WO2007000684A1 - Dispositif de commande de lampe - Google Patents

Dispositif de commande de lampe Download PDF

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Publication number
WO2007000684A1
WO2007000684A1 PCT/IB2006/051980 IB2006051980W WO2007000684A1 WO 2007000684 A1 WO2007000684 A1 WO 2007000684A1 IB 2006051980 W IB2006051980 W IB 2006051980W WO 2007000684 A1 WO2007000684 A1 WO 2007000684A1
Authority
WO
WIPO (PCT)
Prior art keywords
inverter
converter
voltage
frequency
driving device
Prior art date
Application number
PCT/IB2006/051980
Other languages
English (en)
Inventor
Ulrich Boeke
Original Assignee
Koninklijke Philips Electronics N.V.
Philips Intellectual Property & Standards Gmbh
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 Koninklijke Philips Electronics N.V., Philips Intellectual Property & Standards Gmbh filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2007000684A1 publication Critical patent/WO2007000684A1/fr

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
    • H05B41/26—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
    • H05B41/282—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
    • H05B41/2825—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 by means of a bridge converter in the final stage
    • H05B41/2828—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 by means of a bridge converter in the final stage using control circuits for the switching elements
    • 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
    • H05B41/282—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
    • H05B41/2821—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 by means of a single-switch converter or a parallel push-pull converter in the final stage
    • H05B41/2824—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 by means of a single-switch converter or a parallel push-pull converter in the final stage using control circuits for the switching element

Definitions

  • the present invention relates to a lamp driving device comprising a DC/AC inverter, being arranged to receive a DC voltage and to deliver an AC voltage with a controllable power level and at a desired frequency to a lamp load.
  • Such a device is disclosed e.g. in US, 6259615, Bl, where fluorescent lamps are fed by a full-bridge inverter.
  • the phase shift between the two half-bridge branches of the full-bridge converter is used to control the output power of the inverter. Thanks to the use of this phase shift as a control parameter, the switching frequency can be kept at the desired level. Thereby, undesirable "beat" effects can be avoided when the fluorescent lamps are used in a backlighting arrangement in connection e.g. with an LCD panel.
  • full-bridge inverter configuration is rather complex. In normal designs, full-bridge inverters are considered at power levels exceeding 500 W. Therefore it is less desirable to use a full-bridge configuration in an LCD backlighting arrangement, that requires no more than 5- 10 W.
  • An object of the present invention is therefore to provide a less complex and thus less expensive solution that still allows e.g. a fluorescent lamp to be fed by an inverter at a desired frequency.
  • the device then comprises: a DC/DC converter generating said DC voltage as an intermediary voltage from an input voltage, means for extracting a parameter corresponding to one of the switching frequency or the output current of the
  • DC/AC inverter and means for controlling the DC/DC converter, based on said parameter, to deliver an intermediate voltage, such that the desired power level is delivered at the desired frequency.
  • the intermediate voltage fed to the inverter, as a control parameter, the inverter switching frequency is allowed to be fixed.
  • a less complex half-bridge arrangement may be used.
  • the DC/DC converter may be a flyback converter, or, as an alternative, a dual- output converter.
  • the parameter preferably corresponds to the inverter output current, and the inverter switching frequency is then clamped to the desired frequency.
  • the device comprises switching means, allowing the switching frequency to deviate from the desired value during startup.
  • Fig. 1 is a block diagram, illustrating an embodiment of the invention.
  • Fig. 2 illustrates schematically a load resonant inverter arrangement, where the switching frequency is manipulated.
  • Fig. 3 illustrates a controllable flyback converter.
  • Fig. 4 illustrates a controllable dual output converter.
  • Fig. 1 is a block diagram, illustrating an embodiment of the invention.
  • a fluorescent lamp 5, e.g. used in an LCD backlighting arrangement is driven by a lamp driving device comprising a DC/DC converter 3 and a DC/AC inverter 4.
  • the DC/DC converter 3 receives an input voltage V IN via a rectifier 2 from a mains voltage 1 , or from a battery arrangement (not shown).
  • the DC/DC converter produces an intermediary voltage V DC , that may be e.g. 12 V (a typical value when the circuitry is used in the backlighting arrangement of a laptop computer).
  • the intermediary voltage is fed to the DC/AC inverter 4.
  • a lamp current controller 6 compares a measured lamp current signal k with a reference signal i re f and generates a control signal V C TRL that controls the output of the DC/DC converter 3, such that the inverter output current is kept at a desired value.
  • a control block 7 controls the switching frequency f sw of the inverter 4. During normal operation (i.e. after start up) this frequency is clamped to a desired switching frequency f sy n c h, that in this embodiment is delivered from a display block 8. During start-up however, it may be advantageous to allow the switching frequency to deviate from this value.
  • a start-up procedure is now described. When the display, in which the lamp driver is used, is switched on, the display block 8 switches the inverter 4 on by setting an inverter input (on/off) high. During start-up, i.e. until the lamp(s) has reached its operating temperature, the inverter switching frequency f sw is not controlled by the control block 7.
  • the inverter input voltage V DC would be fixed, and a varying delivered power would result in a varying inverter switching frequency.
  • the inverter switching frequency can however be kept constant and bound to the desired frequency of f sy n c h, although the amount of power delivered to the lamp is changed. By keeping the inverter switching frequency at the desired value, electromagnetic interference with other parts of e.g. a display device may be avoided.
  • a general idea with the present invention is to provide a lamp driving arrangement where the switching frequency of the inverter may be kept at a desired value, i.e. where the switching frequency f sw is not used to control the power level of the inverter. Instead the intermediate DC voltage is used as a control parameter. As illustrated above, this can be achieved by extracting the inverter output current and controlling this current by changing the intermediate voltage, while the switching frequency and phase is clamped to an external reference signal f sy nch.
  • the switching frequency f sw of the inverter may be extracted and compared with the reference signal f sy n c h. This may be done e.g. using a PLL circuit (Phase Locked Loop) that provides a DC output corresponding to the frequency difference between f sw and f sy n c h. This DC output may be used to control the DC/DC converter 3 to deliver a DC voltage that keeps f sw synchronized with f sync h within a wide inverter power output range.
  • PLL circuit Phase Locked Loop
  • Fig. 2 illustrates schematically an example of a load resonant inverter arrangement, where the switching frequency is manipulated.
  • the inverter is based on an integrated circuit 13 "UBA2070 CCFL (Cold Cathode Fluorescent Lamp) ballast driver IC" produced by Philips Semiconductors.
  • This circuit comprises an internal VCO (Voltage Controlled Oscillator) arrangement 15.
  • the integrated circuit 13 drives first and second series coupled MOSFET switches 17a, 17b by alternatingly activating the same, such that the connection point between the switches 17a, 17b alternates between earth potential and a driving voltage V DD -
  • This connection point is connected to an LC circuit formed by a capacitor 19 and a first transformer winding 21.
  • a load circuit comprises a second winding 23, attached to the same transformer, and the lamp 25. More lamps may be connected in parallel with this lamp 25, each lamp then having its own ballast impedance, typically a capacitor in series with the lamp.
  • the integrated circuit thus drives the load circuit in order to light the lamp 25.
  • a feedback network generates a feedback signal. Based on this signal, the inverter is made to oscillate when the inverter is allowed to operate freely.
  • the inverter switching frequency should however, during normal operation, be clamped to a reference signal f sy n c h.
  • a control block 7 In the above indicated integrated circuit 13, the internal VCO 15 is accessible at a connection (no. 3), where a capacitor 29 is to be attached in order to determine a property of the inverter. During conventional operation, this capacitor is charged and discharged by means of an internal current source in the integrated circuit.
  • the control block comprises first and second series coupled MOSFET switches 26, 27, each being controlled by an AND gate 28a, 28b, respectively.
  • One 26 of the series coupled MOSFET switches is connected to a supply voltage V DD and the other 27 to earth.
  • One input of each AND gate is connected to the on/off input of the control block, such that, if this input is low, both AND gate outputs are low and the gates are blocking (always low). In this state the inverter switching frequency is allowed to vary.
  • the inputted reference signal f sy n c h propagates through the AND gates 28a, 28b, one (28b) of which has a negated input, such that their output signals are complementary.
  • the AND gates 28a, 28b drive the gates of the MOSFET switches 26, 27.
  • the first and second switches are thus activated in a complementary fashion, such that the connection point between the switches alternates between being connected to earth and a driving voltage V DD - This connection point is connected to the above mentioned VCO terminal.
  • the capacitor 29 can be charged and discharged by the control block 7, forcing the inverter to switch at a desired frequency.
  • the internal resistance of the control block should be low enough, such that it dominates over the effect of the internal current source in the integrated circuit 13.
  • the inverter can be manipulated to operate at a desired frequency.
  • the skilled person may find many other ways of achieving this.
  • other inverter driving circuits than the one mentioned above can be manipulated in a similar way.
  • the inverter switching frequency may be controlled to a value that is preferred with regard to EMI (electromagnetic interference) issues in relation to other parts of the display device.
  • Fig. 3 illustrates a controllable DC/DC converter in the form of a flyback converter, which is of course well known per se.
  • a control circuit 31 is capable of activating a MOSFET switch 33. When this is done an input voltage Vj n , e.g. from a rectifier circuitry, is connected to earth via the primary winding of a transformer 35. Then a current begins to ramp through the primary winding, until the control circuit 31 switches the MOSFET 33 off. When this happens, energy, stored in the transformer during the build-up phase, induces a current through the secondary winding of the transformer 35, which is connected via a rectifying diode 37 to an output capacitor 39, providing the converter output voltage, in this case 12 V.
  • an opto-coupler element 45 receives a fraction of the output voltage, and generates an output current if, that is inputted to the control circuit 31.
  • a feedback arrangement is accomplished that allows the provision of an accurate output voltage, even if the load varies.
  • the transformer 35 and the opto-coupler element 45 provides mains insulation.
  • a third resistor 47 and a series coupled additional transistor 49 is added in parallel with the voltage divider arrangement.
  • the added components may change the relation between the feedback current if and the actual output voltage, such that an output voltage e.g. resulting in a suitable inverter output current may be achieved.
  • Fig. 4 illustrates a controllable dual output converter, used in a similar manner as the flyback-converter in Fig. 3.
  • the dual output converter is disclosed per se in EP
  • This DC/DC converter may thus be used to supply both a signal processing module 51 of a display, receiving the first output voltage V a , and a backlighting arrangement 53 of the same display, receiving the second output voltage V b .
  • the converter comprises a control circuit 55 being capable of driving two
  • MOSFET switches 57a, 57b such that a primary circuit 59, comprising a transformer primary winding may receive voltages with two different polarities.
  • Each output branch comprises an output circuit 61, 63, respectively.
  • the output circuits 61, 63 are each connected to a secondary winding of the transformer but at different polarities.
  • Each branch further comprises a feedback circuit 65, 67, respectively.
  • the feedback circuit of the lamp driver branch may be provided with an additional resistor and an additional transistor, as described in connection with Fig. 3, so that the voltage V b can be controlled in such a way that e.g. the inverter output current is kept at a desired value, as described earlier.
  • the display signal processing module 51 may thus provide the lamp driver 53 with a desired synchronizing frequency signal f sy n c h, and the lamp driver may generate a control signal VcTRL in correspondence the desired output current.
  • the invention relates to a lamp driver with a load resonant inverter, which can be driven to deliver a desired power output level at desired frequency.
  • the frequency can be chosen such, that interference with a display system can be avoided when the lamp driver is used in the backlighting system of this system.
  • the lamp driver comprises means for determining a parameter corresponding to the switching frequency or the output current of the inverter, a DC/DC converter delivering an intermediate DC voltage to supply the inverter, and means for controlling the output of the DC/DC converter, such that the desired inverter switching frequency at the desired power level is achieved.

Landscapes

  • Circuit Arrangements For Discharge Lamps (AREA)
  • Liquid Crystal Display Device Control (AREA)

Abstract

La présente invention se rapporte à un dispositif de commande de lampe comportant un inverseur à résonance de charge (4), qui peut être commandé pour délivrer un niveau de puissance de sortie souhaité à une fréquence souhaitée. La fréquence peut être choisie de sorte qu'il soit possible d'éviter l'interférence avec un système d'affichage lorsque le dispositif de commande de lampe est utilisé dans le moyen de rétroéclairage de ce système. Le dispositif de commande de lampe comporte un moyen (6) permettant de déterminer un paramètre correspondant à la fréquence de commutation ou le courant de sortie de l'inverseur, un convertisseur CC/CC délivrant une tension CC intermédiaire pour alimenter l'inverseur, et un moyen de régulation de la sortie du convertisseur CC/CC, de sorte qu'il soit possible d'obtenir le niveau de puissance souhaité à la fréquence de commutation d'inverseur souhaitée.
PCT/IB2006/051980 2005-06-27 2006-06-20 Dispositif de commande de lampe WO2007000684A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP05105706.5 2005-06-27
EP05105706 2005-06-27

Publications (1)

Publication Number Publication Date
WO2007000684A1 true WO2007000684A1 (fr) 2007-01-04

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2006/051980 WO2007000684A1 (fr) 2005-06-27 2006-06-20 Dispositif de commande de lampe

Country Status (2)

Country Link
TW (1) TW200708200A (fr)
WO (1) WO2007000684A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009030106A1 (de) 2009-06-22 2010-12-23 Minebea Co., Ltd. Verfahren zur Ansteuerung von Gasentladungslampen
US7888442B2 (en) 2005-05-17 2011-02-15 Sun Chemical Corporation Size selective catalysis with ion exchange resins

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5140229A (en) * 1990-04-28 1992-08-18 Koito Manufacturing Co., Ltd. Lighting circuit for vehicular discharge lamp
US5872429A (en) * 1995-03-31 1999-02-16 Philips Electronics North America Corporation Coded communication system and method for controlling an electric lamp
US6208089B1 (en) * 1999-03-12 2001-03-27 Koito Manufacturing Co., Ltd. Discharge-lamp lighting circuit
DE20103718U1 (de) * 2001-03-05 2001-06-21 Glp Light Production Gmbh Vorschaltgerät für einen nach einer Kennlinie zu betreibenden Verbraucher
US20020060893A1 (en) * 2000-11-22 2002-05-23 Samsung Electro-Mechanics Co., Ltd. LCD backlight inverter
DE10063328A1 (de) * 2000-12-19 2002-06-27 Hella Kg Hueck & Co Einrichtung zum Starten und Betreiben einer Gasentladungslampe in einem Kraftfahrzeug
US20020101196A1 (en) * 2000-09-15 2002-08-01 Lightech Electronics Industries Ltd. Electronic ballast for high-intensity discharge lamps
US20020145393A1 (en) * 2001-01-24 2002-10-10 City University Of Hong Kong Novel circuit designs and control techniques for high frequency electronic ballasts for high intensity discharge lamps
US20040090801A1 (en) * 2002-11-13 2004-05-13 Qing Chen Highly efficient, tightly regulated dc-to-dc converter
US20050067981A1 (en) * 2003-09-30 2005-03-31 International Rectifier Corporation Simplified topology for HID lamps

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5140229A (en) * 1990-04-28 1992-08-18 Koito Manufacturing Co., Ltd. Lighting circuit for vehicular discharge lamp
US5872429A (en) * 1995-03-31 1999-02-16 Philips Electronics North America Corporation Coded communication system and method for controlling an electric lamp
US6208089B1 (en) * 1999-03-12 2001-03-27 Koito Manufacturing Co., Ltd. Discharge-lamp lighting circuit
US20020101196A1 (en) * 2000-09-15 2002-08-01 Lightech Electronics Industries Ltd. Electronic ballast for high-intensity discharge lamps
US20020060893A1 (en) * 2000-11-22 2002-05-23 Samsung Electro-Mechanics Co., Ltd. LCD backlight inverter
DE10063328A1 (de) * 2000-12-19 2002-06-27 Hella Kg Hueck & Co Einrichtung zum Starten und Betreiben einer Gasentladungslampe in einem Kraftfahrzeug
US20020145393A1 (en) * 2001-01-24 2002-10-10 City University Of Hong Kong Novel circuit designs and control techniques for high frequency electronic ballasts for high intensity discharge lamps
DE20103718U1 (de) * 2001-03-05 2001-06-21 Glp Light Production Gmbh Vorschaltgerät für einen nach einer Kennlinie zu betreibenden Verbraucher
US20040090801A1 (en) * 2002-11-13 2004-05-13 Qing Chen Highly efficient, tightly regulated dc-to-dc converter
US20050067981A1 (en) * 2003-09-30 2005-03-31 International Rectifier Corporation Simplified topology for HID lamps

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7888442B2 (en) 2005-05-17 2011-02-15 Sun Chemical Corporation Size selective catalysis with ion exchange resins
DE102009030106A1 (de) 2009-06-22 2010-12-23 Minebea Co., Ltd. Verfahren zur Ansteuerung von Gasentladungslampen
US8525429B2 (en) 2009-06-22 2013-09-03 Minebea Co., Ltd. Method for controlling gas discharge lamps
DE102009030106B4 (de) * 2009-06-22 2015-07-30 Minebea Co., Ltd. Verfahren zur Ansteuerung von Gasentladungslampen

Also Published As

Publication number Publication date
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