Traditional incandescent and halogen light bulbs create light by conducting electricity through a resistive filament, and heating the filament to a very high temperature so as to produce visible light. The incandescent lamps typically include a transparent glass enclosure with a tungsten filament inside, a glass stem with lead wires, and a medium base for electrical connection. The halogen lamps also typically include a glass enclosure, a glass stem, a medium base and a capsule light engine with one or more filaments and halogen vapor inside. Nowadays incandescent and halogen lamps are being replaced by LED lamps, mainly because LED lamps are much more efficient and save energy, and usually have a much longer service life.
At present, LED lamps with plastic envelopes are available in the market which include a light engine having LED light sources mounted on a metal core printed circuit board, a heat sink thermally coupled with the light engine, a driver inside the heat sink, a base, and a translucent and diffusive envelope. Electrical AC mains power is connected to the base, and the driver converts the AC mains power to direct current to drive the LEDs at a given power and to generate visible light. The light passes through the diffusive plastic envelope to provide a diffuse illumination. During operation, the LED's generate visible light as well as thermal energy. Some of the thermal energy is removed from the LED's by the heat sink. The heat sink thermals are dissipated somewhat by radiation and convection. Without the heat sink, the LED temperature may rise to a point where its service life is shortened, and may even be damaged.
Compared to LED lamps with plastic envelopes, traditional gas filled glass envelope incandescent and halogen lamps still have several merits. They typically have near-4π light distribution which is suitable for most applications. The material cost of the incandescent and halogen lamps is much cheaper, compared to the LED lamps described above. Also they are simple in structure and the manufacturing technology of these lamps is well developed and highly automated, further reducing the cost of these lamps to the consumer.
Recently, filament style LED lamps have been produced that attempt to leverage the merits of the incandescent and halogen lamps. Filament style LED lamps typically include gas tight glass envelopes, LED filament packages, and a gas disposed within the envelopes to dissipate heat. A number of LED dies are placed in a transparent strip substrate and coated with a mixture of phosphor and silicone to form the LED filament. These style lamps generally have near-4π angular light distribution (sometimes referred to as “omnidirectional”), are light weight and have a simple structure. However, the typical filament LED lamp is usually higher in cost because it uses a large number of costly LED dies. Because the envelope is sealed, provisions must be made to dissipate the heat generated by the LEDs. The ability to provide a similar amount of lumens in a package similar to those presently in use would be advantageous. Providing a sealed glass envelope LED lamp that manages heat dissipation, in addition to utilizing present well developed and automated manufacturing technology would also be advantageous.
It has been ascertained that many of the components of LED lamps, such as encapsulation materials, integrated circuits, printed circuit boards, solder, insulation, conformal coatings, and adhesives, may emit or “out-gas” volatile organic carbons (VOCs) during operation. The VOCs cause surface contamination and degrade the lumen output of the LED light sources over time. To overcome this problem and other problems of traditional LED lamps with plastic envelopes, LED filament lamps, and sealed glass LED lamps in general, the disclosed embodiments provide a LED lamp that is light weight, has a simple structure, and lower cost with heat and VOC production management features.
The disclosed embodiments are directed to an LED lamp assembly that includes a glass envelope, an LED platform supported by a stem arrangement disposed within the envelope, a base hermetically sealed to the envelope, a gas disposed within the envelope providing thermal conductivity between the LED platform and the envelope, and a getter disposed within the envelope for absorbing volatile organic compounds.
The getter may include an oxygen generating material.
The LED platform may include a metal core printed circuit board formed into a shape with multiple sides with LED light sources mounted on exterior surfaces of the multiple sides.
The getter may be mounted on at least one of the exterior surfaces of the multiple sides using one or more surface mounting pads.
The getter may be mounted on at least one of the exterior surfaces of the multiple sides by one or more flanges inserted into corresponding slots of the exterior surfaces.
The getter may be implemented as a deposit of oxygen generating material in a recess on at least one of the exterior surfaces.
The getter may be mounted on the stem arrangement disposed within the envelope.
The LED platform may include an LED filament arrangement and the getter may be mounted on the stem arrangement and disposed within the LED filament arrangement.
The getter may be implemented as an oxygen generating material applied as a coating on the stem arrangement.
The gas disposed within the envelope may include a selected ratio of helium to oxygen that achieves the thermal conductivity and provides a predetermined lumen output over a predetermined time period, and the getter may include a material that generates oxygen to maintain the ratio.
The getter may be temperature activated and selected dimensions of the LED platform may provide a heat dissipation that maintains a temperature of the getter within a range that provides the selected ratio of helium to oxygen.
Selected dimensions of the LED platform may provide a convective heat transfer within the envelope to maintain a consistent temperature throughout the interior of the envelope.
The gas disposed within the envelope may include a ratio of between 80% helium to 20% oxygen.
The gas disposed within the envelope may include a ratio of 85% helium to 15% oxygen.
The gas disposed within the envelope may include a ratio of between 80% helium to 20% oxygen and 85% helium to 15% oxygen.
The disclosed embodiments are also directed to an LED lamp assembly that includes a glass envelope, an LED platform supported by a stem arrangement disposed within the envelope, a base hermetically sealed to the envelope, a gas mixture disposed within the envelope having a helium-oxygen ration for providing thermal conductivity between the LED platform and the envelope and for absorbing volatile organic compounds outgassed by components of the LED platform, and a getter comprising an oxygen generating material disposed within the envelope for maintaining the helium-oxygen ratio.
The getter may be mounted to a metal core printed circuit board of the LED platform, where the metal core printed circuit board has a shape with multiple sides and LED light sources mounted on exterior surfaces of the multiple sides.
The getter may be mounted on the stem arrangement disposed within the envelope and at least partially enclosed by the LED platform.
The getter may be applied as a coating on the stem arrangement and may be at least partially surrounded by the LED platform.
The foregoing and other aspects of the disclosed embodiments are made more evident in the following detailed description, when read in conjunction with the attached figures, wherein:
The disclosed embodiments are directed to an LED lamp assembly that provides sufficient lumen output, thermal management, color control, and light distribution characteristics that may be manufactured using existing incandescent production techniques. Thermal management, color control, and sufficient lumen output are among the significant challenges facing most LED lamp designs, in particular applications for retrofitting existing light fixtures with LED light sources. These constraints are clearly evident when evaluating cost effective commercially available retrofit LED lamps. The disclosed embodiments are directed to an improved performance LED lamp having a low cost glass envelope and manufactured by high speed machines used for standard incandescent lamps. This existing glass envelope technology is highly desirable because the envelope is easily identified by consumers and is easily supported by current manufacturing components, machinery and techniques. For example, a halogen lamp finishing process that installs a halogen capsule inside a glass envelope may be easily adapted to install the LED platform of the disclosed embodiments. The resulting LED lamp may have a look and feel almost indistinguishable from an existing incandescent lamp, have a longer life, and may be produced at a reasonable cost.
The envelope 110 may generally enclose the LED platform 120 and the stem arrangement 130 and may be constructed of glass, translucent ceramic, or other suitable material for transmitting light while maintaining a gas tight or gas impermeable enclosure. While an “A” type envelope is shown, it should be understood that the disclosed embodiments may include any suitable envelope shape. At least one surface of the envelope 110 may inherently diffuse light or may include at least a partial coating, frosting, texturing, a specular coating, a dichroic coating, embedded light scattering particles, or any other surface characteristic or material for diffusing light. The surface characteristic or material may increase the light output by reducing light bounce losses. In some embodiments, the surface characteristic or material may operate to minimize or counteract any volatile organic carbon (VOC) release from components within the envelope 110. The envelope 110 may be vacuum sealed to a flange 135 of the stem arrangement and may be filled with a gas as described in detail below.
In the embodiment shown in
Referring to
Still referring to
The LED mounting board 121 may be made of a material suitable for mounting the LEDs and other electronic components. As shown in the example of
While a standard MCPCB may have an exemplary thickness of approximately 2 mm, the LED mounting board 121 of the disclosed embodiments may be flexible and bendable and may have an exemplary thickness of about 0.1 mm-0.8 mm in order to facilitate forming the LED mounting board 121 into various shapes. In some embodiments, the LED mounting board 121 may comprise a single sheet or piece formed into a shape with multiple sides for mounting the LEDs 122. While the LED mounting boards 121, and 505 described below, of the disclosed embodiments are described in terms of polygons and polyhedrons, it should be understood that the LED mounting boards 121, 505 may have any shape suitable for implementing the embodiments disclosed herein including, for example, hexagonal, cross, and herringbone shapes.
While in some embodiments, support points for the LED mounting boards 121, 505 may be limited to conductors 132 connected to pins 123, in this embodiment, the steeple 525 may also provide a support point for maintaining the LED mounting board 505 in a position on the first support 133 of the stem arrangement 130. Support points for maintaining the LED mounting board 505 in position may also be provided by other structures, including one or more support wires extending from the first support 133 of the stem arrangement 130.
Returning to
As mentioned above, various components of the LED lamp 100 may release VOCs during lamp operation and degrade the lumen output of the LEDs 122. Oxygen generally reacts with VOCs to avoid the lumen degradation and chromaticity changes.
As a result, it would be advantageous to maintain a mixture of gasses including at least helium and oxygen within the envelope 110. However, while helium may have higher thermal conductivity compared to other common gases such as nitrogen, neon, argon, or krypton, the presence of oxygen in the envelope may largely deteriorate the thermal dissipating capability of helium. Referring to the example shown in
Referring again to
Referring to
As shown in
As disclosed herein, the getters 700, 900, 1000, 1100, 1300 may be temperature activated. For example, in some embodiments, the oxygen generating material 705 may begin generating oxygen upon reaching a threshold temperature. Furthermore, the oxygen produced by the oxygen generating material 705 may increase as the ambient temperature increases. At the same time, it would advantageous to maintain a ratio of helium to oxygen that achieves both an acceptable thermal conductivity and an acceptable lumen output over the life of the LED lamp, as disclosed above. In some embodiments, the ratio of helium to oxygen may be maintained by regulating the temperature within the envelope 110. Furthermore, in at least one embodiment, the temperature within the envelope may be maintained between approximately 80° C. and approximately 90° C.
In one or more embodiments, the dimensions of the LED platform 120, when implemented as LED mounting boards 121, 505, 810, 915, 1005, 1115, 1305, may be selected such that upon the lamp 100 reaching operating temperature, the heat dissipation of the mounting boards 121, 505, 810, 915, 1005, 1115, 1305 maintains the temperature of the getter within a range that provides the ratio of helium to oxygen that achieves both an acceptable thermal conductivity and an acceptable lumen output over the life of the LED lamp. Furthermore, the dimensions of the LED platform 120 may be selected such that the dimensions of the mounting boards 121, 505, 810, 915, 1005, 1115, 1305 may enhance convective heat transfer within the envelope 110 to maintain a consistent temperature throughout the interior of the envelope 110.
Returning to
Referring to
Each of the embodiments of the LED mounting boards 121, 505, 810, 915, 1005, 1115, 1305 and the LED filament arrangement 1205 may be sized to fit through the smallest dimension of the envelope 110, while also providing a surface area that affords both an enhanced optical distribution and an enhanced thermal distribution. In particular, the various LED arrangements provides an almost 4π light distribution along with better thermal spreading and transfer of heat to the envelope.
Because the LED mounting boards 121, 505, 810, 915, 1005, 1115, 1305 and the LED filament arrangement 1205 meet the size limitations of the envelope, a manufacturing process similar to the halogen bulb finishing process may be achieved. For some embodiments, existing production lines may be utilized for manufacturing with only slight modifications to the process (i.e. fill-gas changes and flame adjustments).
Using a helium-oxygen filled envelope in one or more embodiments enables efficient and fast transport of the heat away from the LEDs to the surface of the envelope and thus to the outside environment, while maintaining the lumen output of the LEDs. Low atomic mass gas cooling using a selected ratio of helium to oxygen provides operating temperatures within specified bounds of LED operation. Effective heat transport has been demonstrated at fill pressures as low as approximately 50 Torr, however any suitable fill pressure may be utilized.
Various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, all such and similar modifications of the teachings of the disclosed embodiments will still fall within the scope of the disclosed embodiments.
Various features of the different embodiments described herein are interchangeable, one with the other. The various described features, as well as any known equivalents can be mixed and matched to construct additional embodiments and techniques in accordance with the principles of this disclosure.
Furthermore, some of the features of the exemplary embodiments could be used to advantage without the corresponding use of other features. As such, the foregoing description should be considered as merely illustrative of the principles of the disclosed embodiments and not in limitation thereof.
Filing Document | Filing Date | Country | Kind |
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PCT/CN2017/083937 | 5/11/2017 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2018/205223 | 11/15/2018 | WO | A |
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Number | Date | Country | |
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20200248876 A1 | Aug 2020 | US |