A light emitting diode, led, based lighting device comprising at least two light emitting diode, led, strings for emitting light, as well as a corresponding method

Abstract

A Light Emitting Diode, LED, based lighting device, comprising a power source, a first LED string comprising a first plurality of LEDs connected in series, wherein said first LED string is connected to said power source, a second LED string comprising a second plurality of LEDs connected in series, wherein an output of said second LED string is connected to an output of said first LED string and a one-to-many, 1:N, switch, wherein an input of said switch is connected to said power source and wherein outputs of said switch are connected to subsequent inputs of LEDs in said second LED string, respectively, such that a position of said one-to-many, 1:N, switch determines the number of LEDs in the second LED string that are powered by the power source.

Description

[0001] A LIGHT EMITTING DIODE, LED, BASED LIGHTING DEVICE COMPRISING AT LEAST TWO LIGHT EMITTING DIODE, LED, STRINGS FOR EMITTING LIGHT, AS WELL AS A CORRESPONDING METHOD

[0002] TECHNICAL FIELD

[0003] The present disclosure generally relates to the field of lighting and, more specifically, to an LED based lighting device comprising at least two Light Emitting Diode, LED, strings of which a light output can be controlled.

[0004] BACKGROUND

[0005] In recent years, the lighting industry has witnessed a transformation with the adoption of Light Emitting Diode, LED, technology. Among the many innovations in this particular technical field, LED-based lighting devices that have multiple LED strings connected in parallel have been developed as an efficient solution for various applications. These devices offer enhanced performance, greater flexibility, and improved reliability compared to traditional lighting sources.

[0006] The basic concept of these LED-based lighting devices is associated with the design of parallel LED strings. In this configuration, multiple strings of LEDs are interconnected in parallel to a common power source. Each LED string consists of several individual LEDs, and these strings share the same supply while dividing the total current provided by the power source.

[0007] One of the advantages of this parallel arrangement is related to redundancy. Should one LED string fail or encounter issues, the remaining strings may continue to function, ensuring uninterrupted illumination. This robustness makes parallel LED configurations particularly suitable for critical applications where continuous lighting is required.

[0008] LED-based lighting devices with parallel LED strings offer advanced features that allow users to customize the colour temperature of the emitted light. Colour temperature may refer to the perceived warmth or coolness of the light, measured in, for example, Kelvins. By adjusting the current flowing through each LED string, users can vary the colour temperature to achieve the desired ambiance or task-specific lighting. This flexibility makes these devices suitable for a range of environments, from cozy residential spaces to clinical, daylight-simulating settings.

[0009] Another feature of these LED lighting devices is related to the ability to control the uplight-downlight ratio. Uplight refers to the portion of light that is directed upwards, often contributing to ambient or indirect lighting. Downlight, on the other hand, directs light downwards, providing focused illumination. Users can manipulate the ratio of uplight to downlight by adjusting the intensity of specific LED strings. This control empowers architects and designers to fine-tune the lighting environment, enhancing aesthetics, comfort, and functionality.

[0010] LED-based lighting devices with parallel LED strings may thus represent a significant advancement in the lighting industry. Their parallel configuration ensures reliability and redundancy, while the ability to customize colour temperature and uplight- downlight ratios opens up new possibilities for creating tailored lighting experiences in diverse settings.

[0011] One of the driving forces for innovators is to reduce the complexity and / or the footprint of these LED-based lighting devices without sacrificing functionality too much.

[0012] SUMMARY

[0013] It would be advantageous to achieve a Light Emitting Diode, LED, based lighting device comprising two LED strings, wherein the LED based lighting device is realized such that number of LEDs powered by the power source can be controlled.

[0014] In a first aspect of the present disclosure, there is provided Light Emitting Diode, LED, based lighting device, comprising: a power source; a first LED string comprising a first plurality of LEDs connected in series, wherein said first LED string is connected to said power source; a second LED string comprising a second plurality of LEDs connected in series, wherein an output of said second LED string is connected to an output of said first LED string; a one-to-many, 1 :N, switch, wherein an input of said switch is connected to said power source and wherein outputs of said switch are connected to subsequent inputs of LEDs in said second LED string, respectively, such that a position of said one-to-many, 1 :N, switch determines the number of LEDs in the second LED string that are powered by the power source. The inventors have found that it may be beneficial to construe the LED based lighting device in such a way that the number of LEDs that are actually being powered by the power source may be controlled.

[0015] The control may be realized by the introduction of the one-to-many, 1 :N, switch. The input of the switch is connected, directly or indirectly, to the power source and the outputs of the switch are connected to subsequent inputs of the LEDs in the second LED string. This accomplished that the position of the one-to-many, 1 :N, switch determines the number of LEDs in the second LED string that are actually powered by the power source.

[0016] This may be explained using a simple example.

[0017] A first LED string comprises five LEDs that are connected in series. The input of the first LED, i.e. the anode of the first LED, is connected to the power source. The output of the first LED, i.e. the cathode of the first LED, is connected to the input of the second LED. The output of the second LED is connected to the input of the third LED. The output of the third LED is connected to the input of the fourth LED. The output of the fourth LED is connected to the input of the fifth LED. The output of the fifth LED is connected to the power source.

[0018] A second LED string comprises five LEDs that are connected in series. The input of the first LED, i.e. the anode of the first LED, is connected to one of the outputs of the 1 :N switch. The output of the first LED, i.e. the cathode of the first LED, is connected to the input of the second LED. The input of the second LED is also connected to one of the outputs of the 1 :N switch. The output of the second LED is connected to the input of the third LED. The input of the third LED is also connected to one of the outputs of the 1 :N switch. The output of the third LED is connected to the input of the fourth LED. The output of the fourth LED is connected to the input of the fifth LED. The output of the fifth LED is connected to the output of the fifth LED of the first LED string.

[0019] In this particular example, the 1 :N switch is in fact a 1 :3 switch. There are three possible states for the switch. A first state in which the power source is connected, via the switch, to the input of the first LED. A second state in which the power source is connected, via the switch, to the input of the second LED. A third state in which the power source is connected, via the switch, to the input of the third LED. If the power source is connected, via the switch, to the input of the third LED, then the first and the second LED would be floating. This would mean that only the third LED, the fourth LED and the fifth LED would actually be powered and illuminating light. The above demonstrates that the state of the switch determines the number of LEDs that are being activated in the second string.

[0020] In an example, the power source is a constant current based power source.

[0021] A voltage source provides a constant voltage difference, voltage potential, between its terminals, maintaining a fixed voltage output, such as 5 volts or 12V for example. However, the current that flows through a circuit connected to a voltage source varies depending on the impedances of the components in the circuit. Higher resistance results in lower current, and lower resistance results in higher current. In essence, a voltage source keeps its output voltage constant but allows current to fluctuate based on the circuit's impedances.

[0022] On the other hand, a current source provides a constant current regardless of the voltage across it. It maintains a fixed current output, such as 1 ampere or 10 ampere. The voltage across a circuit connected to a current source varies based on the impedances of the circuit. It automatically adjusts the voltage across it to maintain the specified current, making it load-independent. In essence, a current source keeps current constant while allowing voltage to vary as needed.

[0023] In an example, the LED based lighting device further comprises: a third LED string comprising a third plurality of LEDs, wherein an output of said third LED string is connected to said output of said first LED string, a second one-to-many, 1 :N, switch, wherein an input of said second switch is connected to said power source and wherein outputs of said second switch are connected to subsequent inputs of LEDs in said third LED string, respectively, such that a position of said second one-to-many, 1:N, switch determines the number of LEDs in the second LED string that are powered by the power source.

[0024] The advantage of this particular example is that multiple LED strings may be controlled. The number of LEDs in the second LED string may be controlled as well as the number of LEDs in the first LED string. This provides flexibility and more tuning properties compared to an embodiment wherein the number of LEDs in a single LED string may be controlled only.

[0025] In a further example, the second LED string further comprises one or more diodes connected in series with said second plurality of LEDs, and wherein at least one output of said one-to-many, 1 :N, switch is connected to an input of said one or more diodes.

[0026] When replacing some LEDs by diodes, or adding diodes to the second LED string, that would make the light emitting surface of a luminaire, in certain cases, more uniform. Only slightly decreasing the efficiency. This may be used for calibrating purposes, for example in uplight-downlight applications.

[0027] In a further example, the LED based lighting device further comprises: a many-to-one, N: 1, switch, wherein an output of said switch is connected to said power source, and wherein input of said switch are connected to subsequent inputs of LEDs in said second LED string and to corresponding subsequent inputs of LEDs in said first LED string, respectively, such that said position of said one-to-many, 1 :N, switch together with a position of said many-to-one, N: 1, switch determine the number of LEDs in the first LED string and the second LED string to be powered by the power source.

[0028] The advantage of this particular example is that the N: 1 switch may act as a dimmer. The same number of LEDs in the strings, for example two LEDs in the first LED string and thus also two LEDs in the second LED string, may be enabled / active. This would thus, effectively, emulate a dimming function.

[0029] In another example, the first and second LED string comprise a same type of LEDs.

[0030] In this particular application, the first LED string may be directed downwards and the second LED string may be directed upwards, or vice versa.

[0031] In another example, the power source is a current based power source, and said LED device further comprises: a control mechanism to control an amount of current provided by said current based power source based on a voltage over said first LED string.

[0032] In a further example, the device comprises: voltage absorption units arranged in between outputs of said switch and subsequent inputs of LEDs in said second LED string, respectively.

[0033] The voltage absorption units may comprise non-LED based diodes.

[0034] The switch may be a mechanical switch.

[0035] A mechanical switch is a means of enabling or disabling LEDs in various LED based lighting devices. These switches are designed to physically open or close an electrical circuit, interrupting or allowing the flow of current to the LEDs. When the switch is in a particular position, the input is connected to one of the multiple outputs, i.e. the circuit is closed, and electricity flows, illuminating the LEDs.

[0036] In a second aspect of the present disclosure, there is provided a method of operating an Light Emitting Diode, LED, based lighting device in accordance with any of the previous claims, wherein said method comprises the steps of: connecting, by said one-to-many, 1 :N, switch said input of said switch to said power source and connecting one of said outputs of said switch to said input, such that said position of said one-to-many, 1:N, switch determines the number of LEDs in the second LED string that are powered by the power source.

[0037] It is noted that the advantages as explained with reference to the first aspect of the present disclosure, being the Light Emitting Diode, LED, based lighting device, are also applicable to the second aspect of the present disclosure, being the method of operating such a LED based lighting device.

[0038] In an example, the LED based lighting device further comprises a third LED string comprising a third plurality of LEDs, wherein an output of said third LED string is connected to said output of said first LED string and a second one-to-many, 1 :N, switch, wherein an input of said second switch is connected to said power source and wherein outputs of said second switch are connected to subsequent inputs of LEDs in said third LED string, respectively, wherein the method further comprises the step of: connecting, by said one-to-many, 1 :N, switch said input of said second switch to said power source and connecting one of said outputs of said second switch to said input, such that said position of said second one-to-many, 1 :N, switch determines the number of LEDs in the third LED string that are powered by the power source.

[0039] In a further example, the method further comprises: controlling, by a control mechanism, an amount of current provided by said current based power source based on a voltage over said first LED string.

[0040] In another example, the device further comprises voltage absorption units arranged in between outputs of said switch and subsequent inputs of LEDs in said second LED string, respectively.

[0041] In yet another example, the method further comprises the step of: receiving, by said switch, tactile input from a user with respect to said position of said switch.

[0042] The present disclosure is described in conjunction with the appended figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

[0043] In the appended figures, similar components and / or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[0044] The above and other aspects of the disclosure will be apparent from and elucidated with reference to the examples described hereinafter.

[0045] BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Fig. 1 discloses an example of a Light Emitting Diode, LED, based lighting device in accordance with the present disclosure;

[0047] Fig. 2 discloses another example of an LED based lighting device in accordance with the present disclosure;

[0048] Fig. 3 discloses a further example of an LED based lighting device in accordance with the present disclosure;

[0049] Fig. 4 discloses yet another example of an LED based lighting device in accordance with the present disclosure;

[0050] Fig. 5 discloses an example of a method in accordance with the present disclosure.

[0051] DETAILED DESCRIPTION

[0052] It is noted that in the description of the figures, same reference numerals refer to the same or similar components performing a same or essentially similar function.

[0053] A more detailed description is made with reference to particular examples, some of which are illustrated in the appended drawings, such that the manner in which the features of the present disclosure may be understood in more detail. It is noted that the drawings only illustrate typical examples and are therefore not to be considered to limit the scope of the subject matter of the claims. The drawings are incorporated for facilitating an understanding of the disclosure and are thus not necessarily drawn to scale. Advantages of the subject matter as claimed will become apparent to those skilled in the art upon reading the description in conjunction with the accompanying drawings.

[0054] The ensuing description above provides preferred exemplary embodiment s) only, and is not intended to limit the scope, applicability or configuration of the disclosure. Rather, the ensuing description of the preferred exemplary embodiment(s) will provide those skilled in the art with an enabling description for implementing a preferred exemplary embodiment of the disclosure, it being understood that various changes may be made in the function and arrangement of elements, including combinations of features from different embodiments, without departing from the scope of the disclosure.

[0055] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." As used herein, the terms "connected," "coupled," or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, electromagnetic, or a combination thereof. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word "or," in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0056] These and other changes can be made to the technology in light of the following detailed description. While the description describes certain examples of the technology, and describes the best mode contemplated, no matter how detailed the description appears, the technology can be practiced in many ways. Details of the system may vary considerably in its specific implementation, while still being encompassed by the technology disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the technology should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the technology with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the technology to the specific examples disclosed in the specification, unless the Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the technology encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the technology under the claims.

[0057] Fig. 1 discloses an example 1 of a Light Emitting Diode, LED, based lighting device in accordance with the present disclosure.

[0058] The Light Emitting Diode, LED, based lighting device 1 comprises a power source 3. In this particular case, the power source 3 is a current power source meaning that it is arranged to provide for a constant current. The voltage over the power supply may fluctuate, i.e. depending on the impedances of the components connected to the current source.

[0059] The LED based lighting device 1 further comprises a first LED string 2 comprising a first plurality of LEDs connected in series, wherein said first LED string 2 is connected to said power source 3.

[0060] The present disclosure is not limited to a number of LEDs in the second LED string 2. The number of LEDs may be somewhere between 10 to 40 or the like. In some cases, the number of LEDs may even be hundreds or thousands of LEDs - all depending on the specifical application of the LED based lighting device.

[0061] A second LED string 4 is provided comprising a second plurality of LEDs connected in series, wherein an output 8 of said second LED string 4 is connected to an output 9 of said first LED string 2.

[0062] Further, a one-to-many, 1:N, switch 5 is provided, wherein an input 7 of said switch is connected to said power source 3 and wherein outputs 6 of said switch are connected to subsequent inputs of LEDs in said second LED string, respectively, such that a position of said one-to-many, 1:N, switch determines the number of LEDs in the second LED string that are powered by the power source.

[0063] For example, an example of a mechanical 1:N switch is a rotary selector switch with multiple positions. In a three-position rotary switch, it is possible to mechanically rotate the switch to connect to one of three different inputs of LEDs of the second LED string 4. These types of switches may be used in various applications, such as in audio equipment to select different audio sources or in industrial control systems to choose between different operating modes.

[0064] Fig. 2 discloses another example 18 of an LED based lighting device in accordance with the present disclosure.

[0065] It is noted that the same reference numerals are used among the figures for indicating the same, or similar, feature and / or purpose.

[0066] In this particular example, a further LED string 11 is shown, wherein the further LED string 11 is connected, via its different inputs of its LEDs, to the power source 4 using a further switch 12. The input 13 of this switch 12 is thus connected to the power source 3 and the outputs 14 of this switch 12 are connected to subsequent inputs of LED of the further LED string 11. Multiple switches may thus be employed, wherein each switch may be used to control the number of LEDs in a particular LED string, i.e. used to enable / disable certain LEDs in a particular LED string.

[0067] Fig. 3 discloses a further example 21 of an LED based lighting device in accordance with the present disclosure.

[0068] The difference with the example shown in figure 1 is related to the diodes having reference numerals 22 and 23. In this particular case, the diodes 22, 23 are non-LED based diodes. These diodes 22, 23 may accomplish some sort of calibration process. For example, if it is desired to have a current ratio of 50:50 between the first and second LED string and, at the same time, have 20 LEDs in the first LED string and 18 LEDs in the second LED string, it may be useful to introduce to non-LED diodes in the second LED string. This would make the total impedances of both LED strings the same. Then, depending on the state of the switch, one or more diodes or LEDs may be disabled / activated in the second LED string.

[0069] Fig. 4 discloses yet another example 31 of an LED based lighting device in accordance with the present disclosure.

[0070] Different to the embodiment shown in figure 1 is the introduction of a many- to-one N: 1 switch 32 at the output of the LED strings, i.e. between the outputs of the LED strings and the power supply. The inputs of the many-to-one N: 1 switch 32 are connected to subsequent inputs of the LEDs of the different LED strings, as indicated with reference numeral 32.

[0071] Based on the position of the switch 32, multiple LEDs may be deactivated / activated in the LED strings, such that the switch 32 may act as a dimmer.

[0072] Fig. 5 discloses an example of a method in accordance with the present disclosure.

[0073] The method is directed to operating an Light Emitting Diode, LED, based lighting device in accordance with any of the previous examples.

[0074] A first step comprises the operating 41 of the switch. In other words connecting, by said one-to-many, 1 :N, switch said input of said switch to said power source and connecting one of said outputs of said switch to said input, such that said position of said one-to-many, 1 :N, switch determines the number of LEDs in the second LED string that are powered by the power source. A second step comprises providing current 42 by the power source to the LED strings and a third step comprises providing illumination 43 by the different LEDs in the LED strings.

[0075] To reduce the number of claims, certain aspects of the technology are presented below in certain claim forms, but the applicant contemplates the various aspects of the technology in any number of claim forms. For example, while some aspect of the technology may be recited as a computer-readable medium claim, other aspects may likewise be embodied as a computer-readable medium claim, or in other forms, such as being embodied in a means-plus-function claim.

[0076] In the description above, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of implementations of the disclosed technology. It will be apparent, however, to one skilled in the art that embodiments of the disclosed technology may be practiced without some of these specific details.

[0077] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope thereof.

Claims

CLAIMS:

1. A Light Emitting Diode, LED, based lighting device, comprising: a power source; a first LED string comprising a first plurality of LEDs connected in series, wherein said first LED string is connected to said power source; a second LED string comprising a second plurality of LEDs connected in series, wherein an output of said second LED string is connected to an output of said first LED string; a one-to-many, 1 :N, switch, wherein an input of said switch is connected to said power source and wherein outputs of said switch are connected to subsequent inputs of LEDs in said second LED string, respectively, such that a position of said one-to-many, 1 :N, switch determines the number of LEDs in the second LED string that are powered by the power source, wherein the one-to-many, 1 :N, switch is a mechanical switch.

2. An LED based lighting device in accordance with claim 1, wherein said power source is a constant current based power source.

3. An LED based lighting device in accordance with any of the previous claims, wherein said LED based lighting device further comprises: a third LED string comprising a third plurality of LEDs, wherein an output of said third LED string is connected to said output of said first LED string, a second one-to-many, 1 :N, switch, wherein an input of said second switch is connected to said power source and wherein outputs of said second switch are connected to subsequent inputs of LEDs in said third LED string, respectively, such that a position of said second one-to-many, 1 :N, switch determines the number of LEDs in the second LED string that are powered by the power source.

4. An LED based lighting device in accordance with any of the previous claims, wherein second LED string further comprises one or more diodes connected in series withsaid second plurality of LEDs, and wherein at least one output of said one-to-many, 1:N, switch is connected to an input of said one or more diodes.

5. An LED based lighting device in accordance with any of the previous claims, wherein said LED based lighting device further comprises: a many-to-one, N: 1, switch, wherein an output of said switch is connected to said power source, and wherein input of said switch are connected to subsequent inputs of LEDs in said second LED string and to corresponding subsequent inputs of LEDs in said first LED string, respectively, such that said position of said one-to-many, 1 :N, switch together with a position of said many-to-one, N: 1, switch determine the number of LEDs in the first LED string and the second LED string to be powered by the power source.

6. An LED based lighting device in accordance with any of the previous claims, wherein said first and second LED string comprise a same type of LEDs.

7. An LED based lighting device in accordance with any of the previous claims, wherein said power source is a current based power source, and wherein said LED device further comprises: a control mechanism to control an amount of current provided by said current based power source based on a voltage over said first LED string.

8. An LED based lighting device in accordance with any of the previous claims, wherein said device comprises: voltage absorption units arranged in between outputs of said switch and subsequent inputs of LEDs in said second LED string, respectively.

9. An LED based lighting device in accordance with claim 6, wherein said voltage absorption units comprise non-LED based diodes.

10. A method of operating an Light Emitting Diode, LED, based lighting device in accordance with any of the previous claims, wherein said method comprises the steps of: connecting, by said one-to-many, 1 :N, switch said input of said switch to said power source and connecting one of said outputs of said switch to said input, such that saidposition of said one-to-many, 1:N, switch determines the number of LEDs in the second LED string that are powered by the power source.

11. A method in accordance with any of the claims 10, wherein said LED based lighting device further comprises a third LED string comprising a third plurality of LEDs, wherein an output of said third LED string is connected to said output of said first LED string and a second one-to-many, 1:N, switch, wherein an input of said second switch is connected to said power source and wherein outputs of said second switch are connected to subsequent inputs of LEDs in said third LED string, respectively, wherein the method further comprises the step of: connecting, by said one-to-many, 1 :N, switch said input of said second switch to said power source and connecting one of said outputs of said second switch to said input, such that said position of said second one-to-many, 1 :N, switch determines the number of LEDs in the third LED string that are powered by the power source.

12. A method in accordance with any of the claims 10 - 11, wherein the method further comprises: controlling, by a control mechanism, an amount of current provided by said current based power source based on a voltage over said first LED string.

13. A method in accordance with any of the claims 10 - 12, wherein said device further comprises voltage absorption units arranged in between outputs of said switch and subsequent inputs of LEDs in said second LED string, respectively.

14. A method in accordance with any of the claims 10 - 13, wherein said method further comprises the step of: receiving, by said switch, tactile input from a user with respect to said position of said switch.

Images