阅读说明：本技术 提供均匀照明的大面积圆形灯具的led条配置 (LED strip configuration for large area circular luminaire providing uniform illumination ) 是由 T·范博梅尔 R·A·M·希克马特 于 2020-05-04 设计创作，主要内容包括：本公开涉及一种发光模块(100),包括一个或多个柔性细长发光二极管(LED)条(110)和混合腔室(150)。每个LED条包括其上安装了多个LED(111)的第一侧(112)、与所述第一侧相对的第二侧(113)、和两个纵向边缘(114)。混合腔室(150)被布置成混合由所述LED发射的光,并且包括基座(151)。每个LED条的纵向边缘(114)之一被布置成面对混合腔室的基座(151)。每个LED条(110)的至少一部分被弯曲(或折叠)以从混合腔室的中心部分朝向一个或多个外部点(132)径向延伸,使得一个或多个发光二极管条(110)一起形成数量为N的细长臂(130)。每个细长臂包括LED条的两个分段,其中这些分段形成细长臂的相对侧。(The present disclosure relates to a light emitting module (100) comprising one or more flexible elongated Light Emitting Diode (LED) strips (110) and a mixing chamber (150). Each LED strip comprises a first side (112) on which a plurality of LEDs (111) is mounted, a second side (113) opposite to the first side, and two longitudinal edges (114). A mixing chamber (150) is arranged to mix light emitted by the LEDs and comprises a base (151). One of the longitudinal edges (114) of each LED strip is arranged facing the base (151) of the mixing chamber. At least a portion of each LED strip (110) is bent (or folded) to extend radially from a central portion of the mixing chamber towards one or more outer points (132), such that the one or more light emitting diode strips (110) together form a number N of elongated arms (130). Each elongated arm comprises two segments of the LED strip, wherein the segments form opposite sides of the elongated arm.)

1. A light emitting module (100) comprising:

-one or more flexible elongated light emitting diode bars (110), each flexible elongated light emitting diode bar (110) having a first side (112) on which a plurality of light emitting diodes (111) is mounted, a second side (113) opposite to the first side, and two longitudinal edges (114);

-a mixing chamber (150) arranged to mix light emitted by the light emitting diode (111), the mixing chamber (150) having a base (151);

wherein one of the longitudinal edges (114) of each of the one or more light emitting diode bars (100) is arranged facing the base (151) of the mixing chamber (150);

wherein at least a portion of each of the one or more light emitting diode bars (110) is curved to extend radially from a central portion of the mixing chamber (150) towards one or more outer points (132) such that the one or more light emitting diode bars (110) together form a number N of elongated arms (130),

wherein each elongated arm (130) comprises two segments of one of the one or more light emitting diode bars (110), the segments forming opposite sides (131) of the elongated arm, and

wherein the number N is greater than or equal to 3.

2. The light emitting module (100) of claim 1, the one or more flexible elongated light emitting diode bars (110) being flexible elongated light emitting diode bars at least a portion of which are bent to extend radially from a central portion of the mixing chamber (150) towards a number N of outer points (132) to form the number N of elongated arms (130).

3. The light emitting module (100) according to claim 1, wherein each longitudinal edge (114) of the base (151) facing the mixing chamber (150) is arranged against the base (151) or adjacent to the base (151).

4. The light emitting module (100) according to any one of the preceding claims, wherein at least one segment (620 a) of at least one of the one or more light emitting diode bars (110) along an elongated arm of the light emitting diode bar (100) comprises a light emitting diode pitch gradient such that the light emitting diode pitch decreases from a central portion towards an outer point of the elongated arm.

5. The light emitting module (100) according to any one of the preceding claims, wherein at least one section (721) of at least one of the one or more light emitting diode bars (100) between a first light emitting diode (711 a) and a second consecutive light emitting diode (711 b) is folded to shorten the pitch between the first light emitting diode (711 a) and the second light emitting diode (711 b).

6. The light emitting module (100) according to any one of the preceding claims, wherein the light emitting diodes on at least one of the one or more light emitting diode strips (100) are arranged such that the light emitting diode strip comprises a region (822) with light emitting diodes and a region (823) without light emitting diodes, and wherein each region without light emitting diodes is arranged along a side of an elongated arm, which side faces a side of an adjacent elongated arm with light emitting diodes.

7. The light emitting module (100) according to any one of the preceding claims, wherein two adjacent arms are arranged at an angle θ, wherein θ = 360/N.

8. The light emitting module (100) according to any one of the preceding claims, wherein at least a portion (519) of at least one of the one or more light emitting diode bars (110) is arranged along an arc of a circle between the outer points of at least two elongated arms.

9. The light emitting module (100) according to claim 2, wherein the light emitting diode bar (110) is arranged with at least (N-1) valley folds (434) at a central portion of the mixing chamber, and at least (N-1) hill folds (433) form N outer points.

10. The light emitting module (100) according to claim, error! No reference source is found, wherein at least one segment (435) of the light emitting diode bar (110) is substantially straight-the at least one segment (435) forms one side of an elongated arm from one of at least (N-1) mountain folds to one of at least (N-1) valley folds-forming a star shape.

11. The light emitting module (100) according to any one of the preceding claims, wherein in at least a part of the elongated arm (1030) the two segments forming opposite sides of the elongated arm are glued together on a second side of the light emitting diode bar (110).

12. The light emitting module (100) according to any one of the preceding claims, wherein the light emitting diodes are arranged on at least one of the one or more light emitting diode bars (110) such that the light emitting diodes (911 a, 911 b) on opposite sides of the elongated arm are staggered.

13. The light emitting module (100) according to any one of the preceding claims, wherein the mixing chamber (150) further comprises a semi-reflective light exit window (152) being at least partially transmissive of visible light, the semi-reflective light exit window (152) being arranged to couple out light emitted from the plurality of light emitting diodes (111) and mixed within the mixing chamber (150).

14. The light emitting module (100) according to any one of the preceding claims, wherein the mixing chamber (150) has a width (W1) and a height (H), and wherein an aspect ratio of the width (W1) and the height (H) is within the interval of 8 to 60.

15. A method for manufacturing a light emitting module (100) according to any one of claims 1-14, the method comprising:

-providing the mixing chamber (150);

-providing the one or more flexible elongated light emitting diode bars (110);

-for each of said one or more light emitting diode bars (110), arranging one of said longitudinal edges (114) facing a base (151) of said mixing chamber (150); and

-bending at least a portion of each of the one or more light emitting diode bars (110) to extend radially from a central portion of the mixing chamber (150) towards one or more outer points (132) such that the one or more light emitting diode bars (110) together form a number N of elongated arms.

Technical Field

The present disclosure relates generally to the field of solid state lighting, and more particularly to a light emitting module including a flexible light emitting diode strip and a mixing chamber. The disclosure further relates to a method for manufacturing such a light emitting module.

Background

Today, the market presents a wide variety of lighting modules comprising different types of light sources. A common requirement of many light emitting modules is the ability to provide uniform illumination.

Light emitting diode based lighting solutions are highly appreciated for their energy efficiency, long life and low use of potentially harmful materials. However, since light emitting diodes are point sources, these have shown to be problematic in providing uniform illumination.

Various approaches have been used in order to combine the energy efficiency of LED-based lighting modules with uniform illumination. This method includes a structure that allows coupling of LED light into a solid waveguide. However, this solution may lead to losses, since such solid waveguides may absorb light. Another solution is to arrange a large number of LEDs at the bottom of the light-mixing chamber and provide a diffuser to spread the light evenly. However, using such a large number of LEDs may prove expensive, and placing the LEDs close together may result in overheating.

In WO2015101547, a circular light mixing chamber with a diffuse exit window is combined with a set of LEDs arranged on the inside of the side walls of the mixing chamber. This solution provides uniform illumination for smaller light modules. However, for larger area modules, the ability to provide uniform illumination may be reduced.

Therefore, there is a need for alternative lighting modules that can provide uniform illumination.

Disclosure of Invention

It is therefore an object of the present invention to overcome at least some of the above mentioned disadvantages and to provide an improved light emitting module and/or an improved method of manufacturing such a light emitting module.

This and other objects are achieved by means of a light emitting module and a method as defined in the appended independent claims. Further embodiments are defined by the dependent claims.

According to a first aspect of the present disclosure, there is provided a light emitting module comprising one or more flexible elongated Light Emitting Diode (LED) strips and a mixing chamber. Each of the one or more LED strips includes a first side (front side), a second side (back side) opposite the first side, and two longitudinal edges. A plurality of LEDs are mounted on a first side of the LED strip.

The mixing chamber (light mixing chamber) is arranged to mix the light emitted by the LEDs. The mixing chamber has a base. One of the longitudinal edges of each of the one or more LED strips is disposed facing the base.

Further, at least a portion of each of the one or more LED strips is bent (or folded) to extend radially from the central portion of the chamber toward the one or more outer points. By bending/folding, the one or more LED strips together form a number N of elongated arms, each elongated arm comprising two segments of one of the one or more LED strips. The two segments form opposite sides of the elongated arm. The number N of elongated arms is equal to or greater than 3.

In the light emitting module according to the first aspect, each of the one or more LED strips is bent or folded to form one or more radially extending elongated arms. Each of the radially extending elongated arms may be formed from a different bent or folded LED strip. Alternatively, all radially extending elongated arms may be formed together from one bent or folded LED strip.

In the light emitting module according to the first aspect, the one or more flexible elongated light emitting diode bars may be flexible elongated light emitting diode bars, at least a portion of which are bent to extend radially from a central portion of the mixing chamber towards a number N of outer points, thereby forming a number N of elongated arms. In other words, the light emitting module comprises (i) a flexible elongated light emitting diode strip having a first side on which a plurality of light emitting diodes are mounted, a second side opposite to the first side, and two longitudinal edges, and (ii) a mixing chamber arranged to mix light emitted by the LEDs, the mixing chamber having a base. One of the longitudinal edges is arranged facing the base of the mixing chamber. At least a portion of each light emitting diode bar is curved to extend radially from a central portion of the mixing chamber (150) toward a number N of outer points, forming a number N of elongated arms. Each elongated arm comprises two segments of a light emitting diode bar, which segments form opposite sides of the elongated arm. The number N is greater than or equal to 3. In the lighting module, there is at least one flexible elongated LED strip, and the particular LED strip is bent or folded to form at least three elongated arms.

The light emitting module is configured to emit light emitting module light comprising light emitted by the LEDs of the LED strip and mixed within the mixing chamber.

The LEDs may be arranged in a row on the first side. The LEDs may be arranged at an even distance over the LED strip. Alternatively, the distance between the LEDs may be different along the LED strip. The distance between two adjacent LEDs is called the LED pitch. It will be appreciated that the arrangement of the LEDs on the LED strip is such that each elongate arm comprises at least one LED. The LEDs may be arranged on only one side of the elongated arm, or on both sides.

LEDs are point light sources, that is, they provide light from a small area. Placing the LEDs in the mixing chamber may allow light to reflect within the chamber and be mixed. As light from the plurality of LEDs is reflected and mixed within the mixing chamber, the light may become more randomly oriented and, thus, the light emitted by the light emitting module may become more uniform.

In some embodiments, each elongated arm may have substantially the same length. Alternatively, the length of the elongated arm may vary. In particular, the length of the elongated arms may have a repeating pattern, for example a pattern with every other arm having a longer length and every other arm having a shorter length. In other embodiments, the length of the arm is adapted to the shape of the mixing chamber base.

As an example, the length of the arm may be at least 10 cm. In particular, the length of the arm may be at least 15 cm. More specifically, the length of the arm may be at least 20 cm. Even more particularly, the length of the arm may be at least 25 cm, such as, for example, 30 cm.

As an example, the LED strip may have a width (i.e. width of the first side, shortest distance between the longitudinal edges) in the interval of 3-30 mm, denoted W2 in this disclosure. In particular, the LED strip may have a width (W2) in the interval of 5-25 mm. More specifically, the LED bar may have a width (W2) in the interval of 6-20 mm. Such LED-strips may provide mechanical strength while not hindering the mixing of light within the mixing chamber.

In other words, the width of the LED bar (W2) may be less than the height of the mixing chamber, denoted as H in this disclosure. As an example, the width (W2) of the LED-strip and the height (H) of the mixing chamber may be such that 0.05H < W2< 0.5H. Specifically, the relationship between W2 and H may be such that 0.1H < W2< 0.5H. More specifically, the relationship between W2 and H may be such that 0.15H < W2< 0.35H.

The arrangement of the LED-strip with the longitudinal edge facing the base may result in light being emitted from the LEDs towards the side wall of the mixing chamber, i.e. in a direction substantially parallel to the base. This arrangement improves light mixing within the chamber. The enhanced light mixing may in turn contribute to a more uniform illumination. In particular, the LED may be a top emitter (i.e., the LED emits light through the top surface and not through the side surfaces). Such an arrangement of LEDs in combination with the LED-strips as described above may result in more LED light being directed substantially parallel to the base of the mixing chamber, which in turn may increase the uniformity of the light emitting module.

Folding one or more LED strips to extend as elongated arms from a central portion of the mixing chamber may provide more uniform illumination from a substantially circular or elliptical light emitting module. In particular, the central portion of the mixing chamber may be the same as, or directly above, the central portion of the base. Furthermore, smaller or larger modules providing uniform illumination may be achieved, as the bending of the LED strips may result in shorter or longer elongated arms.

According to some embodiments, the longitudinal edge of the LED strip arranged to face the base of the mixing chamber may be arranged more specifically against the base. This may improve the stability of the arrangement.

According to some embodiments, the longitudinal edge facing the base may be arranged near the base, i.e. with a (small) gap between the base and the longitudinal edge facing the base. By near the base is understood in the lower half of the mixing chamber, or even more specifically in the lower half of the mixing chamber (i.e. the bottommost quarter). For example, the gap may be less than 3 cm. In particular, the gap may be less than 1 cm. More specifically, the gap may be less than 0.1 cm.

For example, the LED strips may be held in place using a structure that contacts or forms part of the base or side walls of the mixing chamber. Such retaining means may for example comprise a pin.

Arranging the LED-strip away from the base may result in less heating and thus less necessity for cooling. Arranging the LED strips near the base may result in more light mixing and thus improve the uniformity of the light emitted by the light emitting module.

According to some embodiments, at least one segment of the LED strip may comprise a gradient of LED pitch. The arrangement of the at least one segment may be such that the LED pitch decreases along the elongated arm from the central portion towards the outer points of the base. At least one segment comprising a gradient of LED pitch may be arranged along the elongated arm of the folded portion of the LED strip.

The elongate arms may become further apart from each other as they extend further away from the central portion (of the base) of the mixing chamber. Decreasing the LED pitch (i.e., the distance between successive LEDs) may offset the increase in distance between the elongated arms toward the outer point and thus may provide a more uniform light distribution.

According to some embodiments, at least one section of the LED strip between a first LED and a second consecutive LED may be folded in order to shorten the spacing between the first LED and the second LED. In these embodiments, LED bars with an average pitch, which may be cheaper and/or easier to manufacture, may be used while still improving the uniformity of the light by changing the LED pitch.

According to some embodiments, the LEDs may be arranged on the LED strip such that the LED strip comprises an area with LEDs and an area without LEDs. The bending of at least a portion of the LED strip may be such that each region without LEDs may be arranged along a side of the elongated arm facing a side of an adjacent arm with LEDs. In other words, each area without LEDs faces an area with LEDs positioned along an adjacent elongated arm.

The length of the elongated arm may be indicated as L1. The length of the region L2 without LEDs can be related to L1 by 0.4L1< L2< L1. Specifically, the length of the region without LEDs may be related to L1 by 0.5L1< L2< L1. More specifically, the length of the region without LEDs may be related to L1 by 0.7L1< L2< L1. Most specifically, the length of the region without LEDs may be related to L1 by 0.9L1< L2< L1.

It is further noted that the length of the area without LEDs may be at least 3 cm. In particular, the length of the area without LEDs may be at least 4 cm. More specifically, the length of the area without LEDs may be at least 5 cm. Even more particularly, the length of the area without LEDs may be at least 6 cm.

These embodiments may provide alternative or complementary solutions for providing more uniform illumination. Furthermore, arranging the areas without LEDs in areas where the LEDs may otherwise be more densely arranged due to bending of the LED strip may reduce overheating in these areas. Furthermore, having an area without LEDs facing an area with LEDs may ensure that no (or at least less) dark spots, i.e. spots not illuminated by LEDs, are generated. Depending on the curvature of the LED-strip, the arrangement of the partitions with and without LEDs also helps to obtain a more uniform illumination. For example, the LED-free regions may be arranged in regions where the distance between the elongated arms is short, and avoided in regions where the distance is long.

According to some embodiments, the number N of elongated arms may be in the interval 5-14. In particular, the number N of elongated arms (and thus outer points) may be in the interval 6-12. More specifically, N may be in the interval 7-11. Even more particularly, the number N may be in the interval 8-10. These regions may provide a more uniform light distribution and help reduce dark spots on the light emitting module.

According to some embodiments, the angle between two adjacent arms may be θ = 360/N. Specifically, the angle between each pair of adjacent arms may be θ = 360/N. This embodiment may provide a more uniform light distribution, since the arms are evenly distributed around 360 ° (i.e. the outer points are distributed along the circumference of a circle).

According to some embodiments, at least a portion of the LED strip may be arranged along an arc between outer points of the at least two elongated arms. It will be appreciated that the portion of the LED strip arranged along the arc of a circle comprises at least one LED.

According to some embodiments, the portion arranged along the arc of a circle may be arranged with its second side against a circumferential side wall of the mixing chamber. Arranging the second side towards the circumferential side wall may direct the LEDs inwards such that they face the interior of the mixing chamber. This may improve the uniformity of the light emitted by the LEDs into the mixing chamber, especially for larger modules where the LED strips are complementary along the side walls to the arrangement extending from the central portion of the base.

According to some embodiments, the LED strip may be arranged with at least N-1 valley folds at a central portion of the mixing chamber and with at least N-1 hill folds forming at least N-1 outer points.

In the present disclosure, a valley fold is characterized in that two segments of the LED strip on either side of the fold are folded such that the angle between their respective first sides is reduced. In other words, in the valley fold the LED strip is folded such that the two segments of the LED strip are close to each other on the side with the LEDs. The valley fold results in an angle between the two first sides of the segments of less than 180 deg..

The gable fold is made by folding two segments of the LED strip on either side of the fold, such that first sides of the segments are folded away from each other. The mountain fold results in an angle between the two first sides of the segments of more than 180 deg.. The outer points of the LED strip arrangement may be defined by chevron folds.

According to some embodiments, at least one segment of the LED strip is substantially straight, the at least one segment forming one side of an elongated arm from one of the hill folds (i.e. outer points) to one of the valley folds (at the central portion of the base). The alternating mountain and valley folds with substantially straight segments in between result in a star shape. Such a shape may provide improved light uniformity.

According to some embodiments, the two sections of the LED strip forming opposite sides of the elongated arm may be glued together on their respective second sides along at least a portion of the elongated arm. This embodiment may provide improved thermal management.

According to some embodiments, the LEDs may be arranged on the LED strip such that the LEDs on opposite sides of the elongated arm are staggered. In other words, there may be an offset in the direction of extension of the elongated arm (i.e. towards the outer point) between the LEDs arranged along one side of the elongated arm and the LEDs arranged along the opposite side of the elongated arm. This embodiment may result in improved thermal management, as the LEDs may be more evenly distributed along the arm.

According to some embodiments, the mixing chamber may further comprise a semi-reflective light exit window. The semi-reflective light exit window may be at least partially transmissive to visible light. Furthermore, the light exit window may be arranged to couple out light that has been emitted by the LED and that has been mixed within the mixing chamber. For example, the reflectivity of the semi-reflective light exit window may be in the interval of 30-80% for light emitted by the plurality of LEDs. In particular, the reflectivity may be in the interval 35-70%. More specifically, the reflectivity may be in the interval 38-65%. Even more particularly, the reflectivity may be in the interval 40-60%.

The semi-reflective light exit window may increase the mixing of the light emitted by the LED, as some light is reflected back into the mixing chamber. Too high a reflectivity may result in a loss of efficiency. The increased mixing may allow the light emitting module to provide more uniform illumination.

According to some embodiments, the mixing chamber may have: width (e.g., diameter or longest side), denoted as W1 in this disclosure; and a height H. The aspect ratio of width and height (i.e., W1/H) may be in the interval of 8-60. In particular, the aspect ratio may be in the interval 10-30. More specifically, the aspect ratio may be in the interval 12-20.

Further, the width W1 may be greater than 20 cm. In particular, the width W1 may be greater than 40 cm. More specifically, the width W1 may be greater than 50 cm, such as, for example, 60 cm.

The light emitting module is typically mounted to the ceiling, or even recessed into the ceiling. Therefore, it is generally desirable to have a low height (H). A large aspect ratio may allow for a low height while still providing more illumination. However, if the height is too low, the mixing characteristics of the mixing chamber may be compromised, which may result in reduced uniformity of illumination.

According to a second aspect of the present disclosure, a method for manufacturing a light emitting module is provided. The method may result in a light emitting module according to any of the embodiments described in relation to the first aspect of the present disclosure. The method includes providing a mixing chamber having a base, and providing one or more flexible elongated Light Emitting Diode (LED) strips, each LED strip having a first side, a second side, and two longitudinal edges. On the first side, a plurality of LEDs is arranged. The LEDs may be arranged in a row on the first side. The LEDs may also be arranged at even intervals on the LED strip, or at different intervals.

Further, the method comprises: for each of the one or more LED strips, arranging one of the longitudinal edges of the LED strip to face the base of the mixing chamber; and bending at least a portion of each of the one or more LED strips to form a number N of elongated arms extending radially from a central portion of the chamber toward a number N of outer points. Each elongated arm includes two segments forming at least one of the one or more LED strips on opposite sides of the elongated arm.

It is noted that other embodiments are conceivable, which use all possible combinations of features listed in the above-described embodiments. Thus, the disclosure also relates to all possible combinations of features mentioned herein. Any embodiment described herein may be combined with other embodiments also described herein, and the present disclosure relates to all combinations of features. In particular, it will be appreciated that particular embodiments described with reference to the first aspect of the present disclosure also apply to the method according to the second aspect of the present disclosure.

Drawings

Exemplary embodiments will now be described in more detail with reference to the following appended drawings:

1 a-1 b show schematic illustrations of a light emitting module according to some embodiments;

FIG. 2 shows a schematic view of a portion of an LED bar according to some embodiments;

3 a-3 c illustrate LED strips adapted to be arranged at a mixing chamber base according to some embodiments;

4 a-4 b illustrate folding of an LED strip according to some embodiments;

5 a-5 b show schematic views of an LED strip on or near a mixing chamber base, according to some embodiments;

6 a-6 b illustrate LED bars having a gradient of LED pitch according to some embodiments;

FIG. 7 illustrates an LED strip folded to produce an LED pitch gradient according to some embodiments;

8 a-8 b illustrate an LED bar having regions with LEDs and regions without LEDs according to some embodiments;

FIG. 9 shows a schematic view of an arrangement of LED strips on or near a mixing chamber base, where the LEDs on opposite sides of an elongated arm are staggered, according to some embodiments;

fig. 10 illustrates an LED strip arrangement in accordance with some embodiments, wherein the second sides of the LED strips are glued together at an outer point of the elongated arm;

fig. 11 illustrates an LED strip arrangement in accordance with some embodiments, wherein the longitudinal edges are arranged near the base of the mixing chamber.

As shown in the drawings, the sizes of elements and regions may be exaggerated for illustrative purposes, and thus are provided to illustrate the general structure of embodiments. Like reference numerals refer to like elements throughout.

Detailed Description

Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

With reference to fig. 1 a-1 b, a light emitting module according to some embodiments will be described.

Fig. 1a shows a schematic view of a light emitting module 100 according to some embodiments. The light emitting module 100 comprises a light mixing chamber 150, the light mixing chamber 150 having a base 151, a semi-reflective exit window 152 and a sidewall 153. The light emitting module further comprises a flexible elongated LED strip 110. The light emitting module 100 has a width W1 and a height H. Semi-reflective exit window 152 is separated from module 100 to illustrate the interior of mixing chamber 150. During operation, the exit window 152 will be attached to the sidewall 153 of the module 100. The base 151 and the side walls 153 of the light emitting module 100 together form a cavity (or chamber/container) in which the LED-strip 110 can be placed.

Fig. 1b is a plan view of the interior of the mixing chamber. The LED strip 110 is shown disposed on or near the base 151 of the mixing chamber 150. The LED strip 110 includes a plurality of LEDs 111. The LED strip 110 is folded to form an elongated arm 130, the elongated arm 130 extending radially from a central portion of the base 151 towards a number N of outer points 132. In the present embodiment, N = 6. Each elongated arm 130 is made up of two segments 131 of the LED strip 110 that form opposite sides of the elongated arm 130.

The base 151 of the mixing chamber 150 in the present light emitting module 100 has a circular shape which in combination with the circumferential side wall 153 gives the mixing chamber 150 a cylindrical shape. However, it will be appreciated that the mixing chamber may have other shapes. In particular, the base 151 may have, for example, an oblong shape, an elliptical shape, or an oval shape.

The base 151 and/or the sidewall 153 may have highly reflective inner surfaces. High reflection may mean a reflectivity in the interval of 90-100%. For example, the reflectivity may be higher than 92%. In particular, the reflectivity may be higher than 94%. More specifically, the reflectivity may be higher than 95%.

The arrangement of the LED strip 110 is such that the longitudinal edge of the LED strip 110 is arranged to face the base 151. Specifically, in the present embodiment, the LED bar 110 is arranged against the base 151. This results in the plurality of LEDs 111 being arranged such that light emitted from the LEDs is directed towards the side wall 153 of the mixing chamber, i.e. in a direction substantially parallel to the base 151. The LED 111 may be a top emitter, emitting light through a top surface. Such LEDs, in combination with the arrangement of the LED strips 110, may result in more LED light being directed substantially parallel to the base 151, which in turn may increase the uniformity of the light emitted by the light emitting module.

Furthermore, the arrangement of the LED strip 110 places the LEDs 111 away from the elongated arm 130, said LEDs 111 being arranged on the elongated arm 130. As a result, light emitted by the LEDs 111 may be emitted into the mixing chamber 150 for mixing within the mixing chamber 150.

The LED 111 may be a white LED, i.e. an LED emitting light with a Correlated Color Temperature (CCT) within the interval 2000-8000K. In particular, the LED 111 may be adapted to emit light having a CCT in the region of 2500-. More specifically, the LED 111 may be adapted to emit light having a CCT within the interval of 2700-.

The LEDs 111 may further be adapted to emit white light within 10 SDCM (standard deviation of color matching) from the Black Body Locus (BBL). In particular, the LEDs 111 may be adapted to emit white light within 8 SDCM of the BBL. More specifically, the LED 111 may be adapted to emit light within 5 SDCM of the BBL.

Further, the LED 111 may have a Color Rendering Index (CRI) of at least 80. In particular, the LED 111 can have a CRI of at least 85. More specifically, the LED 111 can have a CRI of at least 88.

In some embodiments, the number of LEDs on the elongated arm may be at least 5. In particular, the number of LEDs on the elongated arm may be at least 8. More specifically, the number of LEDs on the elongated arm may be at least 10.

The semi-reflective exit window 152 may be arranged on top of the mixing chamber 150 (e.g. in contact with the side wall 153, on the opposite side of the base 151) to couple out light emitted by the LEDs 111 and mixed within the mixing chamber 150. The semi-reflective window 152 may, for example, have a reflectivity in the interval of 30-80% for the light emitted by the LED, such that 30-80% of the light is reflected back into the chamber for further mixing. In particular, the reflectivity may be in the interval 35-70%. More specifically, the reflectivity may be in the interval 38-65%. Even more particularly, the reflectivity may be in the interval 40-60%. In the present embodiment, the width W1 of the module 100 corresponds to the diameter of the base 151 and the height H corresponds to the height of the side walls 153. In other embodiments, with differently shaped pedestals, the width W1 may refer to the other widest dimension of the pedestal. The aspect ratio of width W1 and height H (W1/H) may be in the interval 8-60. More specifically, W1/H may be in the interval 9-30. Most particularly, W1/H may be in the interval 10-20.

Referring to fig. 2, an LED strip according to some embodiments will be described.

Fig. 2 shows two views of the same LED bar 110, similar to the view described with reference to fig. 1, one from an upper perspective and the other from a lower perspective. The LED strip 110 is elongated and flexible, in particular it is bendable (foldable). It comprises a first side (front side) 112 on which a plurality of LEDs 111 are mounted. It further comprises a second side (back side) 113 opposite the first side 112. Connecting the first side 112 and the second side 113 along the elongated direction of the LED strip 110 are two longitudinal edges 114 corresponding to the thickness of the LED strip 110. When the LED strip 110 is arranged within a light emitting module, such as the module 100 of fig. 1a, one of the longitudinal edges 114 may be arranged to face, such as abut or be adjacent, the base (151 in fig. 1 a-1 b) of the mixing chamber.

A plurality of LEDs 111 (represented by seven LEDs 111 in the figure) may be arranged in a row on a first side 112 of the LED strip 110 in a direction of longitudinal extension of the LED strip 110. In some embodiments, the LEDs 111 may be arranged equidistantly in a row. However, in some other embodiments, the distance between successive LEDs 111 may vary.

The LED bar 110 has a width W2. The width W2 may be in the interval 3-30 mm. In particular, the width W2 may be in the interval 5-25 mm. More specifically, the width W2 may be in the interval 6-20 mm. Since these widths may provide mechanical strength to the LED strip, it may be arranged as described above while not impeding the mixing of light within the mixing chamber.

It is further noted that the width W2 may be less than the height of the mixing chamber (height in fig. 1 a). As an example, the width W2 and the height H (fig. 1 a) may satisfy the condition of 0.05H < W2< 0.5H. Specifically, the width W2 and the height H (fig. 1 a) may satisfy the condition of 0.1H < W2< 0.5H. More specifically, the relationship between the width W2 and the height H (fig. 1 a) may satisfy the condition of 0.15H < W2< 0.35H.

With reference to fig. 3 a-3 b, an embodiment of an LED strip with supports or other features for arranging the longitudinal edges against the base of the mixing chamber will be described.

Fig. 3a is a cross-sectional view of LED strip 310a taken perpendicular to the extension of LED strip 310 a. LED strip 310a is identical to LED strip 110 as described with reference to fig. 2, except that it has a first longitudinal edge 114 and a second longitudinal edge 314, the second longitudinal edge 314 being adapted to be arranged on the base of the mixing chamber. The second longitudinal edge 314 includes a support 315a to facilitate placement of the second longitudinal edge on a base of a mixing chamber (such as the mixing chamber 150 described with reference to fig. 1). The support 315a extends orthogonally (i.e., at 90 °) from a first side of the LED bar. However, in other embodiments, the support may extend from the second side of the LED strip or on both sides of the LED strip. Further, the angle at which the support extends from the LED strip may be greater or less than 90 °. The support 315a may form a portion of the LED strip 310.

Fig. 3b is an illustration of LED strip 310b as seen from a first side. The LED strip may be identical to LED strip 310 a. The LED strip 310b includes five LEDs 111 and four supports 315 b. It will be appreciated that the figure shows only one section of the LED bar. In this embodiment, support 315b extends at a right angle from LED strip 310 b. Each support 315b is arranged between two consecutive LEDs 111. The support 315b has a rectangular cross section.

Fig. 3c is an illustration of another embodiment of an LED strip 310c, which is identical to LED strip 310b except that support 315c has a triangular cross-section. One side of the triangular cross-section is adapted to be disposed along a base of a mixing chamber, such as mixing chamber 150 of fig. 1.

Embodiments of the LED strips 310a, 310b, 310c may include a plurality of support elements similar to the supports described above. For example, an embodiment of an LED strip may comprise more than 20 support elements/features. Some embodiments of the LED strip may comprise more than 30 support elements. Some embodiments of the LED strip may comprise more than 40 support elements. In particular, in some embodiments of the LED strip, the support elements may be arranged such that each elongate arm comprises a support element. Further, in some embodiments of the LED strip, each elongated arm may comprise a plurality of support elements.

These embodiments illustrate some examples of supports that may facilitate the placement of LED strips on a mixing chamber base. However, it will be appreciated that the LED strips according to various embodiments of the present disclosure may be arranged on the base of the mixing chamber without the aid of a support. For example, the arrangement may comprise some attachment means, such as mechanical attachment means or adhesive. Furthermore, in some embodiments, the support may be adapted to arrange the longitudinal edges of the LED-strip at a distance from the base.

With respect to fig. 4 a-4 b, an arrangement comprising a folded/bent LED strip will be described.

Fig. 4a illustrates a folding of an elongated flexible LED strip 110 having mountain folds 433 and valley folds 434. In the chevron fold 433, the LED strip 110 is bent such that the angle α between two segments of a first side of the LED strip 110 (one segment on each side of the fold) is increased such that α >180 °. Thus, the mountain fold 433 results in an angle α between two segments of the first side of the LED strip 110 being larger than 180 °.

In the valley fold 434, the LED strip 110 is bent (folded) such that the angle β between two segments of a first side of the LED strip (one segment on each side of the fold) decreases such that β <180 °. The valley fold 434 results in an angle β between two segments of the first side of the LED strip 110 of less than 180 °.

Fig. 4b shows an example of an arrangement of LED strips 110. The LEDs of the LED bar 110 are not shown in order not to obscure the figure. However, the LED strip 110 may be identical to any of the LED strips 110 as described with reference to fig. 2. This arrangement is formed by making valley folds 434 (at the center of the shape, at the center portion of the mixing chamber base) and hill folds 433 (forming the outer points of the shape) alternately. The present shape has six valley folds 434 at the center of the shape and five hill folds 433 constitute five of the six outer points, since one outer point is constituted by the first end point 416 and the second end point 417 of the bent/folded part of the LED strip 110 and thus has no fold. In other embodiments, the end points 416, 417 may be located along the elongated arms, or at a central portion of the folded shape.

As shown in the figures, the segment 435 between valley fold 434 and hill fold 433 may be substantially straight, giving the arrangement a star-shaped appearance.

The elongated arms are arranged such that the angle θ between (the centers of) two adjacent elongated arms is 360/N, N = 6 being the number of elongated arms, thus forming a star shape with evenly distributed arms.

With reference to fig. 5 a-5 b, different arrangements of LED strips will be described, wherein a portion of the LED strips are arranged along a circular arc.

Fig. 5 a-5 b are plan views of an LED strip 510 arranged on, near or above the base 151 of the mixing chamber of a light emitting module 500a, 500b, the light emitting module 500a, 500b being identical to the light emitting module 100 described with respect to fig. 1, except that the LED strip 510 comprises a first portion 518a, 518b and a second portion 519. The first portions 518a, 518b are folded to extend as elongated arms from a central portion of the respective base 151 toward the several outer points 132. The second portion 519 is arranged along an arc of a circle. In particular, the portion 519 is arranged along the inner surface of the circumferential side wall 153 such that the LEDs of the LED strip 510 in the second portion 523 face the mixing chamber.

In fig. 5a, the folding/arrangement of the first portion 518a is such that there is a distance between the valley folds 534a at the center of the arrangement. As a result, the backsides (second sides) of the segments of the LED strips that make up the opposite sides of the elongated arm do not touch along the entire length of the elongated arm. Further, the LEDs on either side of the elongated arm are staggered. The interleaving of the LEDs will be described with reference to fig. 9.

In fig. 5b, the folding/arrangement of the first portion 518b is such that there is substantially no distance between the valley folds 534b at the center of the arrangement. The back sides (second sides) of the segments constituting the opposite sides of the elongated arm are at least partially in contact. More specifically, the opposite sides are in contact along the entire length of the elongated arm. This arrangement may provide more uniform illumination.

With reference to fig. 6 a-6 b, an embodiment of an LED strip comprising a gradient of LED pitch will be described.

Fig. 6a shows a portion of an LED strip 610. The LED strip 610 may be identical to the LED strip 110 described above with reference to fig. 2, except that it comprises a first region 620a in which the LED pitch (i.e. the distance between two consecutive LEDs 111) decreases from left to right. The LED strip 610 further includes a second region 620b in which the LED pitch increases from left to right. Each region 620a, 620b comprising a LED pitch may for example comprise at least 4 LEDs, the LED pitch (distance) increasing or decreasing between these 4 LEDs. In particular, each region 620a, 620b comprising a LED pitch may for example comprise at least 6 LEDs. More specifically, each region 620a, 620b comprising a LED pitch may for example comprise at least 7 LEDs.

Fig. 6b shows an LED strip 610 arranged on or near the base 151 of a mixing chamber, which may be identical to the mixing chamber 150 described with reference to fig. 1. The LED strip has been folded into a gable fold between the first region 620a and the second region 620b, such that these regions together form an elongated arm. The LED pitch decreases along the elongated arm from a central portion of the base toward an outer point of the elongated arm. In the outer regions of the elongated arms, where the elongated arms are further from each other, the LEDs are arranged closer together. Thus, with this arrangement, the emitted light can be diffused more uniformly.

Referring to fig. 7, an embodiment will be described in which the LED pitch gradient is provided by folding a strip of LEDs.

Fig. 7 is an illustration of a segment of an LED strip 710, identical to the LED strip 110 described with reference to fig. 2, according to some embodiments. The segment of the LED strip comprises a first LED 711a and a second consecutive LED 711 b. The area of the LED strip 721 between the first LED 711a and the second LED 711b is folded to reduce the separation between the two LEDs 711a, 711 b. This technique of folding the LED strip between the LEDs may be used to adjust the LED pitch gradient along the elongated arm of the LED strip. This technique may be used to form a light emitting module such as, for example, the one described with reference to fig. 6 b.

With reference to fig. 8 a-8 b, an embodiment will be described in which the LED strip comprises areas with LEDs and areas without LEDs.

Fig. 8a illustrates a portion of an elongated flexible LED strip 810. The LED strip 810 is similar to the LED strip 110 described with reference to fig. 2, except that the LED strip 810 includes a first area 822 with LEDs 111 and a second area 823 without LEDs.

Fig. 8b illustrates an LED strip 810 arranged on or near the base 151 of the mixing chamber. During folding of the LED strip, valley folds have been formed between the first area 822 with LEDs 111 and the second area 823 without LEDs. As a result, the first region 822 and the second region 823 form a part of two adjacent elongated arms (i.e., two different elongated arms) such that they face each other. It can be seen that the second region 823 without LEDs is located near the central portion of the base from which the elongate arm extends, such that the second region 823 without LEDs is the region of the LED strip located close to the region of the adjacent arm 822 with LEDs. In this embodiment, the absence of LEDs in some areas where the elongated arms are closer to each other may contribute to a more uniform illumination.

The length L2 of the area 823 without LEDs may be related to the length L1 of the elongated arm. For example, the relationship between the length L2 of the region without LEDs and the length L1 of the elongated arm may be 0.4L1< L2< L1. Specifically, the relationship may be 0.5L1< L2< L1. More specifically, the relationship may be 0.7L1< L2< L1. Most specifically, the relationship may be 0.9L1< L2< L1.

It is further noted that the length L2 of the area 823 without LEDs may be at least 3 cm. Specifically, the length L2 of the area 823 without LEDs may be at least 4 cm. More specifically, the length L2 of the area 823 without LEDs may be at least 5 cm. Even more particularly, the length L2 of the area 823 without LEDs can be at least 6 cm.

With reference to fig. 9, an arrangement of LED strips with LEDs staggered along an elongated arm will be described.

The light emitting module 900 shown in fig. 9 is identical to the light emitting module 100 described with reference to fig. 1, except that the LEDs 911a on one side of the elongated arm 930 and the LEDs 911b on the other (opposite) side of the elongated arm 930 are interleaved. Since the LED 911a on one side of the elongated arm 930 is not placed at the same level (along the length of the elongated arm 930) as the LED 911b on the other side of the elongated arm 930, the heat generation in the elongated arm can spread out more evenly. This may result in better thermal management.

Referring to fig. 10, an arrangement of LED strips according to some embodiments will be described, wherein the back sides of the LED strips (in the elongated arms) are glued together.

Fig. 10 is an illustration of an LED strip 110. The LEDs of the LED strip are not shown so as not to obscure the illustration. The LED-strips are bent/folded into a star-shaped arrangement. In a portion of each formed elongated arm 1030 of the LED strip arrangement, the back sides of the segments forming the elongated arm 1030 are glued together using an adhesive 1035. In this figure, the adhesive is placed in the outer portion of the elongated arm. However, in other embodiments, the adhesive may be placed in other portion(s) of the elongated arm, or along the entire elongated arm. The adhesive on the backside of the LED strip may improve thermal management.

With reference to fig. 11, embodiments will be described in which the LED strips are arranged with longitudinal edges adjacent to the base of the mixing chamber, according to some embodiments.

The light emitting module 1100 is identical to the light emitting module 100 of fig. 1a, except that the LED-strip 1110 is arranged with a small gap h between the base 1151 and the LED-strip 1110. The LED strip 1110 in this embodiment is attached to the inside of the side wall 1153. The gap H is less than the height H of the mixing chamber 1150. In particular, the gap H may be such that H < H/2. More specifically, the gap may be such that H < H/4. For example, the gap h may be less than 3 cm. In particular, the gap h may be less than 1 cm. More specifically, the gap h may be less than 0.1 cm.

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. For example, the segments of the LED strip forming the elongated arm may be partially bent, curved or folded to provide different illumination. Furthermore, the arrangement of the LEDs on the LED strip may vary. The shape and reflectivity of the mixing chamber may vary.

Although the features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements.

Additionally, 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, 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.