EP2222137A1 - System and method for automatic and safe detection of earth faults and interwire short circuits for DC lamp circuits - Google Patents
System and method for automatic and safe detection of earth faults and interwire short circuits for DC lamp circuits Download PDFInfo
- Publication number
- EP2222137A1 EP2222137A1 EP09002228A EP09002228A EP2222137A1 EP 2222137 A1 EP2222137 A1 EP 2222137A1 EP 09002228 A EP09002228 A EP 09002228A EP 09002228 A EP09002228 A EP 09002228A EP 2222137 A1 EP2222137 A1 EP 2222137A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- driving circuit
- signal lamp
- driving
- power supply
- voltage
- 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.)
- Granted
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Classifications
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- 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
- H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
- H05B47/20—Responsive to malfunctions or to light source life; for protection
- H05B47/21—Responsive to malfunctions or to light source life; for protection of two or more light sources connected in parallel
-
- 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
- H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
- H05B47/20—Responsive to malfunctions or to light source life; for protection
- H05B47/26—Circuit arrangements for protecting against earth faults
Definitions
- the invention relates to a driving circuit system for driving at least two DC signal lamps.
- signal lamps are normally controlled via a two-wire circuit. For safety reasons these wires have to be supervised whether there is a short circuit to earth or between two wires to avoid the unintended lightening of a signal lamp.
- a driving circuit system for driving at least two DC signal lamps comprising:
- the above object is achieved, in accordance with the invention, by a method for detecting earth faults and interwire short circuits in the driving circuit system described above, wherein in a normal operation mode of the driving circuits, in which a signal lamp is turned on by connecting it to the positive and negative poles of the first power supply via the switches, an earth fault of a driving circuit is detected due to a leckage current measured by the central amperemeter, an interwire short circuit between wires of two driving circuits is detected due to a difference of the currents measured by the locals amperemeters of one of the two driving circuits, and an interwire short circuit between wires of one driving circuit is detected due to a comparison between the measured current and the expected current computed by both the measured voltage and the resistance of the wires and of the signal lamp.
- a driving circuit system which supports automatic supervision and detection of earth faults and interwire short circuits within safety-critical systems using DC current for switching electrical devices.
- the driving circuit system 1 for driving two DC signal lamps 2a, 2b comprises:
- First power supply 3 is powerful enough to supply all signal lamps 2a, 2b simultaneously.
- Second power supply 4 may to be less powerful because it has to supply one signal lamp only.
- Power supply U E resulting from the different potentials can be very weak because it is used for earth fault detection only.
- the central amperemeter 6 is placed between the two power supplies 3,4 to check earth faults. Periodical testing of the central amperemeter 6 is done by closing the switch S E .
- the driving circuit system 1 specifies three voltages: U 1 and U 2 for signal lamp supply and U E for earth fault detection.
- Each driving circuit 10a, 10b comprises:
- Each signal lamp 2a, 2b is connected with the switches S 3 , S 4 by a two- wire cable, wherein the resistance of the signal lamp 2a, 2b is represented by R v and the resistance of one wire 11 is represented by R L .
- the switches S 1 -S 4 can be implemented by relays or any semiconductor switch. The correct working of the switches S 1 -S 4 is checked by measuring the voltage V 1 -V 4 between the connections of the switches S 1 -S 4 and the occurrence of the expected current and is done by the control unit 17. All local amperemeters 13 and voltmeters 15 1 -154 are provided with low-pass filters (not shown). In addition to the diodes 16, further protective components (not shown) can be provided to avoid distortion caused by inductive load switching.
- Each control unit 17 of the driving circuit 10a, 10b is controlled by the master control 7 and can be realized for example by a microcontroller.
- Each control unit 17 supervises the voltages U A ,V 1 -V 4 and currents I E , I H , I R , actuates the switches S 1 -S 4 and defines the output voltage of the DC-DC converter 12.
- the master control 7 commands a control unit 17 to switch on or off the signal lamp 2a, 2b, determines an operation mode of a control unit 17 and organizes the process of measurement of earth faults EF and interwire short circuits ISC. Errors which have been detected by control units 17 are reported to the master control 7 immediately.
- the driving circuits 10a, 10b can be operated in a "normal operation mode" and a "test operation mode".
- a signal lamp 2a, 2b is turned on by connecting it to the positive and negative poles of the first power supply 3 via the switches S 1 -S 4 . If a signal lamp 2a, 2b has to be turned on switches S 1 and S 2 are in position 1, SH is in position 1 and S R in position 2. If a signal lamp has to be turned off switches S EH and S ER are in position 1, switches S H and SR in position 2.
- Interwire short circuits ISC between the two wires 11 of one driving circuits 10a, 10b can be deduced by measurement of U A and knowledge of I H and Rv and R L .
- the expected value of I H can be calculated.
- I H U A / (R v + 2 R L ).
- a deviation is an evidence for the occurrence of a short circuit or a wire breaking.
- R L of wire 11 may however alter depending on temperature influences R L can be measured in the test operation mode which is explained hereinafter.
- RL has to be known for the detection.
- the master control 7 regulates the permission of a driving circuit 10a, 10b to switch into the test operation mode. If a driving circuit 10a, 10b has finished the test master control 7 is informed accordingly.
- driving circuit 10a If, for example, driving circuit 10a is in the test operation mode the switches S 1 , S 2 move into position 2 and the driving circuit 10a is connected to second power supply 4. If its signal lamp 2a was turned on it still remains turned on except for the short moment of alternating the power supply.
- the electrical potential of the driving circuit 10a is below that of driving circuit 10b, i.e. of all other driving circuits. Any possible interwire short circuits ISC between this unit 10a and the others will lead to a leckage current I E .
- the potential difference at least amounts to voltage U E .
- the leakage current I E can be detected by calculating the difference of I H and I R if its signal lamp 2a is turned on. If signal lamp 2a is turned off, leakage current I E leads to values of I H and I R unequal to zero.
- Switch S E is closed and I E must arise, otherwise a fault of switch SE, of amperemeter IE or ground connection must be supposed.
Landscapes
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
a first DC power supply (3) having a first voltage (U1) for driving the signal lamps (2a, 2b),
a second DC power supply (4) having a second voltage (U2) for driving only one of the signal lamps (2a, 2b), the negative poles of the first and second power supplies (3, 4) being on different potentials,
a central amperemeter (6) provided between the two power supplies (3, 4),
and driving circuits (10a, 10b) for each signal lamp (2a, 2b), each driving circuit (10a, 10b) comprising:
- a first two-way change-over switch (S1) connected to the positive pole of either the first or second power supply (3, 4),
- a second two-way change-over switch (S2) connected to the negative pole of either the first or second power supply (3, 4),
- a third two-way change-over switch (S3) connecting one wire (11) of the signal lamp (2a, 2b) to either the first or the second switch (S1, S2),
- a fourth two-way change-over switch (S4) connecting the other wire (11) of the signal lamp (2a, 2b) to either the first or second switch (S1, S2),
- two local amperemeters (13) for measuring the current (IH, IR) in both wires (11) of the signal lamp (2a, 2b),
- a local voltmeter (14) for measuring the voltage (UA) applied to the signal lamp (2a, 2b), and
- a control unit (17) for controlling the four switches (S1-S4) and for detecting both earth faults (EF) within a driving circuit (10a, 10b) and interwire short circuits (ISC) between two driving circuits (10a, 10b), based on the measured currents and voltages.
Description
- The invention relates to a driving circuit system for driving at least two DC signal lamps.
- In electronic interlockings signal lamps are normally controlled via a two-wire circuit. For safety reasons these wires have to be supervised whether there is a short circuit to earth or between two wires to avoid the unintended lightening of a signal lamp.
- Within conventional AC based lamp circuits, supervision of interwire short circuits has to be done periodically by supervision staff. Checking by staff is very expensive.
- Although DC based signal lamp circuits have not been commonly used in the past, there is an increasing interest for using LEDs as signal lamps within interlocking.
- It is the object of the invention to further develop a system and a method for automatic and safe detection of earth faults and interwire short circuits within a driving circuit system for driving at least two DC signal lamps.
- This object is achieved, in accordance with the invention, by a driving circuit system for driving at least two DC signal lamps, comprising:
- a first DC power supply having a first voltage for driving the signal lamps,
- a second DC power supply having a second voltage for driving only one of the signal lamps, the negative poles of the first and second power supplies being on different potentials,
- a central amperemeter provided between the two power supplies,
- and driving circuits for each signal lamp, each driving circuit comprising:
- a first two-way change-over switch connected to the positive pole of either the first or second power supply,
- a second two-way change-over switch connected to the negative pole of either the first or second power supply,
- a third two-way change-over switch connecting one wire of the signal lamp to either the first or the second switch,
- a fourth two-way change-over switch connecting the other wire of the signal lamp to either the first or second switch,
- two local amperemeters for measuring the current in both wires of the signal lamp,
- a local voltmeter for measuring the voltage applied to the signal lamp, and
- a control unit for controlling the four switches and for detecting both earth faults within a driving circuit and interwire short circuits between two driving circuits, based on the measured currents and voltages.
- In a second aspect the above object is achieved, in accordance with the invention, by a method for detecting earth faults and interwire short circuits in the driving circuit system described above, wherein in a normal operation mode of the driving circuits, in which a signal lamp is turned on by connecting it to the positive and negative poles of the first power supply via the switches, an earth fault of a driving circuit is detected due to a leckage current measured by the central amperemeter, an interwire short circuit between wires of two driving circuits is detected due to a difference of the currents measured by the locals amperemeters of one of the two driving circuits, and an interwire short circuit between wires of one driving circuit is detected due to a comparison between the measured current and the expected current computed by both the measured voltage and the resistance of the wires and of the signal lamp.
- According to the invention, a driving circuit system is provided which supports automatic supervision and detection of earth faults and interwire short circuits within safety-critical systems using DC current for switching electrical devices.
- Further advantages can be extracted from the description and the enclosed drawing. The features mentioned above and below can be used in accordance with the invention either individually or collectively in any combination. The embodiments mentioned are not to be understood as an exhaustive enumeration but rather have exemplary character for the description of the invention.
- The invention is shown in the drawing, in which:
- Fig. 1
- shows schematically a driving circuit system for driving two DC signal lamps.
- As shown in
Fig. 1 , thedriving circuit system 1 for driving twoDC signal lamps - a first
DC power supply 3 having a first voltage U1 for driving bothsignal lamps - a second
DC power supply 4 having a second voltage U2 for driving only one of thesignal lamps second power supplies second power supply 4 is connected toearth 5 and the second voltage U2 is less than the first voltage U1, - a
central amperemeter 6 provided between the twopower supplies power supplies - a switch SE for connecting the negative pole of the
first power supply 3 to thenegative pole 4 of thesecond power supply 4, i.e. toearth 5. -
driving circuits signal lamp - a
master control 7 controlling thedriving circuits -
First power supply 3 is powerful enough to supply allsignal lamps Second power supply 4 may to be less powerful because it has to supply one signal lamp only. Power supply UE resulting from the different potentials can be very weak because it is used for earth fault detection only. Thecentral amperemeter 6 is placed between the twopower supplies central amperemeter 6 is done by closing the switch SE. In other words, thedriving circuit system 1 specifies three voltages: U1 and U2 for signal lamp supply and UE for earth fault detection. - Each
driving circuit - a first two-way change-over switch S1 connected to either the positive pole of the first or
second power supply - a second two-way change-over switch S2 connected to either the negative pole of the first or
second power supply - a third two-way change-over switch S3 connecting one
supply wire 11 of thesignal lamp - a fourth two-way change-over switch S4 connecting the
other supply wire 11 of thesignal lamp - a DC-DC converter or
voltage regulator 12 connecting the first and third switches S1,S3, for generating a variable output voltage for thesignal lamp local amperemeters 13 for measuring the current IH, IR in bothwires 11 of thesignal lamp - a
local voltmeter 14 for measuring the voltage U A applied to thesignal lamp - further local voltmeters 151-154 for measuring the voltages V 1-V 4 between the connections of each of the four switches S1-54,
- two
diodes 16 connected in parallel to thesignal lamp - a
control unit 17 for controlling the four switches S1-S4 and for detecting both earth faults EF within adriving circuit driving circuits - Each
signal lamp signal lamp wire 11 is represented by RL . The switches S1-S4 can be implemented by relays or any semiconductor switch. The correct working of the switches S1-S4 is checked by measuring the voltage V1-V4 between the connections of the switches S1-S4 and the occurrence of the expected current and is done by thecontrol unit 17. Alllocal amperemeters 13 and voltmeters 151-154 are provided with low-pass filters (not shown). In addition to thediodes 16, further protective components (not shown) can be provided to avoid distortion caused by inductive load switching. - Each
control unit 17 of thedriving circuit master control 7 and can be realized for example by a microcontroller. Eachcontrol unit 17 supervises the voltages UA ,V1-V4 and currents IE, IH, IR, actuates the switches S1-S4 and defines the output voltage of the DC-DC converter 12. Themaster control 7 commands acontrol unit 17 to switch on or off thesignal lamp control unit 17 and organizes the process of measurement of earth faults EF and interwire short circuits ISC. Errors which have been detected bycontrol units 17 are reported to themaster control 7 immediately. - In safety critical systems the master control, the control unit, voltmeters, amperemeters have to be duplicated to accomplish the requirements of such a system (two channels supervising each other). In this case, switching on
signal lamps - The
driving circuits - In the normal operation mode of the driving
circuits signal lamp first power supply 3 via the switches S1-S4. If asignal lamp position 1, SH is inposition 1 and SR inposition 2. If a signal lamp has to be turned off switches SEH and SER are inposition 1, switches SH and SR inposition 2. - If an earth fault EF occurs leckage current IE is caused and can be detected by every
control units 17. Ifsignal lamp wires 11 ofdifferent driving circuits wires 11. Therefore a special test is necessary, which is explained hereinbelow. - Interwire short circuits ISC between the two
wires 11 of onedriving circuits wire 11 may however alter depending on temperature influences RL can be measured in the test operation mode which is explained hereinafter. RL has to be known for the detection. - At any time exactly one of the driving
circuits master control 7 regulates the permission of adriving circuit driving circuit test master control 7 is informed accordingly. - If, for example, driving
circuit 10a is in the test operation mode the switches S1, S2 move intoposition 2 and the drivingcircuit 10a is connected tosecond power supply 4. If itssignal lamp 2a was turned on it still remains turned on except for the short moment of alternating the power supply. - Now the electrical potential of the driving
circuit 10a is below that of drivingcircuit 10b, i.e. of all other driving circuits. Any possible interwire short circuits ISC between thisunit 10a and the others will lead to a leckage current IE. The potential difference at least amounts to voltage UE. Additionally the leakage current IE can be detected by calculating the difference of IH and IR if itssignal lamp 2a is turned on. Ifsignal lamp 2a is turned off, leakage current IE leads to values of IH and IR unequal to zero. - Earth fault detection is not guaranteed at all in this operation mode. This operation mode takes a short time though. If
signal lamp 2a is turned off a further test step happens: The output of DC-DC converter 12 is reduced and S4 changes intoposition 1 so that thesignal lamp 2a is provided with reduced inverted voltage. Thediode 16 with a low voltage drop (for example: Shottky diode) is connected in parallel to thesignal lamp 2a. Taking into account the voltage drop, RL can be calculated by measurement of UA and IH. The knowledge of value of RL has been known for the detection of an interwire short circuit within onedriving circuit 10a (see normal operation mode). - At the end a further test step is carried out: Switch SE is closed and IE must arise, otherwise a fault of switch SE, of amperemeter IE or ground connection must be supposed.
- At the end of the test operation mode of a
driving circuit 10a all switches S1-S4 and the voltage of DC-DC converter 12 regain the original state as defined in the normal operation mode.
Claims (12)
- Driving circuit system (1) for driving at least two DC signal lamps (2a, 2b), comprising:a first DC power supply (3) having a first voltage (U1) for driving the signal lamps (2a, 2b),a second DC power supply (4) having a second voltage (U2) for driving only one of the signal lamps (2a, 2b), the negative poles of the first and secondpower supplies (3, 4) being on different potentials,a central amperemeter (6) provided between the two power supplies (3, 4), and driving circuits (10a, 10b) for each signal lamp (2a, 2b), each driving circuit (10a, 10b) comprising:- a first two-way change-over switch (S1) connected to the positive pole of either the first or second power supply (3, 4),- a second two-way change-over switch (S2) connected to the negative pole of either the first or second power supply (3, 4),- a third two-way change-over switch (S3) connecting one wire (11) of the signal lamp (2a, 2b) to either the first or the second switch (S1, S2),- a fourth two-way change-over switch (S4) connecting the other wire (11) of the signal lamp (2a, 2b) to either the first or second switch (S1, S2),- two local amperemeters (13) for measuring the current (IH, IR) in both wires (11) of the signal lamp (2a, 2b),- a local voltmeter (14) for measuring the voltage (UA) applied to the signal lamp (2a, 2b), and- a control unit (17) for controlling the four switches (S1-S4) and for detecting both earth faults (EF) within a driving circuit (10a, 10b) and interwire short circuits (ISC) between two driving circuits (10a, 10b), based on the measured currents and voltages.
- Driving circuit system according to claim 1, characterized by a DC-DC converter (12) connecting the first and third switches (S1, S3), for generating a variable output voltage for the signal lamp (2a, 2b).
- Driving circuit system according to claim 1 or 2, characterized by further local voltmeters (151-154) for measuring the voltages (V1-V4) between the connections of each of the four switches (S1-S4).
- Driving circuit system according to any one of the preceding claims, characterized in that each driving circuit (10a, 10b) comprises at least one diode (16) connected in parallel to the signal lamp (2a, 2b).
- Driving circuit system according to any one of the preceding claims, characterized in that the negative pole of the second power supply (4) is connected to earth (5).
- Driving circuit system according to any one of the preceding claims, characterized in that the second voltage (U2) is less than the first voltage (U1).
- Driving circuit system according to any one of the preceding claims, characterized by a master control (7) controlling the control units (17) of all driving circuits (10a, 10b).
- Driving circuit system according to any one of the preceding claims, characterized in that a switch (SE) is provided for connecting the negative pole of the first power supply (3) to the negative pole of the second power supply (4).
- Method for detecting earth faults (EF) and interwire short circuits (ISC) in a driving circuit system (1) according to any one of the preceding claims, wherein in a normal operation mode of the driving circuits (10a, 10b), in which a signal lamp (2a, 2b) is turned on by connecting it to the positive and negative poles of the first power supply (3) via the switches (S1-S4), an earth fault (EF) of a driving circuit (1 a, 1 b) is detected due to a leckage current (IE) measured by the central amperemeter (6), an interwire short circuit (ISC) between wires (11) of two driving circuits (10a, 10b) is detected due to a difference of the currents (IH, IR) measured by the locals amperemeters (13) of one of the two driving circuits (10a, 10b), and an interwire short circuit (ISC) between wires (11) of one driving circuit (10a, 10b) is detected due to a comparison between the measured current (IH, IR) and the expected current computed by both the measured voltage (UA) and the resistance (RL, RV) of the wires (11) and of the signal lamp (2a, 2b).
- Method according to claim 9, characterized in that in a test operation mode of one driving circuit (10a, 10b), in which only one signal lamp (2a, 2b) is connected to the second power supply (4) via the switches (S1-S4), an interwire short circuit (ISC) between the driving circuit (10a) and another driving circuit (10b) is detected due to a leckage current (IE) measured by the central amperemeter (6) and, if the signal lamp (2a, 2b) is turned on, due to a difference of the currents (IH, IR) measured by the locals amperemeters (13) of the driving circuit (10a, 10b), and, if the signal lamp (2a, 2b) is turned off, due to currents (IH, IR) measured by the locals amperemeters (13) being unequal to zero.
- Method according to claim 10, characterized in that in the test operation mode of one driving circuit (10a, 10b), a reduced inverted voltage is applied to the signal lamp (2a, 2b), when turned off, the resistance (RL) of the wires (11) of the signal lamp (2a, 2b) is calculated by measuring UA and IH and taking into account the voltage drop at a diode (16) connected in series to the signal lamp (2a, 2b).
- Method according to one of the claims 9 to 11, characterized in that, in particular at the end of the test operation mode of one driving circuit (10a, 10b), the negative pole of the first power supply (3) and the negative pole of the second power supply (4) are connected which causes the leckage current (IE) measured by the central amperemeter (6) to arise.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE602009000291T DE602009000291D1 (en) | 2009-02-18 | 2009-02-18 | System and method for automatic and safe detection of ground faults and intermediate cable short circuits for DC lamp circuits |
EP09002228A EP2222137B1 (en) | 2009-02-18 | 2009-02-18 | System and method for automatic and safe detection of earth faults and interwire short circuits for DC lamp circuits |
AT09002228T ATE485703T1 (en) | 2009-02-18 | 2009-02-18 | SYSTEM AND METHOD FOR AUTOMATIC AND SAFE DETECTION OF GROUND FAULTS AND INTERCABLE SHORT CIRCUITS FOR DC LAMP CIRCUITS |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP09002228A EP2222137B1 (en) | 2009-02-18 | 2009-02-18 | System and method for automatic and safe detection of earth faults and interwire short circuits for DC lamp circuits |
Publications (2)
Publication Number | Publication Date |
---|---|
EP2222137A1 true EP2222137A1 (en) | 2010-08-25 |
EP2222137B1 EP2222137B1 (en) | 2010-10-20 |
Family
ID=40910848
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP09002228A Not-in-force EP2222137B1 (en) | 2009-02-18 | 2009-02-18 | System and method for automatic and safe detection of earth faults and interwire short circuits for DC lamp circuits |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP2222137B1 (en) |
AT (1) | ATE485703T1 (en) |
DE (1) | DE602009000291D1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015165769A1 (en) * | 2014-05-01 | 2015-11-05 | Koninklijke Philips N.V. | A safety protection arrangement for a lighting arrangement. |
EP3465868A4 (en) * | 2016-06-02 | 2019-12-04 | Eaton Intelligent Power Limited | Redundant power supply and control for light fixtures |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20070159750A1 (en) * | 2006-01-09 | 2007-07-12 | Powerdsine, Ltd. | Fault Detection Mechanism for LED Backlighting |
US20080231198A1 (en) * | 2007-03-23 | 2008-09-25 | Zarr Richard F | Circuit for driving and monitoring an LED |
US20080238344A1 (en) | 2007-03-29 | 2008-10-02 | Koito Manufacturing Co., Ltd. | Light Emitting Apparatus |
-
2009
- 2009-02-18 EP EP09002228A patent/EP2222137B1/en not_active Not-in-force
- 2009-02-18 AT AT09002228T patent/ATE485703T1/en active
- 2009-02-18 DE DE602009000291T patent/DE602009000291D1/en active Active
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20070159750A1 (en) * | 2006-01-09 | 2007-07-12 | Powerdsine, Ltd. | Fault Detection Mechanism for LED Backlighting |
US20080231198A1 (en) * | 2007-03-23 | 2008-09-25 | Zarr Richard F | Circuit for driving and monitoring an LED |
US20080238344A1 (en) | 2007-03-29 | 2008-10-02 | Koito Manufacturing Co., Ltd. | Light Emitting Apparatus |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015165769A1 (en) * | 2014-05-01 | 2015-11-05 | Koninklijke Philips N.V. | A safety protection arrangement for a lighting arrangement. |
CN106256171A (en) * | 2014-05-01 | 2016-12-21 | 皇家飞利浦有限公司 | Safeguard protection arrangement for illuminating arrangement |
US9756700B2 (en) | 2014-05-01 | 2017-09-05 | Koninklijke Philips N.V. | Safety protection arrangement for a lighting arrangement |
CN106256171B (en) * | 2014-05-01 | 2018-10-12 | 皇家飞利浦有限公司 | Safeguard protection arrangement for illuminating arrangement |
EP3465868A4 (en) * | 2016-06-02 | 2019-12-04 | Eaton Intelligent Power Limited | Redundant power supply and control for light fixtures |
Also Published As
Publication number | Publication date |
---|---|
DE602009000291D1 (en) | 2010-12-02 |
ATE485703T1 (en) | 2010-11-15 |
EP2222137B1 (en) | 2010-10-20 |
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