Lighting arrangement with light gradient

Abstract

A LED arrangement (100) in which the LED light sources (1101…i) are arranged in sequence with increasing CCT. With the increasing CCT the difference in CCT between neighbouring LED light sources in the primary subset decreases and the difference in CCT between neighbouring LED light sources in the secondary subset increases, an improved smooth light gradient in CCT is achieved.

Description

[0001] Lighting arrangement with light gradient

[0002] FIELD OF THE INVENTION

[0003] The present invention generally relates to lighting arrangements. In particular, the lighting arrangements comprise light sources achieving a smooth and light gradient in the correlated color temperature (CCT).

[0004] BACKGROUND OF THE INVENTION

[0005] The use of light emitting diodes (LED) for illumination purposes continues to attract attention. Compared to incandescent lamps, fluorescent lamps, neon tube lamps, etc., LEDs provide numerous advantages such as a longer operational life, a reduced power consumption, and an increased efficiency related to the ratio between light energy and heat energy. In particular, LED filament lamps are highly appreciated as they are very decorative.

[0006] In lighting design, with the use of LEDs, a light gradient may refer to the change in CCT of light across a space or an object. A gradual shift in CCT from one area to another can create a sense of depth and dimension, while abrupt changes in CCT may make people feel uncomfortable.

[0007] To achieve a light gradient, a combination of different LED light sources with varying CCTs may be used. Alternatively, in some lighting arrangements, lighting fixtures with adjustable CCTs are used. For example, warm white (2700K) fixtures may be used in one area and cool white (5000K) fixtures in another, gradually blending the two to create a cohesive overall effect.

[0008] The goal of a light gradient is to create a comfortable and pleasing environment, and to highlight specific areas or features within a space. By making an improved smooth light gradient in CCT, an improved lighting effect can be achieved.

[0009] US 2022 / 287163 discloses a luminaire adapted to apply an auto-gradient effect across pixels has an interface coupled by a connection to a controller. The controller has electronic circuitry that receives a predetermined start light parameter for a start pixel of a luminaire and receives a predetermined end light parameter for an end pixel of the first luminaire, the predetermined end light parameter greater than the predetermined start light parameter. The controller circuitry then automatically interpolates a gradient effect for a middle light parameter of each of a plurality of middle pixels of the luminaire based on the start and end predetermined light parameters. The controller circuitry then outputs control signals having the start, end and middle light parameters to the start, end and middle light pixels, respectively, through the connection and to the interface.

[0010] SUMMARY OF THE INVENTION

[0011] In light of the above, it is of interest to provide alternative lighting arrangements in order to improve their optical performance and lighting effects. These and other objects are achieved by providing a LED lighting arrangement having the features in the independent claims. Preferred embodiments are defined in the dependent claims.

[0012] Hence, according to an aspect of the present invention, there is provided a LED arrangement, configured to emit arrangement light. The LED arrangement comprises a plurality of LED light sources 110 / ;, i>4, wherein each LED light source is configured to emit LED light source light, and each LED light source comprises at least one LED, wherein the plurality of LED light sources is arranged along a first direction, Ai, and wherein the correlated color temperature, CCT, of the emitted LED light source light from the plurality of LED light sources increases along the first direction, Ai, and wherein the plurality of LED light sources comprises, along the first direction, Ai, a primary subset of m LED light sources, m is an integer and i>m>3, of the plurality of LED light sources, and subsequently, along the first direction, Ai, a secondary subset 130b of n LED light sources, n is an integer and i-m>n>3, of the plurality of LED light sources. For each LED light source, 110 / , / is an integer and j=l, ... ,m-2, of the primary subset of m LED light sources, a difference, DI, between the CCT of the emitted LED light source light from LED light source, 110 / +2, and the CCT of the emitted LED light source light from LED light source, 110 / + / , and, and a difference, D2, between the CCT of the emitted LED light from light source, 110 / + / , and the CCT of the emitted LED light from light source,! 10 / , fulfil Di - D2 < 0, and wherein, for each LED light source, 110i, k is an integer and k=l, ... ,n-2, of the secondary subset of n LED light sources, a difference, D3, between the CCT of the emitted LED light from LED light source, 110i+2, and the CCT of the emitted LED light source light from LED light source, 110*+ / , and a difference, D4, between the CCT of the emitted LED light source light from LED light source, 110*+ / , and the CCT of the emitted LED light source light from LED light source, 110*, fulfil D3 - D4 > 0, and D4 - Di > 0 when j=m-2 and k=l, wherein the CCT and Di, D2, D3 and D4 are measured in degrees Kelvin. Thus, the present invention is based on the idea of providing a LED arrangement in which the LED light sources are arranged in sequence with increasing CCT. With the increasing CCT, the difference in CCT between neighboring LED light sources in the primary subset decreases and the difference in CCT between neighboring LED light sources in the secondary subset increases, whereby an improved smooth light gradient in CCT is achieved.

[0013] In some embodiments, at least one of a difference in luminous flux, DLF, and a difference in luminous intensity, DLI, between each neighboring LED light sources of the plurality of LED light sources is within 20%, preferably within 10%. The obtained effect is a further improved smooth light gradient in said arrangement. The reason is limited differences in luminous and / or intensity between neighboring LED light sources.

[0014] In some embodiments, at least one of a difference in luminous flux, DLF, and a difference in luminous intensity, DLI, between at least two LED light sources of the plurality of LED light sources is at least 30% or at least 50%. The obtained effect is improved decorative and / or general lighting of said arrangement. The reason is that the luminous flux and / or intensity is substantially increased in said arrangement.

[0015] With the above arrangements, the power between neighboring LED light sources may be kept substantially constant.

[0016] In some embodiments, each of the differences Di, D2, D3 and D4has a respective minimum value, Dmin, wherein 300K > Dmin > 100K or 300K > Dmin > 150K. The obtained effect is a further improved smooth light gradient in said arrangement. The reason is that these differences are very subtle.

[0017] In some embodiments, the CCT of the emitted LED light from the respective LED light sources associated with the respective minimum value, Dmin, is within a range of 3000K> CTT > 2500K.

[0018] With these arrangements, the differences in CCT in this CCT range are only slightly visible by humans.

[0019] In some embodiments, the arrangement light is white light having a correlated color temperature in a range from 2700K to 3500K or 2500K to 4000K, and / or a color rendering index, CRI, of at least 80, preferably at least 85. Due to this arrangement, the LED arrangement may have an improved smooth light gradient and a high light quality. Although one or more LED light sources provide LED light source light having a CCT outside the correlated color temperature of a range of the arrangement light, the arrangement light has a correlated color temperature suited for the application i.e. typically 2700K to 3500K or 2500Kto 4000K. Thus, the arrangement light provides functional light while some LED light sources, e.g. LED filaments, provide decorative light.

[0020] In some embodiments, the plurality of LED light sources comprises at least 5, 6 or at least 7 LED light sources. Due to this arrangement, the LED arrangement may have an improved smooth light gradient.

[0021] In some embodiments, each LED light source of the plurality of LED light sources comprises a wavelength converter comprising a luminescent material, the luminescent material is configured to at least partly convert LED light emitted by the at least one LED into converted light. Due to this arrangement, the LED arrangement may have an improved smooth light gradient.

[0022] In some embodiments, each LED light source of the plurality of LED light sources is a LED filament. Due to this arrangement, the LED arrangement may have an improved smooth light gradient. A LED filament comprises a plurality of LED dies arranged on a first major surface of an elongated carrier. An encapsulant may cover the plurality of LED dies and at least part of the (first major surface of the) elongated carrier. The encapsulant may comprises a phosphor material configured to at least partly convert die light emitted by the plurality of LED dies into converted die light and / or a scatterer material configured to at least partly scatter die light emitted by the plurality of LED dies into scattered die light.

[0023] In some embodiments, the LED filaments are arranged parallel or perpendicular to the first direction, Ai.

[0024] In some embodiments, at least two arrays of the LED filaments overlap with respect to a second direction, A2, perpendicular to the first direction, AL In a preferred embodiment, each LED filaments of the plurality of LED light sources may be arranged in a staggered configuration i.e. an arrangement in any of various zigzags, alternations, or overlappings of position. For example, each LED filament of the plurality of LED light sources may partly overlap with another LED filament of the plurality of LED light sources.

[0025] With these arrangements, the LED arrangement may provide alternative light effect with a smooth light gradient.

[0026] In some embodiments, the CCT of the emitted LED light source light from the plurality of LED light sources has a maximum value CCTmax, and a minimum value CCTmin, wherein CCTmax- CCTmin> lOOOK or CCTmax- CCTmin> 1500K or CCTmax- CCTmin> 2000K. Due to this arrangement, the LED arrangement may have an improved smooth light gradient with sufficient difference in CCT. It will be appreciated that the lighting arrangement of the present invention may be suitable for use in a number of lighting devices, luminaires, or the like. Thus, the lighting arrangement may be beneficial in substantially any area for illumination purposes.

[0027] According to another aspect of the present invention, there is provided a LED lamp. The LED lamp comprises a light-transmissive e.g. transparent envelope at least partly encloses a LED arrangement according to any exemplifying embodiment of the present invention, and a base arranged to mechanically and electrically connect the LED arrangement to a socket of a luminaire. The present embodiment is advantageous in that the LED lamp, comprising the lighting arrangement is aesthetically attractive and provides light which has desirable properties such as smooth light gradient thus to provide high comfort for observers.

[0028] Further objectives of, features of, and advantages with, the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art will realize that different features of the present invention can be combined to create embodiments other than those described in the following.

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] This and other aspects of the present invention will now be described in more details, with reference to the appended drawings showing embodiment(s) of the invention.

[0031] Figs, la-lc schematically show lighting arrangements according to exemplifying embodiments of the present invention.

[0032] Figs. 2a-2c schematically show exemplary LED filament arrangements according to embodiments of the present invention.

[0033] Fig. 3 schematically shows a LED lamp according to an exemplifying embodiment of the present invention.

[0034] DETAILED DESCRIPTION

[0035] Figs, la-lc schematically show LED arrangements 100 according to an exemplifying embodiment of the present disclosure. The LED arrangement 100 is configured to emit arrangement light. The LED arrangement 100 may comprise a plurality of LED light sources that are arranged in sequence with increasing CCT. In some embodiments, the light sources with the increasing CCT the difference in CCT between neighbouring LED light sources first decreases and then increases. Specifically, in some embodiments, the LED arrangement 100 may comprise a plurality of LED light sources 110 / ... / ,z> . Preferably i>5, more preferably i>6, most preferably i>7. Each of the LED light sources is configured to emit LED light source light. The LED light source light is white light preferably having a correlated color temperature in a range from 1700 K to 6500 K. Each LED light source comprises at least one LED 120. The plurality of LED light sources 110 / ;is arranged along a first direction, Ai, and the correlated color temperature (CCT) of the emitted LED light source light from the plurality of LED light sources increases along the first direction, AL The difference in the increasing CCT along the first direction, Al, between each neighboring LED light sources first decreases and then increases. Specifically, according to some embodiments, as shown in Fig. la, the plurality of LED light sources comprises a primary subset 130a of m LED light sources of the plurality of LED light sources along the first direction, Ai, m is an integer and i>m>3, and subsequently, along the first direction, Ai, a secondary subset 130b of n LED light sources of the plurality of LED light sources, n is an integer and i-m>n>3. For each LED light source, 110 / , of the primary subset of m LED light sources, / is an integer and j=l, ... ,m-2, a difference, Di, between the CCT of the emitted LED light source light from LED light source, 110 +2, and the CCT of the emitted LED light source light from LED light source, 110 / + / , and a difference, D2, between the CCT of the emitted LED light source light from LED light source, 110 / + / , and the CCT of the emitted LED light source light from LED light source, 110 / , fulfil Di - D2 < 0. For each LED light source, 110*, of the secondary subset of n LED light sources, k is an integer and k=l, ... ,n-2, a difference, D3, between the CCT of the emitted LED light source light from LED light source, 110i+2, and the CCT of the emitted LED light source light from LED light source, 110*+ / , and a difference, D4, between the CCT of the emitted LED light source light from LED light source, 110*+ / , and the CCT of the emitted LED light source light from LED light source, 110*, fulfil D3 - D4 > 0, and when j=m-2 and k=l, fulfil D4 - Di > 0. The primary subset 130a and the secondary subset 130b shown in Fig. la is only an exemplary arrangement of the light sources, and the arrangement of the light sources may have other alternatives. In some embodiments, the primary subset 130a and the secondary subset 130b may be arranged to be adjacent to each other, as shown in Fig. lb. In other embodiments, the primary subset 130a and the secondary subset 130b may overlap e.g. from the last second light source 110m-2 of the primary subset 130a, as shown in Fig.lc.

[0036] In some embodiments, at least one of a difference in luminous flux (DLF) and a difference in luminous intensity (DLI) between each neighboring LED light sources of the plurality of LED light sources is within 20%, preferably within 15%, more preferably within 10%, most preferably within 5%. According to some embodiments, this can be accomplished by using different currents. According to some other embodiments, at least one of the DLF and the DLI between at least two LED light sources of the plurality of LED light sources is at least 30%, for example, the luminous flux and / or luminous intensity increases of 3 or more consecutive LED light sources.

[0037] In some embodiments, each of the differences Di, D2, D3 and D4may have a respective minimum value, Dmin, wherein 300K > Dmin > 150K and the CCT of the emitted LED light from the respective LED light sources associated with the respective minimum value, Dmin, is within a range of 3000K > CTT > 2500K such as 2700K. With these arrangements, these differences in CCT in this CCT range are only slightly visible by humans. In some embodiments, each of the differences Di, D2, D3 and D4 may have a respective maximum value, Dmax, wherein 700K > Dmax > 45 OK and the CCT of the emitted LED light from the respective LED light sources associated with the respective maximum value, Dmax, is within a range of 2300K > CTT > 1500K such as 2000K or CTT > 3000K. With these arrangements, these differences in CCT in this CCT range are well visible and are desired by humans.

[0038] In some embodiments, the arrangement light is white light having a CCT in a range from 2700K to 3500K, preferably 2800 to 3300K, more preferably 2850K to 3200K, most preferably 2900K-3100K and a color rendering index, CRI, of at least 80, preferably at least 85, more preferably at least 88, most preferably at least 90. In some embodiments, the plurality of LED light sources comprises at least 5 LED light sources or at least 6 LED light sources. According to some preferred embodiments, the plurality of LED light sources comprises at least 7 LED light sources. According to some embodiments, each LED light source of the plurality of LED light sources, 110 / .. , comprises a wavelength converter comprising a luminescent material, the luminescent material is configured to at least partly convert LED light emitted by the at least one LED into converted light. In some embodiment, each LED light source of the plurality of LED light sources 110 / is a LED filament. In some embodiments, each LED light source of the plurality of LED light sources 110 is a phosphor converted (PC) LED light source, especially a PC LED filament.

[0039] Figs. 2a-2c schematically illustrate different embodiments of the arrangements of the LED filaments.

[0040] According to some embodiments, the LED filaments are arranged parallel or perpendicular to the first direction, Ai, as shown in Figs. 2a to 2c. According to some preferred embodiments, neighboring LED filament light sources are parallelly arranged at a close distance D to each other. For example, D may be in a range from 1 mm to 20 mm. In embodiments, all LED filament of the plurality of LED light sources may be arranged parallel with respect to each other.

[0041] According to some other embodiments, at least two arrays of the LED filaments overlap with respect to a second direction, A2, perpendicular to the first direction, Ai as shown in Figs. 2b and 2c.

[0042] In some embodiments, the CCT of the emitted LED light source light from the plurality of LED light sources has a maximum value CCTmax, and a minimum value CCTmin, wherein CCT max “ CCTmin > 2000K.

[0043] Fig. 3 schematically shows a view of a LED lamp 300. The LED lamp comprises a light-transmissive envelope 200 which at least partly encloses a LED arrangement 100 according to above, and a base 301 arranged to mechanically and electrically connect the LED arrangement to a socket 201 of a luminaire 203.

[0044] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

Claims

CLAIMS1. A light emitting diode, LED, arrangement (100), configured to emit arrangement light, comprising: a plurality of LED light sources (110 / ), i>6, wherein each LED light source is configured to emit LED light source light, and each LED light source comprises at least one LED (120), wherein the plurality of LED light sources is arranged along a first direction, Ai, and wherein the correlated color temperature, CCT, of the emitted LED light source light from the plurality of LED light sources increases along the first direction, Ai, and wherein the plurality of LED light sources comprises, along the first direction, Ai, a primary subset (130a) of m LED light sources, m being an integer and i>m>3, of the plurality of LED light sources, and subsequently, along the first direction, Ai, a secondary subset (130b) of n LED light sources, n being an integer and i- in>n>3. of the plurality of LED light sources, wherein, for each LED light source, 110 / , j being an integer and j=l, ... ,m-2, of the primary subset of m LED light sources, a difference, Di, between the CCT of the emitted LED light source light from LED light source, 110 / +2, and the CCT of the emitted LED light source light from LED light source, 110 / + / , and a difference, D2, between the CCT of the emitted LED light source light from LED light source, 110 / + / , and the CCT of the emitted LED light source light from LED light source, 110 / , fulfil Di - D2 < 0, and wherein, for each LED light source, 110i, k being an integer and k=l, ... ,n-2, of the secondary subset of n LED light sources, a difference, D3, between the CCT of the emitted LED light source light from LED light source, 110i+2, and the CCT of the emitted LED light source light from LED light source, 110*+ / , anda difference, D4, between the CCT of the emitted LED light source light from LED light source, 110*+ / , and the CCT of the emitted LED light source light from LED light source, 110*, fulfil D3- D4> 0, andD4- Di > 0 when j=m-2 and =1, wherein the CCT and Di, D2, D3 and D4are measured in degrees Kelvin.

2. The LED arrangement according to claim 1, wherein at least one of a difference in luminous flux, DLF, and a difference in luminous intensity, DLI, between each neighboring LED light sources of the plurality of LED light sources is within 20%.

3. The LED arrangement according to claim 1, wherein at least one of the difference in luminous flux, DLF, and the difference in luminous intensity, DLI, between at least two LED light sources of the plurality of LED light sources is at least 30%.

4. The LED arrangement according to any one of the preceding claims, wherein each of the differences Di, D2, D3 and D4has a respective minimum value, Dmin, wherein 300K > Dmin > 150K.

5. The LED arrangement according to claim 4, wherein the CCT of the emitted LED light from the respective LED light sources associated with the respective minimum value, Dmin, is within a range of 3000K > CTT > 2500K.

6. The LED arrangement according to any one of the preceding claims, wherein each of the differences Di, D2, D3 and D4has a respective maximum value, Dmax, wherein 700K > Dmax > 45 OK.

7. The LED arrangement according to claim 6, wherein the CCT of the emitted LED light from the respective LED light sources associated with the respective maximum value, Dmax, is within a range of 2300K > CTT > 1500K or CTT > 3000K.

8. The LED arrangement according to any one of the preceding claims, wherein the arrangement light is white light having a CCT in a range from 2700K to 3500K and a color rendering index, CRI, of at least 80.

9. The LED arrangement according to any of the preceding claims, wherein the plurality of LED light sources comprises at least 5 LED light sources.

10. The LED arrangement according to any one of preceding claims, wherein each LED light source of the plurality of LED light sources (110 / i) comprises a wavelength converter comprising a luminescent material, the luminescent material is configured to at least partly convert LED light emitted by the at least one LED into converted light.

11. The LED arrangement according to claim 10, wherein each LED light source of the plurality of LED light sources (110 / ... z) is a LED filament.

12. The LED arrangement according to claim 11, wherein the LED filaments are arranged parallel or perpendicular to the first direction, Ai.

13. The LED arrangement according to claim 11, wherein at least two arrays of the LED filaments overlap with respect to a second direction, A2, perpendicular to the first direction, Ai.

14. The LED arrangement according to any one of the preceding claims, wherein the CCT of the emitted LED light source light from the plurality of LED light sources has a maximum value CCTmax, and a minimum value CCTmin, wherein CCTmax - CCTmin > 2000K.

15. A LED lamp (300), comprising: a light-transmissive envelope (200) at least partly enclosing a LED arrangement according to any one of claims 1-14, anda base (301) arranged to mechanically and electrically connect the LED arrangement to a socket (201) of a luminaire (203).

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