High-density illumination system

• US 7,520,642 B2
• Filed: 04/05/2007
• Issued: 04/21/2009
• Est. Priority Date: 01/24/2003
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Digital Optics International Corporation
• Inventors: Cox, Arthur, Holman, Robert L.
• Primary Examiner(s): Husar; Stephen F
• Application Number:
  US11/784,046
• Publication Number:
  US 20070211449A1
• Time in Patent Office: 747 Days
• Field of Search: 362/19, 362242-245, 362/328, 362/331, 362/343, 362/545, 362/800, 349/61
• US Class Current: 362/328
• CPC Class Codes: F21K 9/68 Details of reflectors forming part of the light source
• CPC Class Codes: G02B 17/002 Arrays of reflective systems
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 5/10 with curved faces
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133605 including specially adapted reflectors
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/12044 OLED
• CPC Class Codes: H01L 2933/0091 : Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/58 : Optical field-shaping elements
• CPC Class Codes: H01L 33/60 : Reflective elements
• CPC Class Codes: H04N 9/315 : Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20
• CPC Class Codes: Y10S 362/80 : Light emitting diode

Abstract

A compact and efficient optical illumination system featuring planar multi-layered LED light source arrays concentrating their polarized or un-polarized output within a limited angular range. The optical system manipulates light emitted by a planar array of electrically-interconnected LED chips positioned within the input apertures of a corresponding array of shaped metallic reflecting bins using at least one of elevated prismatic films, polarization converting films, micro-lens arrays and external hemispherical or ellipsoidal reflecting elements. Practical applications of the LED array illumination systems include compact LCD or DMD video image projectors, as well as general lighting, automotive lighting, and LCD backlighting.

Claims

1. An illuminating system, comprising:

an electrical interconnection system for interconnecting at least one LED light emitting element to a power source;

at least one LED light emitting element positioned on a common light-emitting plane;

a first light redirecting element disposed above the at least one LED light-emitting element on said common light emitting plane, each said first light redirecting element including at least one diffusing medium, a diffusing layer, and a component, said component selected from the group consisting of a metallically reflecting bin and a lens system, said metallically reflecting bin having a circular or rectangular cross-section with mathematically curving shape necessitated by meeting the geometrical relationship between input and output aperture sizes, A_inSin ²θ

_in=A_outSin²θ

_out, where

A_inis;

if circular, the area of the reflecting bin inlet π

r_in², r_in being the radius of the bin'"'"'s inlet opening, and

if rectangular, (x_in)(y_in)

θ

_in is the maximum half-angle emitted by the at least one LED at bin'"'"'s input opening disposed above it, the full beam angle being 2θ

_in,

A_out is the area of the aperture existing at the bin'"'"'s ideal height H given as

if circular, H=(r_in+r_out)/Tanθ

_out with r_out being the diameter of the bin'"'"'s ideal output aperture, and θ

_out is the corresponding output beam'"'"'s half-angle, the beam'"'"'s full angle being 2θ

_out;

if rectangular, H being the larger of H₁=0.5(x_in+x_out)/Tanθ

_out,x and H₂=0.5 (y_in+y_out)/Tanθ

_out,y with x_out and y_out being the aperture edge sizes, θ

_out,x and θ

_out,y being the corresponding output beam half-angles in each orthogonal meridians;

and H_bin is the actual bin height of the metallically reflecting bin of the first light redirecting element, H_bin is equal to or less than the ideal bin height H;

a second light redirecting element disposed beyond said first light redirecting element comprised of at least one condensing element having effective focal length F and an elevation above said first light redirecting means in the range 0 to 2 F above the output plane of said first light redirecting layer;

said at least one condensing element of the second light redirecting layer selected from the group consisting of a Fresnel lens, two sequentially stacked Fresnel-type cylindrical lenses where the axes of each form an angle of 90-degrees with each other, a reflecting plane having a circular or rectangular cutout that allows for a substantial portion of the emitted light to pass outwards without change in brightness or angular direction, and two sequentially stacked lenticular lenses where the axes of each form an angle of 90-degrees with each other; and

an output aperture disposed beyond said second light redirecting element, said output aperture containing at least one of a clear window and a spatial light modulator.

2. The illuminating system as defined in claim 1 wherein the first light redirecting element comprises metallically reflecting bins having a clear output aperture and a clear input aperture formed by at least one mathematically-tapered metallically reflecting sidewall extending therebetween, centers of each said metallically reflecting bin being centered on a center of a corresponding one of the LED light emitting element.

3. The illuminating system as defined in claim 1 wherein said first light redirecting element comprises at least one of lenses and systems of lenses centered on the center of a corresponding one of the LED light emitting element.

4. The illuminating system as defined in claim 1 wherein said first light redirecting element comprises at least one of a passive diffuser, a holographic diffuser and active diffuser including a transparent phase holding secondary diffuser spherical particles that fluoresce and/or scatter the light passing through the particles, the center of each said passive and active diffuser centered on a center of the corresponding one of the LED light emitting element.

5. The illuminating system as defined in claim 1 wherein said second light redirecting element is disposed a distance above said output plane of said first light redirecting element approximately equal to said effective focal length F of said second light redirecting element.

6. The illuminating system as defined in claim 1 wherein said effective focal length F of said second light redirecting element is greater than the distance H_bin in which said output plane of said first light redirecting element stands above said common light emitting plane of said first light redirecting element, and in which the distance between said second light redirecting element and said output plane of said first light redirecting element falls in the range between 0 and 0.25 F.

7. The illuminating system as defined in claim 1 wherein said effective focal length F of said second light redirecting element is chosen to change said output beam angles emitting from said first light redirecting element, and in which the distance between said second light redirecting element and said output plane of said first light redirecting element falls approximately in the range of 0.5 F and 1.5 F.

8. An illuminating system, comprising:

an electrical interconnection system for interconnecting at least one LED light emitting element to a power source;

at least one LED light emitting element positioned on a common light-emitting plane;

a first light redirecting element disposed above the at least one LED light-emitting element on said common light emitting plane, each said first light redirecting element including at least one diffusing medium, a diffusing layer, and a component, said component selected from the group consisting of a metallically reflecting bin and a lens system, said metallically reflecting bin having a circular or rectangular cross-section with mathematically curving shape necessitated by meeting the geometrical relationship between input and output aperture sizes, A_inSin²θ

_in=A_outSin²θ

_out, where

A_in is (x_in)(y_in);

θ

_in is the maximum half-angle emitted by the at least one LED at bin'"'"'s input opening disposed above it, the full beam angle being 2θ

_in,

A_out is the area of the aperture existing at the bin'"'"'s ideal height H given as H being the larger of H₁=0.5 (x_in+x_out)/Tanθ

_out,x and H₂=0.5 (y_in+y_out)/Tanθ

_out,y with x_out and y_out being the aperture edge sizes, θ

_out,x and θ

_out,y being the corresponding output beam half-angles in each orthogonal meridians;

and H_bin is the actual bin height of the metallically reflecting bin of the first light redirecting element, H_bin is equal to or less than the ideal bin height H;

a second light redirecting element disposed beyond said first light redirecting element comprised of at least one condensing element having effective focal length F and an elevation above said first light redirecting means in the range 0 to 2 F above the output plane of said first light redirecting layer;

said at least one condensing element of the second light redirecting layer selected from the group consisting of a Fresnel lens, two sequentially stacked Fresnel-type cylindrical lenses where the axes of each form an angle of 90-degrees with each other, a reflecting plane having a circular or rectangular cutout that allows for a substantial portion of the emitted light to pass outwards without change in brightness or angular direction, and two sequentially stacked lenticular lenses where the axes of each form an angle of 90-degrees with each other; and

an output aperture disposed beyond said second light redirecting element, said output aperture containing at least one of a clear window and a spatial light modulator.

9. The illuminating system as defined in claim 8 wherein the first light redirecting element comprises metallically reflecting bins having a clear output aperture and a clear input aperture formed by at least one mathematically-tapered metallically reflecting sidewall extending therebetween, centers of each said metallically reflecting bin being centered on a center of a corresponding one of the LED light emitting element.

10. The illuminating system as defined in claim 8 wherein said first light redirecting element comprises at least one of lenses and systems of lenses centered on the center of a corresponding one of the LED light emitting element.

11. The illuminating system as defined in claim 8 wherein said first light redirecting element comprises at least one of a passive diffuser, a holographic diffuser and active diffuser including a transparent phase holding secondary diffuser spherical particles that fluoresce and/or scatter the light passing through the particles, the center of each said passive and active diffuser centered on a center of the corresponding one of the LED light emitting element.

12. The illuminating system as defined in claim 8 wherein said second light redirecting element is disposed a distance above said output plane of said first light redirecting element approximately equal to said effective focal length F of said second light redirecting element.

13. The illuminating system as defined in claim 8 wherein said effective focal length F of said second light redirecting element is greater than the distance H_bin in which said output plane of said first light redirecting element stands above said common light emitting plane of said first light redirecting element, and in which the distance between said second light redirecting element and said output plane of said first light redirecting element falls in the range between 0 and 0.25 F.

14. The illuminating system as defined in claim 8 wherein said effective focal length F of said second light redirecting element is chosen to change said output beam angles emitting from said first light redirecting element, and in which the distance between said second light redirecting element and said output plane of said first light redirecting element falls approximately in the range of 0.5 F and 1.5 F.