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]
  • H05B45/20—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]
  • H05B45/30—Driver circuits
  • H05B45/395—Linear regulators
  • H05B45/397—Current mirror circuits
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
  • F21S4/00—Lighting devices or systems using a string or strip of light sources
• • 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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
  • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Definitions

• the invention relates to a color-tunable module and in particular to a LED module which allows color and/or color temperature tuning.
• the LED module comprises a number of lighting means, and in particular at least two LED strings, each comprising at least one LED of different color or color temperature and in particular emitting light of different spectra, preferably white spectra with different color temperatures, and allows to adjust the color and/or color temperature of the light emitted from the module to a mixed color or color temperature .
• the module can allow a dimming, i.e. reducing the brightness of the emitted light, which is typically referred to in percentages where, for example, a 50% dimming means a reduction of the brightness of the emitted to 50%, and where a 95% dimming refers to the brightness being reduced to 5% of the maximum brightness.
• a dimming i.e. reducing the brightness of the emitted light
• a 95% dimming refers to the brightness being reduced to 5% of the maximum brightness.
• a color-tunable LED module comprising a LED arrangement comprising at least two LED strings, each comprising at least one preferably white LED, the LED strings being connected in an anti-parallel manner and the LED strings emitting different spectra, preferably white spectra with different color temperature, and a LED driver driving the LED arrangement and which is configured to output a DC voltage switched between two polarities, wherein the duty cycle of the polarities, i.e. the ratio of the time period of a first polarity compared to the time period of a second opposite polarity, is adjustable .
• the module can comprise a control unit adapted to monitor a voltage and/or current and to detect and to evaluate a modulation of the voltage and/or current supplied to the module or (rectified by) an AC/DC converter.
• the control unit may determine at least one of a color tuning signal, a color temperature tuning signal and/or a dimming signal from the detected modulation.
• the control unit can output at least one control signal to the LED driver. It may vary the duty cycle of the at least one polarity based on the determined tuning/dimming signal.
• the LED driver can change the polarities and their duty cycle based on the at least one control signal.
• the module is configured to only receive tuning and/or dimming signals via supply lines.
• the supply lines are used to electrically supply the module and connect the module directly or indirectly to an energy source, e.g. mains .
• a LED string may comprise a linear regulator and/or at least one protection diode, preferably a Schottky diode.
• the LED strings can be connected to the driving circuit by only two wires .
• the LED driver may set the duty cycle of the polarities based on the tuning signal.
• the LED driver can comprise an inverter.
• the LED driver may drive a first LED string based on the at least one control signal and a second LED string based on the inverted at least one control signal.
• the LED driver can supply at least the first LED string when the LED driver switches to one polarity.
• the LED driver can supply at least the second LED string when the LED driver switches to the opposite polarity.
• the LED driver may perform dimming of the LED strings by reducing the t on -time of the duty cycle of the polarities applied to the LED arrangement .
• the t on time set for tuning can be reduced according to a dimming signal.
• the control unit can be part of the AC/DC converter.
• the module can be a flexible tape, a stripe, a chain or a spot shaped means .
• Fig. 1 shows a schematic arrangement
• Fig. 2 shows two examples of a LED driver
• FIG. 3 shows another example of a LED driver with LED strings.
• Fig. 4 shows yet another example of a LED
• Fig. 5 exemplarily shows color tuning
• Fig. 6 exemplarily shows color tuning
• the color-tuning or dimming according to the invention is achieved by signals modulated on the electrical supply of the LED module without the reguirement of an additional connection for supplying tuning and/or dimming signals.
• a LED module 1 according to the invention is shown which is supplied by an AC voltage ACi n , which is converted to a DC voltage by an AC/DC converter.
• the module 1 also shows a LED arrangement 2 with a number of interdigitating LEDs, which represent at least two LED strings connected in and anti-parallel fashion.
• every second LED belongs to one LED string and based on the polarity of the voltage supplied to the LED arrangement 2, only half of the LEDs will be activated.
• Each LED string can show a current regulator and/or a protection diode to control a current through associated LED string, especially to a nominal value.
• Fig. 1 also shows a bridge or LED driver, which is used to switch polarity of the DC voltage V dc supplied by the AC/DC converter.
• V dc DC voltage supplied by the AC/DC converter.
• the color temperature tuning only one of the LED string is driven (duty cycle is 100% as to one polarity) to tune the LED arrangement 2 to the color/color temperature of this one LED string.
• the LED strings supplied from the LED-driver (or bridge) can contain the same number of LEDs.
• the polarity switching can be also understood as a PWM modulation of a signal, when the PWM signal is high, one LED is supplied and when the PWM signal is low, a second LED string is supplied.
• the LED driver can supply at least two groups of LED strings, wherein one LED string group is active at one polarity, while the other group of LED strings is active when the opposite polarity is active.
• the invention is especially beneficial as it allows using a standard LED driver with a component controls the LED driver (or bridge) .
• This can be a control unit as shown in Fig. 1.
• the control unit may also be part of the AC/DC converter. This is indicated by the dotted box 10 in Fig.
• the AC/DC converter may modulate the output DC voltage V dc and hence may supply at least one control signal, e.g. a PWM modulated signal, to the LED driver/bridge.
• the control signal may then be used to control the polarity switching performed by the LED driver.
• control unit may detect modulation of the electrical supply and controls the bridge/LED driver.
• control unit can output control signals to the LED driver (or bridge), which may be in form of PWM modulated signals .
• the lighting means/LED strings of the LED arrangement can have color coordinates A and B (indicated as grey and black LEDs in Fig. 1) . These LED strings are connected in an anti-parallel fashion.
• the LED driver (or bridge) changes or inverts the polarity of the supply voltage supplied to the LED strings periodically according to a preset control signal supplied to the LED driver and hence controls the duty cycle of the LED string A and the LED string B to adjust to a desired color temperature or color .
• a dimming signal can be also applied by simply reducing the ton-time of the voltage or current supplied to a/each LED string, i.e. the voltage/current supplied to the LED strings is not divided in a way that the sum of the overall t on -time of the LED strings is always 100%.
• a LED string may also be switched-off for some time in order to reduce the brightness of the emitted light. That means, that the t on -time for each LED string is reduced, when dimming should be performed.
• the LED driver can be voltage or current controlled and can accept PWM and different voltage/current level signals. If the LED driver (bridge) is controlled by PWM signals, the LED driver may synchronize the polarization to the PWM signal. In particular the polarity can have a substantially higher freguency than the input PWM freguency so that dimming of the LED strings does not affect the color setting.
• Figs. 2a and 2b show two exemplary setups of LED drivers LD, LD' according to the invention.
• Fig. 2a shows a LED driver LD with a FET or MOSFET transistor bridge circuit to periodically switch the supply voltage V in to the LED strings with different polarity depending on the control signals PWMl and PWM2.
• control signal PWMl is high
• diagonal switches Ml and M3 could be activated and polarity could be switched to apply V in to the LED string with diodes Dl to D7.
• control signal PWM2 is high, diagonal switches M2 and M3 could be activated and polarity could be switched to apply V in to the LED string with diodes D10 to D16.
• only one diagonal should be active at the same time .
• Fig. 2B shows a similar LED driver LD' arrangement, in which the FET transistors Ml to M4 are replaced by bipolar transistors Ql to Q4, again controlled by signals PWMl and PWM2.
• each LED string may contain an optional protection diode D19/D20 and/or a linear regulator Q2, R3, D17, D18/Q1, Rl, D8, D9 to adapt the current through the LED strings 5, 6.
• Fig. 4 shows an LED driver LD'' which is controlled by only a single control signal PWM.
• the LED driver LD'' contains an inverter Al, which inverts the control signal PWM.
• the bridge diagonal M2, M3 is deactivated. Therefore, there is no necessity for applying two control signals. That means that one diagonal of the full bridge is activated when the control signal reaches one value, for example high, while the other diagonal of the bridge is active when the same control signal reaches its other level, for example low.
• one LED string is active when the other LED string is not active.
• the LED module 1 preferably is a flexible tape and is supplied with a 24 Volt DC voltage which can be produced by the AC/DC converter shown in Fig. 1.
• the current regulators can be placed anywhere in each of the LED strings 5, 6 and can be a VCR (Voltage Controlled Resistor) with an optional current setting resistor.
• the current applied to the LED strings 5, 6 preferably is set so that the light output in lumen (lm) is the same for the/all temperatures of the LED strings.
• the protection diode for an LED string 5.6 can preferably be a Schottky diode . As the inventive arrangement allows for a very compact setup of the reguired circuitry, the invention can especially be applied if color tuning is needed and space is limited in an application.
• the module hence can be realized in form of stripes, chains or spots.
• the number of LEDs can be higher and especially at least twice the number of LED components that would be reguired in a module without color tuning.
• the invention does not need more LEDs.
• Fig. 5 shows an example of how the polarity change can be used to adjust color or color temperature.
• one LED string can have a color temperature of 2700 Kelvin and one LED string a color temperature of 6000 Kelvin.
• the dashed light on top shows an activation of the 2700 Kelvin LED string, which means that the LED string is active 100% of the time and hence polarity only is switched to power one LED string (which means that only one diagonal of the LED driver is active) .
• the 6000 Kelvin LED string is off.
• the LED arrangement 2 should be tuned to 6000 Kelvin, only the 6000 Kelvin LED string should be illuminated and the polarity has to be controlled to only power this string, which means that the 2700Kelvin string is not powered. This is shown by the solid line labeled with 6000K. If an intermediate temperature should be set, the DC voltage is switched between two polarities and the duty cycle of the polarities, i.e. the ratio of the time period of the first polarity compared to the time period of the second opposite polarity, is adjusted. In other words, both LED strings are powered for some time, the t on -time.
• the LED strings can be activated in an alternating manner, which means that the t on time is, in the example shown, set to be about 50% for each LED string. That means that the duty cycle for each polarity is about 50%. That means that the t on -time for one LED string is about 50%.
• the t on time for the 2700 Kelvin LED string (dashed signal high (h) ) is almost the same as the t on time of the 6000 Kelvin LED string (solid signal high (h) ) with corresponding t 0f f time (signals low (1) ) .
• the duty cycle changes, and, for example, the t on time of the 6000 Kelvin LED string is longer than the 2700° Kelvin LED string.
• one LED string can be activated according to the first control signal PWMl and the second LED string can be activated according to the second control signal PWM2. If, in addition, dimming should be performed, the t on -time for each LED string activation can be reduced as shown in Fig. 6.
• the 2700 Kelvin LED string is only powered with a t on time of e.g. 50%, if a dimming level of 50% should be set and the color temperature of 2700 Kelvin should be emitted (the 6000 Kelvin LED string is off) .
• the same is the case, if the light temperature of 6000 Kelvin should be set at a dimming level of 50%:
• the t on time of the 6000 Kelvin LED string is only about half of the t on time set for emission at full brightness (see Fig. 5) (in this case the 2700 Kelvin string is off) .
• the t on time of the 6000 Kelvin LED string is denoted by t on 6oooK in Fig. 5 and 6, while the t on time of the 2700 Kelvin LED string is denoted by t on 2700K-
• the t on - time i.e. the time an LED string is switched on is reduced according to the dimming level.
• the switch- on time ton for the LED strings for tuning purposes is determined and set according to the desired color/color temperature, in case of dimming the switch-on time t on is reduced in corresponding to the amount of dimming desired. Therefore, the ratio of the time period of a first polarity compared to the time period of a second opposite polarity is not only adjusted due to tuning, but also due to dimming commands.
• the switch-on time t on determined for color tuning is reduced. This can lead to phases where al strings are off.
• the polarity switching at the LED strings is typically performed at freguencies above 100 Hz.

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

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• 2015
  • 2015-02-16 DE DE202015100733.7U patent/DE202015100733U1/de not_active Expired - Lifetime
• 2016
  • 2016-01-08 WO PCT/EP2016/050264 patent/WO2016131558A1/en active Application Filing
  • 2016-01-08 AT ATGM9003/2016U patent/AT17197U1/de not_active IP Right Cessation

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