Illumination – Plural light sources – With modifier
Reexamination Certificate
1999-09-16
2001-05-08
Quach, Y. (Department: 2875)
Illumination
Plural light sources
With modifier
C362S259000, C362S800000
Reexamination Certificate
active
06227679
ABSTRACT:
FIELD OF INVENTION
The present invention relates to light bulbs. More specifically, the invention relates to light bulbs comprised of light emitting diodes (LED). The LED light bulb permits a 360° field of view wherein the light intensity is about the same for all viewing angles.
BACKGROUND OF THE INVENTION
Incandescent light bulbs are commonly used for indicator lamps, task lamps, general lighting, decorative lamps, warning lamps, traffic lamps and the like. However, incandescent bulbs are generally inefficient in terms of energy use and subject to frequent replacement due to their limited lifetime. Significant savings can be made by the use light bulbs wherein the source of light is from light emitting diodes (LED). LEDs consume a fraction of the energy used to illuminate incandescent bulbs and last much longer.
The problem with LEDs, without special light dissipating optics, is that the light intensity varies as a function of viewing angle. As shown in
FIG. 1
, the maximum light intensity is generally observed when the viewing angle is 0° or head-on and the least at 90° or when you view the device from the side. Thus, light bulbs made from LEDs of this type have the problem of being viewed with sufficient intensity at various viewing angles other than head-on.
U.S. Pat. No. 5,561,346 to Byrnes is directed to a lamp comprising a plurality of LEDs extending from opposed rounded surfaces to project light radially about the lamp. The patent requires special reflecting optics for projecting the light 360° around the lamp.
Accordingly, it is an object of this invention to provide an LED light bulb that can be viewed from various viewing angles wherein the light intensity is constant without the need for special light dissipating optics or special light reflecting optics.
SUMMARY OF THE INVENTION
The present invention is directed to an LED light bulb for use as an indicator lamp, task lamp, general lighting, decorative lamp, traffic lamp or warning lamp. The LED light bulb generally comprises a base portion and a generally circular and flat disc perpendicularly oriented and attached to the base portion. The disc is a printed circuit board with a plurality of interconnected LEDs concentrically mounted on the disc wherein a portion of the LEDs are outwardly splayed at an angle away from a center axis point of the disc. The LEDs, when energized, collectively transmit light 360 degrees about the surface of the disc. The light intensity is about the same for different viewing angles. The LED light bulb includes circuitry means for providing a current to the LEDs.
In a preferred embodiment, the LED light bulb comprises a conical housing wherein the housing has an interior support structure for mounting the circuit board. Preferably, a portion of LEDs are splayed outwardly away from the central axis point at angles of about 20 to about 80 degrees from the disc. Preferably, the portion of LEDs that are outwardly splayed are at angles of about 55 to 60 degrees from the disc.
The LED light bulb may further comprise a light transmissive cap attached to the housing wherein the light transmissive cap may be colored. Alternatively, the LEDs emits light at a wavelength that is a function of its material and dopants.
Circuitry means preferably comprises a full wave rectifier for converting an AC current into a DC current. The LEDs may be connected in parallel or in series. The inventive LED light bulbs economically consume less than 1 watt of energy when in use.
REFERENCES:
patent: 5561346 (1996-10-01), Byrne
patent: 5726535 (1998-03-01), Yan
patent: 5774098 (1998-06-01), Kawashima et al.
patent: 5803579 (1998-09-01), Turnbull et al.
patent: 5806965 (1998-09-01), Deese
patent: 5848837 (1998-12-01), Gustafson
patent: 5850126 (1998-12-01), Kanbar
patent: 5865529 (1999-02-01), Yan
patent: 5931570 (1999-08-01), Yamuro
patent: 5947588 (1999-09-01), Huang
Xiang Zhang Qi
Zhang Zhou Kui
Quach Y.
Watts, Hoffman, Fisher & Heinke, CO, LPA
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