EP0020493B1 - Fluorescent lamp lighting system - Google Patents

Fluorescent lamp lighting system Download PDF

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Publication number
EP0020493B1
EP0020493B1 EP19790901332 EP79901332A EP0020493B1 EP 0020493 B1 EP0020493 B1 EP 0020493B1 EP 19790901332 EP19790901332 EP 19790901332 EP 79901332 A EP79901332 A EP 79901332A EP 0020493 B1 EP0020493 B1 EP 0020493B1
Authority
EP
European Patent Office
Prior art keywords
transistor
lamps
ballast
current
lamp unit
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.)
Expired
Application number
EP19790901332
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0020493A1 (en
EP0020493A4 (en
Inventor
Don F. Widmayer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Controlled Environment Systems Inc
Original Assignee
Controlled Environment Systems Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Controlled Environment Systems Inc filed Critical Controlled Environment Systems Inc
Publication of EP0020493A1 publication Critical patent/EP0020493A1/en
Publication of EP0020493A4 publication Critical patent/EP0020493A4/en
Application granted granted Critical
Publication of EP0020493B1 publication Critical patent/EP0020493B1/en
Expired legal-status Critical Current

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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
    • 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

Definitions

  • the present invention relates to fluorescent lamp lighting systems for illumination purposes and the like.
  • GB-B 2,007,880 (Don Frederick WIDMAYER), published after the priority date of the present application, there is described an energy conserving lighting system in which a plurality of fluorescent lamps are powered by a poorly regulated voltage supply which provides a decreasing supply voltage with increasing arc current so as to generally match the. volt-ampere characteristics of the lamps.
  • a transistor ballast and control circuit connected in the arc current path controls the arc current and hence the light output in accordance with the total ambient light, i.e. the light produced by the lamps together with whatever further light is produced by other sources such as daylight.
  • a transistor ballast is utilised in combination with an inductive ballast. The transistor ballast provides current control over a wide dynamic range up to a design current maximum at which maximum the transistor is saturated and the inductive. ballast takes over the current limiting function.
  • a basic arc control circuit such as is disclosed in the above mentioned GB-B-2007880 (Don Frederick WIDMAYER) is altered so as to use an operational amplifier and a transformer power supply.
  • a transformer 102 steps down the line voltage (which may be 116 VAC, 277 VAC or other available line voltages) to a 10 VAC voltage appearing on the isolated secondary winding thereof.
  • a diode 104 acts as a half-wave rectifier so as to permit the positive half-cycle of the secondary voltage to charge a capacitor 108 connected across the secondary to a level approximately 14 VDC above the voltage of the common bus, referred to hereinafter as the signal common.
  • This voltage level will hereinafter be referred to as the plus or positive supply.
  • a further diode 106 permits the negative half cycle of the 10 VAC secondary voltage to charge a capacitor 110 to a level approximately 14 VDC below signal common, which level will hereinafter be referred to as the minus supply.
  • a resistor 82'" is connected in series combination with a zener diode 78"', with zener diode 78'" being connected to the signal common bus and resistor 82'" to the plus supply, as shown, in order to provide a regulated voltage above the signal common voltage above for signal generation purposes.
  • a plus and minus power supply is desirable, although a single sided supply can be employed, when an operational amplifier is used.
  • FIG. 1 shows operational amplifier 116 connected in a differential input configuration.
  • the setting of a potentiometer 64'" provides a reference signal at the plus input of operational amplifier 116.
  • a light controlled variable resistance photocell 74"' which is connected to a resistor 112 and a resistor 114 as shown, is connected to the minus input.
  • the function of potentiometer 64'" can also be replaced by a remote program signal, signal generator or the like in an application requiring remote adjustment of the reference signal.
  • junction node 113 is connected to the minus input of operational amplifier 116 through resistor 114.
  • Resistor 114 is part of an RC time constant network that further includes a capacitor 118. This network helps to prevent abrupt changes in the output of the system where this is desirable.
  • the RC network might be modified to different component values or be removed with the minus input of operational amplifier 116 can be connected directly to the junction of photocell 74''' and resistor 112.
  • the output of operational amplifier 116 is connected to a further diode 120.
  • the latter is also connected to a diode 122 whose anode is also connected to the junction of a pair of voltage divider resistors 124 and 126.
  • resistors 124 and 126 are selected such that the junction voltage, i.e., the voltage on the anode of diode 122, provides a minimum "on” signal through diode 122 to a transistor 60"'. Hence, transistor 60''' is "on” at some minimum level related to the voltage division of resistor 124 and 126 whenever the system has AC line power.
  • Transistor 60''' drives a control transistor 26''' via a resistor 128 which acts as a current source to minimize component thermal drifts and the like.
  • Transistor 26"' is connected through a diode bridge formed by diodes 92', 94', 96' and 98' to an inductive ballast 100' for a pair of lamps L 1 ' and L 2 '. Ballast 100' and the connections to lamps L 1 ' and L 2 ' are conventional.
  • Transistor 26"' normally operates in the active region, thereby limiting the current in the ballast primary only when the lamps are ignited.
  • transistor 26"' is effectively saturated “on” during the "lamps off” portion of the AC cycle so full magnetising and lamp filament current is provided at least up to lamp ignition.
  • the full line voltage is applied to the ballast 100' until the lamps ignite.
  • the ballast 100' is provided with magnetizing current and the lamps have their rated cathode current when applicable.
  • the bridge diodes 92', 94', 96' and 98' rectify the AC of the ballast 100' and transistor 26"', being located in the DC leg, permits DC control techniques to be employed.
  • the signal information for the closed loop is thus generated at a 120 Hz rate for a 60 Hz system and a 100 Hz rate for a 50 Hz system, and in approximately 6 millisecond bursts from the lamps for a 60 Hz system and in 8 milliseconds bursts for a 50 Hz system. These bursts of light are averaged by the time constant circuit associated with operational amplifier 116.
  • the minimum signal provided by diode 122 will back bias diode 120, with diode 122 providing a minimum signal from voltage divider resistors 124 and 126 to transistor 60"'.
  • the signal from diode 120 or diode 122 turns on transistor 60'" through resistors 128 and transistor 26'" is saturated “on” as long as the lamps have not ignited. It is noted that a transistor is saturated “on” when that transistor has sufficient minority carriers in the base region so as not to limit any current which would flow through the collector diode. Expressed another way, the collector current of the transistor is now unlimited and will remains so to the extent of the availability of minority base region carriers.
  • the primary ballast transformer 100' essentially receives the full line voltage and the saturated transistor 26"' conducts the magnetizing current of ballast 100' (together with the load current of the lamp heaters if rapid start lamps are used).
  • the lamps ignite.
  • Current through lamps L 1 and L 2 then rises to a level dependent on base drive of transistor 26"', as explained hereinabove. Once this current level is reached, the transistor 26"' comes out of saturation and the current flow is not limited. At this time, the circuit voltages adjust due to the fact that the change in circuit current ceases.
  • ballast primary voltage is then once again equal to the line voltage minus the small saturation voltage of the saturated transistor-diode bridge combination.
  • the operation of the circuit of Figure 1 described above is repeated during a part of each half cycle of the line voltage depending on the duration of the current limiting period.
  • the base drive or regulated collector current of transistor 26"' is set by the closed loop completed through lamps L 1 and L 2 and photocell 74"'.
  • the loop response is slowed down by the RC network formed by resistor 114 and capacitor 118 such that fast changes in light level are averaged over a several second time period.
  • the loop can also have a fast response by providing adjustments to, or the elimination of, the RC network.
  • the value of current limiting provided in response to a related light level is set by setting the tap or wiper of potentiometer 64''' to produce the desired output voltage.
  • Feedback is provided by sensing the light output from the lamps L 1 and L 2 and/or some other light components via a light collecting lens CL attached to a bundle of fiber optics FO to transmit a measure of the ambient light level at a given location to photocell 74'" generally located with the control circuitry within a lamp fixture without using electrical conductors. This ensures that the selected lamp current will be limited to a level related to the reference signal level.
  • the feedback light produces a voltage at the junction of photocell 74'" and resistor 112.
  • the minimum level signal is established by adjustment of the reference or command signal potentiometer (element 64"') so as to establish a minimum reference signal level at the transistor summing point.
  • the control transistor is saturated “on” for the period of time during each AC half cycle that the lamps are not ignited. Therefore, firing of the lamps is not inhibited and once the lamps fire, the control transistor then operates in a new unsaturated linear range up to the point that the ballast limits the current. Further, with the use of a sufficient input reference signal, the ballast will provide limiting and the control transistor is again saturated with lamps "on". This sequence repeats itself each half cycle.
  • each pair of lamps in a fixture has an AC inductive ballast; in fact, many fixtures contain four lamps with two ballasts in the ballast compartment of the fixture. While an individual system could be used for each ballast, substantial savings might be realized if two or more ballasts could be operated from a single control system.
  • two ballasts cannot be operated in parallel from a single system because the lamp pairs, in effect, act in a manner somewhat analogous to zener diodes. Specifically, one pair inevitably ignites and thereafter, while the other pair may subsequently ignite, this pair will operate in a low uncontrolled current region so that only the pair that first reaches the arc discharge region is controlled. This behaviour of paralleled ballasts is due to the arc-discharge phenomena and is a substantial obstacle to realizing the economies referred to above.
  • Figure 2 corresponds to Figure 1 with addition of a second pair of lamps L 3 and L 4 and an associated ballast, and the same reference numerals are used for common components.
  • Figure 2 corresponds to Figure 1 with addition of a second pair of lamps L 3 and L 4 and an associated ballast, and the same reference numerals are used for common components.
  • another four diode bridge formed by diodes 134, 136, 138 and 140, a control transistor 141, and a pair of emitter resistors 130 and 132 are connected as shown in Figure 2. It is noted that one of these emitter resistors, viz., emitter resistor 130, is added in the emitter leg of transistor 26''' and the base lead of transistor 141 is connected to the junction between resistor 128 and transistor 26"'.
  • ballasts in other fixtures.
  • the fixture with the sensing and reference signal circuitry will hereinafter be referred to as the "master unit” and the second ballast and/or other fixtures with other ballast(s), together with their full wave bridges and control transistors with emitter resistors, will hereinafter be referred to as "follower units”.
  • the power supply, as well as transistor 60'" of the master unit must be suitably rated to provide sufficient signal levels to accommodate the needs of a plurality of control transistors.
  • Electro-optical devices can also be employed to eliminate wiring used in conductive coupling between master and follower units.
  • FIG 3 another embodiment of the master-follower concept is illustrated.
  • Figure 3 is similar to Figure 2 and like elements have been given the same reference numerals.
  • the advantage of the embodiment of Figure 3 over that of Figure 2 is that the currents flowing in the primaries of the one or more follower ballasts are more precisely matched or sealed.
  • a further transistor 60 1 and further operational amplifier 116 1 are also incorporated in the follower circuit.
  • the reference signal supplied to the plus input of operational amplifier 116 1 is derived from the voltage generated across emitter resistor 130 and the feedback or minus base input to operational amplifier 116 1 is derived from the voltage generated across emitter resistor 132.
  • operational amplifier 116 1 With a rated forward yoltage gain of 50,000, operational amplifier 116 1 provides maximum output for less than a millivolt of differential signal input. Because of this, the embodiment of Figure 3 provides precise current matching or scaling of a plurality of ballast currents. The transistor currents can be scaled by providing an appropriate ratio between the values of the respective emitter resistors.
  • follower units could be provided for many ballasts with interconnecting signal wiring from the master unit or optical coupling devices.
  • signals can be coded and transmitted and thereafter received and decoded at selected fixtures.
  • the current-matching capability of the circuit of Figure 3 is so precise that the full- wave bridge formed by diodes 134, 136, 138 and 140 and the second ballast 142 could be eliminated and the collector of transistor 141 connected directly to the collector of transistor 26' ' ' as indicated in chain-dashed lines so as to increase the current capacity of the master unit.
  • the light turn-on/ turn off problem This occurs for example, when someone forgets to turn off the lights when leaving an area and/or when maintenance personnel turn lights on after hours for longer than necessary.
  • Some buildings are not equipped with light turn-on and turn-off programs and many software programs and/or sensors are available for doing the same thing.
  • the cost of the magnetic conductors, housings, power handling wiring and other power switching problems inhibit the provision of automatic programming for light systems.
  • a computer signal delivered to any master or single unit could shut off the lights controlled thereby by the addition of simple circuitry which would serve to pull the base of transistor 60'" in Figure 3 negative to the point of providing shut off.
  • a photo-transistor or other optical device denoted 144
  • a resistor 146 connected to the minus 15 volt power supply bus.
  • the software program referred to above would, at the appropriate time, energize a light emitting diode (not shown) to switch the photo-transistor 144 "on”, thereby pulling the base of transistor 60"', negative to the point of cut off. This would of course turn off transistor 26"' and terminate flow of the ballast magnetizing currents and hence cut off power to the lamps.
  • the present invention is particularly applicable to illuminating light, the invention would also be useful in many photographic and other technical or scientific applications where light control is of a definite advantage.
  • a simple yet highly efficient energy conserving system is provided in accordance with the invention which controls-the level of light from a fluorescent lamp(s) and which has applications for controlling the quantity and other characteristics of the outputs of gaseous arc discharge lamps in general, as well as special purpose load devices, over a wide dynamic operating range.
  • the actual savings which can be realized would amount to millions of barrels of oil where the principles of the invention were utilized on a sufficiently widespread basis.
  • inductive ballast is shown in the specific embodiments illustrated, other ballasts can be employed and that the term "reactive ballast" as used in this application refers to inductive or capacitive ballasts.

Landscapes

  • Circuit Arrangements For Discharge Lamps (AREA)
  • Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)
EP19790901332 1978-09-26 1980-04-22 Fluorescent lamp lighting system Expired EP0020493B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US94584278A 1978-09-26 1978-09-26
US945842 1978-09-26

Publications (3)

Publication Number Publication Date
EP0020493A1 EP0020493A1 (en) 1981-01-07
EP0020493A4 EP0020493A4 (en) 1982-04-22
EP0020493B1 true EP0020493B1 (en) 1986-03-12

Family

ID=25483619

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19790901332 Expired EP0020493B1 (en) 1978-09-26 1980-04-22 Fluorescent lamp lighting system

Country Status (7)

Country Link
EP (1) EP0020493B1 (es)
JP (1) JPS5598500A (es)
CA (1) CA1128605A (es)
DE (1) DE2967585D1 (es)
FR (1) FR2443183A2 (es)
MX (1) MX149353A (es)
WO (1) WO1980000776A1 (es)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2165407B (en) * 1984-10-02 1988-01-20 Ferranti Plc Gas laser power supply apparatus

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3114283A (en) * 1960-10-31 1963-12-17 Bausch & Lomb Light sensing method and apparatus therefor
US3482142A (en) * 1967-12-29 1969-12-02 Sylvania Electric Prod Regulating system for arc discharge devices having means to compensate for supply voltage and load variations
US3479560A (en) * 1967-12-29 1969-11-18 Sylvania Electric Prod Arc discharge regulating device having means to compensate for supply voltage variations
DE2019240A1 (de) * 1969-04-23 1970-11-12 Fuji Photo Film Co Ltd Kopiervorrichtung fuer Farbphotographie
CA1128604A (en) * 1977-11-07 1982-07-27 Don F. Widmayer Energy conserving automatic light output system

Also Published As

Publication number Publication date
EP0020493A1 (en) 1981-01-07
FR2443183B2 (es) 1984-06-15
JPS5598500A (en) 1980-07-26
EP0020493A4 (en) 1982-04-22
FR2443183A2 (fr) 1980-06-27
WO1980000776A1 (en) 1980-04-17
CA1128605A (en) 1982-07-27
MX149353A (es) 1983-10-26
DE2967585D1 (en) 1986-04-17

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