Patent Application
20110121726
1. Field of Invention
The present embodiments relate generally to light-emitting devices, and particularly to light-emitting devices using a light-emitting diode (LED) as the light source.
2. Description of the Prior Art
A light-emitting diode (LED) can often provide light in a more efficient manner than an incandescent light source and/or a fluorescent light source. The relatively high power efficiency associated with LEDs has created an interest in using LEDs to displace conventional light sources in a variety of lighting applications. For example, in some instances LEDs are being used as traffic lights, to illuminate displays systems and so forth. Furthermore, LEDs are being incorporated into residential and commercial lighting applications displacing less efficient and less durable light devices. Many technological advances have led to the development of high power LEDs by increasing the amount of light emission from such devices.
As LEDs have increasingly become desirable for their long lifespan, efficient energy consumption and durability, a need to configure LED lighting devices to fit and function similar to traditional lighting sources has arisen.
Solid-state lamp devices are provided.
In one aspect, a device is provided comprising a base having a first and second electrical terminal, a driver, an LED electrically connected to the driver, a housing mounted to the base, wherein the housing is in thermal communication with the LED and a portion of the driver device.
In another aspect, a device is provided comprising a base having a first and second electrical terminal, a driver having at least two portions, wherein one portion is partially disposed within the base and the second portion produces a greater amount of heat, an LED electrically connected to the driver device, a housing mounted to the base, wherein the housing is in thermal communication with both the LED and second portion of the driver.
In another aspect, a driver device is provided having a first portion for receiving an alternating current, and a second portion thermally isolated from the first portion, wherein the second portion outputs more heat than the first portion; an LED electrically connected to the driver device; and a heat sink thermally connected to the second portion.
Other aspects, embodiments, and features will become evident from the detailed description and the accompanying figures. The accompanying figures are schematic and are not intended to be drawn to scale. In the figures, each identical or substantially similar component that is illustrated in various figures is represented by a single numeral or notation.
For purposes of clarity, not every component is labeled in every figure. Nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention. All patent applications and patents incorporated herein by reference are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control.
a-b are electrical schematics representative of a segmented driver device attached to an LED source.
a-b illustrate various placements of driver devices in a solid-state lamp assembly.
a-b are exploded views of an MR-16 solid-state lamp.
a-e are illustrative of cross-sectional views of the internal designs used in various solid-state lamp embodiments
LEDs have become increasingly desirable to replace traditional filament based lighting sources because of their durability, longer lifespan, and increased electrical efficiency. Filament based lighting sources have been the standard in industry for several decades and as a result have an infrastructure designed around such a lighting solution such as one shown in
a-b are electrical schematics representative of a segmented driver device attached to an LED source.
In the embodiment shown in
Generally, the current on the primary portion of the electronic driver 100a is much lower than the current on the secondary portion. The higher current often results in an increased output of heat across that portion of the electronic driver. One reason an increased amount of current is desired is because in some embodiments, a larger surface-emitting or vertical chip LED is used. In order to maintain the same current density as used by smaller LEDs, the driver must produce higher current entering into the larger LED used in many of the embodiments described. As such, the secondary portion of the driver will produce more heat as it produces more current to maintain this current density. Additionally, more light will be produced as a result.
The secondary portion receives the electrical input from the primary portion via electrical leads (such as 26 shown in
Suitable LEDs have been described in commonly-owned U.S. Pat. No. 6,831,302 which is incorporated herein by reference. In some embodiments, the LED may have a vertical design (i.e., emit light vertically from an upper surface) and/or large emission area. For example, the emission surface may have at least one edge (and, in some cases, all edges) having a length of at least 1 mm, at least 2 mm, at least 3 mm, at least 4 mm, or at least 5 mm.
In some embodiments, the lighting source (e.g., lamp) includes a single LED chip. In other cases, the lighting source may include more than one LED chip (e.g., a multi-chip configuration).
In some embodiments, the LED(s) emit white light. In some embodiments the electricity to light output efficacy is greater than 82%. Combining a single LED emitting white light at a desired color temperature, with the segmented driver devices described herein, while managing the heat output as discussed below allows for the solid-state lamp to be more efficient, last longer while maintaining a high percentage of initial lumen output, easier to maintain, and operate in the same sockets over traditional filament-based lamps.
In certain embodiments, the solid-state lamp may have a power factor that is greater than or equal to 0.70 and in most embodiments from 0.88 to 0.90. The output frequency may also be greater than or equal to 120 Hz. In addition, in some embodiments when the solid-state lamp is connected to a power source and in the off state no power is drawn from the power system or grid.
b is an electronic schematic of an electronic driver 100b having a primary portion being separate by both a thermal separation 24 and an electrical separation 25 from the secondary portion. As shown in
The primary portion 28 in the embodiment shown in
The spatial layout of the electronic driver 200, for example in a PAR lamp configuration, is important due to the need to maintain the same form and fit of traditional lamp designs. In some embodiments, it is desirable to position the driver such that it is separated from the heat sink that sits directly underneath the LED. The separation may be for purposes of electrical isolation. However, it may also be desirable to separate the driver for more efficient cooling of the system. In other embodiments, it may be for purposes of miniaturization of the entire lamp sub-system. In most LED lamp designs, the driver is positioned underneath or in close-proximity to the LED. In some embodiments, it may be desirable to position the driver in alternative locations for miniaturization or heat-sinking purposes.
The secondary portion 32 of the electronic driver device 200 generally produces greater amounts of heat. Therefore, it is advantageous to use a metal core printed circuit board (MCPCB) or similarly configured circuit board designed to effectively distribute heat away from both the secondary portion 32 as well as LED 34 mounted directly to the inner area of the secondary portion 32. As mentioned, LED 34 may have a large surface-emitting area greater than 1 mm2, 3 mm2, 9 mm2 and 12 mm2, which may produce upwards of 10 watts of heat depending upon how much current is being driven through LED 34.
Included in the secondary portion 32 of the embodiment shown in
Though not shown in the embodiment found in
Attached to LED 34 is an optical dome 44. Optical dome 44 may be used in shaping the output of light emitted from LED 34. This optical dome 44 may also be coated or otherwise implanted with a phosphor or other color converting mechanism to help create a different monochromatic or polychromatic emission than the original emission produced from LED 34.
a-b show various placements segmented electronic driver devices may be placed within a solid-state lamp assembly.
a illustrates an embodiment where the primary portion 28 of an electronic driver is placed within base 52 of the lamp 70a. As shown, a thermal separation 24 exists between 28 and the secondary portion 32. This thermal separation may consist of an air gap, insulation or other means configured to place the portion of the driver with the highest output of heat in an area of the lamp configured to handle heat dissipation in an efficient manner. The portion of the driver that does not have a high output of heat may then be strategically located in an area of the lamp that is not needed for optical, thermal or other uses. At times this may be the base portion of the lamp.
LED 34 is mounted on top of the secondary portion 32 in the bottom portion of the cavity produced by housing 50 and above the base portion. In some embodiments the base portion may be too small to house the entire primary portion 28 and a part of 28 may protrude into the rest of the housing 50. The base of the lamp is considered to be the proximal end of the lamp while the portion of the housing where the light escapes or that is furthest away from the base is the distal end of the lamp.
Housing 50 may act as both a heat sink and a reflector for light emitted by LED 34. A portion of the inner surface 56 of the housing 50 may be coated, polished, or otherwise plated to reflect light emitted from LED 34. Housing 50 may be made of aluminum or other thermally conductive material as housing 50 as acts as part of a heat distribution and dissipation system for the lamp. Though not shown in this embodiment, housing 50 may also be comprised of protruding heat fins designed to transfer heat.
b shows another embodiment wherein the secondary portion 32 is placed within the extruded portion of housing 50. Placing the secondary portion 32 in this region of the housing may be advantageous because of the close proximity to an outer area of the embodiment where a majority of the cooling and heat dissipation occurs. In addition, it is located away from the LED 34 another major heat source. Though not specifically shown in this embodiment, a cavity or slot may be formed in the outer extruded portion of the housing to contain the secondary portion 32 therein. In some instances, the secondary portion 32 may be comprised of a flexible circuit, so as to conform to the shape of the housing 50. In most retrofit lamp designs used for replacing incandescent lamps, the housing maintains a constant curvature. Thus, having a flexible secondary portion would be ideal in these situations particularly where wall thickness may be of concern, as flexible circuits tend to be thinner than regular printed circuit boards.
In both
The base usually ends where the housing portion begins. Often the LED(s) are mounted on the top portion of the base. Sometimes an LED is mounted to the secondary portion of a driver or a pedestal that is connected to the base portion. However, as shown in
The housing usually starts at the point where the LED is mounted and usually flares noticeably outward from the base portion. Though in some embodiments the housing and the base are comprised of one continuous piece the distinction may be less significant, but principally the housing begins at the flaring out point which may be a dramatic angle, parabolic curve or otherwise. For additional clarity, the housing usually contains the optical portion of the lamp, heat fins, and generally extends outwardly from the base having a much larger diameter or width than the base. It is also conceived that a portion of the base extends into the housing portion or that the housing mounts to a ridge of the base. See for example
Though not shown in
Optical coverings, not shown in
As mentioned, some of the embodiments presented are designed to replace current filament based lighting devices commonly referred to as PAR-XX with the XX being a dimension of the diameter of the housing at its widest point. The XX number is usually multiplied by ⅛″ to give the opening size of the lighting device. PAR is an acronym for parabolic aluminized reflector. Thus, several of the embodiments of this invention are directed towards configuring equivalent replacements for the PAR series of lighting devices currently available, but not limited to only those current designs. Equivalency referring in part to similar size, shape, at least as much lumen output, at least as electrically efficient, providing the same output angles, fitting the same sockets, and using the same power systems currently used in residential and commercial places.
One of the advantages of having an external shell 110 is that it is able to maintain a lower temperature than the outer housing 50 or protruding heat fin 102. One concern with filament-based lamps is the amount of heat these lamps produce, which in turn creates a very hot package or outer housing that in many instances may cause burns to human skin if held too long while in use or just after the lamp has been turned off. The external shell in this embodiment may be maintained at temperatures wherein human hands can handle the lamp either while in use and/or immediately after the lamp has been turned off. Also as a result, the heat fin 102 and housing 50 may be designed to dissipate even higher amounts of heat without a concern for causing either bodily damage or heat damage to immediately surrounding objects. In several embodiments the external shell is designed to maintain a temperature of less than 65° Celsius, while allowing for up to 10 watts of heat to be dissipated from the solid-state lamp. This calculation is based on a horizontal usage of the lamp where the chimney effect is still present, but not as effective as when the lamp is oriented vertically e.g. the light emitting surface in a PAR design is pointed to the ceiling or to the ground.
The external shell 110 may be made of metal or plastic. Though it is not shown in
In some instances, the solid-state lamp as shown in
Also shown in
Heat may also be dissipated into the ambient air directly above LED 34 inside the cavity portion formed by the housing. In this instance it has been contemplated of creating another chimney effect by placing at least one hole entering into the cavity portion near the mounted LED and having at least another hole towards the open portion of the housing where the emitted light exits the lamp. However, this might not be ideal for all embodiments as it may be desirous to seal off the system.
a-b illustrate exploded views of embodiments of an MR-16 replacement solid-state lamp device. As illustrated, the lamps in
a shows an additional TIR or total internal reflective optic that is contained within housing 306. For some embodiments using this type of optic the inner surface of housing 306 may not need to be polished as light emitted from an LED is reflected of the side walls until it passes through the top emission surface.
a-e are illustrative of cross-sectional views of the internal designs used in various solid-state lamp embodiments described herein. The internal shapes of the housing are a part of an optical system that allow for a particular distribution. Present in the lighting industry are various standards for lamps emitting light at particular angles, with particular light intensities or candelas across those angles. The designs in
Using
As mentioned, an optical element at the emission portion of a lamp (as shown in
Secondary optics as 312 and 313 shown in
The active region of an LED can include one or more quantum wells surrounded by barrier layers. The quantum well structure may be defined by a semiconductor material layer (e.g., in a single quantum well), or more than one semiconductor material layers (e.g., in multiple quantum wells), with a smaller electronic band gap as compared to the barrier layers. Suitable semiconductor material layers for the quantum well structures can include InGaN, AlGaN, GaN and combinations of these layers (e.g., alternating InGaN/GaN layers, where a GaN layer serves as a barrier layer). In general, LEDs can include an active region comprising one or more semiconductors materials, including III-V semiconductors (e.g., GaAs, AlGaAs, AlGaP, GaP, GaAsP, InGaAs, InAs, InP, GaN, InGaN, InGaAlP, AlGaN, as well as combinations and alloys thereof), II-VI semiconductors (e.g., ZnSe, CdSe, ZnCdSe, ZnTe, ZnTeSe, ZnS, ZnSSe, as well as combinations and alloys thereof), and/or other semiconductors. Other light-emitting materials are possible such as quantum dots or organic light-emission layers.
The n-doped layer(s) 135 can include a silicon-doped GaN layer (e.g., having a thickness of about 4000 nm thick) and/or the p-doped layer(s) 133 include a magnesium-doped GaN layer (e.g., having a thickness of about 40 nm thick). The electrically conductive layer 132 may be a silver layer (e.g., having a thickness of about 100 nm), which may also serve as a reflective layer (e.g., that reflects upwards any downward propagating light generated by the active region 134). Furthermore, although not shown, other layers may also be included in the LED; for example, an AlGaN layer may be disposed between the active region 134 and the p-doped layer(s) 133. It should be understood that compositions other than those described herein may also be suitable for the layers of the LED.
As a result of openings 139, the LED can have a dielectric function that varies spatially according to a pattern which can influence the extraction efficiency and/or collimation of light emitted by the LED. In the illustrative LED 34, the pattern is formed of openings, but it should be appreciated that the variation of the dielectric function at an interface need not necessarily result from openings. Any suitable way of producing a variation in dielectric function according to a pattern may be used. For example, the pattern may be formed by varying the composition of layer 135 and/or emission surface 138. The pattern may be periodic (e.g., having a simple repeat cell, or having a complex repeat super-cell), periodic with de-tuning, or non-periodic. As referred to herein, a complex periodic pattern is a pattern that has more than one feature in each unit cell that repeats in a periodic fashion. Examples of complex periodic patterns include honeycomb patterns, honeycomb base patterns, (2×2) base patterns, ring patterns, and Archimedean patterns.
In some embodiments, a complex periodic pattern can have certain openings with one diameter and other openings with a smaller diameter. As referred to herein, a non-periodic pattern is a pattern that has no translational symmetry over a unit cell that has a length that is at least 50 times the peak wavelength of light generated by active region 134. Examples of non-periodic patterns include aperiodic patterns, quasi-crystalline patterns, Robinson patterns, and Amman patterns.
In certain embodiments, an interface of a light emitting device is patterned with openings which can form a photonic lattice. Suitable LEDs having a dielectric function that varies spatially (e.g., a photonic lattice) have been described in, for example, U.S. Pat. No. 6,831,302 B2, entitled “Light Emitting Devices with Improved Extraction Efficiency,” filed on Nov. 26, 2003, which is herein incorporated by reference in its entirety. A high extraction efficiency for an LED implies a high power of the emitted light and hence high brightness which may be desirable in various optical systems.
It should also be understood that other patterns are also possible, including a pattern that conforms to a transformation of a precursor pattern according to a mathematical function, including, but not limited to an angular displacement transformation. The pattern may also include a portion of a transformed pattern, including, but not limited to, a pattern that conforms to an angular displacement transformation. The pattern can also include regions having patterns that are related to each other by a rotation. A variety of such patterns are described in U.S. patent application Ser. No. 11/370,220, entitled “Patterned Devices and Related Methods,” filed on Mar. 7, 2006, which is herein incorporated by reference in its entirety.
Light may be generated by the LED as follows. The p-side contact layer can be held at a positive potential relative to the n-side contact pad, which causes electrical current to be injected into the LED. As the electrical current passes through the active region, electrons from n-doped layer(s) can combine in the active region with holes from p-doped layer(s), which can cause the active region to generate light. The active region can contain a multitude of point dipole radiation sources that generate light with a spectrum of wavelengths characteristic of the material from which the active region is formed. For InGaN/GaN quantum wells, the spectrum of wavelengths of light generated by the light-generating region can have a peak wavelength of about 445 nanometers (nm) and a full width at half maximum (FWHM) of about 30 nm, which is perceived by human eyes as blue light. The light emitted by the LED may be influenced by any patterned interface through which light passes, whereby the pattern can be arranged so as to influence light extraction and/or collimation.
In other embodiments, the active region can generate light having a peak wavelength corresponding to ultraviolet light (e.g., having a peak wavelength of about 370-390 nm), violet light (e.g., having a peak wavelength of about 390-430 nm), blue light (e.g., having a peak wavelength of about 430-480 nm), cyan light (e.g., having a peak wavelength of about 480-500 nm), green light (e.g., having a peak wavelength of about 500 to 550 nm), yellow-green (e.g., having a peak wavelength of about 550-575 nm), yellow light (e.g., having a peak wavelength of about 575-595 nm), amber light (e.g., having a peak wavelength of about 595-605 nm), orange light (e.g., having a peak wavelength of about 605-620 nm), red light (e.g., having a peak wavelength of about 620-700 nm), and/or infrared light (e.g., having a peak wavelength of about 700-1200 nm).
Additionally, white light may be produced having a variety of color temperatures in the range from 2500-6800 K. Color temperature of a light source is generally defined by the surface temperature of thermal radiation from an ideal black body radiator and is conventionally stated in units of absolute temperature, kelvin (K). Higher color temperatures, generally above 5,000 K, have more of a blue tint while lower color temperatures (2,700 K to 3,000K and also called warm colors) have more of a yellowish or red tint. The LED may also produce light as defined in the Energy Star program requirements for solid-state lighting luminaires version 1.1 including the seven step chromaticity quadrangles having nominal correlated color temperatures (CCT) of 2700K, 3000K, 3500K, 4000K, 4500K, 5000K, 5700K, 6500K wherein the corresponding CCTs are 2725+/−145, 3045+/−175, 3465+/−245, 3985+/−275, 4503+/−243, 5028+/−283, 5665+/−355, 6530+/−510.
The LEDs may also meet the requirements for variation of chromaticity having a color spatial uniformity within 0.004 from the weighted average point on the CIE 1976 diagram as defined on page 3 of the Energy Star program requirements for solid-state lighting luminaires version 1.1.
Another quantitative measure used in the lighting industry is the color rendering index (CRI). CRI is the ability of a light source to reproduce colors in the same manner as those produced by natural light and is based on a scale of 0-100. The closer to 100 the greater the ability to produce light that will show objects as close to the natural light or a specified reference illuminant. LEDs with a higher CRI number usually have a lower lumen output. This phenomenon occurs for a number of reasons including efficiency of LED materials used to produce the various colors and the eye's sensitivity to particular wavelengths.
The LEDs used in several of the described in embodiments have a CRI greater than 75, greater than 80, greater than 85, and in some instances greater than 90.
The LEDs used in some embodiments may have a lifetime of at least 25,000 hours and at least 35,000 hours wherein the lumen output is maintained at a level of 70% or greater than the initial lumen output of the retrofit lighting device. The LEDs may also exhibit a change of chromaticity over the lifetime (25,000 hours, 35,000 hours) less than or equal to 0.007 on the CIE 1976 diagram.
In certain embodiments, the LED may emit light having a high power. As previously described, the high power of emitted light may be a result of a pattern that influences the light extraction efficiency of the LED. For example, the light emitted by the LED may have a total power greater than 0.5 Watts (e.g., greater than 1 Watt, greater than 5 Watts, or greater than 10 Watts). In some embodiments, the light generated has a total power of less than 100 Watts, though this should not be construed as a limitation of all embodiments. The total power of the light emitted from an LED can be measured by using an integrating sphere equipped with spectrometer, for example a SLM12 from Sphere Optics Lab Systems. The desired power depends, in part, on the optical system that the LED is being utilized within. For example, a display system (e.g., a LCD system) may benefit from the incorporation of high brightness LEDs which can reduce the total number of LEDs that are used to illuminate the display system.
The light generated by the LED may also have a high total power flux. As used herein, the term “total power flux” refers to the total power divided by the emission area. In some embodiments, the total power flux is greater than 0.03 Watts/mm2, greater than 0.05 Watts/mm2, greater than 0.1 Watts/mm2, or greater than 0.2 Watts/mm2. However, it should be understood that the LEDs used in systems and methods presented herein are not limited to the above described power and power flux values.
Some embodiments include lighting devices having a lumen efficacy or lumens per watt (lm/W) greater than 20 lm/W. Additionally, as defined in the Energy Star program requirements for solid-state lighting luminaires version 1.1 some embodiments produce greater than 20 lm/W (e.g. greater than 24 lm/W, 29 lm/W, 30 lm/W, 35 lm/W, 40 lm/W and greater than 45 lm/W). Some embodiments have lumen outputs greater than 50 lumens output (e.g. 100, 150, 200, 300, and greater than 575 lumens output). Each of these embodiments also has a CRI, as described above, greater than 80 while having a lumen output greater than 575. In some embodiments, a single LED chip produces white light with a CRI of 85 or greater and a lumen output of greater than 600.
A lighting intensity benchmark tool has been provided by the government's ENERGY STAR program for achieving a particular candela output based on type, angle, size and current wattage equivalents for standard incandescent PAR and MR lamps. This tool can tool can be found at http://www.drintl.com/temp/ESIntLampCenterBeamTool.xls that was published on Jan. 16, 2009. The solid-state lamp embodiments using a single LED described herein are capable of achieving ENERGY STAR's candela output benchmarks described at the above sight for both incandescent PAR and MR lamps. For 75 Watt incandescent PAR lamps this results in a minimum center beam intensity of 6600 candelas (cd). The same single LED embodiments are capable of achieving the desired candela output for an MR design including producing a minimum center beam intensity of 10261 cd based on a 50 Watts incandescent MR having an output angle of 7 degrees.
Presently, the solid-state lamps described herein can achieve the same candela output and greater when consuming 5-20 Watts of power as compared to the 50 and 75 watt incandescent examples used above in addition to having a longer lifetime or lifespan as described above.
In some embodiments, the luminous flux of the lamp having a single LED is equal to at least 10 times the number of watts of the target incandescent lamp it is trying to replace. For example, the total luminous flux of a lamp having 60 watts would have a luminous flux of 600. Some embodiments, using a single LED at a cool white temperature, produce a total luminous flux up to 2,750 lumens.
In some embodiments, the LED may be associated with a wavelength-converting region (not shown). The wavelength-converting region may be, for example, a phosphor region. The wavelength-converting region can absorb light emitted by the light-generating region of the LED and emit light having a different wavelength than that absorbed. In this manner, LEDs can emit light of wavelength(s) (and, thus, color) that may not be readily obtainable from LEDs that do not include wavelength-converting regions.
Some of the single LEDs used in conjunction with various retrofit lighting devices include having surface emission areas larger than 1 mm2, (e.g. larger than 3 mm2, larger than 9 mm2) In some instances, the radiation emitted is uniform at all angles or Lambertian. The larger surface emitting LEDs also allow for greater output of radiation or light allowing for at least the same and often greater lumen output than traditional filament based lighting devices.
In some embodiments 85% of total lumens are within 0°-60° zone that is bilaterally symmetrical, 85% of total lumens are within 0°-90° zone that is bilaterally symmetrical, and others 35% of total lumens are within 120°-150° zone that is bilaterally symmetrical.
When a structure (e.g., layer, region) is referred to as being “on”, “over” “overlying” or “supported by” another structure, it can be directly on the structure, or an intervening structure (e.g., layer, region) also may be present. A structure that is “directly on” or “in contact with” another structure means that no intervening structure is present. The above description is merely illustrative. Having thus described several aspects of at least one embodiment of this invention including the preferred embodiments, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.
This application claims priority to U.S. Provisional Application No. 61/263,590 filed Nov. 23, 2009 and U.S. Provisional Application No. 61/264,435 filed Nov. 25, 2009, both of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61263590 | Nov 2009 | US | |
| 61264435 | Nov 2009 | US |
