Illumination – Modifier mountable on light source envelope
Reexamination Certificate
2001-05-04
2003-08-19
O'Shea, Sandra (Department: 2875)
Illumination
Modifier mountable on light source envelope
C362S800000, C362S326000, C362S340000, C362S026000, C313S512000, C313S513000
Reexamination Certificate
active
06607286
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 lens includes a body. The body further includes a central axis running along a length of the body and a first surface for coupling to a light source. There is also a sawtooth lens portion which refracts light emitted from the light source such that a majority of light emitted from the sawtooth lens portion is generally perpendicular to the central axis of the body. Additionally, there is a funnel-shaped lens portion connected to the sawtooth lens portion where the funnel-shaped lens portion reflects light emitted from the light source such that a majority of light emitted from the funnel-shaped lens portion is generally perpendicular to the central axis of the body.
In accordance with another embodiment of the invention, a lens cap attachable to a light source includes a body. The body further includes a central axis running along a length of said body and a first surface for coupling to a light source. There is also a sawtooth lens portion which refracts light emitted from the light source such that a majority of light emitted from the sawtooth lens portion is generally perpendicular to the central axis of the body. Additionally, a funnel-shaped lens portion is connected to the sawtooth lens portion where the funnel-shaped lens portion reflects light emitted from the light source such that a majority of light emitted from the funnel-shaped lens portion is generally perpendicular to the central axis of the body. There is also an attachment means for coupling the lens cap to the light source where the attachment means is coupled to the sawtooth lens portion.
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: 5302778 (1994-04-01), Maurinus
patent: 5335157 (1994-08-01), Lyons
patent: 5608290 (1997-03-01), Hutchisson et al.
patent: 5897201 (1999-04-01), Simon
patent: 6044196 (2000-03-01), Winston et al.
patent: 6450661 (2002-09-01), Okumura
patent: 0 450 560 (1991-10-01), None
patent: WO 99/13266 (1999-03-01), None
Sasser Gary D.
Stewart James W.
West Robert S.
Leiterman Rachel V.
Lumileds Lighting U.S. LLC
Patent Law Group LLP
Ton Anabel
LandOfFree
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