Patent Application
20130294086
1. Technical Field
The subject matter of the present disclosure relates to lighting and lighting devices and, more particularly, to embodiments of a lamp that utilizes a directional light source and a reflector to generate an optical intensity distribution substantially similar to the optical intensity distribution of common incandescent lamps.
2. Description of Related Art
Incandescent lamps (e.g., integral incandescent light bulbs and halogen light bulbs) mate with a lamp socket via a threaded base connector (i.e. an “Edison base” in the context of an incandescent light bulb), a bayonet-type base connector (i.e. bayonet base in the context of an incandescent light bulb), or other standard base connector. These incandescent lamps are often in the form of a unitary package that includes components to operate the lamps from a source of standard electrical power (e.g., 110 V and/02 220 V AC and/or 12 VDC and/or DC batteries). In the case of an incandescent lamp, the lamp comprises an incandescent filament operating at high temperature and radiating efficiently excess heat into the ambient. Moreover, the majority of incandescent lamps are naturally omni-directional light sources providing light with a substantially uniform optical intensity distribution (a “intensity distribution”).
Energy efficient lighting technologies include solid-state lighting devices such as LEDs, lamps having LEDs as a light source (LED lamp), and other LED-based devices often have performance that is superior to incandescent lamps. The superior performance of a solid-state lighting device can be quantified by its useful lifetime (e.g., its lumen maintenance and its reliability over time) and its higher efficacy as measured in Lumens per Electrical Watt (LPW)). For example, the lifetime of an incandescent lamp is typically in the range of approximately 1,000 to 5,000 hours as compared to the lifetime of LED-based lamps typically exceeding 25,000 hours. In another example, the efficacy of an incandescent lamp is typically in the range of 10 to 30 LPW as opposed to the efficacy of LED-based lamps being typically in the range of 40 to 100 LPW.
LED-based devices do have one significant disadvantage in some applications; namely, LED-based devices are highly unidirectional by nature. For example, common LED-based devices are flat and usually emit light from only one side of the device. Thus, although superior with respect to certain performance aspects, the intensity distribution of many commercially available LED lamps designed to be suitable alternative and/or replacement for incandescent lamps cannot replicate the intensity distribution of incandescent lamps in satisfactory manner or to a sufficient extent.
Another challenge related to solid-state lighting technologies is the need to find a way to dissipate heat adequately. For example, LED-based devices are highly sensitive to temperature variations with respect to the performance and reliability of the LED-based devices as compared to incandescent lamps containing incandescent or halogen filaments. This temperature sensitivity challenge is often addressed by placing a heat sink in contact with or in thermal contact with the LED-based device. Unfortunately, the heat sink, depending on the placement thereof, may block all or a portion of the light that the LED lamp emits, thus, may limit further the ability of the LED lamp to generate light with a more uniform optical intensity distribution. Moreover, physical constraints on lamps such as regulatory limits that define maximum dimensions for all lamp components, including light sources, limit further an ability to dissipate heat sufficiently and efficiently for LED-based lamps
Accordingly, a LED lamp that further encourages households and commercial establishments to convert from conventional incandescent lamps and to install more energy efficient lamps (e.g., LED lamps) is desirable. Consequently, a need exists for a lamp that more closely generates light with a uniform optical intensity distribution that is consistent with an incandescent lamp while delivering superior performance with respect to average lifespan of the lamp and to efficacy. Additionally, a need exists for a solid-state lighting device such as an LED lamp that dissipates heat effectively and efficiently without adversely affecting the uniformity of the optical intensity distribution of the LED lamp.
The present disclosure describes, in one embodiment, a lamp that comprises an envelope forming an interior volume and a reflector disposed in the interior volume. The reflector comprises a facet having a first end and a second end proximate, respectively, an outer peripheral edge and a center axis of the reflector. The facet has an exterior facet profile with a first face, a second face opposing the first face, and a facet edge disposed therebetween. In one example, the first face and the second face are configured to at least partially reflect light.
The present disclosure describes, in one embodiment, a lamp that comprises a light-emitting diode device with an optical axis and a reflector spaced apart from the light-emitting diode device. The reflector has a center axis aligned with the optical axis and comprises a plurality of facets disposed circumferentially about the center axis. The facets have an exterior facet profile with a first face, a second face opposing the first face, and a facet edge disposed therebetween. The lamp also comprises an envelope in surrounding relation to the reflector. The lamp further comprises a heat dissipating assembly with a heat dissipating element spaced apart from the outer surface of the envelope forming an air gap.
The present disclosure describes, in one embodiment, a reflector for use in a lamp. The reflector comprises a plurality of facets disposed circumferentially about a center axis that form an outer peripheral edge. The facets have an exterior facet profile with a first face, a second face opposing the first face, and a facet edge disposed therebetween. In one example, the exterior facet profile comprises a first profile proximate the outer peripheral edge of the reflector and a second profile proximate the center axis that is different from different from the first profile.
Other features and advantages of the disclosure will become apparent by reference to the following description taken in connection with the accompanying drawings.
Reference is now made briefly to the accompanying drawings, in which:
Where applicable like reference characters designate identical or corresponding components and units throughout the several views, which are not to scale unless otherwise indicated.
The lamp 100 also comprises a light diffusing assembly 110, a heat dissipating assembly 112, and a light source 114 that is capable of generating light. The light diffusing assembly 110 includes an envelope 116 with an outer surface 118 and an inner surface 120 that surrounds an interior volume 122. The light diffusing assembly 110 also includes a reflector 124 located within the interior volume 122 of the envelope. The reflector 124 has a top 126 and a bottom 128, wherein light from the light source 114 enters the reflector 124 at the bottom 128.
Examples of the lamp 100 generate comfortable room lighting, e.g., similar to incandescent A-19 lamps. As set forth more below, the reflector 124 can include a plurality of facets disposed circumferentially about the central axis 104. These facets have geometry that reflect and/or diffuse light from the light source 114, thus enhancing the characteristics of illumination of the lamp 100. In one example, the facets form and/or reflect light in a manner consistent with a total internal reflection (TIR) lens and similar lossless reflective properties. As a reflector, light from the light source 114 strikes surfaces of the facets at such a steep angle with respect to the normal of the surface (or greater than a so-called critical angle for lens material) that the light cannot pass through the surface and instead reflects off these surfaces as if the surfaces were covered with a material that is reflective.
The outer surface 118 and the inner surface 120 of the envelope 116 are made from a light-transmissive material. In some examples, the light-transmissive material used to make the envelope 116 is selected from the group comprising glass, acrylic, diffusing polycarbonate, other commercially available diffusing polymers (e.g., Teijin ML5206, MAKROLON®), or any combination thereof. In other examples, the material that the envelope 116 comprises is inherently light-diffusive (e.g., opal glass) or can be made light-diffusive by means of a variety of methods such as frosting and/or texturizing the outer surface 118 and/or the inner surface 120 in order to increase light diffusion. In one example, the envelope 116 comprises a coating (not shown) such as enamel paint and/or other light-diffusive coating (available, for example, from General Electric Company, New York, USA). Suitable types of coatings are found on common incandescent and fluorescent light bulbs. In yet another example, manufacturing techniques may be deployed that embed light-scattering particles, fibers, and/or other light scattering media in the material that comprises the envelope 116.
At a relatively high level, use of the reflector 124 in embodiments of the lamp 100 generate light with a relative optical intensity distribution (or “optical intensity”) at a level of approximately 100±20% over the range of values for the latitudinal co-ordinate 0 between zero degrees) (0° and one hundred thirty-five degrees) (135° or greater, where 100% corresponds to the average intensity over the range. In one embodiment, the lamp 100 maintains a relative optical intensity of 100±20% for values of the latitudinal co-ordinate of less than or approximately equal to one hundred fifty degrees (150°. These optical intensity distribution profiles comply with target values for optical intensity that the Department of Energy (DOE) sets for solid-state lighting devices as well as other applicable industry standards and ratings (e.g., ENERGY STAR®). The levels and distributions of optical intensity of the lamp 100 render the lamp 100 a suitable replacement for, or alternative to, conventional incandescent light bulb. Moreover, the physical characteristics and dimensions of the lamp 100 are substantially consistent with the physical profile of such common incandescent light bulbs, wherein the outer dimension defines boundaries within which the lamp 100 must fit. Examples of this outer boundary dimension meet one or more regulatory limits or standards (e.g., ANSI, NEMA, etc.). In one embodiment, the envelope 116 can be substantially hollow and have a curvilinear geometry (e.g., spherical, spheroidal, ellipsoidal, toroidial, ovoidal, and/or numerically generated freeform shape) that diffuses light.
The reflector 124 fits within the interior volume 122 of the envelope 116 in a position to intercept light emitted by the light source 114. As shown in
In one exemplary embodiment, the light source 214 is a planar LED-based light source that emits light into a hemisphere having a Lambertian intensity distribution, compatible with the light diffusing assembly 210 for producing omni-directional illumination distribution. In one embodiment, the planar LED-based Lambertian light source includes a plurality of LED devices (e.g., LEDs 232) mounted on a circuit board (not shown), which is optionally a metal core printed circuit board (MCPCM). The LED devices may comprise different types of LEDs. In one embodiment, at least one of a first type of LED may be combined with at least one of a second type of LED, wherein the first and second types of LEDs have respective spectra and intensities that mix with each other in order to render white light of a desired color temperature and color rendering index (CRI). In one embodiment, the first type of LED output white light, which in one example has a greenish rendition (achievable, for example, by using a blue or violet emitting LED chip that is coated with a suitable “white” phosphor). The second type of LED output red and/or orange light (achievable, for example, using a GaAsP or AlGaInP or other epitaxy LED chip that naturally emits red and/or orange light). The light from the first type of LED and from the second type of LED blend together to produce improved color rendition. In another embodiment, the planar LED-based light source can also comprise a single LED or an array of LED emitters incorporated into a single LED device, which may be a white LED device and/or a saturated color LED device and/or so forth. In another embodiment, the LED emitter is an organic LED comprising, in one example, organic compounds that emit light.
The top 310 of the reflector 308 may be coated with a reflective material (e.g., silver foil) in order to further reduce the amount of light that passes through the reflector 308. In one embodiment, the reflector 308 is configured to reflect light so the trajectory of the reflected light has a latitudinal value (e.g., latitudinal value θ of
The opening 304 provides access to the interior volume 306 of the envelope 302. The opening 304 has a diameter d that, in one example, is sized and configured to fit about a light source (e.g., light source 114, 214 of
In the cross-section of
Variations in the contour of the envelope 302 can influence the intensity distribution the light diffusing assembly 300 exhibits (e.g., by defining the features of the spheroid geometry in the transmissive outer area). In one example, the spheroid geometry of the light diffusing assembly 300 has a generally flatter shape than a sphere, e.g., having a shape of an oblate spheroid, thus creating the flattened (or substantially flattened) top and peripheral radial curvatures as shown in
Examples of the envelope 302 of the light diffusing assembly 300 may be formed monolithically as a single unitary construction or as components that are affixed together. Materials, desired optical properties, and other factors (e.g., cost) may dictate the type of construction necessary to form the geometry (e.g., the spheroid geometry) of the light diffusing assembly 300. In another exemplary embodiment, the light diffusing assembly 300 has a multi-component construction in which the spheroid geometry can be approximated by a discrete number of planar sheet diffusers assembled in an axisymmetric arrangement following the surface of a spheroid. In certain embodiments, sheet diffusers are utilized because the sheet diffusers can exhibit potentially high diffusion of light with relatively low loss or absorption of light compared with monolithically-formed, three-dimensional diffusers. Multi-component structures can exhibit the same optical properties as the diffusive envelope 302 discussed above (e.g., land, thus, embodiments of the lamp (e.g., lamp 100, 200 of
Examples of the reflector 500 can be rotationally symmetric, wherein the exterior facet profile and other features are substantially the same for all of the facets (e.g., facets 512, 514) that make up the body 502. In one example, the number of facets (e.g., facets 512, 514) is in the range of about twenty to about forty, although dimensions and other factors (e.g., optical properties) can cause the number of facets 512, 514 to increase and decrease, as desired. As shown in
The valleys 522 can have various shapes and forms that can influence the optical properties of the reflector 500. In one example, the end of first face 514 and the end of second face 516 meet at a point (or substantially sharp interface) that forms the valley 522 into a “V” shape. In other examples, the valley 522 includes a flat segment and/or radial segment that mates with the end of the first face 514 and the end of the second face 516. This configuration forms the valley 522 with a flat bottom or, in the case of the radial segment, with a “U” shape. The dimensions of the flat segment (and radial segment) can be minimized to achieve an acceptable level of performance and internal reflection from the reflector 500. Likewise, in one embodiment, the exterior facet profile can be rounded along at least a portion of the facet edge 520, wherein such rounding may result from manufacturing, finishing, and/or polishing processes. However, the radii of such rounded peaks should be minimized in order to achieve acceptable performance and internal reflection from the reflector 500.
As best shown in
In one example, the mating boundary 536 represents the interface between the triangular form factor 526 and the rectangular form factor 528. A first angle 538 and a second angle 540 define the angle created between the mating boundary 536 and the first face 516 and the second face 518, respectively. In one example, the first angle 538 and the second angle 540 are substantially equal. This disclosure also contemplates examples of the exterior facet profile in which the first angle 538 and the second angle 540 have a value in the range of about 45° to about 55°, and in one particular configuration the value is about 50°. In other examples, the first angle 538 is different from (e.g., greater than and/or less than) the second angle 540.
As set forth above, the reflector 500 can exhibit optical properties that are similar to TIR lenses that do not require any secondary processing such the application of a reflective coating, treatment, or layer to any of the surfaces of the reflector 500. In one embodiment, the reflector 500 consists of a single unitary piece in order to facilitate ease of manufacture and to help reduce costs and expenses related to the manufacture of the reflector 500. In another embodiment, a reflective coating or layer (e.g., silver foil or metallic paint) may be selectively applied to the top surfaces of the reflector 500, e.g., along the edge 520 of the facets 512 and/or the central aperture 524. This reflective coating can reduce the amount of light emitted from a light source (e.g., the light source 114, 214 (
The following examples further illustrate alternate configurations and designs for reflectors 124, 224 of
As used herein, an element or function recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural said elements or functions, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the claimed invention should not be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
This written description uses examples to disclose embodiments of the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
| Number | Date | Country | |
|---|---|---|---|
| 61643056 | May 2012 | US |
