Illumination – Light source and modifier – Including reflector
Reexamination Certificate
2001-05-04
2003-07-29
O'Shea, Sandra (Department: 2875)
Illumination
Light source and modifier
Including reflector
C362S308000, C362S310000
Reexamination Certificate
active
06598998
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to light emitting devices and more particularly to side emitting light emitting diodes (LEDs).
2. Description of Related Art
FIG. 1A
illustrates a conventional LED package
10
. LED package
10
has a hemispherical lens
12
of a type well-known in the art. Package
10
may also have a reflector cup (not shown), in which an LED chip (not shown) resides, that reflects light emitted from the bottom and sides of the LED chip toward the observer. In other packages, other types of reflectors reflect the LED chip's emitted light in a particular direction.
Lens
12
creates a field of illumination
14
roughly along a longitudinal package axis
16
of LED package
10
. The vast majority of light emitted from an LED package
10
with a hemispherical lens
12
is emitted upwards away from LED package
10
with only a small portion emitted out from the sides of LED package
10
.
FIG. 1B
illustrates a known light emitting diode (LED) package
30
with a longitudinal package axis
26
. LED package
30
includes an LED chip
38
, a lens
32
with straight vertical sidewall
35
and a funnel-shaped top surface
37
. There are two main paths in which the light will travel through package
30
. The first light path P
1
is desirable with the light emitted from chip
38
and traveling to surface
37
where total internal reflection (TIR) causes the light to exit through sidewall
35
at approximately 90 degrees to the longitudinal axis. The second light path P
2
is light emitted from chip
38
towards sidewall
35
at an angle causing TIR or a reflection from sidewall
35
causing the light to exit package
30
at an angle not close to perpendicular to the longitudinal axis. This path is not desirable and limits the efficiency of side extracted light.
FIG. 2
illustrates the conventional LED package
10
of
FIG. 1
coupled along an edge of a portion of a refractive light guide
20
. LED package
10
is positioned on the edge of light guide
20
along the width of light guide
20
. Light rays R
1
, R
2
, R
3
emitted by LED package
10
are propagated along the length of light guide
20
.
FIG. 3
illustrates a plurality of conventional LED packages
10
positioned along the width of light guide
20
of FIG.
2
. These conventional LED/light guide combinations are inefficient as they require a large number of LED packages
10
to illuminate the light guide and result in coupling inefficiencies due to relatively small acceptance angles. These conventional LED packages
10
must be arranged along the entire length of one side of light guide
20
to fully illuminate light guide
20
.
A need exists for an LED package to couple efficiently to shallow reflectors and thin light guides. A need also exists for an LED package to allow these secondary optical elements to have relatively large illuminated areas.
SUMMARY OF THE INVENTION
Light emitting devices with side emission of light allow light guides and reflectors to have very thin profiles with large illuminated areas.
In accordance with one embodiment of the invention, a light emitting device includes a light emitting diode package. The package has a front surface and a back surface and contains a light emitting diode for emitting light at least in a first direction approximately normal to the front surface away from the package. There is also a lens extending from the front surface of the package for receiving light from the diode. The lens is shaped to redirect light received from the diode, including the light in the first direction, such that a majority of light emitted from the lens is generally parallel to the front surface of the package.
In accordance with another embodiment of the invention, a method of emitting light from a light emitting diode includes generating a light output from a light emitting diode package. The package has a front surface and a back surface and contains a light emitting diode for emitting light at least in a first direction approximately normal to the front surface away from the package. The method also includes redirecting light from the light emitting diode using a lens extending from the front surface of the package for receiving light from the diode, including the light in the first direction where the lens redirects light such that a majority of light emitted from the lens is generally parallel to the front surface of the package.
This invention will be more fully understood in light of the following detailed description taken together with the accompanying drawings.
REFERENCES:
patent: 4192994 (1980-03-01), Kastner
patent: 4342908 (1982-08-01), Henningsen et al.
patent: 4698730 (1987-10-01), Sakai et al.
patent: 5140220 (1992-08-01), Hasegawa
patent: 5302778 (1994-04-01), Maurinus
patent: 5335157 (1994-08-01), Lyons
patent: 5404282 (1995-04-01), Klinke et al.
patent: 5452190 (1995-09-01), Priesemuth
patent: 5608290 (1997-03-01), Hutchisson et al.
patent: 5777433 (1998-07-01), Lester et al.
patent: 5806955 (1998-09-01), Parkyn, Jr. et al.
patent: 5894195 (1999-04-01), McDermott
patent: 5894196 (1999-04-01), McDermott
patent: 5897201 (1999-04-01), Simon
patent: 5898267 (1999-04-01), McDermott
patent: 6030099 (2000-02-01), McDermott
patent: 6044196 (2000-03-01), Winston et al.
patent: 6048083 (2000-04-01), McDermott
patent: 6177761 (2001-01-01), Pelka et al.
patent: 6450661 (2002-09-01), Okumura
patent: 0450560 (1991-10-01), None
patent: WO 98/26212 (1998-06-01), None
patent: WO 99/13266 (1999-03-01), None
patent: WO 01/07828 (2001-02-01), None
Parkyn et al., The Black Hole™: Cuspated waveguide-injectors and illuminators for LEDs; Part of the SPIE Conference on Nonimaging Optics: Maximum Efficiency Light Transfer V, Denver, CO, Jul. 1999.
Hyper ARGUS® LED, Hyper-Bright, 3mm (T1) LED, Non Diffused; Mar. 1, 2000; Infineon Technologies, pp. 1-9.
“Backlighting LED 3mm”, Telefunken Electronic Creative Technologies, Edition A, 10/90, pp. 1-4.
Sasser Gary D.
Stewart James W.
West Robert S.
Alavi Ali
Leiterman Rachel V.
Lumileds Lighting U.S. LLC
O'Shea Sandra
Patent Law Group LLP
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