US20070228990A1 - Safety circuit for electro-luminescent lamp ballast - Google Patents
Safety circuit for electro-luminescent lamp ballast Download PDFInfo
- Publication number
- US20070228990A1 US20070228990A1 US11/727,276 US72727607A US2007228990A1 US 20070228990 A1 US20070228990 A1 US 20070228990A1 US 72727607 A US72727607 A US 72727607A US 2007228990 A1 US2007228990 A1 US 2007228990A1
- Authority
- US
- United States
- Prior art keywords
- ballast
- lamp
- current
- circuit
- shutting down
- 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.)
- Abandoned
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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
- 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
- H05B41/285—Arrangements for protecting lamps or circuits against abnormal operating conditions
- H05B41/2851—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions
-
- 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
-
- 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]
-
- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S315/00—Electric lamp and discharge devices: systems
- Y10S315/07—Starting and control circuits for gas discharge lamp using transistors
Definitions
- the invention relates to Electro-luminescent (EL) lamps and, more particularly, to a safety circuit, for an EL lamp system, herein called Smart Faults Detection and Protection (SFD&P).
- EL Electro-luminescent
- SFD&P Smart Faults Detection and Protection
- Typical EL lamps are applied in frame systems.
- the size of the EL lamp can be 2,500 square inches or more and the applied voltage can be between 100-350 VAC or even higher. If people touch the electrode of EL lamp, current may flow through the human body to ground, thus possibly causing physical injury.
- GFI Ground Fault Interrupt
- an isolated ballast In an isolated ballast, line input is isolated from an output high voltage terminal. Thus, an isolated ballast could prevent stray leakage current flow to a grounded fixture since there is no return current path back to a secondary of the ballast.
- An isolated ballast with a GFI circuit could detect leakage current when a person touches the electrode of an EL lamp. However, when a person replaces an EL lamp, if the lighting fixture of the EL lamp is floating, there is still a leakage current coupled to the lighting fixture which can flow to the human body and back to ballast secondary output. The magnitude of the coupled leakage current depends on parasitic capacitance between the El lamp and the fixture, and at times can be up to 10 mA. Thus, even with an isolated ballast, there is still a risk of getting shocked when replacing such an EL lamp.
- An EL lamp with a ground shield and an isolated ballast could solve the above-mentioned problem, since there is no parasitic capacitance from the EL lamp to the lighting fixture.
- an isolated ballast is connected with a ground shield of the EL lamp and if the EL lamp is destroyed by a metal tip, if a person touches the defective part, leakage current will flow through the human body to the ground shield and couple back to the EL lamp. This shock current could be as high as 60 mA and depends on the parasitic capacitance between the ground shield and the rear electrode of EL lamp.
- An object of the invention is to fulfill the need referred to above.
- this objective is obtained by providing a safety circuit for a ballast of an electro-luminescent (EL) lamp.
- the EL lamp had an electrical ground shield on at least a portion thereof and has a separate ground lead.
- the ballast is an isolated ballast with a line input being isolated from an output.
- the ballast is constructed and arranged to be electrically connected with the separate ground lead.
- the circuit includes a current sensing structure constructed and arranged to connect between the separate ground lead and a potential ground of the ballast. In the event a user contacts the EL lamp to replace the EL lamp or contacts a defective EL lamp, the ballast is shut down based on a value of current sensed by the current sensing structure.
- a method for controlling a ballast for powering an electro-luminescent (EL) lamp.
- the ballast has a line input isolated from an output.
- the method provides an EL lamp having an electrical ground shield on at least a portion thereof and having a separate ground lead.
- the ballast is electrically connected with the separate ground lead. Current between the separate ground lead and a potential ground of the ballast is sensed.
- the ballast is shut down based on a value of current sensed by the current sensing structure.
- FIG. 1 is a schematic of an EL lamp system including a ballast having a safety circuit, provided in accordance with the principles of an embodiment of the invention.
- a safety circuit for an EL lamp ballast, generally indicated at 11 , is shown in accordance with the principles of the present invention.
- the ballast 11 is an isolated ballast with a line input being isolated from an output.
- the ballast 11 powers an EL lamp 12 having a ground shield.
- the safety circuit includes a Smart Faults Detection and Protection (SFD&P) circuit, generally indicated at 13 .
- SFD&P Smart Faults Detection and Protection
- the ballast 11 with the SFD&P circuit 13 , together with the EL lamp 12 defines an EL lamp system 19 .
- the isolated ballast 11 includes a three-wire input, generally indicated at 14 , an isolated AC-DC converter, generally indicated at 15 , and a DC-AC inverter, generally indicated at 16 , providing AC current to the EL lamp 12 .
- an aluminum foil 17 is laminated on at least a portion of a rear side of the EL lamp 12 and a separate ground lead 18 is electrically connected to the SFD&P circuit 13 .
- the SFD&P circuit 13 includes a current sensing structure, preferably in the form of a resistor 20 (e.g., a few ohms), placed between the separate ground lead 18 and potential ground (PG) of the ballast 11 .
- the leakage current will flow through human body to the ground lead 18 to the current sensing resistor 20 . Since the voltage drop is low, an active rectifier 22 and an amplifier 24 are connected to the sensing resistor 20 providing an amplified signal 21 .
- the voltage drop (signal 21 ) of the sensing resistor 20 is preferably measured by an analog to digital converter 23 and a controller 25 , such as a microprocessor.
- the converter 23 can be part of the controller 25 .
- the controller 25 will shut down the ballast 11 when current sensed by the sensing resistor 20 exceeds a trip or threshold value of current.
- a trip latch circuit can be connected to the amplifier to shut down the ballast 11 when a leakage current flow to a person is measured.
- the safety circuit 10 protects a user when replacing an EL lamp and when touching a defective EL lamp.
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Optics & Photonics (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
- Electroluminescent Light Sources (AREA)
- Arrangement Of Elements, Cooling, Sealing, Or The Like Of Lighting Devices (AREA)
Abstract
Description
- This application claims the benefit of the earlier filing date of U.S. Provisional Application No. 60/787,533, filed on Mar. 31, 2006 which is incorporated by reference herein in its entirety.
- The invention relates to Electro-luminescent (EL) lamps and, more particularly, to a safety circuit, for an EL lamp system, herein called Smart Faults Detection and Protection (SFD&P).
- Typical EL lamps are applied in frame systems. Thus, the size of the EL lamp can be 2,500 square inches or more and the applied voltage can be between 100-350 VAC or even higher. If people touch the electrode of EL lamp, current may flow through the human body to ground, thus possibly causing physical injury.
- It has long been known to apply a Ground Fault Interrupt (GFI) circuit to the ballast for fluorescent lamps. A conventional GFI circuit uses a current sensor to measure unbalanced current between input live and neutral. Most of the ballasts are non-isolated circuits. These GFI circuits can be applied to the non-isolated ballast for an EL lamp. Thus, when a person touches the electrode of EL lamp, the conventional GFI circuit will shut down the ballast. However, when EL lamp is put into a grounded lighting frame or fixture, there is a large parasitic capacitance (a few nF) between the fixture and EL lamp, thus resulting in high leakage current from the EL lamp to ground. This stray leakage current will trip the GFI circuit and shut down the ballast. Hence, the conventional GFI circuits cannot accurately discriminate between stray leakage current and the leakage current that occurs due to a true fault condition.
- In an isolated ballast, line input is isolated from an output high voltage terminal. Thus, an isolated ballast could prevent stray leakage current flow to a grounded fixture since there is no return current path back to a secondary of the ballast. An isolated ballast with a GFI circuit could detect leakage current when a person touches the electrode of an EL lamp. However, when a person replaces an EL lamp, if the lighting fixture of the EL lamp is floating, there is still a leakage current coupled to the lighting fixture which can flow to the human body and back to ballast secondary output. The magnitude of the coupled leakage current depends on parasitic capacitance between the El lamp and the fixture, and at times can be up to 10 mA. Thus, even with an isolated ballast, there is still a risk of getting shocked when replacing such an EL lamp.
- An EL lamp with a ground shield and an isolated ballast could solve the above-mentioned problem, since there is no parasitic capacitance from the EL lamp to the lighting fixture. However, if an isolated ballast is connected with a ground shield of the EL lamp and if the EL lamp is destroyed by a metal tip, if a person touches the defective part, leakage current will flow through the human body to the ground shield and couple back to the EL lamp. This shock current could be as high as 60 mA and depends on the parasitic capacitance between the ground shield and the rear electrode of EL lamp.
- Thus, there is a need to provide a new safety circuit for an EL lamp to protect a user when replacing an EL lamp and when touching a defective EL lamp.
- An object of the invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is obtained by providing a safety circuit for a ballast of an electro-luminescent (EL) lamp. The EL lamp had an electrical ground shield on at least a portion thereof and has a separate ground lead. The ballast is an isolated ballast with a line input being isolated from an output. The ballast is constructed and arranged to be electrically connected with the separate ground lead. The circuit includes a current sensing structure constructed and arranged to connect between the separate ground lead and a potential ground of the ballast. In the event a user contacts the EL lamp to replace the EL lamp or contacts a defective EL lamp, the ballast is shut down based on a value of current sensed by the current sensing structure.
- In accordance with another aspect of the invention, a method is provided for controlling a ballast for powering an electro-luminescent (EL) lamp. The ballast has a line input isolated from an output. The method provides an EL lamp having an electrical ground shield on at least a portion thereof and having a separate ground lead. The ballast is electrically connected with the separate ground lead. Current between the separate ground lead and a potential ground of the ballast is sensed. The ballast is shut down based on a value of current sensed by the current sensing structure.
- Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.
- The invention will be better understood from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawing in which:
-
FIG. 1 is a schematic of an EL lamp system including a ballast having a safety circuit, provided in accordance with the principles of an embodiment of the invention. - With reference to
FIG. 1 , a safety circuit, generally indicated at 10, for an EL lamp ballast, generally indicated at 11, is shown in accordance with the principles of the present invention. The ballast 11 is an isolated ballast with a line input being isolated from an output. The ballast 11 powers anEL lamp 12 having a ground shield. The safety circuit includes a Smart Faults Detection and Protection (SFD&P) circuit, generally indicated at 13. The ballast 11, with the SFD&Pcircuit 13, together with theEL lamp 12 defines anEL lamp system 19. - In the embodiment, the isolated ballast 11 includes a three-wire input, generally indicated at 14, an isolated AC-DC converter, generally indicated at 15, and a DC-AC inverter, generally indicated at 16, providing AC current to the
EL lamp 12. - Preferably, an
aluminum foil 17 is laminated on at least a portion of a rear side of theEL lamp 12 and aseparate ground lead 18 is electrically connected to the SFD&Pcircuit 13. More particularly, in the embodiment, the SFD&Pcircuit 13 includes a current sensing structure, preferably in the form of a resistor 20 (e.g., a few ohms), placed between theseparate ground lead 18 and potential ground (PG) of the ballast 11. - When a person or user touches the electrode of the
EL lamp 12 or fixture of the EL lamp, the leakage current will flow through human body to theground lead 18 to thecurrent sensing resistor 20. Since the voltage drop is low, anactive rectifier 22 and anamplifier 24 are connected to thesensing resistor 20 providing an amplifiedsignal 21. The voltage drop (signal 21) of thesensing resistor 20 is preferably measured by an analog todigital converter 23 and acontroller 25, such as a microprocessor. Theconverter 23 can be part of thecontroller 25. Thecontroller 25 will shut down the ballast 11 when current sensed by thesensing resistor 20 exceeds a trip or threshold value of current. Instead of using themicroprocessor 25, a trip latch circuit can be connected to the amplifier to shut down the ballast 11 when a leakage current flow to a person is measured. - Thus, it can be appreciated that the
safety circuit 10 protects a user when replacing an EL lamp and when touching a defective EL lamp. - The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.
Claims (21)
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/727,276 US20070228990A1 (en) | 2006-03-31 | 2007-03-26 | Safety circuit for electro-luminescent lamp ballast |
US12/313,669 US8018174B2 (en) | 2006-03-31 | 2008-11-20 | Safety circuit for electro-luminescent lamp ballast |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US78753306P | 2006-03-31 | 2006-03-31 | |
US11/727,276 US20070228990A1 (en) | 2006-03-31 | 2007-03-26 | Safety circuit for electro-luminescent lamp ballast |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/313,669 Continuation US8018174B2 (en) | 2006-03-31 | 2008-11-20 | Safety circuit for electro-luminescent lamp ballast |
Publications (1)
Publication Number | Publication Date |
---|---|
US20070228990A1 true US20070228990A1 (en) | 2007-10-04 |
Family
ID=38655999
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/727,276 Abandoned US20070228990A1 (en) | 2006-03-31 | 2007-03-26 | Safety circuit for electro-luminescent lamp ballast |
US12/313,669 Expired - Fee Related US8018174B2 (en) | 2006-03-31 | 2008-11-20 | Safety circuit for electro-luminescent lamp ballast |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/313,669 Expired - Fee Related US8018174B2 (en) | 2006-03-31 | 2008-11-20 | Safety circuit for electro-luminescent lamp ballast |
Country Status (2)
Country | Link |
---|---|
US (2) | US20070228990A1 (en) |
WO (1) | WO2007126739A2 (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5574336A (en) * | 1995-03-28 | 1996-11-12 | Motorola, Inc. | Flourescent lamp circuit employing a reset transistor coupled to a start-up circuit that in turn controls a control circuit |
US7378806B2 (en) * | 2005-12-29 | 2008-05-27 | General Electric Company | Output short circuit protection for electronic ballasts |
-
2007
- 2007-03-26 WO PCT/US2007/007417 patent/WO2007126739A2/en active Application Filing
- 2007-03-26 US US11/727,276 patent/US20070228990A1/en not_active Abandoned
-
2008
- 2008-11-20 US US12/313,669 patent/US8018174B2/en not_active Expired - Fee Related
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5574336A (en) * | 1995-03-28 | 1996-11-12 | Motorola, Inc. | Flourescent lamp circuit employing a reset transistor coupled to a start-up circuit that in turn controls a control circuit |
US7378806B2 (en) * | 2005-12-29 | 2008-05-27 | General Electric Company | Output short circuit protection for electronic ballasts |
Also Published As
Publication number | Publication date |
---|---|
US8018174B2 (en) | 2011-09-13 |
US20090146574A1 (en) | 2009-06-11 |
WO2007126739A2 (en) | 2007-11-08 |
WO2007126739A3 (en) | 2008-10-23 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: CEELITE LLC, PENNSYLVANIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LIANG, CHIN-PING;LIU, CHANG-YI;REEL/FRAME:019159/0263 Effective date: 20070321 |
|
AS | Assignment |
Owner name: CEELITE, INC., PENNSYLVANIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:RILITE CORPORATION;CEEMEE, INC.;CEELITE, LLC;AND OTHERS;REEL/FRAME:020951/0691 Effective date: 20080328 |
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AS | Assignment |
Owner name: TMG COLLATERAL AGENT, LLC, PENNSYLVANIA Free format text: SECURITY AGREEMENT;ASSIGNOR:CEELITE, LLC;REEL/FRAME:021695/0342 Effective date: 20071015 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO PAY ISSUE FEE |