LED FILAMENT AND LED FILAMENT LAMP

Abstract

There is provided a light emitting diode, LED, filament lamp (100) which provides LED filament lamp light (100′). The LED filament comprises a first linear array of LEDs (101) and a second linear array of LEDs (106), and a carrier (103). The first linear array of LEDs (101) are arranged on a first surface (102) of the carrier (103) and includes only first LEDs (104) which are configured to emit first white light (105). The second linear array of LEDs (106) are arranged on a second surface (107) of the carrier (103), opposite to said first surface (102), and includes only second LEDs (108) which are configured to emit color controllable light (109). The LED filament light (100′) comprises the first white light (105) and/or the color controllable light (109).

Claims

1. A light emitting diode filament for providing LED filament light, comprising: a first linear array of LEDs arranged on a first surface of a carrier including only first LEDs configured to emit first white light. a second linear array of LEDs arranged on a second surface of the carrier, opposite to said first surface, including only second LEDs configured to emit color controllable light, wherein the LED filament light comprises the first white light ands the color controllable light wherein the first LEDs comprise UV LEDs emitting UV light and/or blue LEDs emitting blue light, the UV LEDs and/or blue LEDs being covered by a first encapsulant comprising a luminescent material configured to at least partly convert the UV light and/or the blue light into converted light, wherein the white light comprises (i) the converted light and optionally (ii) the non-converted UV light and/or the non-converted blue light, and wherein the second linear array of LEDs comprises a plurality of M groups, each group comprising a red LED, a green LED and a blue LED.

2. The LED filament according to claim 1, wherein the first encapsulant is provided as a continuous layer over the first LEDs and at least part of the first surface of the carrier.

3. The LED filament according to claim 1, wherein M is at least 5 and the first linear array of LEDs comprises at least 10 first LEDs.

4. The LED filament according to claim 1, wherein the second LEDs are covered by a second encapsulant comprising a light scattering material configured to scatter the color controllable light, wherein the second encapsulant is provided as a continuous layer over the second LEDs and at least part of the second surface of the carrier, wherein the second encapsulant is free from a luminescent material.

5. The LED filament according to claim 1, wherein the carrier is translucent.

6. The LED filament according to claim 1, wherein the first LEDs are arranged at equidistance in the first linear array and have a first pitch, wherein the second LEDs are arranged at equidistance in the second linear array and have a second pitch, and wherein the first pitch is different from the second pitch.

7. The LED filament according to claim 1, wherein the first white light having a color temperature in the range from 1800 to 2500K.

8. The LED filament according to claim 1, wherein the first linear array of LEDs and the second linear array of LEDs are both arranged on a same single planar surface which is folded such that the first linear array of LEDs is arranged on the first surface of a carrier, and the second linear array of LEDs is arranged on the second surface of a carrier opposite to said first surface.

9. A LED filament lamp comprising at least one LED filament according to claim 1, a light transmissive envelope at least partly surrounding said LED filament, and a connector for electrically and mechanically connecting said LED filament lamp to a socket.

10. The LED filament lamp according to claim 9, wherein the LED filament lamp comprises a controller configured to individually control the power supplied to the first linear array of LEDs, and the blue LEDs, the green LEDs and the red LEDs of the second linear array of LEDs.

11. The LED filament lamp according to claim 9, wherein (i) the second surfaces of each LED filament are arranged in a direction facing the inner side of the light transmissive envelope, or (ii) the first surfaces of each LED filament are arranged in a direction facing the inner side of the light transmissive envelope.

12. A method for controlling a LED filament according to claim 1, comprising powering the first linear array of LEDs, and simultaneously and independently controlling a color and/or color temperature of the color controllable light emitted by the second linear array of LEDs.

13. The method according to claim 12, wherein the second linear array of LEDs are controlled to emit color controllable light which is second white light.

14. The method according to claim 13, wherein the second linear array of LEDs are controlled to emit second white light having a same color temperature as first white light.

15. The method according to claim 13, wherein the first white light having a relatively warm color temperature, and the second linear array of LEDs are controlled to emit second white light with a relatively cool color temperature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0048] FIG. 1a-g show schematic drawings of a LED filament 100 according to embodiments of the present invention;

[0049] FIG. 2a-c show schematic drawings of a LED filament 100 according to an embodiment of the present invention;

[0050] FIG. 3 shows a schematic drawing of a side-view of a LED filament lamp 200 according to an embodiment of the present invention;

[0051] FIG. 4 shows a schematic drawing of a top view of a LED filament lamp 200 according to an embodiment of the present invention;

[0052] FIG. 5 shows a luminaire comprising a reflector and the LED filament lamp according to an embodiment of the present invention.

[0053] The schematic drawings are not necessarily on scale.

[0054] The same features having the same function in different figures are referred to the same references.

DETAILED DESCRIPTION

[0055] FIG. 1a-g show schematic drawings of a LED filament 100 according to an embodiment of the present invention. As depicted in FIG. 1a-g, the LED filament 100 provides LED filament light 100′. The LED filament 100 comprises a first linear array of LEDs 101 and a second linear array of LEDs 106. The first linear array of LEDs 101 are arranged on a first surface 102 of a carrier 103 including only first LEDs 104 which are configured to emit first white light 105. The second linear array of LEDs 106 arranged on a second surface 107 of the carrier 103, opposite to said first surface 102, including only second LEDs 108 configured to emit color controllable light 109. The LED filament light 100′ comprises the first white light 105 and/or the color controllable light 109. In this example, the first surface 102 of a carrier 103 does not comprise any LEDs which emit color controllable light 109 and second surface 107 of the carrier 103 does not comprise any LEDs which provides white light 105.

[0056] As depicted in FIG. 1d-g, the first LEDs 104 comprise UV LEDs 110 which emit UV light 111 and/or blue LEDs 112 emitting blue light 113. The UV LEDs 110 and/or blue LEDs 112 being covered by a first encapsulant 114 comprising a luminescent material 115 configured to at least partly convert the UV light 111 and/or the blue light 113 into converted light 116. The white light 105 comprises (i) the converted light 116 and optionally (ii) the non-converted UV light 111 and/or the non-converted blue light 113.

[0057] As depicted in FIG. 1d-g, the first encapsulant 114 is provided as a continuous layer 117 over the first LEDs 104 and at least part of the first surface 102 of the carrier 103.

[0058] As depicted in FIG. 1a-g, the second linear array of LEDs 106 comprises a plurality of M groups 118, each group 118 comprises a red LED 119a, a green LED 119b and a blue LED 119c.

[0059] As depicted in FIG. 1a-g, M is at least 5 and the first linear array of LEDs 101 comprises at least 10 first LEDs 104.

[0060] As depicted in FIG. 1d-g, the second LEDs 108 are covered by a second encapsulant 120 comprising a light scattering material 121 configured to scatter 122 the color controllable light 109 (see also FIG. 3, which is introduced here below). The second encapsulant 120 is provided as a continuous layer 123 over the second LEDs 108 and at least part of the second surface 107 of the carrier 103. The second encapsulant 120 is free from a luminescent material 115.

[0061] As depicted in FIG. 1a-g, the carrier 103 is translucent 124.

[0062] As depicted in FIG. 1a-g, the first LEDs 104 are arranged at equidistance in the first linear array 101 and have a first pitch P1. The second LEDs 108 are arranged at equidistance in the second linear array 106 and have a second pitch P2. The first pitch P1 is different from the second pitch P2. In this example, P1>P2. The pitch between the RGB LEDs in a cluster may be smaller than the pitch between neighboring LEDs of two different clusters (i.e. between neighboring clusters). The obtained effect is improved color mixing.

[0063] As depicted in FIG. 1a-g, the first white light 105 may have a color temperature in the range from 1800 to 2500 K.

[0064] FIG. 2a-c show schematic drawings of a LED filament 100 according to an embodiment of the present invention. As depicted in FIG. 2, the first linear array of LEDs 101 and the second linear array of LEDs 106 are both arranged on a same single planar surface 125 which is folded (or bended) such that the first linear array of LEDs 101 is arranged on the first surface 102 of a carrier 103, and the second linear array of LEDs 106 is arranged on the second surface 107 of a carrier 103 opposite to said first surface 102.

[0065] FIG. 3 shows a schematic drawing of a side-view of a LED filament lamp 200 according to an embodiment of the present invention. As depicted in FIG. 3, The LED filament lamp 200 comprises a light transmissive envelope 126 and a connector 127. The light transmissive envelope 126 at least partly surrounds said LED filament 100. The connector 127 is arranged for electrically and mechanically connecting said LED filament lamp 200 to a socket 128. The LED filament lamp 200 may also comprise a controller 130 and/or a driver 130′ and/or an antenna 130″.

[0066] FIG. 4 shows a schematic drawing of a top view of a LED filament lamp 200 according to an embodiment of the present invention. As depicted in FIG. 4, the second surfaces 107 of each LED filament 100 are arranged in a direction facing the inner side of the light transmissive envelope 126. Alternatively the first surfaces 102 of each LED filament 100 are arranged in a direction facing the inner side of the light transmissive envelope 126. In this way the spatial-spectral light distribution is improved i.e. is more homogeneous.

[0067] As depicted in FIG. 3, a method for controlling a LED filament 100 is shown. The method comprises powering the first linear array of LEDs 101, and simultaneously and independently controlling a color and/or color temperature of the color controllable light 109 emitted by the second linear array of LEDs 106. The second linear array of LEDs 106 may be controlled to emit color controllable light 109 which is second white light 129. In a first example, the second linear array of LEDs 106 are controlled to emit second white light 129 which has a same color temperature as first white light 105. The difference in color is preferably less than 200 K, more preferably less than 150 K, most preferably less than 100 K. In a second example, the first white light 105 has a relatively warm color temperature, and the second linear array of LEDs 106 are controlled to emit second white light 129 with a relatively cool color temperature. The difference in color temperature is preferably at least 500 K, more preferably at least 600 K, most preferably at least 700 K.

[0068] A LED filament is typically providing LED filament light and comprises a plurality of light emitting diodes (LEDs) arranged in a linear array. Preferably, the LED filament has a length L and a width W, wherein L>5 W. The LED filament may be arranged in a straight configuration or in a non-straight configuration such as for example a curved configuration, a 2D/3D spiral or a helix. Preferably, the LEDs are arranged on an elongated carrier like for instance a substrate, that may be rigid (made from e.g. a polymer, glass, quartz, metal or sapphire) or flexible (e.g. made of a polymer or metal e.g. a film or foil).

[0069] In case the carrier comprises a first major surface and an opposite second major surface, the LEDs are arranged on at least one of these surfaces. The carrier may be reflective or light transmissive, such as translucent and preferably transparent. The LED filament may comprise an encapsulant at least partly covering at least part of the plurality of LEDs. The encapsulant may also at least partly cover at least one of the first major or second major surface. The encapsulant may be a polymer material which may be flexible such as for example a silicone. Further, the LEDs may be arranged for emitting LED light e.g. of different colors or spectrums. The encapsulant may comprise a luminescent material that is configured to at least partly convert LED light into converted light. The luminescent material may be a phosphor such as an inorganic phosphor and/or quantum dots or rods.

[0070] The term “substantially” herein, such as in “substantially all light” or in “substantially consists”, will be understood by the person skilled in the art. The term “substantially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term “substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” includes also embodiments wherein the term “comprises” means “consists of”. The term “and/or” especially relates to one or more of the items mentioned before and after “and/or”. For instance, a phrase “item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term “comprising” may in an embodiment refer to “consisting of” but may in another embodiment also refer to “containing at least the defined species and optionally one or more other species”.

[0071] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0072] The devices herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation.

[0073] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “to comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. 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.

[0074] The invention further applies to a device comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

[0075] The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.