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WO1999004382A1 - Dispositif de commande de lampes electroluminescentes - Google Patents

Dispositif de commande de lampes electroluminescentes

Info

Publication number
WO1999004382A1
WO1999004382A1 PCT/GB1998/002134 GB9802134W WO9904382A1 WO 1999004382 A1 WO1999004382 A1 WO 1999004382A1 GB 9802134 W GB9802134 W GB 9802134W WO 9904382 A1 WO9904382 A1 WO 9904382A1
Authority
WO
WIPO (PCT)
Prior art keywords
lamp
microprocessor
voltage
electroluminescent
inverter circuit
Prior art date
Application number
PCT/GB1998/002134
Other languages
English (en)
Inventor
Peter Alan Walker
John Graham Gaskin
Original Assignee
Inmatic Limited
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 Inmatic Limited filed Critical Inmatic Limited
Priority to AU84505/98A priority Critical patent/AU8450598A/en
Publication of WO1999004382A1 publication Critical patent/WO1999004382A1/fr

Links

Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • 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
    • H05B44/00—Circuit arrangements for operating electroluminescent light sources
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/06—Details of flat display driving waveforms
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/04—Maintaining the quality of display appearance
    • G09G2320/043—Preventing or counteracting the effects of ageing
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/04—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions
    • G09G3/06—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions using controlled light sources
    • G09G3/12—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions using controlled light sources using electroluminescent elements
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Definitions

  • the present invention relates to an electroluminescent lamp driver for providing power to a variety of different electroluminescent display panels without any change to the electric circuits employed.
  • An electroluminescent display panel is made up of a number of lamp segments each of which is either a single electroluminescent (EL) lamp or a group of lamps with a common electrical connection. All the parameters for driving the electroluminescent lamps and for selecting which lamp or lamps are being lit, is under software control. Therefore any size and number of electroluminescent lamps can be lit, up to the maximum output capacity of the driver.
  • EL electroluminescent
  • the same basic hardware can be used to drive a display panel that is designed to each customer's requirement.
  • the electroluminescent lamps have a limited life they can be replaced with a new display panel of the same type or a completely new layout.
  • the software controlling the microprocessor must be changed to suit the new display.
  • Software has been designed to allow these changes to be made easily by using a separate table to hold all the main parameters. This table can be inside the microprocessor or on a separate device, i.e. EEPROM, flash memory or a Smartcard. Measurements are taken to confirm that the lamps are being driven at the correct level dependent on the ageing characteristics of the lamp.
  • an electroluminescent (EL) lamp driver for driving an EL display panel comprising a plurality of lamp segments, said driver comprising an inverter circuit for supplying to said display panel a high AC driving voltage, microprocessor means for controlling the characteristics of said AC voltage inverter, switch means controlled by said microprocessor for selectively switching individual lamp segments, a measurement circuit for deriving a feedback signal indicative of the AC driving voltage and means for applying said feedback signal to the microprocessor as a control signal.
  • EL electroluminescent
  • said measurement circuit includes means for altering the feedback voltage in accordance with the number of lamp segments which are selected by said switch means at any one time.
  • said altering means comprises a plurality of resistors, each connected at one end to a respective lamp segment and connected such that, when a particular lamp is selected by said switch means, its resistor is connected in shunt with the measurement circuit and when a lamp is not selected by said switch means, its resistor is connected in series with the measurement circuit.
  • the switch means comprises lamp selection switches with there being one switch for each EL, each switch being connected to an EL lamp at one end and having a control electrode connected to a respective output port of the microprocessor, such that said switches are switched on by the supply of a small current directly from the output ports of the microprocessor.
  • said inverter circuit allows current to pass through the primary windings of a transformer, whereby inputs to the inverter circuit are connected to and controlled by a microprocessor such that only one output is active at a time so that each half of the transformer in the inverter circuit is driven alternately.
  • the microprocessor runs a program enabling access to all parameters relating to particular display panels, such that the on/off ratio and drive levels of the input voltage to the inverter circuit may be varied by the said microprocessor according to the particular display panel selected.
  • the parameters relating to particular display panels are stored in a table in the memory of the microprocessor. Alternately the table is stored on a separate device such as EEPROM, flash memory or a Smartcard.
  • FIG. 1 is a block diagram of an embodiment of a lamp driver according to the present invention
  • Figure 2 shows the Input/Output ports of the microprocessor device forming part of the lamp driver of Figure 1
  • Figure 3 is an electrical diagram of the Inverter Circuit forming part of the lamp driver of Figure 1,
  • FIG 4 shows typical input and output wave forms of the inverter circuit of Figure 3
  • Figure 5 shows the input and output wave forms of the inverter circuit for maximum loads
  • Figure 6 shows the inputs and output wave forms of the inverter circuit for minimum loads
  • Figure 7 shows the operation of the voltage measurement circuit forming part of the lamp driver of Figure 1
  • FIG 8 is an electrical diagram of an embodiment of a lamp driver according to the invention.
  • the main elements of the lamp driver are shown in Figure 1 and are a microprocessor device, an inverter circuit, lamp selection switches and a lamp voltage measurement circuit.
  • the microprocessor device is from the SGS-Thomson ST6 family. This consists of a range of devices in two basic sizes, 20 pin and 28 pin.
  • the printed circuit board of the invention has been designed to accept both sizes.
  • the device chosen is a micro-controller as it has all the input/output ports, program memory (ROM), variable memory (RAM) all on a single integrated circuit (ICl).
  • ROM program memory
  • RAM variable memory
  • ICl integrated circuit
  • the type of manufacturer is not a major consideration as long as all the required functions are available. These functions could be on one single IC or made up of using separate
  • the Input/Output ports of the 28 pin microprocessor device are shown in Figure 2. There are 2 output ports Al and A2 which drive the inverter circuit, 1 output port A0 controls the EL lamp discharge path via triac Zl 7 of the inverter circuit and which also controls the indicator LED
  • Output ports A3..A6, BO, B6, C4, C7 are used to select each lamp using a triac switch. In the present embodiment either 8 or 16 EL lamps can be used. However, this number can easily be increased by using data switches and decoding the output lines from the micro-controller.
  • a to D analogue to digital converter
  • Positive going (high) pulses on each output pin Al and A2 in turn, turn on drive transistors TR1 and TR2 forming part of the inverter circuit, shown in Figure 3, which transistors pass current through the respective primary windings of a step-up transformer Tl . Only one output is active at a time so that each half of the transformer in the inverter circuit is driven alternately. The frequency of these pulses determine the output frequency of the inverter circuit. The on/off ratio of the pulses determines the primary drive current which sets the output voltage. Therefore the optimum drive conditions can be set up by the measurement circuit and software within the micro-controller.
  • the high/low ratio of the pulse signals on plus Al and A2 can be changed to compensate for the fall in light output. This will result in a constant light level for the life of the lamp.
  • the output port AO of the inverter circuit controls a triac switch Z17 (see Figure 8) via a resistor RIO which allows the resistor R12 to be connected or disconnected to 0 volts. This is done for short periods while A 1 and A2 are both low and will rapidly discharge (the load capacitor) C 1 and the EL-lamp between positive and negative half cycles. This output also controls the LED D20 via Rl . This is used to indicate the working condition of the unit.
  • the printed circuit board has been laid out to take two different size micro-controllers.
  • the smaller 20 pin device has the first 8 outputs available, whereas the 28 pin device has all 16 outputs. These are used to select EL lamps using the triac switches Zl to Z16 via diodes Dl to D16.
  • the SGS Thomson micro-controller has several input lines that can be internally connected to an Analogue to Digital (A to D) converter.
  • a to D Analogue to Digital
  • One such input B7 is used to measure the voltage level applied to any of the electroluminescent lamp segments. This measurement can be used to control the drive conditions of each lamp so that the voltage does not exceed the maximum rated level for the lamp. It can also be used to confirm that the correct display panel has been connected and each lamp is working correctly.
  • the high gain transistors TR1 and TR2 act like switches which are controlled by the microprocessor output terminals Al and A2.
  • the transformer Tl has a high secondary to primary turns ratio to produce a high level ac voltage up to a maximum of 600 volts pk-pk.
  • Transformer Tl is custom designed to produce a smooth output wave form from a fast switching input voltage.
  • the primary is centre tapped to allow equal current flow in both directions which alternates the primary voltage.
  • the centre tap is connected to +9 volts which is supplied via SKI.
  • Only one transistor TR1 or TR2 will be switched on at any time connecting the outside primary terminals of Tl to 0 volts via the resistors R4 and R5.
  • the components R3, C2 and R2, C4 reduce the switch on speed of the transistors.
  • a dc voltage is switched at a frequency of between 1500 Hz and 1900 Hz across the primary windings of the transformer Tl.
  • a high voltage is produced across the secondary winding at the same frequency.
  • this secondary voltage is not rectified but is applied as an ac voltage to directly drive the electroluminescent lamps.
  • the frequency and output voltage are under the control of the microprocessor with feedback provided via the measurement circuit.
  • the brightness of the lamp is determined by the AC voltage and the frequency.
  • the frequency is chosen to suit the type of phosphor used by the manufacturer of EL lamps. Light is produced during the transition from positive to negative or negative to positive potential across the terminals of the lamp. Therefore the shape of the wave form is not of particular importance. However, the transitions must be smooth to avoid damaging the lamps. This is achieved by the choice of transformer T 1 and the addition of a load capacitor C 1.
  • the resistor R6 is intended to limit the output current under fault conditions.
  • Figure 4 shows the relationship between the switching wave forms Al and A2 and the output wave form V-out of the secondary of Tl measured at connector pin LP1.
  • Al is high the transistor TR1 is switched on and when A2 is high the transistor TR2 is switched on.
  • One cycle of the output wave form is produced by the following sequence:-
  • This process continues and creates an ac output wave form which is not a sine wave or square wave.
  • the shape is dependent on the size of the electroluminescent lamp that is connected to the output.
  • Figure 5 shows the microprocessor outputs Al and A2 that would be needed to generate an out wave form to drive a large electroluminescent lamp or a number of smaller lamps which are ON at the same time.
  • the periods (a) and (f) are set to the maximum time to achieve the same output voltage swing V-out.
  • the transistor switches TR1 and TR2 will remain on for longer. There is only a very short time when both transistors are off.
  • Figure 6 shows the same output voltage reached by V-out for the condition when a small electroluminescent lamp is connected to output LP1.
  • the peak-to-peak voltage remains the same so that a small lamp has the same brightness as a large lamp.
  • the rise time of the output voltage V-out is faster. Therefore the transistor switch TR1 and TR2 are only on for a short time between (a) and (b) and (e) and (f) as Al and A2 are high for a short period only.
  • This inverter circuit is improved by discharging the output voltage V-out just before the transition from the maximum positive voltage to the negative half cycle and from the maximum negative voltage to the positive half cycle.
  • the voltage is quickly discharged through the resistor R12 when the triac switch Z17 is turned on by the output port AO.
  • the transformer Tl can achieve the required output voltage with less power in the primary windings. This is another unique technical feature of this invention.
  • the triacs Zl to Z16 are commonly used for switching high voltage wave forms.
  • devices rated at 600v ac are used.
  • a lower power device has been chosen which can be driven directly from an output port of the micro-controller.
  • the triacs are switched on by supplying a small current directly from the output ports of the micro-controller into the gate of the triac.
  • the connection to each triac is via the diodes Dl to D16.
  • a series diode is used to avoid the risk of current flowing in the wrong direction and damaging the micro-controller. During the times when the triacs are being switched on or off the Inverter circuit is not operating so that the voltages are at a lower level.
  • each electroluminescent lamp in the display panels must be electrically connected to an in-line socket of 0.1 inch pitch.
  • the electroluminescent lamp panels are manufactured so that all lamps have one of their terminals connected to a common point. This is always connected to the output of the inverter circuit via LP1. In this way the high ac voltage is applied to one terminal of every lamp.
  • the second terminal of each lamp is connected to a respective triac switch Zl to Z16 via the plug pins LP3 to LP 18. When a triac is switched on this terminal is connected to 0 volts and a small current flows through the lamp making it light, j
  • FIG. 7 illustrates the operation of the EL lamp selection.
  • LP1 is the output from the inverter circuit.
  • switches Sa, Sb, Sc and Sd connected to EL lamps represented by La, Lb, Lc and Ld.
  • 0 would be one triac for each electroluminescent lamp (normally 8 or 16).
  • any lamp or combination of lamps can be switched on or off. The time they are on is determined by the software and the display table. This also controls the output level (brightness) of each lamp. If more than one lamp 0 is switched on, this invention will compensate for the additional load by increasing the inverter circuit drive conditions to keep the output ac voltage constant.
  • the measurement circuit is only used to confirm that the correct lamp has been connected and the voltages are within the normal operating limits.
  • internal EEPROM memory is used within the micro-controller to keep a record of the run time of an electroluminescent lamp panel.
  • a specially written program is used for controlling the microcontroller so that the voltage applied to the lamp is measured and adjusted to be at the correct level for the age of the lamp. In this way the lamp is kept at a constant brightness level.
  • the measurement circuit consists of 2 single-in-line resistor packs SILl and SIL2, resistors
  • R7, R8 and R9 capacitor C9 and diodes D17 and D18.
  • the output from the circuit is applied to pin B7 of the micro-controller which has been configured as an A-to-D converter.
  • the operation of the measurement circuit is illustrated in Figure 7.
  • the electroluminescent lamps can be considered as acting like capacitors. Each lamp is connected to a high value resistor Ra, Rb, Re and Rd which are part of the single-in-line resistor packs SILl or SIL2. R7 is also a high value resistor. When the triac switches are off, the high AC voltage appears on both sides of the electroluminescent "capacitors". In this example, when the switch Sb is closed the electroluminescent lamp Lb becomes a capacitive load as one terminal of Lb is now connected to Ov.
  • the capacitive load seen by the inverter which depends on the size of the lamp Lb.
  • the ac voltage on the switch side of all the non-selected lamps La, Lc and Lb is the same as the AC voltage driving the selected lamp Lb.
  • This voltage is divided down by a resistor chain (Ra, Re, Rd in parallel plus R7 and R8) to a low AC voltage across the resistor R8.
  • This is rectified by diode D17, smoothed by capacitor C9 and measured as a DC voltage at B7.
  • This DC voltage is in direct proportion to the original high AC.
  • the DC voltage is connected to the micro-controller input pin B7 to be read by the internal A to D converter.
  • B7 has a high impedance compared to R9.
  • D18 and R9 are for the protection of the microcontroller against voltages exceeding +5 volts.
  • the micro-controller ICl requires a +5 volt DC supply to pin 1 shown as VDD. This is provided by a 3 pin regulator REG which converts the +9 volt input from socket SKI to a +5 volt output. The 3 rd terminal of REG is connected to Ov from SKI. This is also connected to the VSS pin on ICl. C7 and C8 are electrolytic capacitors.
  • Resistor Rl 1, capacitor C4 and diode D19 form a reset circuit.
  • the presently described embodiment does not have a ON switch so ICl has a delayed start up to allow the voltages to stabilise after a connection is made to SKI.
  • Capacitors C5, C6 and crystal XI form an oscillator circuit with ICl.
  • the software has been written to be as flexible as possible and the unit has not been designed for any particular design of display panel.
  • the program can switch on any EL lamp or combination of lamps and drive the inverter circuit to provide the required output level for the desired on- time.
  • the ability to set different output drive levels from the invert circuit is unique to this invention. All the parameters relating to a particular display panel are held in a separate table (or tables) which are accessed by the main program.
  • the tables can be in the ROM memory of a OTP (One
  • Time Programmable device together with the main program.
  • the software has been written so that even this type of device can be re- programmed and a new table added (up to the memory limit of the device).
  • the table could be in EEPROM (Electrically Erasable Readonly Memory) or FLASH memory, which can be inside or outside the microprocessor IC.
  • the table could be on a plug in device such as a Smart card to allow for quick and easy changes of the display panels.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Optics & Photonics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Electroluminescent Light Sources (AREA)
  • Control Of El Displays (AREA)

Abstract

La présente invention concerne un dispositif de commande de lampes électroluminescentes permettant de commander un panneau afficheur électroluminescent réalisé à partir d'un grand nombre de segments à lampes. Ce dispositif de commande comprend un circuit inverseur permettant d'alimenter le panneau afficheur électroluminescent avec une haute tension de commande c.a., des microprocesseurs, des commutateurs, un circuit de mesure permettant d'obtenir un signal de rétroaction correspondant à la tension de commande c.a., ainsi que des dispositifs permettant d'appliquer le circuit de rétroaction sur le microprocesseur comme un signal de commande. Les caractéristiques de l'inverseur de la tension c.a. ainsi que les commutateurs sont commandés par le microprocesseur, de manière à mettre sélectivement sous tension les unités de segments à lampes.
PCT/GB1998/002134 1997-07-18 1998-07-17 Dispositif de commande de lampes electroluminescentes WO1999004382A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU84505/98A AU8450598A (en) 1997-07-18 1998-07-17 Electroluminescent lamp driver

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9715172.4 1997-07-18
GB9715172A GB2327523B (en) 1997-07-18 1997-07-18 Electroluminescent lamp driver

Publications (1)

Publication Number Publication Date
WO1999004382A1 true WO1999004382A1 (fr) 1999-01-28

Family

ID=10816076

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1998/002134 WO1999004382A1 (fr) 1997-07-18 1998-07-17 Dispositif de commande de lampes electroluminescentes

Country Status (3)

Country Link
AU (1) AU8450598A (fr)
GB (1) GB2327523B (fr)
WO (1) WO1999004382A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10062363A1 (de) * 2000-12-14 2002-07-04 Bsh Bosch Siemens Hausgeraete Elektronischer Schaltkreis und Verfahren zur Erzeugung einer Speisespannung
SG151144A1 (en) * 2007-10-04 2009-04-30 Singapore Polytechnic A system for driving a capacitive load

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2373910B (en) * 2001-03-29 2003-02-12 Spiridon Vlahos Illuminated displays
EP1526760A1 (fr) * 2003-10-21 2005-04-27 IEE INTERNATIONAL ELECTRONICS & ENGINEERING S.A. Circuit de contrôle pour lampes electroluminescentes multiples
GB0412058D0 (en) * 2004-05-28 2004-06-30 Pelikon Ltd Driving electroluminescent displays
US20090073156A1 (en) * 2006-02-10 2009-03-19 Pelikon Limited Drive Circuits for Capacitive Loads

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EP0187347A2 (fr) * 1985-01-08 1986-07-16 Hewlett-Packard Company Circuit de commande pour un panneau électroluminescent
JPH0447698A (ja) * 1990-06-13 1992-02-17 Canon Inc Ｅｌランプ駆動装置
WO1993007733A1 (fr) * 1991-10-11 1993-04-15 Norand Corporation Circuit d'attaque pour panneaux electroluminescents et analogue
US5493183A (en) * 1994-11-14 1996-02-20 Durel Corporation Open loop brightness control for EL lamp
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GB2106299B (en) * 1981-09-23 1985-06-19 Smiths Industries Plc Electroluminescent display devices
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Publication number Priority date Publication date Assignee Title
EP0187347A2 (fr) * 1985-01-08 1986-07-16 Hewlett-Packard Company Circuit de commande pour un panneau électroluminescent
JPH0447698A (ja) * 1990-06-13 1992-02-17 Canon Inc Ｅｌランプ駆動装置
WO1993007733A1 (fr) * 1991-10-11 1993-04-15 Norand Corporation Circuit d'attaque pour panneaux electroluminescents et analogue
US5565739A (en) * 1992-02-26 1996-10-15 Seg Corporations Power supply with the main inventive concept of periodically drawing power from a DC source
US5493183A (en) * 1994-11-14 1996-02-20 Durel Corporation Open loop brightness control for EL lamp

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Title
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PATENT ABSTRACTS OF JAPAN vol. 016, no. 236 (E - 1210) 29 May 1992 (1992-05-29) *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10062363A1 (de) * 2000-12-14 2002-07-04 Bsh Bosch Siemens Hausgeraete Elektronischer Schaltkreis und Verfahren zur Erzeugung einer Speisespannung
SG151144A1 (en) * 2007-10-04 2009-04-30 Singapore Polytechnic A system for driving a capacitive load

Also Published As

Publication number Publication date
AU8450598A (en) 1999-02-10
GB9715172D0 (en) 1997-09-24
GB2327523A (en) 1999-01-27
GB2327523B (en) 1999-12-15

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