A Light-Emitting Diode (LED), as used herein, is a semiconductor light source for generating a light at a specified wavelength or a range of wavelengths.
As the concerns for energy price and environment continuously increase, people are looking into ways to reduce energy consumption and to lengthen the lifetimes of lighting devices. Incandescent light bulbs (or lamps) known to the inventors have shorter life times and consume significantly more energy to achieve the same level of lighting performance in comparison to light bulbs made with LED devices.
A Light-Emitting Diode (LED), as used herein, is a semiconductor light source for generating light at a specified wavelength or a range of wavelengths. An LED emits light when a voltage is applied across a p-n junction formed by oppositely doping semiconductor compound layers of the LED. Different wavelengths of light can be generated using different materials by varying the bandgaps of the semiconductor layers and by fabricating an active layer within the p-n junction. With the increased concerns for energy price and environment, there is a continuing effort in developing improved LED light bulbs to replace known incandescent light bulbs.
Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
It is understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. Of course, the description may specifically state whether the features are directly in contact with each other. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
The LED assembly 50 may include a single or a number of LED light emitters 42 mounted on a substrate 45. The substrate 45 is at least at the same level as the interface 44 between the bulb 10 and the housing 30. The substrate 45 can be placed above the interface 44. If a number of LED light emitters 42 are mounted on substrate 45, the LED light emitters are electrically connected to one another. The electrical connection could be serial, parallel, or a combination thereof LED light emitters 42 may be made by growing a plurality of light-emitting structures on a growth substrate. The light-emitting structures along with the underlying growth substrate are separated into individual LED dies. At some point before or after the separation, electrodes or conductive pads are added to the each of the LED dies to allow the conduction of electricity across the structure. LED dies are then packaged by adding a package substrate, optional phosphor material, and optical components such as lens(es) and reflector(s) to become light emitters, in accordance with some embodiments.
On the backside of substrate 45, there could be electrical connecting devices (not shown), such as wires or other types of connections, that provide electrical contacts between the LED light emitters 42, the bottom contact 25 and the metallic element 22 described above. On the backside of substrate 45, there could be a heat sink 60 physically coupled to substrate 45 to dissipate the heat generated by the LED light emitters 42, in accordance with some embodiments. In some embodiments, there is an electrical circuit assembly 70 on the backside of substrate 45 and in the hollowed space within the housing 30 and/or base 20. The electrical circuit assembly 70 is electrically connected to the LED light emitters 42, the bottom contact 25 and the metallic element 22. It may be used to adjust power taken in from an external power source to current/voltage for lighting the LED light emitters 42. The electrical circuit assembly 70 may also perform other control functions, such as controlling the amount of light emitted by the LED light emitters 42, etc.
Incandescent light bulbs known to the inventors that generate light by heating up metal filament wires shine light in all directions, ENERGY STAR™ that sets standards for energy efficient consumer products has standards for LED-based light bulbs that intend to replace the traditional incandescent light bulbs. One of the standards for omnidirectional LED-based light bulbs is to emit light toward the backside as well as toward the front side of the light bulbs to mimic the lighting pattern of conventional incandescent light bulbs, The ENERGY STAR™ standard for omnidirectional LED-based light bulbs is to have at least 5% of light (or flux) emitting in the zone from 135° to 180° out of the 0° to 180° angle range.
The housing 230 is similar to housing 30 of
The LED assembly 250 includes a number of LED light emitters 42 that are mounted on two levels of substrate surfaces, as shown in
The shape and slope of surface 46 can be made to enable sufficient light directed toward the backside of bulb 200 to meet the requirement defined by ENERGY STAR™ for LED-based light bulbs. The r1 is kept as large as possible, in some embodiments, to allow sufficient space to house a cooling devices for LED light emitters 42 on substrate 45′. In some embodiments, the radius r1 is in a range from about 4 mm to about 28 mm. In some embodiments, the radius r2 is in a range from about 5 mm to about 30 mm. In some embodiments, the ratio of r1/r2 is in a range from about 0.4 to about 0.95. The height of the substrate 45′ is “h”. In some embodiments, the height is in a range from about 5 mm to about 30 mm.
In some embodiments, bulb 210 has a shape of a partial sphere, as shown in
In some embodiments, multiple LEDs are placed near each other to generate light of a predetermined color. For example, a blue, a red and a green LEDs can be placed together to generate a white light.
The substrates 45, 45′, and 47 for supporting LED-based light emitters, such as emitters 42, 42U, 42L, 42A, 42B, and 42C, are all shown to be in circular shapes. Other shapes of substrates can also be used to support the LED-based light emitters.
The embodiments of LED assemblies 250, and 250A-250E described above show examples of upper and lower substrates (45′, 45* and 47) and emitters (42, 42U, 42L, 42A, 42B, and 42C). Different numbers of upper and lower emitters can be placed on the upper and lower support substrates to generate different colors, intensities, and light patterns, ENERGY STAR™ specifies minimal amount of light directed toward the back side of light bulb to be at least 5% in the zone (or region) within 135° to 180°. The application of the present application can be configured to have a light pattern that directs equal to or more than 5% of light toward the backside, if needed.
In some embodiments, the percentage of upper LED emitters 42U of all the LED emitters (42U and 42L) is in a range from about 10% to about 70%. In some other embodiments, the percentage of upper LED emitters 42 is in a range from about 30% to about 50%. Different designs of the LED assembly 250 having different bulb shapes and the optional layer 15 of phosphor and/or light-diffuser coating can generate different light colors, intensities and patterns.
The embodiments of an LED-based light bulb and an LED assembly described above provide mechanisms of reflecting generated by LED emitters toward the back of the LED-based light bulb. An upper substrate and a lower substrate are used to support upper and lower LED emitters. A slanted and reflective surface between the upper substrate and the lower substrate reflects light generated by the lower LED emitters toward the backside of the LED-based light bulb.
In some embodiments, a light-emitting-diode-based (LED-based) light bulb is provided. The LED-based light bulb includes a bulb, and a housing. The bulb is disposed on the housing. The LED-based light bulb also includes a base, and the housing is disposed on the base. The base is configured to make electrical contact of a power source. The LED-based light bulb further includes an LED assembly. The LED assembly includes an upper substrate for supporting one or more upper LED emitters and a lower substrate for supporting a plurality of lower LED emitters, and a top surface of the lower substrate is at least at the same level as an interface between the bulb and the housing. The LED assembly also includes a reflective surface extending between an outer edge of the upper substrate and an inner edge of the lower substrate. The reflective surface is configured to direct at least a portion of light generated by the lower LED emitters toward a backside of the LED-based light bulb.
In some other embodiments, an LED assembly for an LED-based light bulb is provided. The LED assembly includes an upper substrate for supporting one or more upper LED emitters, and a lower substrate for supporting a plurality of lower LED emitters. The LED assembly also includes a reflective surface disposed between the upper substrate and the lower substrate, and an outer edge of the upper substrate is connected to an inner edge of the lower substrate by the reflective surface. The reflective surface is slanted away from the bulb, and the reflective surface reflects light generated by the lower LED emitters toward the backside of the LED-based light bulb.
In yet some other embodiments, an LED assembly for an LED-based light bulb is provided. The LED assembly includes a lower substrate for supporting a plurality of lower LED emitters, and an upper substrate for supporting one or more upper LED emitters. A top surface of the upper substrate has a height above the top surface of the lower substrate, wherein the height is in a range from about 5 mm to about 30 mm. The LED assembly also includes a reflective surface disposed between the upper substrate and the lower substrate, and an outer edge of the upper substrate is connected to an inner edge of the lower substrate by the reflective surface. The reflective surface is slanted away from the bulb, and wherein the reflective surface reflects light generated by the lower LED emitters toward the backside of the LED-based light bulb.
The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the detailed description that follows. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. It is understood, however, that these advantages are not meant to be limiting, and that other embodiments may offer other advantages. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.
The present application is a continuation application of U.S. patent application Ser. No. 13/151,857, filed on Jun. 2, 2011, the disclosure of which is hereby incorporated by reference in its entirety.
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Number | Date | Country | |
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20140307435 A1 | Oct 2014 | US |
Number | Date | Country | |
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Parent | 13151857 | Jun 2011 | US |
Child | 14316942 | US |