LED filament lamp

Abstract

An LED filament lamp includes an enclosure having a central axis, a connector attached to the enclosure, and an LED filament assembly disposed within the enclosure and including a plurality of elongated LED filaments, where the LED filament assembly is rotatably disposed about the central axis relative to the connector. A first set of LED filaments is arranged on a first side of the virtual plane intersecting the central axis and has a main illumination direction directed substantially away from the virtual plane. The second group of LED filaments is arranged on the other side of the virtual plane and has a main illumination direction substantially directed towards the virtual plane. By means of the design, light from the two sets of LED lamp filaments is mainly emitted from the same side of the sealing shell, and more specifically, the light is emitted from the side where the LED lamp filaments in the first set are located.

Description

Technical Field

[0001] The present invention relates to an LED filament lamp, ie a lamp comprising an envelope containing a plurality of LED filaments and a connector for mechanical and electrical connection of the lamp. Background Art

[0002] In recent years, LEDs (light emitting diodes) have become the main type of light source in many applications due to their impressive energy efficiency. One example is LED lamps, which have largely replaced incandescent lamps with a heating filament in a hermetically sealed envelope.

[0003] One drawback of LED lamps is that the emitted light can be perceived as different from that of incandescent lamps. Consequently, various efforts have been made to create LED lamps that resemble incandescent lamps. One particular result of these efforts is the LED filament, which consists of multiple LEDs arranged on an elongated carrier and optionally covered by a light-emitting encapsulation. The light emitted from an LED filament is largely similar to the light emitted by the metal wire filament in an incandescent lamp.

[0004] For aesthetic and light distribution purposes, light bulbs with LED filaments (referred to as LED filament lamps) are designed to resemble traditional incandescent light bulbs with one or more visible LED filaments. LED filament lamps have become increasingly popular and are commercially available for both home and commercial use. However, there is a continuing desire to improve the appearance and functionality of these LED filament lamps.

[0005] In some applications, it is desirable to have a lamp with high directionality, that is, a lamp that emits light in a specific direction rather than equally in all directions. Examples of such applications are street lighting and lights in horticulture (e.g., greenhouses). Directionality is usually achieved using reflectors, but with LED filament lamps, other opportunities are also available.

[0006] US2013 / 242580 discloses methods and systems for solid-state lighting devices. In one embodiment, the device includes a solid-state directional light assembly that emits less than omnidirectional light in a directionally oriented manner, a first rotation mechanism, an Edison base that receives the first rotation mechanism, and a second movement mechanism positioned in contact with the light assembly and the first rotation mechanism to provide directional positioning of the light assembly. The first rotation mechanism allows for rotation of the solid-state directional light assembly while maintaining electrical connection through the Edison base. Summary of the Invention

[0007] It is an object of the present invention to provide an LED filament lamp with improved (spatial) light distribution.

[0008] This and other objects are achieved by an LED filament lamp comprising: an enclosure having a central axis; a connector attached to the enclosure, the connector for electrically and mechanically connecting the LED filament lamp to a socket; an LED filament assembly disposed within the enclosure and including a plurality of elongated LED filaments, each LED filament having a plurality of LEDs mounted on a mounting surface of an elongated carrier such that each LED filament has a primary illumination direction substantially perpendicular to the mounting surface and directed away from the plurality of LEDs, wherein the LED filaments are oriented substantially parallel to the central axis about the central axis, wherein the LED filament assembly is rotatably disposed about the central axis relative to the connector, wherein a first group of the LED filaments is disposed on a first side of an imaginary plane intersecting the central axis, wherein each LED filament in the first group has a primary illumination direction directed substantially away from the imaginary plane, and wherein a second group of the LED filaments is disposed on a second side of the imaginary plane opposite the first side, wherein each LED filament in the second group has a primary illumination direction directed substantially toward the imaginary plane.

[0009] With this design, (most) light from both groups of LED filaments will (directly) exit the envelope on the same side, more specifically, the side where the LED filaments in the first group are located. Consequently, substantially all of the light emitted by the lamp will be emitted on one side of the envelope. This LED filament lamp has enhanced directionality, thereby improving light distribution. This can also result in lower reflection losses, for example, due to lower reflections on the reflector in which the LED filament lamp can be arranged.

[0010] The rotatable arrangement of the LED filament assembly ensures that after the lamp is installed in the socket, the LED filament assembly can be rotated to achieve the desired illumination. For example, if the lamp is installed in a street lamp, the LED filament assembly can be rotated so that the LED filament in the LED filament lamp emits light (primarily) toward the street (and not toward a reflector, for example).

[0011] The lamp may include any number of LED filaments, but preferably there are at least two LED filaments in each group, i.e., at least four LED filaments in total. Even more preferably, there are at least five filaments, or even at least six filaments. In another embodiment, the number of LED filaments is less than 10 LED filaments in order to create sufficient openings / open spaces between the LED filaments.

[0012] In one embodiment, the entire enclosure (including the LED filament assembly) can be rotated relative to the connector. Preferably, some kind of locking member is provided to enable a user to secure the enclosure in a desired position.

[0013] In another embodiment, the enclosure is fixed relative to the connector, and the LED filament assembly is rotatable within the enclosure. A suitable rotation mechanism can be provided to enable a user to rotate the LED filament assembly. The rotation mechanism is preferably configured to secure the LED filament assembly to prevent unintentional rotation of the LED filament assembly. Similarly, a locking member can be provided to allow the LED filament assembly to be secured within the enclosure.

[0014] Fixing the LED filament assembly in a desired rotational position may be particularly advantageous where the lamp is subjected to vibrations after installation which cause the LED filaments (or the entire envelope) to move out of their original position. A specific example is a lamp installed in a street lamp.

[0015] Alternatively, or in addition, the LED filament assembly may be freely rotatable and the lamp may include a counterweight configured such that when the lamp is mounted in the socket, the LED filament assembly will rotate until the primary illumination direction (B1, B2) points downwards.

[0016] In one embodiment, there are at least two LED filaments in the first group.The elongated carriers of the at least two LED filaments in the first group may be arranged in parallel.

[0017] In one embodiment, there are at least two LED filaments in the second group.The elongated carriers of the at least two LED filaments in the second group may be arranged in parallel.

[0018] In one embodiment, there are at least two LED filaments in the first group and the second group.The elongated carriers of the LED filaments in the first group may be arranged non-parallel to the LED filaments in the second group.

[0019] In one embodiment, there are at least two LED filaments in a first group and at least two LED filaments in a second group. The elongated carriers of the at least two LED filaments in one or both groups can be arranged in non-parallel planes. This introduces an angular spread between the main illumination directions of the LED filaments in a group. The angular spread in the first and / or second groups is preferably less than 45 degrees, and most preferably less than 20 degrees.

[0020] However, in another embodiment, the main illumination directions of the LED filaments in the second group are parallel, and preferably parallel to the main illumination directions of the LED filaments in the first group. With this design, all LED filaments (in both groups) will have the same main illumination direction.

[0021] In one embodiment, the LED filaments in the second group are oriented so that their main illumination direction intersects the central axis of the envelope. This results in an emission pattern corresponding to a point (or line) light source arranged in the central axis.

[0022] In other embodiments, at least some of the LED filaments in the second group may have a primary illumination direction extending between adjacent LED filaments in the first group. With this design, less light emitted by the LED filaments in the second group will be blocked by the LED filaments in the first group, thereby improving efficiency.

[0023] Possibly, one LED filament in the second group has a main illumination direction that intersects the central axis, and at least two LED filaments in the second group have main illumination directions that do not intersect the central axis.

[0024] In some embodiments, the LED filaments are arranged symmetrically around a central longitudinal axis, i.e., similar to the bullet chamber of a revolver. This results in uniform heat distribution and thus good thermal management.

[0025] In other embodiments, the LED filaments are arranged asymmetrically to provide the desired illumination effect. In one example, the LED filaments are arranged in two groups on opposite sides of the envelope. In other words, the LED filaments in the first group are arranged in a first angular sector of the envelope, while the LED filaments in the second group are arranged in a second angular sector of the envelope opposite the first angular sector. The first and second angular sectors can be less than 120 degrees, or even less than 90 degrees.

[0026] In an embodiment, each LED filament may further include an encapsulant at least partially covering the plurality of LEDs and at least a portion of the mounting surface. The encapsulant may include a light-scattering material configured to scatter at least a portion of light emitted by the plurality of LEDs and / or a luminescent material configured to convert at least a portion of the light emitted by the plurality of LEDs into converted light.

[0027] In an embodiment, the plurality of LEDs may emit blue light (having a peak wavelength in the wavelength range of 420-480 nm). The luminescent materials may be a green-yellow phosphor (eg, YAG) and a red phosphor (eg, KSF).

[0028] In an embodiment, the elongated carrier may be light transmissive, such as translucent, in particular transparent. The encapsulation may also be arranged on the back side of the elongated carrier (opposite the mounting side). The encapsulation on the back side of the elongated carrier may also include luminescent and / or light scattering material. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will now be described in more detail with reference to the accompanying drawings, which show currently preferred embodiments of the invention.

[0030] FIG. 1 a is a perspective view of an LED filament lamp according to a first embodiment of the present invention.

[0031] FIG1 b is a perspective view of an LED filament lamp according to a second embodiment of the present invention.

[0032] Figure 2 is a schematic perspective view of an LED filament that can be used in the present invention.

[0033] Figures 3a to 3e is a cross-section of the lamp in Figure 1 showing different arrangements of the LED filaments. DETAILED DESCRIPTION

[0034] The LED filament lamp 1 in Figure 1 generally comprises a light-transmitting envelope 3 and a connector 2 (sometimes called a "cap"), which is configured to electrically and mechanically connect the lamp to a socket 9, for example, a socket of a lamp. The connector 2 can be connected directly to the envelope, or it can be connected indirectly, that is, there can be an intermediate base between the envelope and the connector. The connector 2 is here a threaded connector that conforms to an existing light bulb socket standard (for example, E27). The envelope 3 can be made of glass or plastic and can be translucent, transparent (clear) or (slightly) diffuse, depending on the desired illumination. The envelope 3 has a central longitudinal axis A, which in the case shown is an axis of symmetry.

[0035] An LED filament assembly 10 comprising a plurality of LED filaments 5, number N, is arranged within the envelope 3. The plurality of LED filaments may comprise at least 4 LED filaments, more preferably at least 5 filaments, most preferably at least 6 LED filaments.

[0036] refer to Figure 2 For the purposes of this disclosure, an LED filament comprises an elongated and generally flat carrier 6 on which a plurality of LEDs 7 are mounted and electrically connected via conductive paths 8 provided on the carrier. Electrical terminals for the connection paths 8 may be provided on only one or both ends of the filament 5.

[0037] The carrier can be made of a rigid material, such as ceramic or metal. Alternatively, it can be made of a flexible material, such as plastic. In this example, the carrier 6 is non-translucent, but a translucent carrier 6 is also possible. The LED (and the carrier) can be covered by a light conversion package 8, which is configured to convert at least a portion of the light emitted from the LED into converted light. For example, the LED can be a blue LED, and the package can include luminescent particles for converting the blue light into white light.

[0038] In the present disclosure, the LED filament has LEDs on only one side of the carrier 6, on the mounting surface 6a. The LEDs 7 and the entire LED filament 5 have a main emission direction B perpendicular to the mounting surface 6a. The side of the carrier opposite the mounting surface can have a highly reflective surface to reduce losses.

[0039] Returning to Figures 1a and 1b, the LED filaments 5 are arranged around a central axis A, similar to the chamber in a revolver. In the illustrated case, the LED filaments 5 are each parallel to the axis A, but they can alternatively be tilted inward (to form a pointed lamp) or outward. The LED filaments 5 can also be tilted to form a spiral indentation. If the LED filaments have a flexible carrier, they can also be curved.

[0040] In the example shown, all LED filaments 5 in the lamp 1 are arranged at a common distance from the inner wall of the envelope 3. For reasons of thermal management, the LED filaments 5 are preferably arranged closer to the inner wall than to the central axis.

[0041] Although not shown in the figures, lamps 1a, 1b include appropriate driver circuitry for driving LED filament 5. Depending on the type and configuration of LED filament 5, various types of drivers may be required / suitable, for example, depending on whether the LED is dimmable. In some cases, the light emitted by the LED filament is controllable, for example, the color or color temperature of the LED filament 5 may be controllable. In this case, lamps 1a, 1b also include appropriate control circuitry and an antenna for wirelessly receiving control signals to adjust, for example, the color or color temperature of the lamp. The LED filament assembly 10 is rotatably arranged relative to the connector 2, so that after the lamp 1 has been securely mounted in the socket 11, the enclosure can be rotated about axis A to a desired position.

[0042] In FIG1a , the enclosure 3 is rotatably fixed relative to the connector 2 , and the LED filament assembly 10 is rotatably arranged within the enclosure 3 . The arrangement 10 can be rotated to a desired position by means of an annular member 4 a . Preferably, the member 4 a is subjected to sufficient friction so that the LED filament assembly 10 does not rotate freely.

[0043] In FIG1 b , the LED filament assembly 10 is fixedly arranged within the capsule 3, and the capsule 3 is instead rotatably attached to the connector 2. In this case, the lamp 1 b also includes a locking member arranged to fix the capsule 3 in the desired position. The locking member is shown here as an annular element 4 b.

[0044] If you will refer to Figures 3a to 3dDiscussed in more detail, the LED filaments 5 are grouped into two groups 51, 52, which are arranged on opposite sides of a virtual plane VP that intersects the central axis A. The first group 51 of LED filaments may include more LED filaments than the second group 52 of LED filaments. The LED filaments 51 in the first group are oriented such that their primary illumination direction faces away from the central axis A (and therefore outside the envelope 3). The LED filaments 52 in the second group are oriented such that their primary illumination direction B2 faces toward the central axis A (and therefore into the envelope 3). Since these groups are positioned relative to each other, this means that light from both groups is emitted on the same side of the envelope and generally in the same direction.

[0045] Will refer to Figures 3a to 3d Discuss various possible layouts of LED filaments 51 and 52. Figures 3a to 3d A lamp with six LED filaments is shown.

[0046] exist Figure 3a In the example, LED filaments 51 and 52 are distributed symmetrically around the central axis A. In other words, for a total of N LED filaments 51 and 52, the angular spacing will be 360 / N degrees. The mounting surfaces 6a of the LED filaments 51 in the first group face radially outward from the axis A, while the mounting surfaces 6a of the LED filaments 52 in the second group face radially inward. Therefore, all principal directions of illumination B1 and B2 are aligned with a radius of the axis A, and the principal direction of illumination B2 of the LED filament 52 will therefore intersect the axis A.

[0047] exist Figure 3b In the example shown, the LED filaments 51 and 52 are again evenly distributed around the axis A. However, in this case, all LED filaments 51 and 52 do not have radially aligned main illumination directions B1 and B2. Instead, the outer LED filaments 51a in the first group are slightly bent inward, resulting in a reduced angular spread of the LED filaments 51 (a more collimated main illumination direction). Similarly, the outer LED filaments 52a in the second group are slightly bent outward, resulting in a reduced angular spread of the LED filaments 52. In the example shown, the angular spread of both groups is approximately 45 degrees.

[0048] like Figure 3c As shown, the outer LED filaments 52a in the second group are oriented so that the main illumination direction extends between adjacent LED filaments 51 in the first group. Therefore, less light will be reflected by the back side of the LED filaments 51, thereby improving efficiency.

[0049] exist Figure 3dIn the embodiment shown, LED filaments 51, 52 are not evenly distributed around axis A. Instead, LED filaments 51 in a first group are arranged closer together in a first angular sector 53, while LED filaments 52 in a second group are arranged in a second angular sector 54. In the illustrated case, sectors 53, 54 are limited to just over 90 degrees. The arrangement of the LED filaments in limited angular sectors 53, 54 results in a separation of the two groups, thereby allowing for a more pronounced light directionality.

[0050] exist Figures 3a to 3d In the embodiment, the LED filaments 51, 52 (the carriers thereof) in each group are arranged in non-parallel planes, i.e., the main illumination directions B1, B2 in each group are non-parallel within the group. In the illustrated example, the angular spread within each group is less than 45 degrees, and may be less than 20 degrees.

[0051] exist Figure 3e In the different embodiments shown, the LED filaments 51, 52 are arranged in parallel planes so that the main illumination directions B1, B2 are parallel in each group. Figure 3e In the embodiment, the LED filaments 51 and 52 in the two groups are also arranged in parallel planes relative to each other, so that B1 and B2 are parallel, but this is not required. The LED filaments 51 and 52 in the two groups can be shifted relative to each other so that the main emission direction B2 of the filaments in the second group extends between adjacent LED filaments 51 in the first group.

[0052] A person skilled in the art realizes that the present invention is by no means limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, the shape and form of the enclosure and the connector may be different. In addition, Figure 3a Other alternative arrangements of LED filaments than those shown in 3e are possible.

Claims

1. An LED filament lamp (1), comprising: a capsule (3) having a central axis (A); a connector (2) attached to the enclosure for electrically and mechanically connecting the LED filament lamp to a socket (11); An LED filament assembly (10) is arranged within the enclosure and comprises a plurality of elongated LED filaments (5; 51, 52); each LED filament having a plurality of LEDs (7) mounted on a mounting surface (6a) of an elongated carrier (6), such that each LED filament has a main illumination direction (B) directed substantially perpendicular to the mounting surface and away from the plurality of LEDs, wherein the LED filaments are oriented around the central axis (A), and each LED filament is oriented substantially parallel to the central axis, wherein the LED filament assembly (10) is rotatably arranged relative to the connector (2) around the central axis (A), wherein a first group of LED filaments (51) is arranged on a first side of a virtual plane (VP) intersecting the central axis, wherein each LED filament (51) in the first group has a main illumination direction (B1) pointing substantially away from the virtual plane (VP), and A second group of LED filaments (52) is arranged on a second side of the virtual plane (VP) intersecting the central axis and opposite to the first side, wherein each LED filament (52) in the second group has a main illumination direction (B2) pointing generally toward the virtual plane.

2. The LED filament lamp according to claim 1, wherein the LED filament assembly (10) is rotatably fixed in the enclosure (3), and the enclosure (3) is rotatably arranged relative to the connector (2).

3. The LED filament lamp according to claim 1, wherein the capsule is fixed to the connector (2), and the LED filament assembly (10) is rotatably arranged in the capsule (3), and the LED filament lamp further comprises a rotating element (4a), and the rotating element (4a) is configured to allow a user to rotate the LED filament assembly (10) relative to the connector (2) and the capsule (3).

4. The LED filament lamp (1) according to claim 2 or 3, further comprising a locking member (4a, 4b), wherein the locking member (4a, 4b) is configured to fix the orientation of the LED filament assembly (10) relative to the connector (2).

5. The LED filament lamp according to any one of the preceding claims, wherein the LED filament assembly (10) is freely rotatable, and wherein the lamp further comprises a counterweight, the counterweight being configured such that when the lamp is mounted in a socket, the LED filament assembly (10) will rotate until the main illumination direction (B1, B2) points downwards.

6. The LED filament lamp according to any one of the preceding claims, comprising at least two LED filaments (51) in the first group and at least two LED filaments (52) in the second group, wherein the elongated carriers (6) of the at least two LED filaments in the first group are arranged in non-parallel planes, and wherein the elongated carriers of the at least two LED filaments in the second group are arranged in non-parallel planes.

7. The LED filament lamp according to claim 6, wherein the angular spread of the main illumination direction of the LED filaments (51) in the first group and / or the LED filaments (52) in the second group is less than 45 degrees, preferably less than 20 degrees.

8. The LED filament lamp according to any one of the preceding claims, wherein each LED filament in the second group has a main illumination direction intersecting the central axis.

9. The LED filament lamp according to any one of the preceding claims, wherein all LED filaments are arranged in parallel planes perpendicular to the virtual plane.

10. The LED filament lamp according to any one of the preceding claims, wherein at least some of the LED filaments in the second group have a main illumination direction extending between adjacent LED filaments in the first group.

11. The LED filament lamp according to any one of the preceding claims, wherein one LED filament in the second group has a main illumination direction that intersects the central axis, and wherein at least two LED filaments (52) in the second group have main illumination directions that do not intersect the central axis.

12. The LED filament lamp according to any one of the preceding claims, wherein the LED filament is arranged symmetrically around the central axis.

13. The LED filament lamp according to any one of claims 1 to 11, wherein the LED filament is asymmetrically arranged around the central longitudinal axis.

14. The LED filament lamp according to claim 13, wherein the LED filaments (51) in the first group are arranged in a first angular sector of the envelope, and the LED filaments (52) in the second group are arranged in a second angular sector of the envelope opposite to the first angular sector, wherein the first angular sector and the second angular sector are less than 120 degrees.

15. The LED filament lamp according to any one of the preceding claims, wherein each LED filament (5; 51, 52) further comprises an encapsulation (9) at least partially covering the plurality of LEDs (7) and at least a portion of the mounting surface (6a), the encapsulation comprising: a light scattering material configured to scatter at least a portion of the light emitted by the plurality of LEDs (7), and / or A luminescent material is configured to convert at least a portion of the light emitted by the plurality of LEDs (7) into converted light.

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