07-03 | Der Kluth Decke Und Licht Gmbh | Illumination arrangement for optical quality control of surfaces has illumination source and matt plate arranged so matt plate is uniformly illuminated by illumination source |
| DE10163957A1 (en) * | 2001-12-23 | 2003-07-03 | Der Kluth Decke Und Licht Gmbh | Electronic voltage adapter for light sources is able to be connected to more than two light sources, especially fluorescent tubes, has rectifier connected to several high frequency generators |
| DE102004002017B4 (en) * | 2004-01-14 | 2019-12-12 | Tridonic Gmbh & Co Kg | Control of control gear for lamps using switching modulation of a DC bus |
| DE102004002027B4 (en) | 2004-01-14 | 2020-03-26 | Tridonic Gmbh & Co Kg | Central PFC with DC output circuit control |
| DE102004002026A1 (en) | 2004-01-14 | 2005-08-04 | Tridonicatco Gmbh & Co. Kg | Control of lamp operating devices via a modulated DC bus |
| DE102004002016A1 (en) * | 2004-01-14 | 2005-08-04 | Tridonicatco Gmbh & Co. Kg | Central supply via several DC output circuits |
| DE102004002018A1 (en) * | 2004-01-14 | 2005-08-04 | Tridonicatco Gmbh & Co. Kg | DC-supplied equipment modules for lamps |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4508996A (en) * | 1980-06-23 | 1985-04-02 | Brigham Young University | High frequency supply system for gas discharge lamps and electronic ballast therefor |
-
1994
- 1994-05-13 AU AU69088/94A patent/AU6908894A/en not_active Abandoned
- 1994-05-13 CA CA 2162889 patent/CA2162889A1/en not_active Abandoned
- 1994-05-13 WO PCT/US1994/005144 patent/WO1994027419A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| WO1994027419A1 (en) | 1994-11-24 |
| AU6908894A (en) | 1994-12-12 |
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