GB2325798A - Mains powered supply for driving electroluminescent material - Google Patents

Mains powered supply for driving electroluminescent material Download PDF

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Publication number
GB2325798A
GB2325798A GB9710975A GB9710975A GB2325798A GB 2325798 A GB2325798 A GB 2325798A GB 9710975 A GB9710975 A GB 9710975A GB 9710975 A GB9710975 A GB 9710975A GB 2325798 A GB2325798 A GB 2325798A
Authority
GB
United Kingdom
Prior art keywords
transistor
electroluminescent material
oscillator
bridge rectifier
mains
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.)
Withdrawn
Application number
GB9710975A
Other versions
GB9710975D0 (en
Inventor
Peter Matthew Watson
Lennox Mark Huck
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.)
MINIFLAME Ltd
Original Assignee
MINIFLAME Ltd
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 MINIFLAME Ltd filed Critical MINIFLAME Ltd
Priority to GB9710975A priority Critical patent/GB2325798A/en
Publication of GB9710975D0 publication Critical patent/GB9710975D0/en
Publication of GB2325798A publication Critical patent/GB2325798A/en
Withdrawn legal-status Critical Current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
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • 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
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02—Details of power systems and of start or stop of display operation
    • 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
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/39—Circuits containing inverter bridges
    • 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]

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)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

The supply comprises a mains powered step-down transformer TF2 feeding a bridge rectifier D1-D4 giving a DC supply for a self-oscillating, high frequency, tuned step-up inverter 2 having a ferrite step-up transformer TF1 with the electroluminescent material (not shown) connected across its secondary winding. A capacitor C2 and a resistor R3 provide feedback to the base of a transistor T2 of the inverter. A light emitting diode LD1 with an integral oscillator is coupled via a transistor T1 and a current limiting resistor R4 to the base of transistor T2 causing intermittent operation of the inverter 2 so that the electroluminescent material flashes. An override switch SW1 may be operated to give a non-flashing mode. A variable resistor VR1 may be adjusted to control the brightness of the electroluminescent material. The supply may be built into an adapter unit which plugs into a mains socket (Figs.2-4). The electroluminescent material may be in sheet, fibre or strip form. Strip form material has a helical electrode (34, Fig.5) separated from a central electrode (32) by a layer (36) of a phosphor coating with a minute metallic sheath. The assembly of electrodes (32, 34) and layer (36) is surrounded by an indium tin oxide layer (38) over which is a polyvinyl chloride outer protective sheath (40).

Description

MLINS-OPERATED POWER SUPPLY APPARATUS FOR BLECTROLUSINESC=NT MATERIAL This invention relates to mains-operated power supply apparatus for electroluminescent material.
Electroluminescent material is known but it is not in wide use. The electroluminescent material could be more widely used in domestic, commercial and industrial applications if it could be simply and easily powered from mains electricity. It is an aim of the present invention to provide apparatus which enables the electroluminescent material simply and easily to be powered from the mains electricity.
Accordingly, in one non-limiting embodiment of the present invention there is provided mains-operated power supply apparatus for electroluminescent material, which apparatus comprises a step down transformer for reducing mains voltage, a bridge rectifier for rectifying the output of the step down transformer, oscillator means for receiving the rectified output of the bridge rectifier, and a step up transformer for stepping up the output of the oscillator means and providing a high frequency power source for driving the electroluminescent material.
The apparatus may be one in which the bridge rectifier is a full wave bridge rectifier. Preferably, the full wave bridge rectifier includes four silicon diodes.
The apparatus may be one in which the oscillator means comprises a self-oscillating tuned step up inverter circuit.
The self-oscillating tuned step up inverter circuit may comprise a light emitting diode having an integral oscillator, a first transistor and a second transistor, the oscillator being so connected to the first transistor as to control the base current of the first transistor, and the first transistor being so connected to the second transistor that the base current of the first transistor controls the collector current of the first transistor, which in turn controls the bias conditions of the second transistor.
The apparatus may include switch means for overriding the oscillator control of the base current of the first transistor. The switch means thus enables the provision of a power supply for the electroluminescent material that causes the electroluminescent material to operate in a non-flashing mode.
The apparatus may include a smoothing capacitor for smoothing the output from the bridge rectifier.
The apparatus may include current limiting means which is connected in series with the base circuit of the second transistor for maintaining operation of the second transistor within safe drive limits. The current limiting means is preferably a resistor. Other types of current limiting means may however be employed.
The apparatus may include a housing and pins which project outwardly from the housing and which are for plugging into an electrical outlet socket. The housing may thus be constructed to be a simple hand held housing so that the apparatus of the present invention can be easily handled for providing the necessary power for the electroluminescent material. This in turn helps to promote the use of the electroluminescent material in domestic, commercial and industrial situations. Usually there will be three of the pins but there may be two of the pins if desired.
The present invention also extends to the combination of the mains-operated power supply apparatus of the present invention and the electroluminescent material.
The electroluminescent material may be, for example, in strip form and/or sheet form and/or fibre form.
Embodiments of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 shows an electrical circuit for mainsoperated power supply apparatus for electroluminescent material; Figure 2 shows an embodiment of the invention in which the circuit of Figure 1 is included in a housing having three pins for fitting in a three pin electrical socket; Figure 3 is a front view of the apparatus shown in Figure 2; Figure 4 is an inside rear view showing how the circuit of Figure 1 can be set out on a printed circuit board; and Figure 5 shows in detail the composition of electroluminescent material in strip form.
In Figure 1, there is shown a circuit 2 forming part of mains-operated power supply apparatus for electroluminescent material. The circuit 2 comprises a step down transformer TF2 for reducing mains voltage.
The transformer TF2 has a primary winding 4 and a secondary winding 6. The secondary winding 6 is connected as shown to four silicon diodes D1, D2, D3 and D4. The diodes D1, D2, D3 and D4 form a full wave bridge rectifier 8 for rectifying the output of the transformer TF2. The output from the bridge rectifier 8 is smoothed by a smoothing capacitor C4.
The circuit 2 includes oscillator means 10 foz receiving the rectified output of the bridge rectifier 8, via the smoothing capacitor C4. The oscillator means 10 is a self-oscillating tuned step up inverter circuit.
This inverter circuit comprises a light emitting diodes 1D1 having an integral oscillator. The inverter circuit also comprises a first transistor T1 and a seconc transistor T2. The oscillator in the light emitting diode LD1 is so connected to the first transistor T1 as to control the base current of the first transistor Ti.
The first transistor T1 is so connected to the second transistor T2 that the base current of the first transistor T1 controls the collector current of th( first transistor T1, which in turns controls the biaC condition of the transistor T2. Resistors R1, R2, R3 R4, R5 and R8 are employed as shown together with capacitors C1 and C2. A variable resistor VR1 ifi connected between the first transistor T1 and the second transistor T2 as shown.
Switch means SW1 is provided for overriding the oscillator control of the base current to the first transistor T1. Thus operation of the switch means SW: provides a power supply for the electroluminescent material that causes the electroluminescent material t operate in a non-flashing mode.
The oscillator means 10 outputs as shown to a primary winding 12 of a step up transformer TF1. The transformer TF1 has a secondary winding 14 with a capacitor C3 connected as shown. The transformer TF1 steps up the output of the oscillator means 10 and provides a high frequency power source for driving the electroluminescent material.
The input to the circuit 2 may be 240 volts or 120 volts. During operation of the circuit 2, the mains voltage is transformed by the transformer TF2 down to 8.4 or 16.9 volts, in order to provide correct drive power for the various electronic component in the circuit 2 to be supplied with power. The output from the transformer TF2 is fed to the bridge rectifier 8 and the output from the bridge rectifier 8 is smoothed by the capacitor C4. The supply is then fed to the light emitting diode D1 having the integral oscillator. The purpose of the oscillator is to control the base current of the transistor T1. This function may be overridden by the switch means SW1 in order to provide a nonflashing mode of operation if required.
The base current of the transistor T1 controls the collector current of the transistor T1. This in turn controls the bias conditions of the transistor T2. The bias can be pre-set by the variable resistor VR1 in order to control the resultant brightness of the electroluminescent material. The resistor R4 is connected in series with the base circuit of the transistor T2 and acts as a current limiting device to maintain the operation of the transistor T2 within safe drive limits.
When the transistor T2 is suitably biased, it forms a self-oscillating tuned step up inverter circuit in conjunction with the transformer TF1. The transformer TF1 is preferably a tuned ferrite transformer TF1. The capacitor C2 and the resistor R3 provide the necessary feedback for the oscillator, constructed around the capacitor C2 and the transformer TF1, to function properly. The transformer TF1 has a ratio of 22:1 and it is tuned by the capacitor C3 to provide a suitable high frequency power source for the electroluminescent material.
The resistor R5 is an optional resistor which may be used to tune the transformer TF1 to the rest of the output circuit if required.
During operation of the circuit 2, the light emitting diode LD1 and the resistor R1 turn the transistor T1 on and off. The resistor R8 and the switch means SW1 turn the transistor T1 on constantly.
The transistor T1 turns the transistor T2 on. The resistor R4 acts as a current limiter as mentioned above. The resistor R4 adjusts the variable resistor VR1. The variable resistor VR1 is able to adjust the current limit to control the brightness of the electroluminescent material in order to brighten or dim the light emitted from the electroluminescent material.
The capacitor C2 and the resistor R3 oscillate.
The capacitor C1 is a feedback for the oscillator. The capacitor C3 tunes to strip/output voltage.
The capacitor C2 and the resistor R3 provide a high frequency to drive the electroluminescent material. The electroluminescent material is such that it has a phosphor coating which gives off a bright light consequent upon receiving the required high frequency drive. By adjusting the frequency, the colour and brightness is able to be varied to give a further lighting effect.
Referring to Figures 2, 3 and 4, there is shown a housing 16 which includes the circuit 2. The housing 16 has three pins 18 for fitting into an electrical socket 20.
The housing 16 is provided with a cable 22 which leads to electroluminescent material 24 which is mounted on a substrate 26. The electroluminescent material 24 may be in any suitable shape to give any desired sign or aesthetic effect.
Figure 4 shows the inside of the housing 10 and how the various electronic components of the circuit 2 can be mounted on a printed circuit board 28. As can be seen, the housing 16 has four holes 30 for receiving fixing screws (not shown) for receiving another part of the housing in order to close the housing 16.
Figure 5 shows in more detail the electroluminescent material 24. More specifically, the electroluminescent material 2 is in strip form and it has a first electrode 32 which is made of copper and which is a centrally positioned longitudinally extending electrode. The electroluminescent material 24 includes a second electrode 34 which is a fine wire helically wound electrode. The first and the second electrodes 32, 34 are separated by a layer 36 made up of a phosphor coating with a minute metallic sheath. The assembly of the first and the second electrodes 32, 34 and the layer 36 is surrounded by a layer 38 which is an indium tin oxide layer. An outer layer 40 forms an outer protective sheath. The outer layer 40 is made of a polyvinyl chloride plastics material.
It is to be appreciated that the embodiments of the invention described above with reference to the accompanying drawings have been given by way of example only and that modifications may be effected. Thus, for example, the electroluminescent material 24 could be in sheet form or fibre form. Also, the housing 16 could be a different shape than shown. The layout of the circuit 2 may be varied if desired.

Claims (14)

1. Mains-operated power supply apparatus for electroluminescent material, which apparatus comprises a step down transformer for reducing mains voltage, a bridge rectifier for rectifying the output of the step down transformer, oscillator means for receiving the rectified output of the bridge rectifier, and a step up transformer for stepping up the output of the oscillator means and providing a high frequency power source for driving the electroluminescent material.
2. Apparatus according to claim 1 in which the bridge rectifier is a full wave rectifier.
3. Apparatus according to claim 2 in which the full wave bridge rectifier includes four silicon diodes.
4. Apparatus according to any one of the preceding claims in which the oscillator means comprises a selfoscillating tuned step up inverter circuit.
5. Apparatus according to claim 4 in which the selfoscillating tuned step up inverter circuit comprises a light emitting diode having an integral oscillator, a first transistor and a second transistor, the oscillator being so connected to the first transistor as to control the base current of the first transistor, and the first transistor being so connected to the second transistor that the base current of the first transistor controls the collector current of the first transistor, which in turn controls the bias condition of the second transistor.
6. Apparatus according to claim 5 and including switch mean for overriding the oscillator control of the base current of the first transistor.
7. Apparatus according to any one of the preceding claims and including a smoothing capacitor for smoothing the output from the bridge rectifier.
8. Apparatus according to any one of the preceding claims and including current limiting means which is connected in series with the base circuit of the second transistor for maintaining the operation of the second transistor within safe drive limits.
9. Apparatus according to claim 8 in which the current limiting means is a resistor.
10. Apparatus according to any one of the preceding claims and including a housing and pins which project outwardly from the housing and which are for plugging into an electrical outlet socket.
11. Apparatus according to claim 10 in which there are three of the pins.
12. Mains-operated power supply apparatus for electroluminescent material, substantially as herein described with reference to the accompanying drawings.
13. The combination of the mains-operated power supply apparatus according to any one of the preceding claims and the electroluminescent material.
14. The combination according to claim 13 and in which the electroluminescent material is in strip form and/or sheet form and/or fibre form.
GB9710975A 1997-05-28 1997-05-28 Mains powered supply for driving electroluminescent material Withdrawn GB2325798A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9710975A GB2325798A (en) 1997-05-28 1997-05-28 Mains powered supply for driving electroluminescent material

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9710975A GB2325798A (en) 1997-05-28 1997-05-28 Mains powered supply for driving electroluminescent material

Publications (2)

Publication Number Publication Date
GB9710975D0 GB9710975D0 (en) 1997-07-23
GB2325798A true GB2325798A (en) 1998-12-02

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Family Applications (1)

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GB9710975A Withdrawn GB2325798A (en) 1997-05-28 1997-05-28 Mains powered supply for driving electroluminescent material

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2418080A (en) * 2004-09-08 2006-03-15 Jin Rong Chang Driving circuit module for connecting to a Christmas light string

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB863658A (en) * 1957-12-31 1961-03-22 Westinghouse Electric Corp Improvements in or relating to transistor electrical inverter systems
GB1308284A (en) * 1971-01-25 1973-02-21 Thorn Electrical Ind Ltd Self-biased class c oscillators
US4637148A (en) * 1985-07-08 1987-01-20 Barlow Dane D Electroluminescent badge
EP0278253A1 (en) * 1987-02-13 1988-08-17 International Business Machines Corporation Circuit for energising an electroluminescent panel
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
WO1997027576A1 (en) * 1996-01-25 1997-07-31 Add-Vision, Inc. Retrofit lighting system that non-invasively interacts with a host machine

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB863658A (en) * 1957-12-31 1961-03-22 Westinghouse Electric Corp Improvements in or relating to transistor electrical inverter systems
GB1308284A (en) * 1971-01-25 1973-02-21 Thorn Electrical Ind Ltd Self-biased class c oscillators
US4637148A (en) * 1985-07-08 1987-01-20 Barlow Dane D Electroluminescent badge
EP0278253A1 (en) * 1987-02-13 1988-08-17 International Business Machines Corporation Circuit for energising an electroluminescent panel
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
WO1997027576A1 (en) * 1996-01-25 1997-07-31 Add-Vision, Inc. Retrofit lighting system that non-invasively interacts with a host machine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2418080A (en) * 2004-09-08 2006-03-15 Jin Rong Chang Driving circuit module for connecting to a Christmas light string

Also Published As

Publication number Publication date
GB9710975D0 (en) 1997-07-23

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732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)