LED filaments and LED filament lamps

Abstract

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

Description

Technical Field

[0001] The present invention relates to an LED filament, an LED filament lamp comprising the LED filament, a lamp comprising a reflector and the LED filament lamp, and a method for controlling the LED filament. Background Art

[0002] Incandescent lamps are rapidly being replaced by solid-state light sources, such as lighting solutions based on light-emitting diodes (LEDs). However, users appreciate and desire retrofit lamps that have the appearance of an incandescent bulb. To this end, one can simply leverage the infrastructure for producing glass-based incandescent lamps and replace the conventional filament with an "LED filament," i.e., a linear array of LEDs arranged on a carrier. One or several such LED filaments can be arranged in a retrofit lamp, i.e., a bulb that has the appearance and interface of a conventional incandescent bulb. Such a retrofit LED bulb would therefore comprise a standard socket (e.g., E27), a light-transmitting (e.g., glass) envelope, and one or more LED filaments arranged in the envelope. Such retrofit bulbs are becoming increasingly popular due to their practical and decorative lighting capabilities.

[0003] Most commercially available LED retrofit lamps include an LED filament that provides white light with a single color temperature. Such LED filaments typically include one type of LED (e.g., a blue or UV LED) covered by a luminescent coating (e.g., a polymer layer including a phosphor). Recently, however, LED filaments controllable between warm white (WW) and cool white (CW) light have been proposed. Such temperature control can be achieved by using a first LED filament that emits WW light and a second LED filament that emits CW light and individually controlling the intensity of each LED filament. Alternatively, an array of alternating blue and red LEDs (RBRBRB) is covered by a luminescent coating. By varying the relative intensities of the red and blue LEDs, the resulting white light will have different color temperatures. Alternatively, as shown in WO2018 / 157428, two identical LED arrays can be provided with different types of phosphors. Likewise, the color temperature can be controlled by controlling the relative intensities of the LEDs in the two arrays.

[0004] However, current color-tunable LED filaments have several disadvantages and / or limitations. They are limited in color and / or color temperature control performance, such as a limited color gamut space and / or color temperature range; and / or they provide an unpleasant appearance in the on-state of the lighting device, such as, for example, a spotty / dark appearance when one LED array is dimmed or turned off (possibly with the appearance of a faulty filament); and / or they provide insufficient spatial light distribution, such as no omnidirectional (white) light; and / or they provide poor light quality, such as not emitting flame light / very warm white light and / or they do not emit white light with a high color rendering index; and / or they cannot be switched to saturated color light (e.g., color controllable).

[0005] US2019 / 017657A1 discloses a filament-type light-emitting diode (LED) light source, which includes a plurality of LED modules, a coupler, and a common connection portion. The LED module has a polygonal prism structure and emits white light with different color temperatures or light of different wavelengths. Each LED module has a strip shape at the corresponding side surface of the polygonal prism structure and includes a first connection electrode and a second connection electrode. The coupler couples the LED modules to maintain the polygonal prism structure. The common connection portion is located at one end of the polygonal prism structure and is commonly connected to the second connection electrode of each LED module.

[0006] US2018 / 328543A1 discloses a lamp comprising a light-transmissive envelope for emitting emitted light and a base connected to the envelope. At least one first LED filament and at least one second LED filament are located within the envelope and are operable to emit light when energized via an electrical path from the base. The first LED filament emits light having a first correlated color temperature (CCT), and the second LED filament emits light having a second CCT, which are combined to generate the emitted light. When the lamp is dimmed, a controller is operable to change the CCT of the emitted light. Summary of the Invention

[0007] It is therefore an object of the present invention to provide an improved or alternative LED filament or an LED filament which overcomes or at least alleviates at least one of the above-mentioned problems of the prior art.

[0008] This and other objects are achieved by providing an LED filament having the features of the independent claim.Preferred embodiments are defined in the dependent claims.

[0009] Therefore, according to the present invention, an LED filament is provided. The LED filament provides LED filament light. The LED filament includes a first linear LED array, a second linear LED array, and a carrier. The first linear LED array is arranged on a first surface of the carrier and includes only first LEDs configured to emit a first white light. The second linear LED array is arranged on a second surface of the carrier, opposite the first surface, and includes only second LEDs configured to emit color-controllable light. The LED filament light includes the first white light and / or color-controllable light.

[0010] The advantages of the present invention are that the LED filament can provide (very) (warm) white light and / or colored light, such as saturated colors, off-black-body-line (BBL) light, and / or high light quality (high color rendering index CRI). The LED filament can provide (very) (warm) white light and colored light sequentially.

[0011] A further advantage of the present invention is that the LED filament provides a pleasing appearance in the on-state.

[0012] One or more of the above effects are achieved because a first LED emitting a first white light (white light LED) is arranged on a first surface of the carrier, and a second LED emitting a color-controllable light (colored LED) is arranged on a second surface of the carrier. For example, a speckled appearance (which may have the appearance of a faulty filament) when one LED array is dimmed or turned off is not present because both arrays are arranged on different surfaces / sides (as opposed to, for example, an RGB-WW or RGB-WW-CW architecture on the same side).

[0013] For example, the LED filament (lamp) disclosed in WO 2018 / 157428 cannot provide white light and / or colored light. The reason is that no colored LEDs are used. In addition, (when colored LEDs are added) the light emitted from such an LED filament provides a speckled appearance. For example, in the case of an LED filament disclosed in WO 2018 / 157428 that provides (very) warm white light, some of the (white) LEDs do not light up, thereby providing a speckled appearance. In the case of using a first LED filament that provides WW light and a second LED filament that provides CW light, in a WW light setting, the second LED filament is turned off (i.e., no light) and has the appearance of a faulty LED filament.

[0014] According to one embodiment of the present invention, the first LED includes a UV LED that emits UV light and / or a blue LED that emits blue light. The UV LED and / or the blue LED are covered by a first package, which includes a luminescent material that is configured to convert the UV light and / or the blue light at least partially (or completely) into converted light. The white light includes (i) converted light and optionally (ii) (unconverted) UV light and / or (unconverted) blue light. Such an architecture is low in cost in terms of materials and / or assembly and provides high-quality light (for example, relative to colored LEDs (RGB LEDs)). The reason is that such LEDs are low in cost, only a single type (or two types) of LEDs are required, and the light of the phosphor is wider than the light of the direct-emitting (colored) LED.

[0015] According to one embodiment of the invention, the first encapsulation is provided as a continuous layer over at least a portion of the first surface of the carrier and the first LED. The resulting effect is a more uniform light emission because light is also generated in the areas between the LEDs.

[0016] According to one embodiment of the present invention, the second linear LED array includes a plurality of groups, each group including a red LED, a green LED and a blue LED. Optionally, LEDs of another color, such as an amber LED, may be added.

[0017] According to one embodiment of the present invention, the first LED comprises a UV LED emitting UV light and / or a blue LED emitting blue light, the UV LED and / or the blue LED being covered by a first package, the first package comprising a luminescent material configured to at least partially convert the UV light and / or the blue light into converted light, wherein white light comprises (i) converted light; and optionally (ii) unconverted UV light and / or unconverted blue light; and the second linear LED array comprises a plurality of groups M in number, each group comprising a red LED, a green LED, and a blue LED. The effect achieved is that the LED filament can provide (very) (warm) white light and / or colored light, for example, saturated color, off-black-body-line (BBL) light, and / or high light quality (high color rendering index CRI). The LED filament can sequentially provide (very) (warm) white light and colored light.

[0018] According to one embodiment of the present invention, the number of the plurality of groups M is at least 5, and the first linear LED array comprises at least 10 first LEDs, more preferably M is at least 10, and most preferably M is at least 12.

[0019] According to one embodiment of the present invention, a second LED is covered by a second encapsulation that includes a light-scattering material configured to scatter the color-controllable light. The second encapsulation can be provided as a continuous layer over at least a portion of the second surface of the carrier and the second LED. The second encapsulation does not contain luminescent material. The resulting effect is improved spatial and spectral light distribution. This is because the light-scattering material mixes the color-controllable light.

[0020] According to one embodiment of the present invention, the carrier is translucent. The carrier can be diffuse, but is preferably transparent. The resulting effect is an improved spatial and spectral light distribution. This is because the first white light and the color-controllable light are emitted bidirectionally: the white light emitted by the first LED also transmits through the carrier, and the color-controllable light also transmits through the carrier.

[0021] According to one embodiment of the present invention, first LEDs are arranged equidistantly in a first linear array and have a first pitch. Second LEDs are arranged equidistantly in a second linear array and have a second pitch. The first pitch is different from the second pitch. This results in better thermal management due to fewer first and second LEDs being aligned relative to each other.

[0022] According to one embodiment of the present invention, the first LED is interleaved with the second LED, which results in better thermal management because no first LED is aligned relative to the second LED.

[0023] According to one embodiment of the present invention, the first LED is aligned with the second LED. The effect achieved is an improved spatial and spectral light distribution. The reason is that the larger area of ​​the transparent carrier can allow light to be transmitted from the first side of the carrier to the second side of the carrier.

[0024] According to one embodiment of the present invention, the length and width of the LEDs are preferably smaller than the distance between adjacent LEDs. For example, the LEDs may have a length (and width) of 0.4 mm, while the distance between adjacent LEDs is 1 mm or 2 mm. The resulting effect is improved spatial and spectral light distribution. This is because the larger area of ​​the transparent carrier allows light to be transmitted from the first side of the carrier to the second side of the carrier.

[0025] According to one embodiment of the present invention, the spacing between RGB LEDs in a cluster is smaller than the spacing between adjacent LEDs in two clusters. The resulting effect is improved color mixing.

[0026] According to one embodiment of the present invention, the first white light has a color temperature ranging from 1800K to 2500K, more preferably from 1900K to 2350K, and most preferably from 2000K to 2300K. Such color temperatures appear to be preferred by customers of LED filament lamps. The color rendering index (CRI) is preferably at least 80, more preferably at least 85, and most preferably at least 90.

[0027] According to one embodiment of the present invention, a first linear LED array and a second linear LED array are both arranged on the same single flat surface. The single flat surface is then folded such that the first linear LED array is arranged on a first surface of a carrier and the second linear LED array is arranged on a second surface of the carrier opposite the first surface. The fold line can be arranged parallel to the length of the LED filament or perpendicular to the length of the LED filament (between the first LED and the second LED).

[0028] According to one embodiment of the invention, the first linear LED array and the second linear LED array are arranged on different carriers.The carriers are subsequently attached to a surface not comprising any LEDs, for example typically glued together.

[0029] The present invention discloses an LED filament lamp according to claim 11.

[0030] According to one embodiment of the present invention, the LED filament lamp further includes a controller, wherein the controller is used to control the LEDs in the first linear LED array and to control the LEDs in the second linear LED array.

[0031] According to one embodiment of the present invention, the LED filament lamp further includes at least one LED filament and a controller configured to individually control the power provided to the red LED, the green LED, and the blue LED of the second linear LED array.

[0032] According to one embodiment of the present invention, an LED filament lamp includes at least one LED filament and a controller configured to individually control power supplied to blue LEDs, green LEDs, and red LEDs of a first linear LED array and a second linear LED array.

[0033] According to one embodiment of the present invention, an LED filament lamp includes at least one LED filament, a light-transmitting envelope at least partially surrounding the LED filament, and a connector for electrically and mechanically connecting the LED filament lamp to, for example, a socket of a lamp. The light-transmitting envelope is preferably transparent. The LED filament lamp may include a driver and / or a controller. The driver may be configured to convert AC current to DC current. The driver may also be configured to adapt the current level. The controller may be configured to independently control a first linear LED array and a second linear LED array.

[0034] According to one embodiment of the present invention, an LED filament lamp includes a plurality N of LED filaments. N is preferably in the range of 3 to 8, more preferably 4 to 7, and most preferably 5 to 6. The plurality of LED filaments may be arranged at a distance different from zero from a longitudinal axis of the LED filament lamp. The plurality of LED filaments may each be at a similar distance from the longitudinal axis. Each LED filament (a first LED and a second LED) may be oriented in a different direction. For example, in the case of three LED filaments, the directions are angles γ0, 120, and 240 degrees; in the case of four LED filaments, the directions are angles γ0, 90, 180, and 270 degrees; in the case of five LED filaments, the directions are angles γ0, 72, 144, 216, and 288 degrees; and in the case of six LED filaments, the directions are angles γ0, 60, 120, 180, 240, and 300 degrees. Angle γ is defined relative to an axis perpendicular to the longitudinal axis.

[0035] According to one embodiment of the present invention, the second surface of each LED filament is arranged to face the inside of the light-transmitting envelope. Alternatively, the first surface of each LED filament is arranged to face the inside of the light-transmitting envelope. In this way, the spatial spectral light distribution is improved, i.e., more uniform.

[0036] According to one embodiment, (i) the second surface of each LED filament is arranged in a direction facing the inner side of the light-transmitting envelope, or (ii) the first surface of each LED filament is arranged in a direction facing the inner side of the light-transmitting envelope. The inner side refers to the central portion (e.g., the longitudinal axis) of the light-transmitting envelope.

[0037] The invention discloses a lamp.

[0038] The luminaire includes a reflector and an LED filament lamp according to the present invention, wherein the LED filament lamp is at least partially arranged inside the reflector. The resulting decorative luminaire provides an improved, attractive, and appealing light effect. This is because the LED filament is visible, but part of the LED filament light is redirected by the reflector toward a certain direction, such as a table or floor.

[0039] The present invention discloses a method for controlling an LED filament according to claim 12.

[0040] According to one embodiment of the present invention, a method for controlling an LED filament includes powering a first linear array of LEDs while independently controlling the color (point) and / or color temperature of color-controllable light emitted by a second linear array of LEDs.

[0041] According to one embodiment of the present invention, a second linear LED array is controlled to emit color-controllable light, namely, a second white light. The color temperature of the second white light may be in the range of 1800K to 6500K. The second white light has a spectral distribution that is different from the spectral distribution of the first white light. The second white light may be generated by combining light from red, green, and blue LEDs.

[0042] According to one embodiment of the present invention, the second linear LED array is controlled to emit a second white light having the same color temperature as the first white light (emitted by the first linear LED array and / or the luminescent material). The result is an LED filament having the advantages described above and a uniform appearance. This is because the same color temperature is emitted from both (opposite) sides (surfaces) of the carrier. Preferably, the color temperature is in the range of 1800K to 2500K, more preferably 1900K to 2400K, and most preferably 2000K to 2300K. The color temperature difference is preferably less than 200K, more preferably less than 150K, and most preferably less than 100K. This may persist for a period of time, for example at least 1 minute or at least 10 minutes.

[0043] According to one embodiment of the present invention, the LED filaments can be arranged in a (3D) spiral or helical configuration. The resulting effect is an improved spatial and spectral light distribution. This is due to the fact that the first white light and the color-controllable light provide the same color temperature. Even if the first white light and the color-controllable light provide the same color temperature, the (3D) spiral or helical configuration still offers the advantage of improved spatial and spectral light distribution. This is because the first white light and the color-controllable light, while providing the same color temperature, have different spectral distributions.

[0044] According to one embodiment of the present invention, a first linear LED array is controlled to emit a first white light having a relatively warm color temperature, and a second linear LED array (106) is controlled to emit a second white light having a relatively cool color temperature. The effect obtained is an improved decorative effect. The reason is that different sides (surfaces) of the carrier emit different color temperatures. The first surface emits relatively warm white light (preferably very warm white light) (i.e., a color temperature in the range of 1800K to 2400K), while the second surface emits relatively cool light (preferably light with good visibility, i.e., light with a color temperature in the range of 2900K to 6500K). The color difference is preferably at least 500K, more preferably at least 600K, and most preferably at least 700K.

[0045] According to one embodiment of the present invention, the color controllable light does not have 15 SDCM from the black body locus.In this embodiment, the color controllable light is typically used to generate a saturated color that can be added to the first white light.

[0046] Other objects, features and advantages of 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. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0048] Figure 1a-1g shows a schematic diagram of an LED filament 100 according to an embodiment of the present invention;

[0049] Figure 2a-2c shows a schematic diagram of an LED filament 100 according to an embodiment of the present invention;

[0050] Figure 3 1 shows a side view schematic diagram of an LED filament lamp 200 according to an embodiment of the present invention;

[0051] Figure 4 1 shows a schematic top view of an LED filament lamp 200 according to an embodiment of the present invention;

[0052] Figure 5 A lamp including a reflector and an LED filament lamp according to one embodiment of the present invention is shown.

[0053] The schematic diagrams are not necessarily drawn to scale.

[0054] Identical features having the same function in different figures are denoted by the same reference numerals. DETAILED DESCRIPTION

[0055] Figure 1a-1g FIG. 1 shows a schematic diagram of an LED filament 100 according to an embodiment of the present invention. Figure 1a-1gAs shown, an LED filament 100 provides LED filament light 100'. The LED filament 100 includes a first linear LED array 101 and a second linear LED array 106. The first linear LED array 101 is arranged on a first surface 102 of a carrier 103 and includes only first LEDs 104 configured to emit a first white light 105. The second linear LED array 106 is arranged on a second surface 107 of the carrier 103, opposite the first surface 102, and includes only second LEDs 108 configured to emit a color-controllable light 109. The LED filament light 100' includes the first white light 105 and / or the color-controllable light 109. In this example, the first surface 102 of the carrier 103 does not include any LEDs that emit the color-controllable light 109, and the second surface 107 of the carrier 103 does not include any LEDs that provide the white light 105.

[0056] like Figure 1d-1g As shown, the first LED 104 includes a UV LED 110 that emits UV light 111 and / or a blue LED 112 that emits blue light 113. The UV LED 110 and / or the blue LED 112 are covered by a first encapsulation 114 that includes a luminescent material 115. The luminescent material 115 is configured to at least partially convert the UV light 111 and / or the blue light 113 into converted light 116. The white light 105 includes (i) converted light 116; and optionally (ii) unconverted UV light 111 and / or unconverted blue light 113.

[0057] like Figure 1d-1g As shown, the first encapsulation 114 is provided as a continuous layer 117 over at least a portion of the first surface 102 of the carrier 103 and the first LED 104 .

[0058] like Figure 1a-1g As shown, the second linear LED array 106 includes a plurality of groups 118, M in number, each group 118 including a red LED 119a, a green LED 119b, and a blue LED 119c.

[0059] like Figure 1a-1g As shown, M is at least 5, and the first linear LED array 101 includes at least 10 first LEDs 104 .

[0060] like Figure 1d-1g As shown, the second LED 108 is covered by a second package 120, which includes a light scattering material 121 configured to scatter 122 the color controllable light 109 (see also FIG. Figure 3, which is described below). The second encapsulation 120 is provided as a continuous layer 123 over at least a portion of the second surface 107 of the carrier 103 and the second LED 108. The second encapsulation 120 is free of the luminescent material 115.

[0061] like Figure 1a-1g As shown, the carrier 103 is translucent 124 .

[0062] like Figure 1a-1g As described above, first LEDs 104 are equidistantly spaced in first linear array 101 and have a first pitch P1. Second LEDs 108 are equidistantly spaced in second linear array 106 and have a second pitch P2. First pitch P1 is different from second pitch P2. In this example, P1 > P2. The spacing between RGB LEDs in a cluster can be smaller than the spacing between adjacent LEDs in two different clusters (i.e., between adjacent clusters). The resulting effect is improved color mixing.

[0063] like Figure 1a-1g As depicted in , the first white light 105 may have a color temperature in the range from 180K to 2500K.

[0064] Figure 2a-2c A schematic diagram of an LED filament 100 according to an embodiment of the present invention is shown. As depicted in FIG2 , a first linear LED array 101 and a second linear LED array 106 are both arranged on a single flat surface 125. The flat surface 125 is folded (or bent) such that the first linear LED array 101 is arranged on a first surface 102 of a carrier 103, and the second linear LED array 106 is arranged on a second surface 107 of the carrier 103 opposite the first surface 102.

[0065] Figure 3 FIG. 1 is a schematic diagram showing a side view of an LED filament lamp 200 according to an embodiment of the present invention. Figure 3 As shown, the LED filament lamp 200 includes a light-transmitting envelope 126 and a connector 127. The light-transmitting envelope 126 at least partially surrounds the LED filament 100. The connector 127 is arranged to electrically and mechanically connect the LED filament lamp 200 to a socket 128. The LED filament lamp 200 may also include a controller 130 and / or a driver 130' and / or an antenna 130".

[0066] Figure 4 FIG. 2 shows a schematic top view of an LED filament lamp 200 according to an embodiment of the present invention. Figure 4As shown, the second surface 107 of each LED filament 100 is arranged in a direction facing the inside of the light-transmitting envelope 126. Alternatively, the first surface 102 of each LED filament 100 is arranged in a direction facing the inside of the light-transmitting envelope 126. In this way, the spatial spectral light distribution is improved, i.e., more uniform.

[0067] like Figure 3 , a method for controlling an LED filament 100 is shown. The method includes powering a first linear LED array 101 and simultaneously and independently controlling the color and / or color temperature of color-controllable light 109 emitted by a second linear LED array 106. The second linear LED array 106 can be controlled to emit the color-controllable light 109 as a second white light 129. In a first example, the second linear LED array 106 is controlled to emit the second white light 129 having the same color temperature as the first white light 105. The color difference is preferably less than 200K, more preferably less than 150K, and most preferably less than 100K. In a second example, the first white light 105 has a relatively warm color temperature, and the second linear LED array 106 is controlled to emit the second white light 129 having a relatively cool color temperature. The color temperature difference is preferably at least 500K, more preferably at least 600K, and most preferably at least 700K.

[0068] An LED filament typically provides LED filament light and includes a plurality of light-emitting diodes (LEDs) arranged in a linear array. Preferably, the LED filament has a length L and a width W, where L > 5W. The LED filament can be arranged in a straight configuration or 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, such as a substrate, which can be rigid (e.g., made of a polymer, glass, quartz, metal, or sapphire) or flexible (e.g., made of a polymer or metal, such as a film or foil).

[0069] In the case where the carrier comprises a first major surface and an opposing second major surface, the LEDs are arranged on at least one of these surfaces. The carrier may be reflective or translucent, such as translucent and preferably transparent. The LED filament may comprise an encapsulation that at least partially covers at least a portion of the plurality of LEDs. The encapsulation may also at least partially cover at least one of the first major surface or the second major surface. The encapsulation may be a polymer material that may be flexible, such as silicone. Furthermore, the LEDs may be arranged to emit, for example, LED light of different colors or spectra. The encapsulation may comprise a luminescent material that is configured to at least partially convert the LED light into converted light. The luminescent material may be a phosphor, such as an inorganic phosphor and / or quantum dots or rods.

[0070] Those skilled in the art will understand the term "substantially" herein, such as "substantially all light" or "substantially including". The term "substantially" may also include embodiments with "wholly", "completely", "all", etc. Therefore, in an embodiment, the adjective substantially may also be deleted. Where applicable, the term "substantially" may also relate to 90% or higher, such as 95% or higher, particularly 99% or higher, even more particularly 99.5% or higher, including 100%. The term "including" also includes embodiments in which the term "including" means "consisting of". The term "and / or" specifically relates to one or more items mentioned before and after "and / or". For example, the phrase "item 1 and / or item 2" and similar phrases may relate to one or more of item 1 and item 2. The term "including" may refer to "consisting of" in one embodiment, but may also refer to "at least comprising the defined species and optionally one or more other species" in another embodiment.

[0071] Furthermore, the terms first, second, third, etc. in the description and claims are used to distinguish between similar elements and not necessarily to describe 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 apparatus herein is described during operation. It will be clear to those skilled in the art that the present invention is not limited to methods of operation or apparatus in operation.

[0073] It should be noted that the above-described embodiments illustrate rather than limit the invention, and that a person 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. The use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in the 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 different elements and by means of a suitably programmed computer. In a device claim enumerating several means, several of these means may be embodied by the same item of hardware. The fact that certain measures are enumerated in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0074] The invention also applies to an apparatus comprising one or more of the features described in the specification and / or shown in the accompanying drawings. The invention also relates to a method or process comprising one or more of the features described in the specification and / or shown in the accompanying drawings.

[0075] The various aspects discussed in this patent can be combined to provide additional advantages. In addition, those skilled in the art will understand that the embodiments can be combined and more than two embodiments can also be combined. In addition, certain features can form the basis of one or more divisional applications.

Claims

1. A light emitting diode (LED) filament (100) for providing LED filament light (100'), comprising: a first linear LED array (101) arranged on a first surface (102) of a carrier (103), wherein the first linear LED array (101) comprises only first LEDs (104) configured to emit a first white light (105); a second linear LED array (106) arranged on a second surface (107) of the carrier (103), the second surface (107) being opposite to the first surface (102), the second linear LED array (106) comprising only second LEDs (108) configured to emit color-controllable light (109); The LED filament light (100') includes the first white light (105) and the color-controllable light (109), wherein the first LED (104) comprises a UV LED (110) emitting UV light (111) and / or a blue LED (112) emitting blue light (113), the UV LED (110) and / or the blue LED (112) being covered by a first package (114), the first package (114) comprising a luminescent material (115), the luminescent material (115) being configured to at least partially convert the UV light (111) and / or the blue light (113) into converted light (116), wherein the white light (105) comprises (i) the converted light (116) and optionally (ii) unconverted UV light (111) and / or unconverted blue light (113), wherein the first LED (104) has a first pitch (P1), and The second linear LED array (106) includes a plurality of groups (118) of M number, each group (118) including a red LED (119a), a green LED (119b), and a blue LED (119c), wherein the second LEDs (108) have a second pitch (P2), and wherein the first pitch (P1) is different from the second pitch (P2).

2. The LED filament (100) according to claim 1, wherein the first encapsulation (114) is provided as a continuous layer (117) over the first LED (104) and over at least a portion of the first surface (102) of the carrier (103).

3. The LED filament (100) according to claim 1 or 2, wherein M is at least 5, and the first linear LED array (101) comprises at least 10 first LEDs (104).

4. The LED filament (100) according to claim 1 or 2, wherein the second LED (108) is covered by a second encapsulation (120), the second encapsulation (120) comprising a light scattering material (121), the light scattering material (121) being configured to scatter (122) the color-controllable light (109), wherein the second encapsulation (120) is provided as a continuous layer (123) over the second LED (108) and over at least a portion of the second surface (107) of the carrier (103), wherein the second encapsulation (120) is free of luminescent material (115).

5. The LED filament (100) according to claim 1 or 2, wherein the carrier (103) is translucent (124).

6. The LED filament (100) according to claim 1 or 2, wherein the first LEDs (104) are arranged equidistantly in the first linear LED array (101), and wherein the second LEDs (108) are arranged equidistantly in the second linear LED array (106).

7. The LED filament (100) according to claim 1 or 2, wherein the first white light (105) has a color temperature in the range from 1800K to 2500K.

8. The LED filament (100) according to claim 1 or 2, wherein the first linear LED array (101) and the second linear LED array (106) are both arranged on a same single flat surface (125), the flat surface (125) being folded so that the first linear LED array (101) is arranged on the first surface (102) of the carrier (103), and the second linear LED array (106) is arranged on the second surface (107) of the carrier (103) opposite to the first surface (102).

9. An LED filament lamp (200), comprising at least one LED filament (100) according to any one of the preceding claims, a light-transmitting envelope (126) at least partially surrounding the LED filament (100), and a connector (127) for electrically and mechanically connecting the LED filament lamp (200) to a socket (128).

10. The LED filament lamp (200) according to claim 9, wherein the LED filament lamp comprises a controller configured to individually control power provided to the blue LED, the green LED and the red LED of the second linear LED array and the first linear LED array.

11. The LED filament lamp (200) according to any one of claims 9 to 10, wherein (i) the second surface of each LED filament is arranged in a direction facing the inner side of the light-transmitting envelope, or (ii) the first surface of each LED filament is arranged in a direction facing the inner side of the light-transmitting envelope.

12. A method for controlling an LED filament (100) according to any one of claims 1 to 11, comprising: The first linear LED array (101) is powered, and the color and / or color temperature of the color-controllable light (109) emitted by the second linear LED array (106) is simultaneously and independently controlled.

13. The method of claim 12, wherein the second linear LED array (106) is controlled to emit color-controllable light (109) as a second white light (129).

14. The method of claim 13, wherein the second linear LED array (106) is controlled to emit a second white light (129) having the same color temperature as the first white light (105).

15. The method of claim 13, wherein the first white light (105) has a relatively warm color temperature and the second linear LED array (106) is controlled to emit a second white light (129) having a relatively cool color temperature.

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