WO1998012901A1 - Fluorescent lamp illumination level control - Google Patents
Fluorescent lamp illumination level control Download PDFInfo
- Publication number
- WO1998012901A1 WO1998012901A1 PCT/AU1997/000606 AU9700606W WO9812901A1 WO 1998012901 A1 WO1998012901 A1 WO 1998012901A1 AU 9700606 W AU9700606 W AU 9700606W WO 9812901 A1 WO9812901 A1 WO 9812901A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- supply voltage
- circuit
- switching device
- lamp
- illumination level
- Prior art date
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
- 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
- H05B41/3921—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations
- H05B41/3927—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations by pulse width modulation
-
- 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
- H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
- H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
- H05B41/295—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps
-
- 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
- H05B41/3921—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations
- H05B41/3924—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations by phase control, e.g. using a triac
Definitions
- This invention relates to a method of and apparatus for controlling the illumination level of fluorescent lamps.
- the invention has particular application to controlled dimming of fluorescent lamps and is hereinafter described in that context.
- lamp dimming normally provides for selective variation of the illumination levels
- the present invention has more general application, to adjustable setting of illumination to fixed levels.
- Fluorescent lamp dimming is effected by gating a solid state switching device (usually a triac) into conduction at a selected phase angle and, hence, over a selected conduction angle during each half-cycle of a mains supply voltage. Also, m order to ensure that illumination is established and sustained during reduced conduction angles, filament heating current is fed through the lamp cathodes during lamp operation as well as during start-up.
- a filament transformer when a three-wire (active, dimmed active and neutral) connection may be made to the lamp from a switched dimmer control circuit or by use of a so-called filament driver when a two-wire (dimmed active and neutral) connection is to be made to the lamp.
- a fluorescent lamp illumination level controller which comprises: means for connecting a phase-angle controlled supply voltage across a circuit containing a fluorescent lamp and a series inductor, means for directing heating current through a circuit that includes the lamp cathodes and the inductor for a time interval during each half-cycle of the supply voltage, and means for varying the time interval inversely with change m the conduction angle of the supply voltage.
- the invention also provides an illumination level controller as above defined when connected in circuit w th a fluorescent lamp and a series inductor .
- the invention provides et method of controlling the illumination level of a fluorescent lamp wherein a phase-angle controlled supply voltage is connected across a circuit containing the fluorescent lamp and a series inductor, wherein heating current is directed through a circuit that includes the lamp cathodes and the inductor for a time interval during each half-cycle of the supply voltage and wherein the time interval of heating current flow through the lamp cathode is varied inversely with change m the conduction angle of the supply voltage.
- the means for directing the heating current through the lamp cathodes and for varying the time interval of current flow during each half-cycle preferably includes a solid state switching device and a gating circuit arranged to gate the switching device into conduction for the required time interval during each half-cycle.
- the illumination level controller functions to maintain the lamp cathodes at a required temperature level when the supply voltage level is not sufficient to sustain gas discharge heating of the cathodes at a sufficiently high level.
- the cathode heating current is caused to flow for the time interval of each half-cycle of the supply during which the switching device is turned on, and as the conduction angle and hence level of the supply voltage increases, so the time interval during which the flow of heating current occurs decreases, and vice versa.
- the controller functions to maintain a balance between maximum illumination, when the supply voltage is at a maximum level (i.e., has a maximum conduction angle) and the duration of current flow to the cathode is minimised, and minimum illumination when the supply voltage is at a minimum level (i.e., has a minimum conduction angle) and the duration of current flow to the cathodes is maximised.
- the switching device when the switching device is gated off in each half-cycle of the supply voltage, the switching device functions to interrupt current flow to the lamp cathodes and, so, to induce the generation of back e f in the inductor that is located m series with the fluorescent lamp.
- the switching device may comprise an ac switching device or a dc switching device in circuit with a rectifier.
- the switching device preferably comprises a field effect transistor, but any other solid state switching device (or arrangement of devices) which can be made to function as a switch during each half-cycle may be employed.
- the illumination level controller may be employed m conjunction with or be integrated with a more-or-less conventional dimming control circuit, and, in such circumstances, the phase-angle controlled supply voltage will be derived directly as the dimmed active voltage output of the dimming control circuit.
- a preferred embodiment of a fluorescent lamp illumination level controller which is suitable for use in conjunction with a dimming control circuit is now described by way of example with reference to the accompanying drawings .
- Figure 1 shows a schematic representation of the illumination level controller in association with a dimming control circuit and a fluorescent lamp circuit
- Figure 2 shows a complete circuit diagram of the illumination level controller, again m association with a dimming control circuit and a fluorescent lamp circuit,
- Figure 3 shows graphical representations of voltage waveforms in various parts of the controller circuit
- Figure 4 shows comparative voltage waveforms under (A) maximum and (B) minimum levels of lamp illumination.
- the illumination level controller 10 is connected in circuit with a fluorescent lamp circuit 11 and a dimming control circuit 12.
- the dimming control circuit 12 is connected to a single phase mains supply voltage 13 and it comprises a conventional triac circuit 14 for which the conduction angle may be varied by a gating circuit 15.
- the output from the dimming control circuit 12 comprises a phase-angle controlled supply voltage V : which is connected across the series circuit 11 containing a fluorescent lamp 16 and an inductor (i.e., a ballast) 17.
- the controller 10 may be considered as having three circuit portions, the first of which provides for connection of the controlled supply voltage V] across the lamp circuit
- the switching device 19 comprises a field effect transistor which is connected across two terminals of a rectifier bridge circuit 21.
- the rectifier bridge 21 is itself connected m circuit with the lamp cathodes 18 and, when gated into conduction, the transistor 19 provides for heating current flow through the lamp cathodes.
- the control circuit 20 is provided to effect on-off gating of the transistor 19 during each half-cycle of the supply voltage Vi, and the control circuit is arranged also to vary the gating time interval as an inverse function of the level (i.e., the r. .s. value) of the supply voltage V, as determined by the conduction angle of the triac 14. This is described in more detail later m this specification.
- the control circuit 20 After expiration of a predetermined time interval of two or three seconds, when the temperature of the cathodes has been raised to a required level, the control circuit 20 functions to turn the transistor 19 OFF, causing the current to drop almost instantly to zero. This m turn induces generation of a back e f in the inductor 17 at a level sufficient to push the voltage V 2 up to approximately 1 kV, causing the lamp to turn ON.
- the control circuit 20 functions to turn the transistor 19 ON and OFF during the period of each half- cycle of the supply voltage V and the ON period of the transistor is controlled as an inverse function of the conduction angle of the supply voltage V, . That is, with a long conduction angle and a resultant "high” level supply voltage, the ON period of the transistor is controlled to be “short”. Conversely, with a short conduction angle and a resultant "low” level supply voltage, the ON period of the transistor is controlled to be "long”.
- the lamp 16 is energised for maximum illumination and the current flow through the lamp under that condition is sufficient to maintain the cathodes 18 at the required operating temperature level.
- the illumination level of the lamp drops and cathode heating is maintained at a required level by current flow through the transistor/cathode circuit for an increasing time interval during each half-cycle, so that lamp illumination is sustained.
- the illumination level controller may be implemented in a form that provides for maximum lamp illumination when the supply voltage output V, from the dimming control circuit 12 has a conduction angle of approximately 150°. Under this condition the OFF period of the transistor 19 is long, in the order of 9 mS during each half-cycle of a 50 Hz supply, and cathode heating is effected primarily as a consequence of "high" energy level gas discharge within the lamp.
- Minimum lamp illumination may be provided when the supply voltage output V, from the dimming control circuit 12 has a conduction angle of approximately 90°. Under this condition the ON period of the transistor 19 is controlled to be long, in the order of 9 mS during each half-cycle of the supply. Under this condition, almost all of the power that is generated during the period of current conduction by the transistor 19 is dissipated in the form of heat m the cathode filaments 18 and a "small" amount of energy is expended in gas discharge within the lamp.
- the illumination level of the lamp under this condition may be reduced to something in the order of 5° 0 of the maximum illumination level but the lamp is prevented from extinguishing by the periodic generation of back emf within the inductor during each half-cycle of the supply, as a consequence of the transistor 19 being turned OFF during the duration of each half-cycle.
- the illumination level controller 10 as shown in Figure 1 may be implemented in various circuit configurations, one of which is shown by way of example m Figure 2.
- the circuit as illustrated in Figure 2 incorporates the same elements as those shown m Figure 1, principally the dimming control circuit 12, the fluorescent lamp 16 and inductor 17, the field effect transistor 19 and the gating control circuit 20.
- the functions of the various circuit components are largely self evident and, where appropriate, are referred to as follows m sub-circuit groupings.
- the gating control circuit 20 includes a dc power supply 25 for a monostable IC oscillator 26.
- the output from the power supply s stabilised by a zener diode 27 and is connected to pin 8 of the oscillator 26.
- the output V 7 of the oscillator 26 is initially held low for the predetermined time interval of two to three seconds. This time interval is determined by the value of the capacitor connected to pin 5 of the oscillator 26.
- the oscillator 26 is triggered once during each half-cycle of the supply voltage via pin 2 by voltage V L going low at or near the zero crossing point of the supply voltage Vi, and the output V derived from pin 3 of the oscillator goes high for a period which is determined by and increases with decreasing level of the voltage V applied to the pins 6, 7 of the oscillator 26.
- the voltage Vr is derived as a dc voltage level which varies inversely as a function of the level of the supply voltage V, and, thus, the output V 7 from the oscillator remains high for a time interval which is proportional to the conduction angle (i.e., r.m.s. voltage level) of the supply voltage Vi .
- the output V from the oscillator is coupled to the gate of the transistor 19 by way of an opto-coupler 28 and, thus, when voltage V goes high, voltage V ⁇ applied to the gate of the transistor 19 goes low.
- the oscillator 26 is triggered by voltage V once during each hall-cycle of the supply voltage Vi, and the output voltage V, of the oscillator goes high.
- the gating voltage V applied to the transistor 19 goes low and the transistor is turned off.
- Current flow through the transistor is terminated and the generation of back emf is, as a result, induced m the inductor 17, resulting m a periodic spike m the voltage V- across the transistor 19.
- the voltage V_ lifts the supply voltage Vi that appears across the lamp 16 during a portion of each half-cycle of the supply voltage.
- the output voltage V 7 of the oscillator goes low.
- the transistor gate voltage V ⁇ consequently goes high and turns the transistor 19 ON until such time as the output voltage V 7 from the oscillator again goes high.
- Figure 4 shows a comparison of the voltage waveforms V,, V . and V ⁇ under maximum and minimum levels of lamp illumination.
- V conduction angle of the supply voltage
- V : increases
- the dc level of voltage V- decreases, causing the period of the transistor gating voltage V- to decrease. Consequently, the interval during which heating current is fed to the lamp cathode decreases and the period during which the lamp is held ON increases.
- maximum illumination is derived when the conduction angle of the supply voltage is at a maximum.
- the magnitude of the spike m the voltage waveform V ⁇ is significantly greater when the voltage supply V is controlled to provide a low level of lamp illumination.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU41063/97A AU728836B2 (en) | 1996-09-18 | 1997-09-16 | Fluorescent lamp illumination level control |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AUPO2447A AUPO244796A0 (en) | 1996-09-18 | 1996-09-18 | Fluorescent lamp illumination level control |
AUPO2447 | 1996-09-18 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998012901A1 true WO1998012901A1 (en) | 1998-03-26 |
Family
ID=3796758
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/AU1997/000606 WO1998012901A1 (en) | 1996-09-18 | 1997-09-16 | Fluorescent lamp illumination level control |
Country Status (2)
Country | Link |
---|---|
AU (1) | AUPO244796A0 (en) |
WO (1) | WO1998012901A1 (en) |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0071346A1 (en) * | 1981-07-27 | 1983-02-09 | Cornell-Dubilier Electronics Inc. | Method and circuit for controlling illumination from a gas discharge lamp |
US4568857A (en) * | 1982-11-09 | 1986-02-04 | Honeywell Ltd. | Fluorescent light controller |
SU1330766A1 (en) * | 1985-09-16 | 1987-08-15 | Харьковский институт инженеров коммунального строительства | Lighting device with a luminescent lamp |
AU5203290A (en) * | 1989-03-29 | 1990-10-04 | H.P.M. Industries Pty Limited | Illumination level controller |
GB2232543A (en) * | 1989-05-18 | 1990-12-12 | Lutron Electronics Co | Fluorescent lamp dimming system |
US5175477A (en) * | 1991-09-30 | 1992-12-29 | David Grissom | Dimmer for fluorescent and incandescent lamps |
US5194782A (en) * | 1991-07-19 | 1993-03-16 | Richardson Robert H | Dimmer for fluorescent lamp |
US5504398A (en) * | 1994-06-10 | 1996-04-02 | Beacon Light Products, Inc. | Dimming controller for a fluorescent lamp |
-
1996
- 1996-09-18 AU AUPO2447A patent/AUPO244796A0/en not_active Abandoned
-
1997
- 1997-09-16 WO PCT/AU1997/000606 patent/WO1998012901A1/en active Application Filing
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0071346A1 (en) * | 1981-07-27 | 1983-02-09 | Cornell-Dubilier Electronics Inc. | Method and circuit for controlling illumination from a gas discharge lamp |
US4568857A (en) * | 1982-11-09 | 1986-02-04 | Honeywell Ltd. | Fluorescent light controller |
SU1330766A1 (en) * | 1985-09-16 | 1987-08-15 | Харьковский институт инженеров коммунального строительства | Lighting device with a luminescent lamp |
AU5203290A (en) * | 1989-03-29 | 1990-10-04 | H.P.M. Industries Pty Limited | Illumination level controller |
GB2232543A (en) * | 1989-05-18 | 1990-12-12 | Lutron Electronics Co | Fluorescent lamp dimming system |
US5194782A (en) * | 1991-07-19 | 1993-03-16 | Richardson Robert H | Dimmer for fluorescent lamp |
US5175477A (en) * | 1991-09-30 | 1992-12-29 | David Grissom | Dimmer for fluorescent and incandescent lamps |
US5504398A (en) * | 1994-06-10 | 1996-04-02 | Beacon Light Products, Inc. | Dimming controller for a fluorescent lamp |
Also Published As
Publication number | Publication date |
---|---|
AUPO244796A0 (en) | 1996-10-10 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6051940A (en) | Safety control circuit for detecting the removal of lamps from a ballast and reducing the through-lamp leakage currents | |
US6111368A (en) | System for preventing oscillations in a fluorescent lamp ballast | |
US7049758B2 (en) | Method of soft-starting a switching power supply having time-based pulse triggering control | |
US6724157B2 (en) | Energy savings device and method for a resistive and/or an inductive load | |
JPH0323928B2 (en) | ||
US7116062B2 (en) | Method of soft-starting a switching power supply including pulse width modulation circuit | |
JP2004505593A (en) | Interface circuit and method | |
US7053562B2 (en) | Lamp containing soft-start power supply | |
EP2070396B1 (en) | Power controller having current limited rms voltage regulated output | |
JPH0119238B2 (en) | ||
JP3842823B2 (en) | Circuit equipment | |
AU728836B2 (en) | Fluorescent lamp illumination level control | |
WO1998012901A1 (en) | Fluorescent lamp illumination level control | |
EP0143884A1 (en) | Energy-saving apparatus for dimming discharge lamps | |
WO2004110107A1 (en) | Energy savings device and method for a resistive and/or an inductive load and/or a capacitive load | |
EP0147922A1 (en) | Ballast circuits for lighting units | |
JPS63133499A (en) | Dimmer of fluorescent lamp and semiconductor switch | |
US7196480B2 (en) | Method of soft-starting a switching power supply containing phase-control clipping circuit | |
JPS6322640Y2 (en) | ||
JPS6057680B2 (en) | discharge lamp dimmer | |
US7462996B2 (en) | Method of operating a lamp with a power controller having current limited RMS regulated output | |
US7375475B2 (en) | Lamp containing power controller having current limited RMS regulated output | |
EP0824850B1 (en) | Dimming controller and method for a fluorescent lamp | |
KR830002176B1 (en) | Discharge lamp lighting device | |
JPS641759Y2 (en) |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): AL AM AT AU AZ BA BB BG BR BY CA CH CN CU CZ DE DK EE ES FI GB GE GH HU ID IL IS JP KE KG KP KR KZ LC LK LR LS LT LU LV GH |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): GH KE LS MW SD SZ UG ZW AT BE CH DE DK ES FI FR GB GR IE IT LU MC |
|
DFPE | Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101) | ||
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
NENP | Non-entry into the national phase |
Ref country code: JP Ref document number: 1998514071 Format of ref document f/p: F |
|
REG | Reference to national code |
Ref country code: DE Ref legal event code: 8642 |
|
122 | Ep: pct application non-entry in european phase | ||
NENP | Non-entry into the national phase |
Ref country code: CA |