Patent Application
20120320602
The present invention generally relates to lighting systems, and more specifically to lighting systems using light-emitting diodes whose outputs are directed by optical elements.
Discrete light sources such as light-emitting diodes (LEDs) are an attractive alternative to incandescent light bulbs in illumination devices due to their smaller form factor, longer lifetime, and enhanced mechanical robustness. For a wide variety of lighting applications, the light from one or more LEDs is frequently diffused and directed by optical elements such as total-internal-reflection (TIR) optics. Thus, even though LEDs are effectively omnidirectional point sources of light, the light from LEDs may propagate through a large area and/or in specific directions.
Traditionally, optical engineers have designed lenses to obtain a desired illumination pattern from an LED or LED system. Lenses, however, can only collect light within their diameters; light outside the diameter of lens is lost, resulting in the need for further optics to capture such light. TIR optics utilize the principle of total internal reflection—whereby light is reflected at the boundary (or boundaries) of the optic and retained therein—and typically encompass the entire light source, thereby reducing or eliminating optical loss.
Multi-LED lamps may include a lens assembly including an arrangement of TIR optics and an LED holder to which the lens assembly attaches. The LED holder physically supports and supplies power to the LEDs. It may also act as (or contain) a heat sink that conducts heat away from the LEDs. The lenses are made of a translucent or transparent TIR material for focusing light from associated of LEDs. TIR ensures that light is directed only to the output face of the optic, and is not lost through the sidewalls.
Existing ways of mechanically fastening the lenses to the LED holder include the use of mounting posts (which affix the lenses to matching holes in the LED holder), “snap” fasteners on the LED holder that engage the lens assembly, and retaining rings. Each of these approaches has drawbacks. Because they occupy space on the LED holder, mounting posts restrict the size of the TIR optics. A grouping of post-mounted TIR lenses must leave room for the posts, and as a result, the lenses cannot be “close-packed” adjacently so as to exploit all available room on the holder.
Snap fasteners that reach around to the front of the lens assembly block a portion of the emitted light, and even if they only engage the sidewall rather than the emitting surface of the lens—or are built into the sidewall—they still occupy space and can reduce the TIR optic's beam output because the sidewall is not smooth. Retaining rings typically also block some of the output light.
In accordance with certain embodiments, the TIR optics themselves have an engagement member that mates with a complementary feature on the LED holder. The engagement member does not interfere with light propagation through or emission from the optical component. Also, it does not enlarge the footprint area occupied by the optical component.
In an aspect, embodiments of the invention feature a TIR optical component comprising a transparent or translucent body that itself comprises at least one sidewall defining a side portion of the body; a top surface for emitting light; a bottom portion opposed to the top portion and including a bottom surface, where bottom portion is configured to receive light from an LED; and an engagement member on the bottom surface for mating with a complementary feature on an LED holder. Light entering the bottom portion is emitted from the top surface substantially without losses through the at least one sidewall. The engagement member does not interfere with light propagation through or emission from the optical component and does not enlarge a footprint area of the optical component.
The bottom surface may or may not be substantially planar, and may surround a cavity for receiving an LED. The sidewall(s) may be a single angled sidewall such that the optical component has a frusto-conical configuration. In various embodiments, the engagement member is at least one tab, at least one hooked catch, at least one recess for receiving a tab, and/or a continuous or discontinuous rib projecting from the bottom surface and recessed from the sidewall.
In another aspect, the invention relates to a lamp assembly comprising a holder for a plurality of LEDs and, mounted on the holder, a plurality of TIR optical components each comprising a transparent or translucent body. The body of each TIR component comprises at least one sidewall defining a side portion of the body; a top surface for emitting light; a bottom portion opposed to the top portion and including a bottom surface, where the bottom portion is configured to receive light from an LED on the holder; and an engagement member on the bottom surface for mating with a complementary feature on the holder. Light entering the bottom portion is emitted from the top surface substantially without losses through the at least one sidewall. The engagement member does not interfere with light propagation through or emission from the optical component and does not enlarge a footprint area of the optical component. The LED holder is configured to support an LED below each of the TIR optical components.
In some embodiments, the TIR optical components are arranged in a close-packed configuration on the LED holder whereby each of the TIR optical components is in contact with at least one (and in some implementations at least three) neighboring TIR optical components. Mating of the engagement members and the complementary features may fixedly retain the TIR optical components on the LED holder, or instead may orient the TIR optical components on the LED holder; in the latter case, the TIR optical components may be fixedly retained on the LED holder by an adhesive, for example. In various embodiments, the bottom surface of each of the TIR optical components surrounds a recess for receiving an LED, and the LED holder is configured such that each supported LED enters the recess of an associated TIR optical component.
Each TIR optical component may have a single angled sidewall so as to exhibit a frusto-conical configuration. The engagement member of each TIR optical component may be at least one tab, at least one hooked catch, at least one recess for receiving a tab, and/or a continuous or discontinuous rib projecting from the bottom surface and recessed from the sidewall. The TIR optical components may be elements of a single lens array or fixture.
These and other objects, along with advantages and features of the invention, will become more apparent through reference to the following description, the accompanying drawings, and the claims. Furthermore, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and permutations. As used herein, the term “substantially” means ±10%, and in some embodiments, ±5%.
In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the present invention are described with reference to the following drawings, in which:
Refer first to
A cavity 125, which extends into the component 100A from the bottom surface 120, receives a discrete light source (typically, and interchangeably referred to herein as, an LED) 128 and traps light emitted therefrom. LED 128 is typically a packaged LED that includes the LED chip, associated electronics, and a package featuring a lens surrounding the chip. LED 128 is positioned such that substantially all of the light that it emits propagates into optic 100A and is confined therein until emerging out its top emission surface 110. The unoccupied space in cavity 125 may, in some embodiments, be filled with an optically compatible material having a refractive index similar or identical to that of component 100A.
The surface to which the component 100A is mounted may be reflective to prevent loss of light through the surface 120. In the illustrated embodiment, surface 120 is an annular ring surrounding cavity 125, but in other embodiments, the surface 120 may extend over the entirety of the bottom portion of component 100A with light coupled into the component by means other than a cavity.
One or more engagement members—in
Numerous variations are possible. In part, the engagement member optimal for a particular TIR optic may depend on whether the feature is used merely to orient the optic or to secure it to the LED holder. As shown in
Each of the wells 210 has along its edge at least one complementary engagement feature 220 for mating with the engagement member of the TIR optic. In
With reference to
The terms and expressions employed herein are used as terms and expressions of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof. In addition, having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. Accordingly, the described embodiments are to be considered in all respects as only illustrative and not restrictive.
