Method for controlling a light emitting diode lighting device and a light emitting diode (LED) based lighting device

Abstract

A method for controlling a multicolor LED lighting device is disclosed. The LED lighting device has at least two series-connected LED light sources supplied with current and with different colormetric values, each controlled by a respective switch operating according to a duty cycle. The method adapts an operating current amplitude supplied to the multicolor LED lighting device based on a color point requested by a user. The method includes receiving a specified colormetric value for the LED lighting device, determining an operating current amplitude for the LED lighting device based on a current profile over a range of colormetric values ​​and the specified colormetric value, and setting the current supplied to the LED light source to the determined operating current amplitude.

Description

[Technical Field]

[0001] The present disclosure relates generally to the field of lighting device control, and more particularly to methods for controlling multicolor light emitting diode (LED) based lighting devices and LED devices. [Background technology]

[0002] A multicolor LED lamp generally has multiple LED light sources of different colors. Each of the LED light sources may be individually controlled by a separate switch, so that the LED light sources may operate independently of each other to produce different output lighting colors. Alternatively, light from two or more LED light sources may be mixed to provide a desired output lighting color.

[0003] In many multicolor LED lamps, pulse width modulation (PWM) is used to control the color and intensity of the LED light source. PWM allows for maximum control of the color of the LED lamp. Alternative control methods, such as current control, can suffer from color variation. Therefore, PWM with a fixed current is the predominant architecture for color control of LED lamps.

[0004] A problem with PWM controlled LED lamps relates to the conflicting requirements for current supplied to the LED light source imposed by the efficiency of the LED lamp and the flux output of the lamp.

[0005] In PWM-controlled LED lamps, the current is fixed for all color points, which can be expressed, for example, as a correlated color temperature (CCT). This compromise is the result of different requirements at different color points. At certain white points, for example 4000K, the efficiency needs to be optimal, which requires the lowest possible current. On the other hand, at other color points, for cost reasons and sometimes size reasons, the luminous flux output may need to be as high as possible with the minimum number of LEDs. A high luminous flux output may require a relatively high current, as opposed to the low current required by high efficiency.

[0006] Due to the above facts, a trade-off usually needs to be chosen, which may reduce not only the luminous flux output capability but also the efficacy of the corresponding LED lamp. Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, there is a real need for a method of controlling an LED lamp that helps to ensure and achieve improved performance with higher luminous flux and higher efficacy of multicolor LED lamps. [Means for solving the problem]

[0008] In a first aspect of the present disclosure, there is provided a method of controlling a light emitting diode (LED) lighting device, the LED lighting device having at least two series-connected LED light sources supplied with current and with different color metric values, each LED light source being controlled by a respective switch coupled in parallel to the respective LED light source and operating according to a duty cycle, the method being carried out by a controller; - receiving designated colormetric values ​​for the LED lighting device; - determining an operating current amplitude for the LED lighting device based on a current profile over a range of colormetric values ​​and the designated colormetric values; - setting the current supplied to the LED light source to the determined operating current amplitude.

[0009] The present disclosure is based on the insight that adapting the operating current amplitude of an LED lighting device having LED light sources with different colormetric values ​​based on a colormetric value, such as color temperature, that represents a color point, makes it possible to optimize the LED lighting device in terms of its efficiency and luminous flux output without making a trade-off between the efficiency and luminous flux output of the LED lighting device.

[0010] The optimization is achieved by a method according to a first aspect of the present disclosure, which first receives designated colormetric values ​​that determine the color appearance of the LED lighting device. The method then determines an operating current amplitude for the LED lighting device based on the designated colormetric values, with reference to a current profile designed for a range of colormetric values. The current supplied to the LED light source is then set to the determined operating current amplitude.

[0011] The current profile is designed so that the luminous flux output of the LED lighting device can be increased for color points other than, for example, 4000K, which typically requires the lowest current, without compromising the overall efficiency of the LED lighting device. As a result, determining the operating current amplitude of the LED lighting device based on the current profile designed for a range of colormetric values ​​and a specified or required colormetric value enables the LED lighting device to have the maximum luminous flux output for color points other than, for example, 4000K.

[0012] In particular, at a color temperature of 4000K, the operating current amplitude may remain low to achieve optimal luminous flux output. On the other hand, for other color temperatures, the operating current amplitude can be increased, thereby achieving higher luminous flux at other color temperatures. The increase in the operating current amplitude must remain within the specified power level of the LED lighting device.

[0013] Thereby, the LED lighting device simultaneously achieves higher or optimal luminous flux output at a first color temperature and higher or optimal power efficiency at a second color temperature. Preferably, at colormetric values ​​with higher luminous flux, the current amplitude is lower than at colormetric values ​​with lower luminous flux. The colormetric value may be the color temperature at which optimal power efficiency is achieved, for example, at 4000K.

[0014] The inventors have discovered that at a particular colormetric value, a user perceives a higher light output, or luminous flux, at a given power than at a different colormetric value at the same power. This means that the efficiency of the LED lighting device will differ at different colormetric values. For example, at 4000K, a user perceives the highest luminous flux per watt. The inventors have realized that at this colormetric value, the power can be the lowest and still allow the user to perceive sufficient light output. At this lower power, the current is lower, resulting in higher efficiency.

[0015] In an embodiment of the present disclosure, the specified colormetric values ​​comprise a set of color coordinates or a color temperature value.

[0016] The color temperature value may be, for example, a CCT value, while the colorimetric value may also be a set of CIE xy coordinates, which may be generated based on a color selected by a user, for example, via a remote control for the LED lighting device.

[0017] In an embodiment of the present disclosure, the specified color metric values ​​are received from a user.

[0018] This allows a user to control the color appearance of the LED lighting device according to their preferences as needed, which helps to provide a better user experience.

[0019] The specified colormetric values ​​may be represented by colors available for selection by the user, for example, via a control panel or remote control device, which may have a variety of color options so that the user can select and set different colors as needed.

[0020] It may be envisioned by those skilled in the art that the user may also customize colors based on the user's needs or mood.

[0021] In an embodiment of the present disclosure, the current profile is a lookup table or a current conversion function that converts color metric values ​​to operating current amplitudes, and the determining step includes a step of converting the specified color metric values ​​to the operating current amplitudes based on the lookup table or the current conversion function.

[0022] The current profile may be designed as a look-up table and made available to the controller, for example, by storing the look-up table in the controller's internal memory. The look-up table can be easily used to facilitate the conversion of color temperature to the operating current amplitude of the LED lighting device. Therefore, the determining step is simple, easy to implement, and essentially consumes little extra resource for the controller.

[0023] In another example, the current profile may be designed as a current transformation function that takes a specified current as an input and generates an appropriate operating current amplitude as an output, and thus the determining step can obtain the operating current amplitude from the transformation function.

[0024] In an embodiment of the present disclosure, the operating current amplitude for the LED lighting device is further determined based on at least one of a reference current and a reference luminous flux output of the LED lighting device.

[0025] It may be considered by those skilled in the art that the operating current amplitude must be within a reference current, such as the nominal current of the LED lighting device itself. In determining the operating current amplitude of the LED lighting device, a reference luminous flux output may also be taken into consideration, allowing the lighting device to achieve improved efficiency and luminous flux output simultaneously.

[0026] In an embodiment of the present disclosure, the method further comprises determining a duty cycle for each switch controlling a corresponding LED light source.

[0027] By this means, the required duty cycle for each LED light source can still be determined independently, thereby allowing the dimming and color appearance of each LED light source to still be individually controlled, allowing the LED light sources to maintain high power efficiency.

[0028] In particular, in an embodiment of the present disclosure, the duty cycle is determined according to at least one of a reference luminous flux output of the LED lighting device and the determined operating current amplitude.

[0029] This also allows for more sophisticated tuning of the color appearance of the LED lighting device.

[0030] In a second aspect of the present disclosure, there is provided a light emitting diode (LED) lighting device having at least two series connected LED light sources supplied with current and having different colormetric values, each LED light source being controlled by a respective switch operating according to a duty cycle, the LED lighting device further comprising a processor for controlling the LED lighting device, the processor comprising: - a receiving module configured to receive designated colormetric values ​​for the LED lighting device; - a determination module configured to determine an operating current amplitude for the LED lighting device based on a current profile over a range of colormetric values ​​and the designated colormetric values; - a setting module configured to set the current supplied to the LED light source to the determined operating current amplitude.

[0031] The LEDs are controlled by the processor operating according to a method for controlling the LED lighting device by determining the operating current amplitude of the LED lighting device based on a specified color temperature, thereby providing the LED lighting device with an optimized output luminous flux and optimized efficiency.

[0032] The functional modules of said processor may be operable to perform respective control functions as described in the method according to the first aspect of the present disclosure.

[0033] It may be considered by those skilled in the art that the processor may be integrated into the internal control unit of the LED lighting device, or alternatively, the processor may be a separate processor disposed, for example, inside a remote control or control panel for controlling the LED lighting device.

[0034] In a third aspect of the present disclosure, there is provided a computer program product having a computer-readable storage medium storing instructions that, when executed on at least one processor, cause the at least one processor to perform a method according to the first aspect of the present disclosure.

[0035] The above and other features and advantages of the present disclosure will be best understood from the following description taken in conjunction with the accompanying drawings, in which like reference numerals indicate identical parts or parts performing the same or equivalent functions or operations. [Brief explanation of the drawings]

[0036] [Figure 1] 1A and 1B show schematic diagrams of series-connected light-emitting diode (LED) light sources of a multi-color LED lighting device. [Figure 2] 1 is a graph that schematically illustrates the relationship between generated luminous flux and current of an LED lighting device. [Figure 3] 1 illustrates, in a flow chart type diagram, a method for controlling an LED lighting device according to an embodiment of the present disclosure. [Figure 4] 10 is a schematic diagram illustrating a current conversion profile designed as a conversion function from a CCT value to an LED current. [Figure 5] 1 is a graph that schematically illustrates a comparison between the luminous flux curves obtained with a fixed current and with a variable current; [Figure 6] 1 illustrates a schematic diagram of a controller for controlling an LED lighting device according to the present disclosure. [Figure 7] 1 illustrates a schematic diagram of an LED lighting device having a controller according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0037] Embodiments contemplated by the present disclosure will now be described in more detail with reference to the accompanying drawings. The disclosed subject matter should not be construed as limited to only the embodiments described herein. Rather, the described embodiments are provided as examples to convey the scope of the subject matter to those skilled in the art.

[0038] FIG. 1 generally illustrates a schematic diagram 10 of a series-connected light-emitting diode (LED) light source for a multicolor LED lighting device. Five LEDs, labeled 11-15, are shown in the diagram 10. The five LEDs 11-15 may be, for example, red, green, blue, warm white, and cool white, respectively. The LEDs 11-15 are connected in a single string and driven with a fixed current (not shown). Pulse-width modulated signals are supplied to switches 110-150, which are used to control the LEDs 11-15 by closing or opening the LEDs, respectively, thereby controlling the color and output luminous flux of the lighting device comprising the LEDs 11-15. Preferably, the switches are arranged in parallel with the LEDs.

[0039] For LED lighting devices, maximum efficacy is typically required near the color point where the LED lighting device's output luminous flux is highest, either due to regulatory considerations or due to power limitations related to the maximum heat that the LED lighting device can withstand. Figure 2 is a graph that schematically illustrates the relationship between the generated luminous flux output and current of an LED lighting device. From Figure 2, it can be seen that at higher currents, more luminous flux output can be generated at extreme correlated color temperatures (CCTs) such as 2200K and 6500K, or at the corners of the color gamut.

[0040] On the other hand, at higher peak currents, the efficiency of LED lamps decreases. As a result, a trade-off is often made between the efficiency and luminous flux output of LED lamps, which reduces the luminous flux capability and efficiency of LED lamps with some LED sources.

[0041] The present disclosure proposes a method and a controller for controlling an LED lighting device having multiple LED light sources, which can help to achieve optimized lighting performance, i.e., lighting performance with higher efficiency and higher luminous flux of the LED lighting device.

[0042] FIG. 3 illustrates in a flow chart type diagram a method 30 for controlling an LED lighting device according to an embodiment of the present disclosure.

[0043] The method 30 may be implemented by a processor or controller used to control an LED lighting device having at least two LED light sources connected in series in a string and supplied with current, each of which is controlled via a respective switch, for example by a pulse width modulation (PWM) signal, so that the LED light sources can be switched on and off according to a required light color scheme.

[0044] The controller may be a built-in module of the LED lighting device or may be a separate control device. For example, the controller may be a processor of the LED lighting device.

[0045] Each LED light source may have a color appearance that is expressed by a colormetric value, such as the correlated color temperature (CCT), or color temperature, expressed as xy coordinates of the Commission Internationale de l'Eclairage (CIE).

[0046] In step 31 "Receive specified colormetric values ​​for LED lighting device," the processor receives colormetric values ​​for a required color. As an example, a user may press a button on a remote control for the LED lighting device to select a particular color, which may generate a signal to the processor. The selected color may be converted to a color temperature or a set of CIE x-y coordinates for the processor, which is used to control the LED lighting device accordingly.

[0047] In step 32, “Determining operating current amplitude for LED lighting device based on current profile and specified colormetric values,” the controller may determine the operating current amplitude for the LED lighting device, i.e., the current for driving each LED light source of the LED lighting device, based on the current profile together with the specified colormetric values.

[0048] The current profile may be designed over a range of x-y coordinates or CCT values. Figure 4 shows a schematic diagram of a current conversion profile designed as a conversion function from CCT values ​​to LED current. The controller can easily determine the appropriate operating current amplitude by using the conversion function shown in Figure 4.

[0049] The currents for various CCT values ​​as shown in Figure 4 are relative currents in arbitrary units. If the current supplied to the LED light source is changed according to a transfer function as shown in Figure 4, the luminous flux output of the lamp can be increased for color points different from 4000K. It can be seen that at maximum luminous flux output, the current amplitude is lowest to meet the efficacy requirement.

[0050] In another example, the current profile may be designed as a look-up table, which may be used to convert the received specified color metric values ​​into appropriate operating current amplitudes for the LED lighting device.

[0051] In determining the operating current amplitude, it may also take into account other factors, such as a reference current or a reference luminous flux output, or a combination of the two. The reference current may be, for example, the nominal current of the LED lighting device. The reference luminous flux output may be a luminous flux that complies with regulations and specifications.

[0052] Next, in step 33 "Setting current supplied to LED light sources to determined operating current amplitude", the processor sets the current supplied to the LED lighting device, i.e., the current driving each of the LED light sources, to the operating current amplitude determined in step 32.

[0053] The determined operating current amplitude enables the LED lighting device to have an optimal luminous flux output, for example, at a specified color temperature. Figure 5 is a graph 50 that schematically illustrates luminous flux output curves obtained with a fixed current and with a variable current. In Figure 5, curve 51 is the luminous flux output curve obtained for the LED lighting device with a current controlled according to the above method, and curve 52 is the luminous flux output curve obtained for the LED lighting device with a fixed current. The luminous flux output is in arbitrary units.

[0054] From Figure 5, it can be seen that when the operating current amplitude supplied to the LED lighting device is changed, for example, according to a colormetric value specified by a user, the luminous flux output of the LED lighting device is increased for color points different from 4000K, thereby optimizing the luminous flux output of the LED lighting device.

[0055] The processor may also determine the required PWM settings in terms of operating current amplitude for the specified color metric in step 34. By way of example, the controller may determine the duty cycle for each PWM signal controlling a respective LED light source. In determining the PWM settings, the method may also consider a reference luminous flux.

[0056] This allows optimizing the efficiency of each LED light source based on the determined operating current amplitude.

[0057] The method therefore makes it possible to control an LED lighting device such that optimized power efficiency and optimized luminous flux output are simultaneously achieved.

[0058] FIG. 6 shows a schematic diagram of a controller 60 for controlling an LED lighting device according to the present disclosure.

[0059] The controller 60 may include a receiving module 61 , a determining module 62 , and a setting module 63 .

[0060] The receiving module 61 is configured to receive specified colormetric values ​​for an LED lighting device, for example, as described above with respect to step 31 of FIG.

[0061] The determination module 62 is configured to determine an operating current amplitude for the LED lighting device based on the current profile over a range of colormetric values ​​and the specified colormetric value, for example, as described above with respect to step 32 of Figure 3. The determination module 62 may also be configured to determine the operating current amplitude taking into account other factors, such as a reference current and / or a reference luminous flux.

[0062] The setting module 63 is configured to set the current supplied to the LED light source to the determined operating current amplitude, for example as described above with respect to step 34 of FIG.

[0063] The determination module 62 may further be configured to determine a PWM setting in terms of an operating current amplitude at a specified color point.

[0064] FIG. 7 illustrates a schematic diagram of an LED lighting device 70 having a controller according to the present disclosure.

[0065] The LED lighting device 70 may include a control unit or control device 710 and a load, such as a luminaire or lighting device 720, including an LED lighting module 721, such LED lighting module having multiple LED light sources. The control device 710 may control the operation of the lighting module 721, for example, according to the methods of the present disclosure. The control device 710 may include a controller such as that described with reference to FIG. 6.

[0066] The control device 710 operates a communication interface 71, such as a network adapter or a transceiver (Tx / Rx) module configured for wireless 72 or wired 73 exchange of messages or data packets with, for example, another LED lighting device in a network. The communication interface 71 may function as a receiving module for the controller 60 for controlling the LED lighting device.

[0067] Network protocols for exchanging data by network-connected devices or nodes may include ZigBee, Bluetooth, and WiFi-based protocols for wireless networks, wired bus networks such as DALI (Digital Addressable Lighting Interface), DSI (Digital Serial Interface), DMX (Digital Multiplex), and KNX (KNX-based systems), and other proprietary protocols.

[0068] The control device 710 further comprises at least one microprocessor (μP) or controller 75 and at least one data repository or storage or memory 76, for storing, among other things, the current profiles, for example, as described above.

[0069] At least one microprocessor or controller 75 communicatively interacts with and controls the communication interface 71 and at least one data repository or storage 76 via an internal data communication and control bus 79 of the control device 710. The at least one microprocessor or controller 75 may operate one or more algorithms or applications and implement methods for controlling the LED lighting device 720.

[0070] At least one microprocessor or controller 75 may function as a decision module and a setting module of the controller 60 for controlling the LED lighting device.

[0071] The lighting fixtures or lighting devices 720 connect to and are controlled from a data communication and control bus 79 by at least one microprocessor or controller 710 via a connecting link 74 .

[0072] The present disclosure is not limited to the examples disclosed above, but may be modified and extended by those skilled in the art beyond the scope of the present disclosure as disclosed in the appended claims without the need to resort to inventive techniques for use in any data communication, data exchange and data processing environment, system or network.

Claims

1. 1. A method of controlling an LED lighting device, the LED lighting device having at least two series-connected LED light sources supplied with current and with different colormetric values, each LED light source being controlled by a respective switch coupled in parallel to the respective LED light source and operating according to a duty cycle, the method being implemented by a processor; receiving designated colormetric values ​​for the LED lighting device; determining an operating current amplitude for the LED lighting device based on a current profile over a range of colormetric values ​​and the designated colormetric values; setting the current supplied to the LED light source to the determined operating current amplitude; the specified colorimetric values ​​include a luminous flux and a set of color coordinates or a color temperature value; A method wherein the operating current amplitude at a colorimetric value having a color temperature value of 4000K is lower than the operating current amplitude at a colorimetric value having a color temperature value other than 4000K.

2. The method of claim 1 , wherein the specified colormetric values ​​are received from a user.

3. 3. The method of claim 1, wherein the current profile is a lookup table or a current conversion function that converts color metric values ​​into operating current amplitudes, and the determining step comprises converting the specified color metric values ​​into the operating current amplitudes based on the lookup table or the current conversion function.

4. 4. The method of claim 1, further comprising determining a duty cycle for each switch controlling a corresponding LED light source.

5. The method of claim 4 , wherein the duty cycle is determined according to at least one of a reference luminous flux output of the LED lighting device and the determined operating current amplitude.

6. an LED lighting device, at least two series-connected LED light sources supplied with current and with different colormetric values; at least two switches, each controlled by a respective switch connected in parallel to said LED light source and operating according to a duty cycle; a processor for controlling the LED lighting device, the processor comprising: a receiving module configured to receive designated colormetric values ​​for the LED lighting device; a determination module configured to determine an operating current amplitude for the LED lighting device based on a current profile over a range of colormetric values ​​and the designated colormetric values; a setting module configured to set the current supplied to the LED light source to the determined operating current amplitude; the specified colorimetric values ​​include a luminous flux and a set of color coordinates or a color temperature value; the operating current amplitude at a colorimetric value having a color temperature value of 4000 K is lower than the operating current amplitude at a colorimetric value having a color temperature value other than 4000 K; an LED lighting device, wherein the current profile is a lookup table or a current conversion function that converts color metric values ​​to operating current amplitudes, and the determination module is configured to convert the specified color metric values ​​to the operating current amplitudes based on the lookup table or the current conversion function.

7. The LED lighting device of claim 6 , wherein the receiving module is configured to receive the specified color metric values ​​from a user.

8. 8. The LED lighting device of claim 6 or 7, wherein the determination module is further configured to determine a duty cycle for each switch controlling a corresponding LED light source.

9. 9. The LED lighting device of claim 8, wherein the determining module is configured to determine the duty cycle according to at least one of a reference luminous flux output of the LED lighting device and the determined operating current amplitude.

10. A computer program comprising a computer readable storage medium storing instructions which, when executed on at least one processor, cause the at least one processor to perform the method of any one of claims 1 to 5.

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