1. A backlight, comprising:
an array of curved mirror sections;
an array of primary light sources, the primary light sources arranged to illuminate a corresponding curved mirror section among the array of curved mirror sections; and
a lens array positioned adjacent the array of primary light sources on a side opposite the array of curved mirror sections,
wherein the curved mirror sections are shaped to reflect light from the corresponding primary light source so as to illuminate a corresponding lens within the lens array, and
the lenses in the lens array are shaped to collimate the light reflected by the corresponding curved mirror sections.
2. The backlight according to claim 1, wherein a radiant exitance at a plane immediately above the lens array varies by less than 50% over an area of the backlight.
3. The backlight according to claim 1, wherein the light collimated by the lens array is such that more than 90% of the light power is contained within an angular cone with a half-width of 10 degrees.
4. The backlight according to claim 1, wherein a central axis of each curved mirror section coincides with a central axis of the corresponding lens and passes through the corresponding primary light source.
5. The backlight according to claim 4, wherein a light emission from each primary light source extends over a polar angular range, \u03b8, relative to an outward normal from an emitting surface of the primary light source, and wherein the outward normal is parallel to the central axes of the corresponding curved mirror section and primary light source.
6. The backlight according to claim 5, wherein a total angular spread of the light emission from each primary light source is restricted to the range 0\xb0<\u03b8<90\xb0 as measured in air.
7. The backlight according to claim 6, further comprising a lens cap placed adjacent each of the primary light sources, the lens cap being configured to alter an emission angular profile of the primary light source to increase light radiance at higher values of \u03b8.
8. The backlight according to claim 7, wherein the lens cap causes total internal reflection of light rays from the primary light source emitted close to a direction of the central axes of the corresponding curved mirror section and lens.
9. The backlight according to claim 1, wherein a surface of each curved mirror section is deformed from being cylindrically symmetric about an axial direction.
10. The backlight according to claim 9, wherein where a central axis of each curved mirror section coincides with the z-axis of a Cartesian coordinate set and a sag of the surface of the curved mirror section is written zM(x, y), a deviation of the surface of the curved mirror section from a parabolic form is represented by:
\u03c3
=
(
min
z
P
,
R
P
\ue89e
{
\u222b
\u222b
mirror
\ue89e
\uf74c
x
\ue89e
\uf74c
y
\ue8a0
z
M
\ue8a0
(
x
,
y
)
–
z
P
–
(
x
2
+
y
2
)
(
2
\ue89e
R
P
)
2
}
\u222b
\u222b
mirror
\ue89e
\uf74c
x
\ue89e
\uf74c
y
\ue8a0
z
M
\ue8a0
(
x
,
y
)
–
z
P
(
m
\ue89e
\ue89e
i
\ue89e
\ue89e
n
)
2
)
1
2
(
2
)
where the integrals are taken over an extent of the curved mirror section, parameters zP and RP represent the z-coordinate of the apex of the curved mirror section and the radius of curvature of the curved mirror section at its center, respectively, the integral in the numerator is minimized with respect to the parameters zP and RP, and the value zP(min) is the value of zP when the numerator has been minimized.
11. The backlight according to claim 10, wherein a value of \u03c3 is at least 0.05.
12. The backlight according to claim 1, wherein a spatial extent of each primary light source, including packaging and necessary wiring, is less than a tenth of an aperture size of the corresponding lens within the lens array.
13. The backlight according to claim 1, wherein the array of curved mirror surfaces, the array of primary light sources and the lens array are configured in tiled arrangement.
14. The backlight according to claim 1, wherein the array of curved mirror surfaces, the array of primary light sources and the lens array are configured in lenticular arrangement.
15. The backlight according to claim 1, wherein the lens array comprises an array of Fresnel lenses.
16. The backlight according to claim 1, wherein a beam waist of light reflected by each curved mirror section is located between the curved mirror section and the corresponding lens within the lens array.
17. The backlight according to claim 1, wherein each curved mirror section and corresponding primary light source and lens form an integrated unit.
18. The backlight according to claim 17, wherein each lens is directly connected to the corresponding curved mirror section, and the corresponding primary light source is embedded within a lens material making up the lens.
19. A display comprising a backlight according to claim 1.
20. An illumination panel comprising a backlight according to claim 1.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A post-tensioned concrete foundation for supporting on its upper surface a structure subject to heavy load and high upset forces, said foundation comprising:
a generally horizontal concrete foundation cap for supporting a tall tower or other structure from an upper surface and having a lower surface engaged with a ground surface; and
a plurality of generally vertical post-tensioned helical anchors circumferentially spaced from one another, each of said helical anchors including at least one helical anchor pipe extending downwardly from said concrete foundation cap lower surface into surrounding soil underneath said concrete foundation cap, and a tensioning element coupled to an upper end of said at least one helical anchor pipe and extending through the concrete foundation cap, an upper end of each of said tensioning elements terminating above said concrete foundation cap upper surface, said tensioning elements pulling said cap downwardly and pulling the at least one helical anchor pipe of each helical anchor upwardly to post-tension said foundation cap and said helical anchors.
2. The post-tensioned concrete foundation of claim 1, wherein said tensioning elements have sleeves to prevent bonding of said tensioning elements with the concrete.
3. The post-tensioned concrete foundation of claim 1, wherein each of said helical anchors includes a plurality of hollow bars assembled end-to-end in substantially linear alignment and coupled together at adjoining ends to form hollow bar helical anchor pipes.
4. The post-tensioned concrete foundation of claim 3, wherein said hollow bar ends are externally threaded and are coupled at said adjoining ends by internally threaded couplers.
5. The post-tensioned concrete foundation of claim 3, wherein the tensioning element of each of said plurality of hollow bar helical anchors is a length of hollow bar.
6. The post-tensioned concrete foundation of claim 4, wherein said couplers have grout holes formed therein.
7. The post-tensioned concrete foundation of claim 1, further comprising an anchor plate surrounding an upper end of each tensioning element and a tension nut threaded onto said tensioning element upper end to retain elongation of said helical anchors upon post-tensioning thereof.
8. The post-tensioned concrete foundation of claim 1, wherein a percentage of the helical anchors is convertible to compression elements with a compressible material placed atop a steel plate in cementitious material below the concrete foundation cap to limit the maximum downward movement of the concrete foundation cap.
9. A post-tensioned concrete foundation for supporting on its upper surface a tall tower or other structure subject to heavy load and high upset forces, said foundation comprising:
a generally horizontal concrete foundation cap for supporting a tall tower or other structure from an upper surface and having a lower surface engaged with a ground surface; and
a plurality of generally vertical post-tensioned helical anchors circumferentially spaced from one another, each of said helical anchors including at least one helical anchor pipe extending downwardly from said concrete foundation cap lower surface into surrounding soil underneath said concrete foundation cap, and a tensioning element coupled to an upper end of said at least one helical anchor pipe and extending through the concrete foundation cap, an upper end of each of said tensioning elements terminating above said concrete foundation cap upper surface, said tensioning elements pulling said cap downwardly and pulling the at least one helical anchor pipe of each helical anchor upwardly to post-tension said foundation cap and said helical anchors.
10. The post-tensioned concrete foundation of claim 9, wherein said tensioning elements have sleeves to prevent bonding of said tensioning elements with the concrete.
11. The post-tensioned concrete foundation of claim 9, wherein each of said helical anchors includes a plurality of hollow bars assembled end-to-end in substantially linear alignment and coupled together at adjoining ends to form hollow bar helical anchor pipes.
12. The post-tensioned concrete foundation of claim 11, wherein said hollow bar ends are externally threaded and are coupled at said adjoining ends by internally threaded couplers.
13. The post-tensioned concrete foundation of claim 11, wherein the tensioning element of each of said plurality of hollow bar helical anchors is a length of hollow bar.
14. The post-tensioned concrete foundation of claim 12, wherein said couplers have grout holes formed therein.
15. The post-tensioned concrete foundation of claim 9, further comprising an anchor plate surrounding an upper end of each tensioning element and a tension nut threaded onto said tensioning element upper end to retain elongation of said helical anchors upon post-tensioning thereof.
16. The post-tensioned concrete foundation of claim 9, wherein a percentage of the helical anchors is convertible to compression elements with a compressible material placed atop a steel plate in cementitious material below the concrete foundation cap to limit the maximum downward movement of the concrete foundation cap.
17. A method for forming a post-tensioned concrete foundation with helical anchors and a concrete foundation cap for supporting on its upper surface a structure subject to high upset and dynamic forces comprising the steps of:
a) Preparing a ground surface for said foundation;
b) Drilling a plurality of helical anchors to depth, each helical anchor including a helical anchor pipe that extends into the ground and a tensioning element atop said anchor pipe;
c) Setting sleeves over said tensioning elements to enable post-tensioning of said helical anchors;
d) Pouring a concreteslurry leveling course encasing electrical, communication, and grounding trench with conduits if conduits are routed under the foundation;
e) After concreteslurry cures, pouring the concrete foundation cap with cementitious material;
f) Allowing said cementitious material in said concrete foundation cap to cure and solidify around, without bonding to, said tensioning elements; and
g) Post tensioning the helical anchors from above the concrete foundation cap using the tensioning elements.
18. The method of claim 17, wherein each of said helical anchor pipes includes a plurality of linearly aligned hollow bars coupled end to end with couplers to form a hollow bar helical anchor pipe, said hollow bar helical anchor pipe having helical discs and said couplers having grout holes formed therein, said method further comprising after step c), the step of pressure grouting the hollow bar helical anchor pipes to force grout out through said grout holes and around said helical discs for ground improvement around the hollow bar helical anchor pipe and helical discs to improve the soil strength, increase the anchor size and improve the bond between the helical anchor pipe and the soil to increase the anchor pullout or downward load resistance thus increasing the foundation loading capacity and stiffness.
19. The method of claim 18, where step g) includes the step of pressure grouting the hollow bar helical anchor pipes to force grout out through said grout holes and around said helical discs for ground improvement around the hollow bar helical anchor pipe and helical discs to improve the soil strength, increase the anchor size and improve the bond between the hollow bar helical anchor pipe and the soil to increase the anchor pullout or downward load resistance thus increasing the foundation loading capacity and stiffness.
20. The method of claim 18, wherein each hollow bar helical anchor pipe has a smooth continuous open annulus, said method including the step of isolating certain zones of the hollow bar helical anchor pipe for pumping measured grout quantities and pressure to specific zones using a packer.
21. The method of claim 17, further comprising the steps, after step c), of:
c-1) Positioning corrugated pipes interior to and around a perimeter of said concrete foundation cap;
c-2) Placing sleeved radial bolts or tendons horizontally across the foundation and securing the radial bolts to the corrugated pipes; and
after step f), the step of tensioning the sleeved horizontally extending radial bolts or tendons from outside the perimeter corrugated metal pipe.
22. The method of claim 17, further comprising adding a steel plate topped with a compressible material below the foundation cap to provide compression anchor capabilities to some of the helical anchors to limit the maximum settlement of the concrete foundation cap, said compressible material allowing the concrete foundation cap to be pulled down so the steel plate contacts the bottom of the concrete foundation cap, limiting additional concrete foundation cap settlement.
23. The method of claim 17, further comprising the steps, after step b), of:
b-1) Pressure grouting each of the helical anchor pipes through grout holes formed in the pipes; and
b-2) Attaching the tensioning elements to upper ends of the helical anchor pipes.