GB2475773A - LED lighting apparatus uses no-load voltage from unlit LED to measure LED light intensity - Google Patents

LED lighting apparatus uses no-load voltage from unlit LED to measure LED light intensity Download PDF

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Publication number
GB2475773A
GB2475773A GB1019518A GB201019518A GB2475773A GB 2475773 A GB2475773 A GB 2475773A GB 1019518 A GB1019518 A GB 1019518A GB 201019518 A GB201019518 A GB 201019518A GB 2475773 A GB2475773 A GB 2475773A
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GB
United Kingdom
Prior art keywords
light
emitting diode
emitting
lighting apparatus
emitting diodes
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
Application number
GB1019518A
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GB201019518D0 (en
GB2475773B (en
Inventor
Peter Brandt
Georg Bauer
Heiko Charle
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GM Global Technology Operations LLC
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GM Global Technology Operations LLC
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Filing date
Publication date
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Publication of GB201019518D0 publication Critical patent/GB201019518D0/en
Publication of GB2475773A publication Critical patent/GB2475773A/en
Application granted granted Critical
Publication of GB2475773B publication Critical patent/GB2475773B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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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]
    • H05B45/10—Controlling the intensity of the light
    • 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
    • G09G3/34—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 by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
    • B60Q3/00—Arrangement of lighting devices for vehicle interiors; Lighting devices specially adapted for vehicle interiors
    • B60Q3/10—Arrangement of lighting devices for vehicle interiors; Lighting devices specially adapted for vehicle interiors for dashboards
    • B60Q3/16—Circuits; Control arrangements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
    • B60Q3/00—Arrangement of lighting devices for vehicle interiors; Lighting devices specially adapted for vehicle interiors
    • B60Q3/10—Arrangement of lighting devices for vehicle interiors; Lighting devices specially adapted for vehicle interiors for dashboards
    • B60Q3/16—Circuits; Control arrangements
    • B60Q3/18—Circuits; Control arrangements for varying the light intensity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
    • B60Q3/00—Arrangement of lighting devices for vehicle interiors; Lighting devices specially adapted for vehicle interiors
    • B60Q3/80—Circuits; Control arrangements
    • H05B33/0845—
    • 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]
    • H05B45/20—Controlling the colour of the light
    • 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]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
    • H05B45/46—Details of LED load circuits with an active control inside an LED matrix having LEDs disposed in parallel lines
    • 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
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0666—Adjustment of display parameters for control of colour parameters, e.g. colour temperature
    • 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
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0693—Calibration of display systems
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2360/00—Aspects of the architecture of display systems
    • G09G2360/14—Detecting light within display terminals, e.g. using a single or a plurality of photosensors
    • G09G2360/145—Detecting light within display terminals, e.g. using a single or a plurality of photosensors the light originating from the display screen

Abstract

The lighting apparatus comprises first, second and third light-emitting diodes (D1, D2, D3, fig 1). These light-emitting diodes emit different coloured light R, G, B. A triggering unit (15, 16, 17, fig 1) is provided such that the three light-emitting diodes each emit light simultaneously in normal operation. A checking unit S1, 22, 23, 21, 24 is provided for operating the light-emitting diodes in a checking mode. In this mode, a current is impressed into one of the light-emitting diodes D3 so that it emits light. Meanwhile the checking unit also uses S1 to connect at least one of the other three light-emitting diodes is in such a way that the voltage generated in the unlit LED by the illumination of the other light-emitting diode is measured. The lighting apparatus may be used for illuminating the interior of a vehicle.

Description

A lighting apparatus for illuminating the interior of a vehicle
Description
The invention relates to a lighting apparatus for illuminat-ing the interior of a vehicle. It is known from the state of the art to use so-called RGB light-emitting diodes (red- green-blue LED5). They contain a red, green and a blue light- emitting diode. The current through these light-emitting dio-des is controlled individually in such a way that the desired light tone is obtained by superposition of the respectively emitted light spectra.
It is described in US Pat. No. 7,507,943 Bl that the respec- tively emitted luminosity of the red, green and blue light-emitting diodes is measured individually. The specification DE 2006 19 504 describes that a photodiode for measuring the light emitted by the light-emitting diodes is provided in an illumination apparatus in addition to the light-emitting dio-des. Checking the luminosity of the light-emitting diodes is necessary because the luminosity decreases with ageing of the light-emitting diodes. Depending on the type of the light- emitting diode, i.e. depending on the color of the light-emitting diode, the age-related decrease of the luminosity is different. As a result, the luminosity of the light-emitting diode is checked with the help of the photodiode for example in order to optionally increase the current through the light-emitting diode with the goal that the illumination ap-paratus will emit the same light over the entire life.
The disadvantageous aspect in the concept as shown in DE 2006 19 504 is the additional need for space for the photodiode and the work required to adjust the measuring circuit with the photodiode to the light-emitting diodes.
It is the object of the present invention to provide a light-ing apparatus, wherein the mentioned disadvantages are to be avoided.
This object is achieved by the subject matter of the indepen- dent claim 1. Advantageous further developments of the inven-tion are shown in the dependent claims.
In accordance with the invention, a lighting apparatus is provided which comprises a first light-emitting diode, a second light-emitting diode and a third light-emitting diode.
These light-emitting diodes differ from one another by the color spectrum of the emitted light.
A triggering unit is provided for the simultaneous triggering of the three light-emitting diodes, so that the three light-emitting diodes will emit light simultaneously in a normal mode.
A checking unit is provided for operating the light-emitting diodes in a checking mode. A current is impressed in this mode into one of the light-emitting diodes in such a way that it makes said light-emitting diode light up. The checking unit is further set up in such a way that in the meantime at least one of the other three light-emitting diodes is switch- ed in such a way that the voltage is measured which is gener-ated by the illumination of the at least one of the other light-emitting diodes.
The lighting apparatus in accordance with the invention uti- lizes one of the light-emitting diodes which is usually pro- vided for illuminating the interior for measuring the lumi- nosity of the respective other light-emitting diode. The ne-cessity to use an additional photodiode can be avoided, thus reducing the number of components and the necessary work for triggering the lighting apparatus in the checking mode. The lighting apparatus can be provided in a more compact manner in a vehicle and the susceptibility to faults will decrease as a result of the lower number of components.
The effect is exploited for this cost-effective implementa-tion of a brightness measurement that a light-emitting diode supplies a no-load voltage when it is illuminated from the outside with a light source. The voltage source can often be loaded at a low level.
The emitted current in the no-load voltage is often less than one microampere in current light-emitting diodes. A Darling- ton amplifier circuit can be used however to sufficiently am-plify the no-load voltage in order to have it measured by a voltage measuring unit.
Preferably, an adjusting circuit is provided for adjusting the trigger currents in normal mode by the light-emitting diodes. This adjustment occurs depending on the voltages as measured in the checking mode. It is not only checked whether the luminosities meet the requirements, but there is an appa- ratus which simultaneously performs the respective adjust-
S
ments for triggering the light-emitting diodes in normal mode.
Preferably, the first light-emitting diode emits a red light, the second light-emitting diode a green light, and the third light-emitting diode a blue light.
An activation circuit is provided in one embodiment for the activation of the checking unit after a predetermined number of ignition cycles. It is thus ensured that the light spec-trum emitted by the lighting system of the vehicle is checked regularly.
In an alternative embodiment, an activation unit is provided for the manual activation of the checking unit,. It is thus ensured that a passenger is not disturbed by the checking of the lighting apparatus. Instead, the check is performed in a garage during an inspection.
The lighting apparatus in accordance with the invention is especially suitable for a vehicle lighting apparatus for il-luminating an interior of a vehicle, which allows that the vehicle lighting can remain stable over the entire life of the vehicle.
In another application, the first light-emitting diode, the second light-emitting diode and the third light-emitting di-ode are arranged as organic light-emitting diodes in a screen. Even in screens there are serious difficulties of keeping the white point in a stable manner, i.e. the appear- ance of the white light. The present invention offers a cost-effective solution to this problem.
The invention also relates to a method for the operation of a lighting in accordance with the invention. The first light-emitting diode is switched on at first and the voltage in the second light-emitting diode and/or the third light-emitting diode is measured. The second light-emitting diode is switch-ed in a further step and the voltage is measured in the first light-emitting diode and/or the third light-emitting diode.
The third light-emitting diode is switched on in a further step and the voltage is measured in the first light-emitting diode and/or the second light-emitting diode.
Preferably, the currents in normal mode through the first light-emitting diode, the second light-emitting diode arid the third light-emitting diode is adjusted depending on the meas-ured voltages.
The invention is now shown in embodiments by reference to the enclosed drawings, wherein: Fig. 1 shows a lighting apparatus for an interior space; Fig. 2 shows details of the control for one of the light-emitting diodes of the lighting apparatus of Fig. 1; Fig. 3 shows a flow chart for the method in accordance with the invention for adjusting a lighting appara-tus.
Fig. 1 shows an embodiment of a lighting apparatus 1. It com-prises a battery 10, with three series connections being switched in parallel on its poles. The first series connec- tion contains a first current source 11 and a first light- emitting diode Dl switched in series thereto, the second se-ries connection contains a second current source 12 and a second light-emitting diode D2 connected in series, and the third series connection contains a third current source 13 and a third light-emitting diode D3 connected in series.
It applies to all three series connections that a first con-nection of the current source 11, 12 and 13 is connected with the plus pole of the battery 10, whereas the second connec- tion of the respective current source 11, 12 and 13 is re-spectively connected to the anode of the light-emitting diode Dl, D2 and D3. The cathodes of the light-emitting diodes Dl, D2 and D3 and the minus pole of the battery 10 are each con-nected with ground 33.
The light-emitting diodes Dl, D2 and D3 differ with respect to the respectively emitted light spectrum. The light-emitting diode Dl emits red light, whereas the light-emitting diode D2 emits green light and the light-emitting diode D3 blue light.
The current sources 11, 12 and 13 are each controlled by a control circuit. The current source 11 concerns the control circuit 15, the current source 12 the control circuit 16 and the current source 13 the control circuit 17. The control circuits 15, 16 and 17 each emit a pulse-width-modulated sig-nal. The pulse widths of the respective pulse-width-modulated signals determine how bright the light-emitting diodes Dl, D2 and D3 will burn. A desired color is set as a result of suit- able settings of the current sources 11, 12 and 13. In a pre-ferred embodiment, a driver of a vehicle has the possibility of choosing the color mixture desired by the same, which is obtained by the relative luminosities of the light-emitting diodes Dl, D2 and D3.
Various types of light-emitting diodes, which are red, green and blue in this case, will age differently. Over time there will be a different color as compared with the time when the vehicle was first put into operation. The triggering of the currents is adjusted accordingly in order to maintain the de-sired color setting even in the case of progressive ageing of the vehicle. No additional photocell is required for this purpose, but the existing light-emitting diodes are also used for measuring the luminosities of the respectively other light-emitting diodes.
Fig. 2 shows a checking unit 18 for the triggering circuit 16 by way of example. Respective checking units are provided for the triggering circuits 16 and 17.
The checking unit 18 comprises a switch 25, a first resistor 20, a second resistor 21, a first transistor 22, a second transistor 23 and an evaluation circuit 24. A first connec-tion of the switch 25 is connected with the anode of the first light-emitting diode Dl, whereas the second connection of the switch 25 is connected with the first connection of the resistor 20. The second connection of resistor 20 is con-nected on its part with the base of the transistor 22, the emitter of which is connected with the emitter of the tran- sistor 23 and a first connection of the resistor 21. The col-lector of the first transistor 22 is connected with the base of the second transistor 23. The collector of the second transistor 23 is connected with ground 33 together with the cathode of the first light-emitting diode Dl and the minus pole of the battery 10. )
The second connection of the resistor 21 is connected with the plus pole of the battery 10. The two connections of the second resistor 21 are connected with inputs of the evalua-tion circuit 24, which on its part triggers the current source 11. The current source 11 comprises a connection (not shown in Fig. 2) from the second connection of the current source 11 to the anode of the first light-emitting diode Dl.
The luminosity of the second light-emitting diode D2 is checked for example in the checking mode. For this purpose, the current source 12 is switched in such a way that the cur-rent which is also set in normal operation for illuminating the interior space flows through the second light-emitting diode D2. The luminosity of the second light-emitting diode D2 is measured with the help of the first light-emitting di-ode Dl. The current source 11 is switched for this purpose to high impedance at its output, so that current source 11 will not impress any current by the current source 11.
A no-load voltage is obtained between the anode and cathode of the light-emitting diode Dl as a result of the light gen-erated by the second light-emitting diode D2. This no-load voltage can be detected with the help of the illustrated Dar-lington amplifier circuit. For this purpose, switch 25 is closed in checking mode, so that the anode potential of the light-emitting diode Dl will also be applied to the base of the first transistor 22. The current through the collector-emitter path of the transistor 22 will increase accordingly, so that the potential on the base of the transistor 23 will also rise. The transistors 22 and 23 are each NPN bipolar transistors of type BC548.
The current through the collector-emitter path of this tran-sistor 23 also increases by the increase of the potential on the base of transistor 23. The current through the resistor 21 thus increases. The voltage dropping via the second resis-tor 21 is measured with the help of the evaluation circuit 24. If this voltage is high, the voltage via light-emitting diode Dl is also high, which is a sign for a high luminosity of the light-emitting diode D2. The photovoltage dropping via the light-emitting diode Dl is thus measured and the bright-ness measured therefrom is compared with a reference value.
This reference value is stored in the memory of the checking circuit 24. If the voltage via resistor 21 falls beneath the reference value, it is concluded that the brightness of the second light-emitting diode D2 is too low. The triggering circuit 24 supplies this information to the control circuit, which then accordingly, increases the trigger current which is provided by the second current source 12.
After this step, the third light-emitting diode D3 is active-iy triggered and is measured with the help of the described measuring circuit.
It is also possible that one of the light-emitting diodes is triggered in such a way that it burns and the other light-emitting diodes will each measure. It is understood that the illustrated apparatus can also be used for considerably larg-er light-emitting diode arrangements, e.g. so-called LED
fields.
It can be summarized that the measurement of the different LED brightness in red/green/blue light-emitting diodes is carried out in such a way that one of the three light-emitting diodes is electrically triggered and illuminates the respectively two non-triggered light-emitting diodes. The re-suiting photovoltages are measured and the resulting brightnesses are compared with a reference value.
The drop in brightness in the course of the life of the light-emitting diodes can be determined by sequential switch-ing of the RGB light-emitting diodes and can be compensated by a purposeful increase in the current.
The illustrated method is performed in one embodiment during an inspection of the vehicle by diagnosis. The calibration of the chromaticity is not noticed by the driver.
Alternatively, the software is stored in the on-board control device and the color calibration is performed after a specif-ic number of ignition cycles.
Fig. 3 shows the method in accordance with the invention for setting the brightness of the light-emitting diode in a flow chart. The first light-emitting diode is switched on in a first step 301 and the currents through the second light-emitting diode D2 and the third light-emitting diode D3 are measured. In a subsequent step 302, the light-emitting diode D2 is switched on while the currents through the first and third light-emitting diode Dl and D3 are measured. In a third step, the third light-emitting diode D3 is switched on and the currents through the first light-emitting diode Dl and the second light-emitting diode D2 are measured. Finally, the current sources 11, 12 and 13 are set in step 304 according to the measured brightnesses in the three steps 301, 302 and 303.
In a modification of the method, the voltage on only one of the two light-emitting diodes is measured in each of the steps 301, 302 and 303.
List of reference numerals 1 Lighting apparatus Battery 11 Current source 12 Current source 13 Current source Triggering circuit 16 Triggering circuit 17 Triggering circuit 18 Checking unit First resistor 21 Second resistor 22 First transistor 23 Second transistor 24 Evaluation circuit or checking circuit Switch 33 Ground 301 Step 302 Step 303 Step Dl First light-emitting diode D2 Second light-emitting diode 03 Third light-emitting diode

Claims (10)

  1. FCLAIMS: 1. A lighting apparatus, comprising the following: -a first light-emitting diode (Dl), a second light-emitting diode (D2), a third light-emitting diode (D3) which each differ from one another by the color spectrum of the emitted light; -a triggering unit (15, 16, 17) for the simultaneous triggering of three light-emitting diodes, with the three light-emitting diodes each emitting light simulta-neously in a normal mode; -a checking unit (18) for operating the light-emitting diodes in a checking mode, in which a current is im-pressed into one of the light-emitting diodes (D2) in such a way that it will make one of the light-emitting diodes (D2) burn, whereas at least one (Dl) of the other three light-emitting diodes is switched in such a way that the voltage which is generated by the burning of at least one of the other light-emitting diodes (Dl) is measured.
  2. 2. A lighting apparatus according to claim 1, characterized in that the current through the at least one of the oth-er light-emitting diodes is measured with the help of a Darlington amplifier circuit (22, 23)
  3. 3. A lighting apparatus according to claim 1 or 2, charac-terized in that an adjusting circuit (24) is provided for adjusting the triggering currents in normal mode by the three light-emitting diodes depending on the voltag-es measured in the checking mode.
  4. 4. A lighting apparatus according to claim 1, characterized in that the first light-emitting diode emits red light, the second light-emitting diode green light and the third light-emitting diode blue light.
  5. 5. A lighting apparatus according to one of the claims 1 to 4, characterized in that an activation circuit (41) is provided for activating the checking unit (18) after a predetermined number of ignition cycles of the vehicle.
  6. 6. A lighting apparatus according to one of the claims 1 to 4, characterized in that an activation circuit (41) is provided for activating the checking unit (18), with the activation circuit being manually switchable by a user.
  7. 7. A lighting apparatus for a vehicle, comprising a light-ing apparatus according to one of the claims 1 to 6 for illuminating the interior of a vehicle.
  8. 8. A screen comprising a lighting apparatus according to one of the claims 1 to 7, wherein the first light-emitting diode, the second light-emitting diode and the third light-emitting diode are arranged as organic light-emitting diodes.
  9. 9. A method for operating a lighting apparatus according to one of the claims 1 to 7, comprising the following steps: -switching on the first light-emitting diode (Dl) and measuring the voltage on the second light-emitting diode (D2) and/or the voltage on the third light-emitting di-ode (D3); -switching on the second light-emitting diode (D2) andSmeasuring the voltage on the first light-emitting diode (Dl) and/or the voltage on the third light-emitting di-ode (D3); -switching on the third light-emitting diode (D3) and measuring the voltage on the first light-emitting diode (Dl) and/or the voltage on the second light-emitting di-ode (D2);
  10. 10. A method according to claim 9, characterized by the fur-ther step: -setting of the currents in normal mode through the first light-emitting diode (Dl), the second light- emitting diode (D2) and the third light-emitting di-ode(D3) depending on the measured voltages.
GB1019518.8A 2009-11-19 2010-11-18 A lighting apparatus for illuminating the interior of a vehicle Expired - Fee Related GB2475773B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102009053911A DE102009053911A1 (en) 2009-11-19 2009-11-19 Lighting device for illuminating a vehicle interior

Publications (3)

Publication Number Publication Date
GB201019518D0 GB201019518D0 (en) 2010-12-29
GB2475773A true GB2475773A (en) 2011-06-01
GB2475773B GB2475773B (en) 2014-07-16

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GB1019518.8A Expired - Fee Related GB2475773B (en) 2009-11-19 2010-11-18 A lighting apparatus for illuminating the interior of a vehicle

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GB (1) GB2475773B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11357088B2 (en) 2016-12-08 2022-06-07 Inova Semiconductors Gmbh Measurement arrangement for detecting aging processes in individual light-emitting diodes

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102012211828B4 (en) 2012-07-06 2023-03-02 Lisa Dräxlmaier GmbH LED lighting for vehicles

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Publication number Priority date Publication date Assignee Title
WO2007057822A1 (en) * 2005-11-21 2007-05-24 Koninklijke Philips Electronics N.V. Lighting device

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Publication number Priority date Publication date Assignee Title
DE4216529A1 (en) * 1992-05-19 1993-11-25 Vdo Schindling Indicator arrangement for motor vehicle - has transparent instrument carrier covering PCB, illumination and reference LED diodes with stabilised voltage supply and trimming resistors
JP2005208486A (en) * 2004-01-26 2005-08-04 Hitachi Ltd Liquid crystal display
DE102005013344A1 (en) * 2005-03-21 2006-09-28 Hella Kgaa Hueck & Co. Lighting apparatus for motor vehicles, has three lighting transmitters each operable by touch-sensitive control panel
JP4607846B2 (en) * 2006-10-19 2011-01-05 ソニー株式会社 Light source device, light source driving device, light emission amount control device, and liquid crystal display device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007057822A1 (en) * 2005-11-21 2007-05-24 Koninklijke Philips Electronics N.V. Lighting device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11357088B2 (en) 2016-12-08 2022-06-07 Inova Semiconductors Gmbh Measurement arrangement for detecting aging processes in individual light-emitting diodes

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GB201019518D0 (en) 2010-12-29
DE102009053911A1 (en) 2011-05-26
GB2475773B (en) 2014-07-16

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20161118