Asymmetric LED bulb optic
View Patent ↗An LED lamp assembly with a central light guide supplying light to a primary reflector where the reflective surface has a circular cross section in the horizontal medial plane and has a parabolic cross section in the vertical plane medial plane and regular combinations of the two planar sections in rotating round the axis from the vertical to the horizontal.
1. An automotive lamp assembly to evenly illuminate an elongated rectangular shell type secondary reflector, the lamp assembly comprising:
a light source emitting light in at least an axial direction;
a light guide with an input window facing the light source for the receipt of light, a body section axially extending in a forward (Z) direction away from the input window, having an internally reflective surface and an output window perpendicular to the axis; and
a primary reflector having a reflective surface positioned opposite the output window and having an axially projected size and shape sufficient to span the output window, the reflector in a first plane (XZ) containing the Z axis, and a first perpendicular (X) to the axis (the medial XZ plane), having a cross section providing a first reflection pattern of light from the light guide at angles varying from 0 to 90 degrees from the Z axis in the first plane (XZ); and in a second plane (YZ) containing the Z axis and a second perpendicular (Y) to the Z axis, (the medial YZ plane), having a cross section providing a second reflection pattern of light from the light guide at angles from 0 to 90 degrees to the Z axis in the second plane (YZ), different from the first reflection pattern; and in planes containing the Z axis intermediate the first plane (XZ) and the second plane (YZ) having a cross section being a combination of the first cross section (XZ) and the second cross section (YZ) providing a reflection pattern of light from the light guide at angles from 0 to 90 degrees intermediate the first reflection pattern and the second reflection pattern.
2. The automotive lamp assembly in claim 1 , wherein the second cross section (YZ) of the primary reflector is a parabola with the focal point located to be axially projected onto the output window.
3. The automotive lamp assembly in claim 1 , wherein the first cross section (XZ) of the primary reflector is a circular section with the center point located so as to be axially projected onto the output window.
4. The automotive lamp assembly in claim 1 , wherein the light guide has a cylindrical outer wall.
5. The automotive lamp assembly in claim 1 , wherein the light guide has a cylindrical inner wall.
6. The automotive lamp assembly in claim 1 , wherein the primary reflector has a reflective surface in the form of a ring.
7. The automotive lamp assembly in claim 1 , wherein the light guide is butted to the primary reflector.
8. The automotive lamp assembly in claim 1 , wherein the light source includes at least one LED facing the input window of the light guide.
9. An automotive lamp assembly comprising:
a light source including at least one LED, facing an input window of a light guide;
the light guide having the input window facing the light source for the receipt of light, a body section axially extending in a forward (Z) direction away from the input window, having an internally reflective surface and an output window perpendicular to the Z axis, wherein the light guide has the form of a hollow tube with a cylindrical outer wall and a cylindrical inner wall; the output window of the light guide being closed positioned opposite a primary reflector;
the primary reflector having a reflective surface positioned opposite the output window and having an axially projected size and shape sufficient to span the output window, the reflective surface in the form of a ring, the reflective surface in a first plane (XZ) containing the Z axis, (the medial XZ plane), having a cross section providing a first reflection pattern of light from the light guide at angles varying from 0 to 90 degrees from the axis in the first plane (XZ) and the first cross section (XZ) being a circular section with the center point located to be axially projected onto the output window; and the reflective surface having in a second plane (YZ) containing the Z axis, (the medial YZ plane), having a cross section providing a second reflection pattern of light from the light guide at angles from 0 to 90 degrees to the axis in the second plane (YZ), different from the first reflection pattern; the second cross section (YZ) being a parabola with the focal point located to be axially projected onto the output window and the reflective surface in planes containing the Z axis intermediate the first plane (XZ) and second plane (YZ) having respective cross sections being combinations of the first cross section (XZ) and the second cross section (YZ) providing respective reflection patterns of light from the light guide at angles from 0 to 90 degrees intermediate the first reflection pattern and the second reflection pattern; and
a secondary reflector having a greater first (X) medial spanning distance than second (Y) medial spanning distance, and the secondary reflector having an approximately rectangular axial projection with a greater first (X) medial spanning distance than second (Y) medial spanning distance.
10. An automotive lamp assembly in claim 1 , wherein the primary reflector has a surface defined in cylindrical coordinates, where r is the radius, w is the angle around the z axis, and z is the distance along the z axis, wherein a parametric representation r(z,w) defines the reflective surface by:
r
(
z
,
w
)
=
a
(
z
)
·
b
(
z
)
a
(
z
)
2
·
cos
2
(
w
)
+
b
(
z
)
2
·
sin
2
(
w
)
a
(
z
)
=
R
+
c
-
c
2
-
(
z
+
c
)
2
b
(
z
)
=
R
+
1
4
F
(
z
+
h
)
2
where
z=is from −h to 0;
where w is the angle around the axis from 0 (horizontal) to 360 degrees;
z is the axial distance from −h to 0;
h is a constant indicating the axial height of the primary reflector;
R is a constant indicating the radial distance from the axis to the parabola;
c is a constant indicating the radius of the circle; and
F is a constant indicating the eccentricity of the parabola.
11. An automotive lamp assembly in claim 10 , wherein
h=−3.0 mm
R=5.12 mm
c=2.75 mm, and
F=0.5 mm.