Luminescent filament-shaped equipment

Abstract

A light emitting device LED filament (1) configured to emit LED filament light in operation, the LED filament (1) comprising: a phosphor structure (3); a plurality of first LEDs (4) adapted to emit first LED light in operation and arranged below the phosphor structure (3); a plurality of second LEDs (5) adapted, in operation, to emit second LED light, the second LED light being red; a plurality of third LEDs (6) adapted to emit, in operation, third LED light, the third LED light being green light; and a plurality of fourth LEDs (7) adapted, in operation, to emit fourth LED light, the fourth LED light being blue; an electronic circuitry (11) coupled to the plurality of LEDs (4, 5, 6, 7); and an elongated carrier (8) on which the plurality of LEDs (4, 5, 6, 7) are arranged on a first major surface (81), where the phosphor structure (3) comprises a phosphor adapted to generate cold white (CW) light and a phosphor adapted to generate warm white (WW) light, and where the first LED lamp comprises or is light at a wavelength of 405 nm, and the phosphor structure (3) is configured to be excited using only light at a wavelength of 405 nm.

Description

Technical Field

[0001] The present invention relates to a light emitting device LED filament, which is configured to emit LED filament light during operation, and the LED filament includes: a phosphor structure; a plurality of first LEDs, which are suitable for emitting first LED light during operation and are arranged below the phosphor structure; a plurality of second LEDs, which are suitable for emitting second LED light during operation and are arranged below the phosphor structure, and the second LED light is red light; a plurality of third LEDs, which are suitable for emitting third LED light during operation and are arranged below the phosphor structure, and the third LED light is green light; a plurality of fourth LEDs, which are suitable for emitting fourth LED light during operation and are arranged below the phosphor structure, and the fourth LED light is blue light; an electronic circuit system coupled to the plurality of first LEDs, the plurality of second LEDs, the plurality of third LEDs and the plurality of fourth LEDs; and a slender carrier.

[0002] WO 2022 / 207603A1 discloses an LED filament lamp, wherein the filament has a first LED filament side, a second LED filament side, an intermediate layer and a plurality of light sources. The plurality of light sources include: a first light source for generating a first white light having a first correlated color temperature CCT1 and being associated with the first filament side; and a second light source for generating a second white light having a second correlated color temperature and being associated with the first filament side, wherein CCT2-CCT1≥500K. The plurality of light sources also include: a third light source for generating a blue third light and being associated with the second filament side; a fourth light source for generating a green fourth light and being associated with the second filament side; and a fifth light source for generating a red fifth light and being associated with the second filament side. The intermediate layer is configured between at least a portion of the first LED filament side and at least a portion of the second LED filament side.

[0003] US2020 / 3553331A discloses a light emitting system, wherein an LED emits a first radiation, the first radiation being characterized by a first wavelength in the range of 390nm-430nm, a first wavelength conversion material being used to convert a portion of the first radiation into a second radiation, the second radiation being characterized by a second wavelength in a second range of about 500nm to about 600nm, a second wavelength conversion material being used to convert a portion of the first radiation into a third radiation, the third radiation being characterized by a third wavelength in a third range of about 600nm to about 700nm. The spectrum has an R9 of at least 80, and is characterized by a violet portion of the spectral power distribution of at least 0.10.

[0004] As used herein, the terms "light emitting device" and "LED" are intended to cover LED packages, LED dies, and bare LEDs.

[0005] As used herein, warm white (WW) light is intended to refer to light having a color temperature in the range of 2000K to 3300K.

[0006] As used herein, cool white (CW) light is intended to refer to light having a color temperature in the range of 3300K to 5300K.

[0007] As used herein, white light similar to daylight is intended to refer to light having a color temperature in the range of 5300K to 7000K or 5300K to 6500K. Background Art

[0008] One current trend in lighting is the use of LED filament lamps. An LED filament lamp is an LED lamp that includes an LED filament and is designed to resemble a traditional incandescent bulb with a visible filament for aesthetic and light distribution purposes, but with the high efficiency of a light emitting diode.

[0009] The LED filament provides LED filament light, comprising 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>5W. The LED filament may be arranged in a straight configuration or a non-straight configuration, such as a bent configuration, a 2D / 3D spiral or a helix. Preferably, the LEDs are arranged on an elongated carrier, such as a carrier, which may 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).

[0010] In case the carrier comprises a first main surface and an opposite second main surface, the LEDs are arranged on at least one of these surfaces.The carrier may be reflective or light transmissive, such as translucent, preferably transparent.

[0011] The LED filament may include 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 and the second major surface. The encapsulation may be a polymer material, which may be flexible, such as silicone. In addition, the LED may be arranged to emit, for example, LED light of different colors or spectra. The encapsulation may include 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.

[0012] An LED filament may include multiple sub-filaments.

[0013] Known tunable white filament lamps consist of at least two filaments, one with a low correlated color temperature (CCT) and the other with a high CCT. Sometimes a single filament is used that combines low CCT and high CCT emission.

[0014] WO2021 / 018646A1 discloses an LED filament comprising a linear array of LEDs arranged on a carrier substrate, wherein the linear array is divided into two independent longitudinal sections, the first longitudinal section only comprising LEDs configured to emit white light, and the second longitudinal section only comprising LEDs configured to emit color-controllable light. It is suggested to confine the colored LEDs to the second longitudinal section of the array so that the first longitudinal section of the array can emit uniform white light with a color temperature within the range of the LEDs in the section.

[0015] When color needs to be added to make a full-color light-emitting diode (LED) filament lamp, the colored LEDs can be added to the lamp as separate filaments. This is generally not preferred because it results in an unsightly appearance. Alternatively, the colored LEDs can be placed on the same surface of the filament substrate, i.e., together with the white LEDs. However, if the RGB LED and white LED filament strings are formed on the same printed circuit board (PCB) or flexible printed circuit (FPC) surface of the filament, unwanted light crosstalk may occur between the RGB LED filament strings and the white LED filament strings, in addition to crosstalk between the cool white (CW) and warm white (WW) LED filament strings. This crosstalk will significantly reduce the color gamut produced by the filament in a clear bulb. For example, when a direct blue LED emits light, it will be absorbed by the red-yellow phosphor layer placed on top of the white LED filament string and will cause an unwanted conversion, thereby producing unwanted red-yellow light. This unwanted red-yellow light emission will cause the filament color point to shift from pure blue to a less saturated color point. This desaturated color appearance is undesirable for color-tunable lamps, especially for demanding color-tunable lamps with a white ambience.

[0016] Furthermore, saturated colors (especially blue) cannot be produced using filament lamps, because direct emitters (LEDs) are covered using phosphors or phosphor mixtures. Blue light will excite some yellow / green-red phosphors, resulting in a very unsaturated blue. However, phosphors are needed to produce cool and warm white light with high light quality.

[0017] One problem with high quality white light and high color rendering index (CRI) on the black body locus (BBL) is that green light contribution is required to produce intermediate correlated color temperature (CCT) white light (color temperature between 2200K and 4500K) on the BBL next to CW (color temperature of 4500K or higher or 3300K or higher) and WW light (color temperature of about 2200K or between 2000K and 3300K) on the BBL. This is detrimental to the look and feel of the filament because when viewing the filament, there is no measure to see the green emitting LED next to the white emitting channel, resulting in a cheap, low quality image.

[0018] Therefore, there is a need to provide a WW-CW filament lamp that is capable of producing high quality white light within the black body locus (BBL) and having a high color rendering index (CRI) during operation.

[0019] Further, more specifically, it is desirable to provide a 5-channel (RGB WW-CW) filament lamp that can produce saturated colors (red, green and blue) and high quality white light with high CRI in the BBL during operation. Summary of the invention

[0020] Therefore, an object of the present invention is to overcome the above problems and to provide a WW-CW filament lamp which, in operation, can produce high quality white light within the black body locus (BBL) and has a high color rendering index (CRI).

[0021] Further, more particularly, it is desirable to provide a 5-channel (RGB WW-CW) filament lamp that can produce saturated colors (red, green and blue) and high quality white light with high CRI in the BBL when in operation.

[0022] It would also be desirable to provide a filament lamp that has improved color uniformity when emitting multiple colors and, therefore, has a high color gamut and improved filament aesthetics.

[0023] According to a first aspect of the present invention, this object and other objects are achieved by a light emitting device LED filament, which is configured to emit LED filament light in operation, and the LED filament includes: a phosphor structure; a plurality of first LEDs, which are suitable for emitting first LED light in operation, and the plurality of first LEDs and the phosphor structure are arranged relative to each other in the following manner: the phosphor structure receives the first light in operation; a plurality of second LEDs, which are suitable for emitting second LED light in operation, the second LED light is red light, and the plurality of second LEDs and the phosphor structure are arranged relative to each other in the following manner: the phosphor structure receives the second light in operation; a plurality of third LEDs, which are suitable for emitting third LED light in operation, the third LED light is green light, and the plurality of third LEDs and the phosphor structure are arranged relative to each other in the following manner: the phosphor structure receives the third light in operation; a plurality of fourth LEDs, which are suitable for emitting fourth LED light in operation, the fourth LED light is blue light, and the plurality of fourth LEDs and the phosphor structure are arranged relative to each other in the following manner: The phosphor structure receives a fourth light in operation; an electronic circuit system coupled to a plurality of first LEDs, a plurality of second LEDs, a plurality of third LEDs, and a plurality of fourth LEDs; and an elongated carrier, the plurality of first LEDs, the plurality of second LEDs, the plurality of third LEDs, and the plurality of fourth LEDs being arranged on a first major surface of the elongated carrier, wherein the phosphor structure includes at least one of the following items: a phosphor suitable for producing cool white (CW) LED filament light, a phosphor suitable for producing warm white (WW) LED filament light in combination with one or more of the second LED light, the third LED light, and the fourth LED light, wherein the phosphor structure is configured to convert less than 10% of the second light, the third light, and the fourth light, and wherein the first LED light includes or is light with a peak wavelength in the range of 380nm-440nm or 380nm–420nm or 380nm-410nm or 400nm-410nm or 405nm, and the phosphor structure is configured to be excited by light with a wavelength corresponding to the wavelength of the first light. In an embodiment, the phosphor structure is configured to convert less than 7%, preferably less than 5%, more preferably less than 2% of the second LED light, the third LED light and the fourth LED light.

[0024] This phosphor structure is used to produce cool white light and warm white light with high light quality. Since the phosphor structure is not excited by blue light (~450nm) or is only excited to a relatively low degree, the direct blue channel (i.e., the fourth light emitted by the plurality of fourth LEDs) will be transmitted through the phosphor layer and not converted. Therefore, when the plurality of first LEDs are in operation and emit the first light, the phosphor structure is excited and they will emit white light together. When one (or more) of the second LED, the third LED and the fourth LED (red LED, green LED and blue LED) dies are in operation and emit LED light, the red LED light, the green LED light and / or the blue LED light will be transmitted through the phosphor structure without generating (undesired) emission. Therefore, using the LED filament as described above according to the present invention, white light with good quality and LED filament light with saturated color can be provided. In addition, the phosphor will scatter the red LED light, the green LED light and / or the blue LED light, thereby enhancing the color uniformity of the LED filament light and improving or increasing the color gamut of the LED filament light. The term "phosphor" may refer to a single phosphor material or a combination of two or more phosphor materials.

[0025] It is worth noting that, in addition to the peak wavelength of the first LED light mentioned above, in an embodiment, it is ensured that the difference between the peak wavelength of the fourth LED light or the blue light and the peak wavelength of the first LED light is greater than 40nm, greater than 45nm or greater than 50nm. In view of the fact that the peak wavelength of the fourth LED light is usually about 460nm in practice, the maximum peak wavelength of the first LED light should be less than 410nm. In an embodiment, the first LED is adapted to emit a first LED light with a peak wavelength of 405nm in operation.

[0026] Therefore, especially if combined with a green LED under the phosphor structure, the conversion percentage of the green light (such as the above-mentioned plurality of third LEDs) by the phosphor structure can be more relaxed, and in particular it no longer needs to be less than 5%, because saturated green is not required to follow the BBL. Therefore, it is thereby possible to provide a WW-CW filament lamp which, in operation, produces high quality white light within the black body locus (BBL) and a high color rendering index (CRI).

[0027] In one embodiment, the first LED is adapted to emit first LED light having a peak wavelength within ±2 nm, ±5 nm, ±10 nm or ±20 nm of 405 nm in operation.

[0028] Using a first light with a peak wavelength within ±2nm, ±5nm, ±10nm or ±20nm of 405nm, or preferably at or above 405nm, provides the following advantages: in the event that some first light leaks through the phosphor layer (this light is barely visible), it may excite some optical brighteners, for example, in fabric or paper, resulting in better white perception (crisp white).

[0029] In one embodiment, the plurality of first LEDs, the plurality of second LEDs, the plurality of third LEDs, and the plurality of fourth LEDs are arranged in a sequence of the first LED followed by a group including the second LED, the third LED, and the fourth LED.

[0030] Such a group comprising the second LED, the third LED and the fourth LED is also referred to as a red green blue group or RGB group. The order of the three LEDs in the RGB group may be, for example, RGB or BRG or any other suitable order.

[0031] Thus, a WW-CW LED filament is obtained which, in operation, can produce high quality white light in the black body locus (BBL) and has a high color rendering index (CRI). In addition, such an LED filament has improved color uniformity when emitting multiple colors, so the aesthetics of the LED filament will also be improved.

[0032] In one embodiment, the LED filament comprises a single single filament string.

[0033] Therefore, a four-channel LED filament with a particularly simple structure is provided.

[0034] In one embodiment, the LED filament includes a first filament string and a second filament string, and the phosphor structure is arranged on the first filament string and the second filament string in the following manner: one of the first filament string and the second filament string includes a phosphor suitable for producing cool white light (CW) in combination with one or more of the second LED light, the third LED light, and the fourth LED light, and the other of the first filament string and the second filament string includes a phosphor suitable for producing warm white light (WW) in combination with one or more of the second LED light, the third LED light, and the fourth LED light.

[0035] Thus, a 5-channel (RGB WW-CW) LED filament is provided which, in operation, produces high quality white light in saturated colors (red, green and blue) and in the black body locus (BBL) and a high color rendering index (CRI).

[0036] In one embodiment, the phosphor adapted to generate WW light comprises a phosphor adapted to generate CW light disposed below the same type of phosphor adapted to generate CW light as the one of the first and second filament strings that comprises the phosphor adapted to generate CW light.

[0037] This enables the LED filament according to the invention to be manufactured using the same production method as chip-on-board (COB) technology. Thus, the manufacture of the LED filament becomes particularly simple.

[0038] In one embodiment, each of the first and second filament strings comprises a plurality of first LEDs adapted to emit a first light in operation, and the plurality of first LEDs and the phosphor structure are arranged relative to each other in such a manner that the phosphor structure receives the first light in operation.

[0039] Thus, high quality and increased intensity white light may be provided in the BBL.

[0040] In one embodiment, each of the first filament string and the second filament string includes: a plurality of second LEDs, which are suitable for emitting a second LED light during operation, the second LED light is red light, and the plurality of second LEDs and the phosphor structure are arranged relative to each other in such a manner that the phosphor structure receives the second light during operation; a plurality of third LEDs, which are suitable for emitting a third LED light during operation, the third LED light is green light, and the plurality of third LEDs and the phosphor structure are arranged relative to each other in such a manner that the phosphor structure receives the third light during operation; and a plurality of fourth LEDs, which are suitable for emitting a fourth LED light during operation, the fourth LED light is blue light, and the plurality of fourth LEDs and the phosphor structure are arranged relative to each other in such a manner that the phosphor structure receives the fourth light during operation.

[0041] This provides an LED filament structure in which the first filament string and the second filament string are substantially identical, thereby resulting in a simplified production process.

[0042] In one embodiment, the first filament string and the second filament string, or the corresponding first LED, second LED, third LED and fourth LED on the first filament string and the second filament string are arranged relative to each other in the following manner: the same LEDs (for example, the corresponding first LEDs) of each filament string are offset relative to each other in the longitudinal direction of the LED filament.

[0043] Thus, a filament lamp is provided which has a still further improved color uniformity and color gamut when emitting multiple colors and thus has improved filament aesthetics.

[0044] In one embodiment, the LED filament includes at least a first filament string and a second filament string, wherein a plurality of first LEDs adapted to emit a first LED light in operation, and a phosphor structure are arranged on the first filament string, and wherein a plurality of second LEDs adapted to emit a second LED light in operation, a plurality of third LEDs adapted to emit a third LED light in operation, and a plurality of fourth LEDs adapted to emit a fourth LED light in operation are arranged on the second filament string.

[0045] Therefore, a five-channel LED filament with a particularly simple structure is provided.

[0046] In one embodiment, the LED filament comprises one or more additional filament strings, wherein an additional plurality of second LEDs adapted to emit a second LED light in operation are arranged on at least one of the one or more additional filament strings, an additional plurality of third LEDs adapted to emit a third LED light in operation are arranged on at least one of the one or more additional filament strings, and an additional plurality of fourth LEDs adapted to emit a fourth LED light in operation are arranged on at least one of the one or more additional filament strings.

[0047] Thus, colored (RGB) light with high saturation and increased intensity is provided.

[0048] In one embodiment, the phosphor is of a type that, when exposed to light, emits in the yellow-red wavelength region and is not excited by light in the green-blue wavelength region.

[0049] In one embodiment, the phosphor structure is of a type that, when exposed to light, emits in one or more of the yellow and red wavelength regions and is not excited by light in one or more of the green and blue wavelength regions.

[0050] In one embodiment, the phosphor structures are of a type that are not excited by light in the blue wavelength region.

[0051] In one embodiment, the phosphor structure is of a type that is not excited by light having a wavelength in the range of 550 nm to 610 nm.

[0052] With any of these embodiments, high quality white light can be provided over a wide CCT range.

[0053] In one embodiment, the phosphor structure comprises at least one phosphor selected from the group consisting of a violet pumped blue (VB) phosphor such as (Sr,Ca,Ba)5(PO4)3Cl:Eu2+, a violet pumped green (VG) phosphor such as (Ba,Sr)MgAl10O17:Mn2+,Eu2+, and a violet pumped red phosphor such as Mg8Ge2O11F2:Mn4+. In a particular embodiment, the phosphor comprises a phosphor of the A3B5O12:Ce type, wherein A in the embodiment comprises one or more of Y, La, Gd, Tb and Lu, in particular (at least) one or more of Y, Gd, Tb and Lu, and wherein B in the embodiment comprises one or more of Al, Ga, In and Sc. In particular, A may comprise one or more of Y, Gd and Lu, such as in particular one or more of Y and Lu. In particular, B may include one or more of Al and Ga, more particularly at least Al, such as substantially all Al. Thus, a particularly suitable phosphor is a cerium-containing garnet material.

[0054] These are particularly suitable yellow / green / red phosphors which exhibit low (royal) blue absorption.

[0055] In one embodiment, the phosphor structure comprises at least one phosphor selected from the group consisting of: a quantum dot material having violet absorption and green, yellow or orange / red emission.

[0056] These are particularly suitable yellow / green / red quantum dot-type phosphors, which exhibit low absorption of (royal) blue light.

[0057] In one embodiment, the LED filament further comprises an encapsulation body at least partially surrounding the plurality of LEDs and providing an elongated carrier.

[0058] Thus, a particularly robust and durable LED filament is provided.

[0059] In one embodiment, at least one of the phosphor adapted to produce CW light and the phosphor adapted to produce WW light forms part of the package.

[0060] Therefore, a particularly simple and compact LED filament is provided.

[0061] In one embodiment, the package further comprises a translucent material.

[0062] The invention also relates to a luminaire or a lamp comprising a light emitting device according to the invention.

[0063] The term "blue light" or "blue emission" particularly relates to light with a wavelength in the range of about 440nm-495nm (including some violet and cyan). The term "green light" or "green emission" particularly relates to light with a wavelength in the range of about 495nm-570nm. The term "yellow light" or "yellow emission" particularly relates to light with a wavelength in the range of about 570nm-590nm. The term "orange light" or "orange emission" particularly relates to light with a wavelength in the range of about 590nm-620nm. The term "red light" or "red emission" particularly relates to light with a wavelength in the range of about 620-nm780nm. The term "pink light" or "pink emission" refers to light with blue and red components. The term "cyan" may refer to one or more wavelengths selected from the range of about 490nm-520nm. The term "amber" may refer to one or more wavelengths selected from the range of about 585nm-605nm, such as about 590nm-600nm. The phrase "light having one or more wavelengths within a wavelength range" and similar phrases may particularly denote that the indicated light (or radiation) has a spectral power distribution having at least an intensity at these one or more wavelengths within the indicated wavelength range. For example, a blue emitting solid state light source will have a spectral power distribution having an intensity at one or more wavelengths within the wavelength range of 440nm-495nm.

[0064] It is noted that the invention relates to all possible combinations of features recited in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiments of the invention.

[0066] Figure 1 A top view of a first embodiment of a light emitting device according to the present invention is shown.

[0067] Figure 2 A top view of a second embodiment of a light emitting device according to the present invention is shown.

[0068] Figure 3 Shown according to Figure 2 Cross-sectional side view of a light emitting device.

[0069] Figure 4 A top view is shown of a third embodiment of a light emitting device according to the present invention.

[0070] Figure 5 Shown are graphs illustrating the emission and excitation spectra of some yellow / green / red phosphors with low (royal) blue absorption by normalized intensity as a function of wavelength.

[0071] Figure 6Graphs illustrating the emission and excitation spectra of some yellow / green / red quantum dot (QD) type phosphors with low (royal) blue absorption are shown by normalized intensity as a function of wavelength.

[0072] Figure 7 A schematic cross-sectional side view of a lamp comprising a light emitting device according to the invention is shown.

[0073] As shown in the figures, the sizes of various layers and regions are exaggerated for illustrative purposes, and thus are provided to illustrate the general structure of an embodiment of the present invention. The same reference numerals in the figures represent the same elements. DETAILED DESCRIPTION

[0074] The present invention will be described more fully below with reference to the accompanying drawings, in which the currently preferred embodiments of the present invention are shown. However, the present invention can be implemented in many different forms and should not be construed as being limited to the embodiments described herein; on the contrary, these embodiments are provided to be comprehensive and complete and to fully convey the scope of the present invention to those skilled in the art.

[0075] Figure 1 A top view of an embodiment of a light emitting device LED filament 1 according to the invention is shown. Generally, regardless of the embodiment, the LED filament 1 comprises a filament string 2 comprising a phosphor structure 3 and a plurality of first LEDs 4 .

[0076] It is worth noting that the concept of the present invention described in this article, i.e., reducing the crosstalk between blue light and phosphor by using a phosphor that is not excited by blue light, is not limited to being applicable to light-emitting devices having a filament shape, but can also be applicable to light-emitting devices such as chip on board (COB), LED light strips or other suitable shapes.

[0077] The first LED 4 is adapted to emit a first LED light in operation. The first LED light includes or is light with a wavelength of 405 nm. The first LED 4 may be adapted to emit a first LED light with a peak wavelength of 405 nm in operation. The first LED 4 may be adapted to emit a first LED light with a peak wavelength within a range of 405 nm (e.g., ±2 nm, ±5 nm, ±10 nm, or ±20 nm) in operation. The first LED 4 and the phosphor structure 3 are arranged relative to each other in the following manner: the phosphor structure 3 receives the first LED light in operation. The phosphor structure 3 is arranged to be in a light receiving relationship with the first LED 4. The first LED 4 is arranged below the phosphor structure 3. The phosphor structure 3 may at least partially cover the first LED 4.

[0078] The LED filament 1 may further comprise a plurality of second LEDs 5. The second LEDs 5 are adapted to emit a second LED light in operation, the second LED light being red light. The second LEDs 5 are red (R) LEDs. The second LEDs 5 and the phosphor structure 3 are arranged relative to each other in such a manner that the phosphor structure 3 receives the second LED light in operation. The phosphor structure 3 is arranged in a light receiving relationship with the second LEDs 5. The second LEDs 5 are arranged below the phosphor structure 3. The phosphor structure 3 may at least partially cover the second LEDs 5.

[0079] The LED filament 1 may further include a plurality of third LEDs 6 adapted to emit a third LED light in operation, the third LED light being green light. The third LEDs 6 are green (G) LEDs. The third LEDs 6 and the phosphor structure 3 are arranged relative to each other in such a manner that the phosphor structure 3 receives the third LED light in operation. The phosphor structure 3 is arranged in a light receiving relationship with the third LEDs 6. The third LEDs 6 are arranged below the phosphor structure 3. The phosphor structure 3 may at least partially cover the third LEDs 6.

[0080] The LED filament 1 may further include a plurality of fourth LEDs 7 adapted to emit fourth LED light in operation, the fourth LED light being blue light. The fourth LEDs 7 are blue (B) LEDs. The fourth LEDs 7 and the phosphor structure 3 are arranged relative to each other in such a manner that the phosphor structure 3 receives the fourth LED light in operation. The phosphor structure 3 is arranged in a light receiving relationship with the fourth LEDs 7. The fourth LEDs 7 are arranged below the phosphor structure 3. The phosphor structure 3 may at least partially cover the fourth LEDs 7.

[0081] Hence, in a broader sense, the first LED 4 may be described as a first LED light adapted to emit, in operation, violet light or UV light.

[0082] In the embodiment shown, three first LEDs 4, three second LEDs 5, three third LEDs 6 and three fourth LEDs 7 are provided. The number of LEDs 4, 5, 6 and 7 can be adjusted to suit the length of the LED filament 1.

[0083] In the illustrated embodiment, the LED filament 1 comprises a filament string 2. Therefore, all LEDs 4, 5, 6 and 7 are arranged on the same filament string 2 of the LED filament 1.

[0084] The LEDs 4, 5, 6 and 7 of the LED filament 1 may be arranged in a sequence of the order of the first LED 4, the second LED 5, the third LED 6 and the fourth LED 7. Alternatively, the LEDs 4, 5, 6 and 7 of the LED filament 1 may be arranged in a sequence of the order of the first LED 4, the fourth LED 7, the second LED 5 and the third LED 6. More generally, the LEDs 4, 5, 6 and 7 of the LED filament 1 may be arranged in a sequence of the first LED 4 followed by a group (i.e., an RGB group) including the second LED 5, the third LED 6 and the fourth LED 7, wherein the three LEDs of the RGB group may be arranged in any suitable order, such as RGB or BRG.

[0085] The LEDs 4, 5, 6 and 7 of the LED filament 1 are arranged on a surface 81 of a carrier 8. Figure 1 Not visible in , but in Figure 3 Surface 81 is a first main surface 81 of carrier 8. Carrier 8 is an elongated carrier 8. Elongated carrier 8 may be a substrate. Elongated carrier 8 or substrate may be a printed circuit board (PCB).

[0086] The electronic circuit system 11 is coupled to the LEDs 4, 5, 6 and 7 to provide power to the LEDs 4, 5, 6 and 7. Figure 1 Not visible in , but in Figure 2 The electronic circuit system 11 may be arranged on or in the elongated carrier 8. The electronic circuit system 11 may include one or more electrical tracks, such as, for example, one electrical track each for the first LED, the second LED, the third LED and the fourth LED.

[0087] The phosphor structure 3 may be, or form part of, an encapsulation 9, which is Figure 3 The encapsulation body 9 at least partially surrounds the LEDs 4, 5, 6 and 7 and the elongated carrier 8. The encapsulation body 9 may also optionally include a translucent material. The translucent material of the encapsulation body 9 may be a polymer, such as a silicone that can withstand high-intensity light and heat. The phosphor structure 3 may be encapsulated by the encapsulation body 9, for example, arranged below the encapsulation body 9 or arranged in the encapsulation body 9 or forming a part of the encapsulation body 9. Alternatively, the phosphor structure 3 may be arranged or provided on top of the encapsulation body 9, for example on an outer surface of the encapsulation body 9.

[0088] Figure 1The LED filament 1 shown is an example of how to make an RGB+white filament according to the present invention. In operation, the first LED 4 plus the phosphor structure 3 are used to provide white LED filament light. The second, third and fourth LEDs 5, 6, 7 can be used to produce LED filament light with different correlated color temperatures (CCT), such as the CCT given by the second blue LED 5 and the phosphor structure 3, and / or to produce colored light with a very large color gamut.

[0089] In operation, when the first LED 4 is turned on, the phosphor structure 3 is excited and the first LED 4 and the phosphor structure 3 will together emit white LED filament light. If one (or more) of the second, third and fourth LEDs 5, 6 and 7 are in operation, the second, third and fourth LED light will be transmitted through the phosphor structure 3 without generating (unwanted) emissions. In this way, an LED filament is provided with which good quality white light as well as saturated colors can be obtained. Furthermore, the phosphor structure 3 will scatter the second, third and fourth LED light, which will enhance the color uniformity of the LED filament light. Figure 1 LED Filament 1 shown is a 4-channel filament.

[0090] The phosphor structure 3 generally and independently of the embodiment includes one or both of a phosphor suitable for producing cold white (CW) light and a phosphor suitable for producing warm white (WW) light, and the phosphor structure 3 is configured to be excited only with light having a wavelength corresponding to the wavelength or wavelength range of the first LED light (e.g., 405 nm). The phosphor structure 3 may also additionally and optionally include a phosphor suitable for producing white light similar to daylight. Generally, it is acceptable that the phosphor structure 3 is suitable for or capable of converting less than, for example, 5% of the light from the second, third, and fourth LEDs 5, 6, 7. For example, in the case where 5% of the blue light (i.e., the fourth LED light) is absorbed and converted by the phosphor structure, the color purity is reduced by about 3% to about 95%, and for 10% absorption and conversion, the color purity is reduced to about 92%. More specifically, a maximum conversion rate of 10%, preferably a maximum conversion rate of 5%, and even more preferably a maximum conversion rate of 2% is acceptable.

[0091] The phosphor structure 3 may be of a type that emits in the yellow-red wavelength range when exposed to light and is not or hardly excited by light in the green-blue wavelength range. The phosphor structure 3 may be of a type that is not or hardly excited by light in the blue wavelength range. The phosphor structure may be of a type that is not or hardly excited by light in the wavelength range of 550nm to 610nm.

[0092] Phosphors suitable for phosphor structure 3 include but are not necessarily limited to the phosphors listed below. Phosphor structure 3 may include one or more of such phosphors. The phosphors listed below are non-limiting examples of phosphors that emit in the yellow-red region and do not (or hardly) use (royal) blue light for excitation. Suitable phosphors include, for example, quantum dot materials with violet light absorption and green, yellow or orange / red emission. Suitable phosphors include, for example, violet pumped blue (VB) phosphors, such as (Sr,Ca,Ba)5(PO4)3Cl:Eu2+, and violet pumped green (VG) phosphors, such as (Ba,Sr)MgAl10 O17:Mn2+, Eu2+, and violet pumped red phosphors, such as Mg8Ge2O11F2:Mn4+.

[0093] Figure 5 The graph of shows the normalized intensity as a function of wavelength for each of the three phosphor materials listed above. Figure 6 The curves of FIG. 1 illustrate the normalized intensity as a function of wavelength for three different quantum dot materials that emit green, yellow, and orange / red light, respectively. In the graphs, the abbreviation "EXC" represents the excitation spectrum of the material, and the abbreviation "EMI" represents the emission spectrum of the material. Figure 5 and Figure 6 The curve of illustrates a phosphor material which emits in the yellow-red region and is not or hardly excited by (royal) blue light.

[0094] Now go to Figure 2 , shows a top view of a light emitting device LED filament 100 according to another embodiment of the present invention. Figure 3 A cross-sectional side view of an LED filament 100 is shown. Figure 2 The LED filament 100 is similar to the above-mentioned Figure 1 The LED filament is different.

[0095] The LED filament 100 includes a first filament string 2a and a second filament string 2b. The phosphor structure 3 is arranged on the first filament string 2a and the second filament string 2b. The phosphor structure 3 includes two parts 3a and 3b. One of the parts 3a, 3b (part 3a in the illustrated embodiment) includes a phosphor suitable for generating cool white (CW) light. The other of the parts 3a, 3b (part 3b in the illustrated embodiment) includes a phosphor suitable for generating warm white (WW) light. Therefore, one of the first filament string 2a and the second filament string 2b (the first filament string 2a in the illustrated embodiment) includes a phosphor suitable for generating cool white (CW) light, and the other of the first filament string 2a and the second filament string 2b (the second filament string 2b in the illustrated embodiment) includes a phosphor suitable for generating warm white (WW) light.

[0096] The phosphor suitable for generating WW light (here included by the second part 3b of the phosphor structure 3) may in this embodiment include a red phosphor arranged below the phosphor suitable for generating CW light, wherein the phosphor suitable for generating CW light is of the same type as the phosphor suitable for generating CW light included by the first part 3a of the phosphor structure 3.

[0097] The first filament string 2a and the second filament string 2b may each include a first, second, third and fourth LED 4, 5, 6, 7, which are arranged in the same manner as described above. Figure 1 In addition, the first filament string 2a and the second filament string 2b (or the corresponding LEDs 4, 5, 6, 7 on the first filament string 2a and the second filament string 2b) can be arranged relative to each other in such a way that the same LEDs (e.g., the first LED 4) of each filament string are arranged offset from each other in the longitudinal direction L of the filament strings 2a, 2b.

[0098] Alternatively, a plurality of first LEDs 4 adapted to emit a first LED light during operation may be arranged on the first filament string 2a, and a plurality of second LEDs 5 adapted to emit a second LED light during operation, a plurality of third LEDs 6 adapted to emit a third LED light during operation, and a plurality of fourth LEDs 7 adapted to emit a fourth LED light during operation may be arranged on the second filament string 2b.

[0099] In either case, an LED filament 100 having more than two filament strings may be provided, wherein the LEDs are arranged as described in any of the above variations. Figure 4 , shows a top view of a light emitting device LED filament 101 according to yet another embodiment of the present invention.

[0100] Figure 4 The LED filament 101 is similar to the above-mentioned Figure 1-Figure 3 The LED filaments described are different.

[0101] The LED filament 101 includes a filament string 2 in any of the above embodiments. Figure 4 In the example, it is shown that Figure 1 The filament string 2 of the illustrated embodiment.

[0102] The LED filament 101 includes one or more additional filament strings, and three additional filament strings 2d, 2e and 2f are shown in the embodiment. On the additional filament string 2d, a plurality of additional second LEDs 5a are arranged, which are suitable for emitting a second LED light in operation. On the additional filament string 2e, a plurality of additional third LEDs 6a are arranged, which are suitable for emitting a third LED light in operation. On the additional filament string 2f, a plurality of additional fourth LEDs 7a are arranged, which are suitable for emitting a fourth LED light in operation.

[0103] therefore, Figure 4 An embodiment is shown, in which according to the above Figure 1-Figure 3 The LED filament 1, 101 of any of the described embodiments may be used with blue, green and red LEDs 5, 6, 7 arranged on separate filaments or filament strings 2d, 2e, 2f.

[0104] It is worth noting that in Figure 4 In the embodiment shown, each of the additional filament strings 2d-2f includes only one of the additional second, third and fourth LEDs 5a-7a. In other variations, each of the additional filament strings 2d-2f may include two or more of the additional second, third and fourth LEDs 5a-7a, such as, for example, an RGB group. Combinations thereof are also possible. In yet another variation, only the first LED 4 may be arranged on the filament string 2.

[0105] at last, Figure 7 An exemplary lamp 12 is shown that includes an LED filament 1 according to any embodiment of the present invention. In the embodiment shown, the LED filament 1 is a substantially straight LED filament. The LED filament 1 of such a lamp may be an LED filament having other shapes in other embodiments, such as, but not limited to, spiral, helical, meandering, twisted, flat, and combinations thereof.

[0106] The lamp 12 also includes a driver or controller 17 configured to control the LED filament light source of the LED filament 1. The controller 17 is configured to power the plurality of LEDs 20 through the electronic circuit system 21 of the LED filament 1. The controller 17 may also be configured to control at least one of the CCT of the LED filament light source light and the CRI of the LED filament light source light. The controller 17 may also be configured to control other parameters related to the LED filament light source and the LED filament light source light.

[0107] The lamp 12 further comprises a housing 13 which at least partially surrounds the at least one LED filament 1. The lamp 12 further comprises a cap 14. Figure 7As shown, the controller 17 is arranged within the housing 13. When the cap 14 is included, the controller 17 can also be arranged within the cap 14 such that it is hidden from sight. The lamp 12 also includes a thread 15 for connection to a socket and a terminal 16 for connection to an electrical energy source.

[0108] The housing 13 of the lamp 12 can also optionally be provided with a coating 18, such as a reflective coating, covering at least a portion of the housing 13.

[0109] Those skilled in the art will recognize that the present invention is not limited to the above preferred embodiments. On the contrary, many modifications and variations can be made within the scope of the appended claims.

[0110] In addition, those skilled in the art, in practicing the claimed invention, can understand and implement modifications to the disclosed embodiments by studying the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The 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.

Claims

1. A light emitting device LED filament (1), configured to emit LED filament light during operation, the LED filament include: Phosphor structure (3), a plurality of first LEDs (4) adapted to emit a first LED light in operation, the plurality of first LEDs (4) and the phosphor structure (3) being arranged relative to each other in such a way that the phosphor structure receives the first LED light in operation, a plurality of second LEDs (5) adapted to emit second LED light in operation, the second LED light being red light, the plurality of second LEDs (5) and the phosphor structure (3) being arranged relative to each other in such a way that the phosphor structure receives the second LED light in operation, a plurality of third LEDs (6) adapted to emit a third LED light in operation, the third LED light being green light, the plurality of third LEDs (6) and the phosphor structure (3) being arranged relative to each other in such a way that the phosphor structure receives the third LED light in operation, a plurality of fourth LEDs (7) adapted to emit fourth LED light in operation, the fourth LED light being blue light, the plurality of fourth LEDs (7) and the phosphor structure (3) being arranged relative to each other in such a way that the phosphor structure receives the fourth LED light in operation, an electronic circuit system (11) coupled to the plurality of first LEDs, the plurality of second LEDs, the plurality of third LEDs, and the plurality of fourth LEDs, and An elongated carrier (8), the plurality of first LEDs, the plurality of second LEDs, the plurality of third LEDs and the plurality of fourth LEDs being arranged on a first main surface (81) of the elongated carrier (8), wherein The phosphor structure (3) comprises at least one of the following: a phosphor suitable for producing cool white CW light; and a phosphor suitable for producing warm white WW light in combination with one or more of the second LED light, the third LED light and the fourth LED light, The phosphor structure (3) is configured to convert less than 10% of the second LED light, the third LED light and the fourth LED light, and wherein The first LED light comprises light having a peak wavelength in the range of 380nm to 440nm, or in the range of 380nm to 410nm, or in the range of 400nm to 410nm, or in the range of 405nm, or the first LED light is light having a peak wavelength in the range of 380nm to 440nm, or in the range of 380nm to 410nm, or in the range of 400nm to 410nm, or in the range of 405nm, and the phosphor structure (3) is configured to be excited by light with a wavelength corresponding to the wavelength of the first light.

2. The LED filament according to claim 1, wherein the plurality of first LEDs (4), the plurality of second LEDs (5), the plurality of third LEDs (6) and the plurality of fourth LEDs (7) are arranged in a sequence of a first LED followed by a group including a second LED, a third LED and a fourth LED.

3. The LED filament according to any one of claims 1 or 2, wherein the LED filament (1) comprises a single filament string (2).

4. The LED filament according to claim 1 or 2, wherein the LED filament (100, 101) comprises a first filament string (2a) and a second filament string (2b), and wherein the phosphor structure (3) is arranged on the first filament string and the second filament string in the following manner: one of the first filament string and the second filament string comprises a phosphor suitable for generating cool white CW light in combination with one or more of the second LED light, the third LED light and the fourth LED light, and the other of the first filament string and the second filament string comprises a phosphor suitable for generating warm white WW light in combination with one or more of the second LED light, the third LED light and the fourth LED light.

5. The LED filament according to claim 4, wherein the phosphor suitable for generating WW light comprises a red phosphor, and the red phosphor is arranged below the phosphor suitable for generating CW light having the same type as the phosphor suitable for generating CW light included in one of the first filament string (2a) and the second filament string (2b) having the phosphor suitable for generating CW light.

6. An LED filament according to claim 4 or 5, wherein each of the first filament string (2a) and the second filament string (2b) comprises a plurality of first LEDs (4), the plurality of first LEDs (4) being adapted to emit a first light in operation, the plurality of first LEDs (4) and the phosphor structure (3) being arranged relative to each other in such a way that the phosphor structure receives the first light in operation.

7. The LED filament according to any one of claims 4 to 6, wherein each of the first filament string (2a) and the second filament string (2b) include: A plurality of second LEDs (5), wherein the plurality of second LEDs (5) are adapted to emit second LED light during operation, wherein the second LED light is red light, and wherein the plurality of second LEDs (5) and the phosphor structure (3) are arranged relative to each other in such a manner that the phosphor structure receives the second light during operation; a plurality of third LEDs (6), wherein the plurality of third LEDs (6) are adapted to emit third LED light during operation, wherein the third LED light is green light, and wherein the plurality of third LEDs (6) and the phosphor structure (3) are arranged relative to each other in such a manner that the phosphor structure receives the third light during operation; and a plurality of fourth LEDs (7), wherein the plurality of fourth LEDs (7) are adapted to emit fourth LED light during operation, wherein the fourth LED light is blue light, and wherein the plurality of fourth LEDs (7) and the phosphor structure (3) are arranged relative to each other in such a manner that the phosphor structure receives the fourth light during operation.

8. The LED filament according to claim 1 or 2, wherein the LED filament comprises at least a first filament string (2a) and a second filament string (2b), wherein The plurality of first LEDs (4) adapted to emit first LED light in operation, and the phosphor structure are arranged on the first filament string (2a), and wherein The plurality of second LEDs (5) adapted to emit a second LED light in operation, the plurality of third LEDs (6) adapted to emit a third LED light in operation, and the plurality of fourth LEDs (7) adapted to emit a fourth LED light in operation are arranged on the second filament string (2b).

9. The LED filament according to any one of the preceding claims 1, 2, 4, 5, 6, 7 and 8, wherein the LED filament (101) comprises one or more additional filament strings (2d, 2e, 2f), and in: a further plurality of second LEDs (5a) adapted to emit a second LED light in operation are arranged on at least one of the one or more further filament strings, A further plurality of third LEDs (6a) adapted to emit a third LED light in operation are arranged on at least one of the one or more further filament strings, and A further plurality of fourth LEDs (7a) adapted to emit fourth LED light in operation are arranged on at least one of the one or more further filament strings.

10. An LED filament according to any one of the preceding claims, wherein the phosphor structure (3) is of a type that, when exposed to light, emits in any one or more of the yellow wavelength region and the red wavelength region, without being excited by light in any one or more of the green wavelength region and the blue wavelength region.

11. The LED filament according to any of the preceding claims, wherein the phosphor structure (3) is of a type that is not excited by light having a wavelength in the blue region.

12. The LED filament according to any of the preceding claims, wherein the phosphor structure (3) is of a type that is not excited by light in the wavelength region of 550 nm to 610 nm.

13. The LED filament according to any one of the preceding claims, wherein the phosphor structure (3) comprises at least one phosphor selected from the group consisting of: Violet-pumped blue (VB) phosphor, (Sr,Ca,Ba)5(PO4)3Cl:Eu2+, Violet-pumped green (VG) phosphor, (Ba,Sr)MgAl10 O17:Mn2+,Eu2+, and Violet-pumped red (VR) phosphor, Mg8Ge2O11F2:Mn4+.

14. The LED filament according to any of the preceding claims, wherein the phosphor structure (3) comprises at least one phosphor selected from the group consisting of: quantum dot material with violet absorption and emission of green, yellow or orange / red light.

15. A lamp or a light (12) comprising an LED filament (1, 100, 101) according to any one of the preceding claims.

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