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
  • H05B41/3924—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
• • 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
  • H05B39/04—Controlling
  • H05B39/08—Controlling by shifting phase of trigger voltage applied to gas-filled controlling tubes also in controlled semiconductor devices
• • 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
  • H05B41/40—Controlling the intensity of light discontinuously
  • H05B41/42—Controlling the intensity of light discontinuously in two steps only

Definitions

• the invention relates to a dimmer arrangement comprising phase- cut means for cutting phase angles in cycles of an AC power supply signal, the phase-cut means being coupled in series with an AC power supply line for carrying the AC power supply signal.
• the invention further relates to a ballast comprising a dimmer arrangement, to a lamp comprising a ballast, and to a lamp socket comprising a ballast.
• Such a dimmer arrangement is known from U.S. Pat. No. 5559395.
• the known dimmer arrangement is used widely in lamp dimming.
• a phase control triac dimmer is provided.
• the triac dimmer is coupled in a power supply line.
• a series circuit consisting of a variable resistor and a capacitor is coupled in parallel with the triac for firing the triac at an arbitrarily selected angle for phase conduction.
• a diac is coupled between a node of the variable resistor and the capacitor, and the gate of the triac.
• the dimmer clips or blocks a portion of each half cycle of the AC voltage immediately after the zero crossing of the voltage and the portion or angle of the half cycle is adjustable.
• the phase angle of the AC voltage can be adjusted and a different phase-cut angle corresponds to a different lighting level.
• every half cycle of the power supply is cut with an arbitrary selected angle. Therefore, harmonic distortion and electromagnetic interference (EMI) cannot be avoided, in particular when the selected angle is large.
• EMI electromagnetic interference
• the conduction phase angle is small, i.e. the phase-cut angle is large, the lamp will possibly be flickering. It is an object of the invention to provide a dimmer arrangement with less harmonic distortion.
• the dimmer arrangement is characterized in that it comprises bypassing means for bypassing the phase-cut means, the bypassing means being arranged to bypass the phase-cut means when not being actuated, and to activate the phase-cut means for a dimming time period when being actuated.
• the invention is based on the insight that by bypassing the phase cut means during a period of non-actuation, for most of the time no phase cutting occurs so that harmonics are greatly reduced as well as the electromagnetic interference and that during the phase cutting only a fixed cut angle is used, which preferably is just above the smallest detectable phase cut angle.
• An embodiment of a dimmer arrangement according to the invention is characterized in that the phase cut angles are fixed. With a fixed phase-cut angle, a ballast circuit controlled by the dimmer arrangement does not have to take into account the value of phase-cut angle, so it can just determine the dimming time period; For minimizing interference, the phase cut angle can be selected as the minimum detectable angle for dimming.
• phase-cut means is arranged to cut either positive or negative halves of the cycles. Phase cutting in only one half cycle can also convey the dimming information due to the fact that the frequency of AC power supply is high. In this way, the harmonic distortion and electromagnetic interference in the circuit are reduced even more during the dimming time period as compared to cutting both positive and negative half cycles.
• bypassing means comprises first actuation means for activating the phase cut means at a frequency of the AC power supply signal, and second actuation means for activating the phase cut means at double the frequency of the AC power supply signal, the first and second actuation being coupled in series. The two actuation means are arranged to transfer different information for dimming.
• ballast in combination with the dimmer arrangement according to the present invention, the ballast comprising a dimming controller for controlling dimming with a control signal, characterized in that the dimming controller is arranged to adjust the control signal in accordance with the dimming time period.
• the ballast controls dimming according to the dimming time period instead of using power supplied to the ballast, so, for dimming, the control of power supplied to the lamp is realized at the output of the ballast circuit instead of at the input of the ballast circuit.
• harmonic distortion in the ballast circuit is reduced.
• Fig 1 shows a first embodiment of a dimmer arrangement 10 according to the invention
• Fig 2A shows a second embodiment of a dimmer arrangement 110 according to the invention
• Fig 2B shows waveforms of several certain voltage signals in dimmer arrangement and ballast according to the invention
• Fig. 3A shows a third embodiment of a dimmer arrangement 210 according to the invention
• Fig 3B shows the waveform of voltage of outputted from a dimmer arrangement according to the invention
• Fig. 4 shows a forth embodiment of a dimmer arrangement 310 according to the invention
• Fig 5 shows a block diagram of ballast according to the invention
• Fig. 6 shows an embodiment of extracting means 463 according to the invention.
• Fig 1 shows a first embodiment of a dimmer arrangement 10 according to the invention.
• Dimmer arrangement 10 comprises a dimmer 20 and bypassing means 30.
• Dimmer 20 is a phase cut dimmer, such as triac dimmer, a thyristor dimmer, a power switch dimmer or a MOSFET dimmer.
• bypassing means 30 is not actuated. As a result, dimmer 20 is bypassed by bypassing means 30, i.e., dimmer 20 is inoperative . In a dimming situation, bypassing means 30 is actuated. Then , AC current passes through dimmer 20, and dimmer 20 cuts phase angles of AC power supply signal AC during a dimming time period
• Fig 2A shows a second embodiment of a dimmer arrangement 110 according to the invention.
• Dimmer arrangement 110 comprises a triac dimmer 120 and bypassing means 130.
• Triac dimmer 120 comprises resistors R1 and R2, and a capacitor C1 coupled in parallel with a triac 140 for firing triac 140 at a fixed phase cut angle PCA for phase conduction.
• a diac 150 is coupled between the resistors R1 and R2 and the gate of triac 140.
• Bypassing means 130 comprises a push button P1. Under normal operating conditions, button P1 is not actuated, i.e., AC current passes through button P1 , and triac dimmer 120 is bypassed. Therefore no phase cutting occurs in AC power supply signal AC.
• a user actuates button P1 for a dimming time period DTP according to a required illumination.
• triac dimmer 120 is coupled into AC power supply line A.
• capacitor C1 is charged positively and the voltage Vd across capacitor C1 rises to the triggering voltage of diac 150.
• triac 140 is fired after a fixed delay angle (namely the phase cut angle, PCA) of the positive half-cycle of AC power supply signal AC.
• PCA phase cut angle
• triac 140 With negatively triggering of diac 150, triac 140 is fired after a fixed delay angle (namely the phase cut angle, PCA) of the negative half-cycle of AC power supply signal AC.
• the fixed delay angle is determined by R1 , R2, C1 and the trigger voltage of diac 150.
• the voltage waveform Vin of AC power supply signal AC cut by dimmer 120 is shown in FIG 2B as the voltage VAB.
• VAB voltage waveform
• VAB voltage waveform of VAB
• PCA phase cut angle PCA.
• Phase cutting occurs only during dimming time period DTP, i.e., the time period the user pushes button P1. Outside dimming period DTP, there is no phase cutting, i.e., AC power supply signal AC has full cycles. Therefore under normal conditions, no harmonic distortion is generated.
• FIG. 3A shows a third embodiment of a dimmer arrangement 210 according to the invention.
• a thyristor 240 is used to replace triac 140 and a diode 232 is arranged parallel to button P1.
• button P1 When button P1 is actuated, every positive half cycle of AC power supply signal AC is cut by a phase cut means 230 with a fixed phase cut angle PCA.
• the voltage of AC power supply signal AC at terminals A and B is shown in Figure 3B. If thyristor 240 and diode 232 are coupled oppositely directions, every negative half cycle of
• AC power supply signal AC is cut by the phase cut means with a fixed phase cut angle PCA.
• Fig. 4 shows a forth embodiment of a dimmer arrangement 310 according to the invention.
• another button P2 is coupled with button P1 in series and is arranged parallel with a diode 342.
• phase cut means 320 works the same as phase cut means 120 as shown in Fig 2A. If only button
• phase cut means 320 works the same as phase cut means 220 as shown in Fig 2A. So separate actuation of buttons P1 and P2 causes different phase cutting of AC power supply signal AC.
• buttons P1 and P2 may represent different requirements of the user. Actuation of button
• buttons P1 and P2 may be buttons that are directly operable by a user, or remotely operable switches operable through remote control unit, such as a well-known infrared remote control device.
• a variable resistor may be introduced for adjusting phase cut angle PCA.
• Fig 5 shows a block diagram of ballast 400 according to the invention.
• Ballast 400 is used in combination with a dimmer arrangement provided in the present invention.
• Ballast 400 comprises an EMI filter 410 for filtering electromagnetic interference, a rectifier 420 for rectifying AC power supply signal AC into DC power supply signal DC, a power factor controller 430 for controlling a power factor, an inverter controller 440 for controlling an inverter, and an inverter 450 for converting DC voltage into a high frequency AC voltage to actuate a lamp.
• Ballast 400 also comprises a dimming controller 460 for controlling dimming.
• Dimming controller 460 comprises extracting means 463 for extracting dimming signal D-SIG from an output 422 of rectifier 420, and signal processing means 456 for converting dimming signal D-SIG into control signal C-SIG.
• the output 422 of rectifier 420 namely the voltage Vs, DC power signal DC, is shown in Fig. 2B.
• DC power signal DC carries a dimming signal D-SIG with a fixed phase cut angel PCA.
• Extracting means 453 extracts from DC power supply DC a dimming signal
• Signal processing means 456 comprises a clock generator 468 for generating a clock signal CLK, shown in Fig 2B. After receiving dimming signal D-SIG from extracting means 453, signal processing means 456 processes dimming signal D-SIG according to clock signal CLK, e.g. by counting the number of pulse signals or counting the time period of the dimming signal D-SIG, and outputs a control signal C-SIG, namely Vd, as shown in Fig 2B.
• Control signal C-SIG is inputted to inverter controller 440.
• Inverter controller 440 is a conventional inverter control IC, such as half bridge control IC which is easily available in the market. In normal situation, inverter controller 440 controls the frequency of the inverter with a current signal O-SIG. In a dimming situation, after controller signal C-SIG is inputted to inverter controller 440, current signal O-SIG is changed according to control signal C-SIG. In a normal situation, control signal inputted to inverter controller 400 is regarded as zero or other value with no effect on current signal O-SIG of inverter controller 400. Inverter controller 440 operates according to the current signal O-SIG.
• Extracting means 463 comprises two comparators A1 and A2 and a low-pass filter comprising resistor R3 and R4 and a capacitor C2.
• a low-pass filter comprising resistor R3 and R4 and a capacitor C2.
• comparator A1 When voltage VS is higher than reference voltage Vrefl , comparator A1 outputs a low level voltage VK.
• the waveform of voltage Vk is shown in FIG 2B.
• voltage VK passes the low-pass filter formed by R3, R4 and C2, unwanted pulse signals are eliminated.
• unwanted pulses are relatively narrow pulses outside dimming time period DTP and pulses after relatively wide pulses in dimming time period DTP.
• the waveform of VF the output of the low-pass filter, is shown in Fig 2B. Low-pass filtered VF is compared with reference voltage Vref2 in comparator A2. Then comparator
• A2 outputs a pulse signal (i.e. dimming signal) corresponding with the dimming time period DTP, namely Vc as shown in Fig 2B. Then Vc , the dimming signal , is inputted to signal processor 466 .
• a pulse signal i.e. dimming signal

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• 2004
  • 2004-07-08 CN CN 200410063622 patent/CN1719963A/zh active Pending
• 2005
  • 2005-06-15 JP JP2007519923A patent/JP2008506226A/ja not_active Withdrawn
  • 2005-06-15 WO PCT/IB2005/051981 patent/WO2006006085A1/en not_active Application Discontinuation
  • 2005-06-15 EP EP05748050A patent/EP1767067A1/en not_active Withdrawn
  • 2005-06-15 CN CNA2005800229950A patent/CN1981564A/zh active Pending

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