Illuminated display with light source destructuring and shaping device

• US 5,956,106 A
• Filed: 02/01/1996
• Issued: 09/21/1999
• Est. Priority Date: 07/27/1993
• Status: Expired due to Term

• Current Assignee: United California Bank (Los Angeles, California) (Old) (BNP Paribas S.A.)
• Original Assignee: Physical Optics Corporation
• Inventors: Petersen, Joel, Lerner, Jeremy
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Parker, Kenneth
• Application Number:
  US08/595,307
• Time in Patent Office: 1,328 Days
• Field of Search: 349/187, 349/112, 349/64, 359/599, 359/12, 359/22, 359/15, 359/25, 430/321, 430/1, 430/2, 430/290, 362/355, 362/800, 264/1.31, 264/1.19, 264/2.5
• US Class Current: 349/64
• CPC Class Codes: G02B 5/0252 using holographic or diffractive means
• CPC Class Codes: G02B 5/0268 characterized by the fabrication or manufacturing method
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 5/0284 used in reflection
• CPC Class Codes: G02B 6/0008 the light being emitted at the end of the fibre
• CPC Class Codes: G02B 6/06 the relative position of the fibres being the same at both ends, e.g. for transporting images
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity
• CPC Class Codes: G03F 7/0005 Production of optical devices or components in so far as characterised by the lithographic processes or materials used therefor
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A light source destructuring and shaping device which both homogenizes and imparts predetermined directionality to light rays emanating from a light source is disclosed. The device comprises a micro-sculpted surface structure which controls the direction in which light propagates in either reflection or transmission. The sculpted surface structure also homogenizes light propagating through it with predetermined directionality. The device may be used in an almost unlimited number of applications which require homogenization and which would benefit from being able to impart directionality to light waves propagating from a light source. These applications include existing diffuser applications and applications wherein it was not practical to use conventional diffusers. The homogenizing and shaping device achieves these benefits with very high transmission or reflection efficiency and with reduced side lobes.

Claims

1. A liquid crystal display system having a homogenizer spaced from a light source, the homogenizer made by a process including:

A. generating random disordered non-planar speckle in a photosensitive medium having a refractive index by exposing said photosensitive medium with coherent light, said coherent light having been diffused through a diffuser, so as to define non-discontinuous and smoothly varying changes in said refractive index of said photosensitive medium, said non-discontinuous and smoothly varying changes scattering collimated light into a controlled pattern with smooth brightness variation;

B. developing said photosensitive medium to form a micro-sculpted surface structure that (i) controls the direction in which light propagates and (ii) homogenizes light with directionality; and

C. making a replica of said micro-sculpted surface structure from said photosensitive medium,

wherein light scattered from said replica of said micro-sculpted surface structure is characterized by said random, disordered and non-planar speckle.

2. The liquid crystal display system as defined in claim 1, wherein said diffuser is a master holographic diffuser.

3. The liquid crystal display system as defined in claim 1, wherein said process further includes:

placing a release agent on said micro-sculpted surface structure so as to form a release coating; and

making said replica by coating a substrate with an epoxy, placing said epoxy against said release coating, curing said epoxy, and separating said epoxy from said release coating.

4. The liquid crystal display system as defined in claim 3, wherein said substrate is selected from the group consisting of a glass substrate, a plastic substrate and a metal substrate.

5. The liquid crystal display system as defined in claim 3, wherein said process further includes making a metal master from said replica using an electroform process.

6. The liquid crystal display system as defined in claim 3, wherein said process further includes:

producing said homogenizer from said metal master by thermoplastic embossing a thermoplastic material with said metal master.

7. A method of displaying data which utilizes the apparatus of claim 1.

8. A liquid crystal display system having a homogenizer with a normal axis, a horizontal direction, and a vertical direction, said homogenizer spaced from a light source and including:

A. a sheet of deformable material having formed therein a micro-sculpted surface structure that (i) controls the direction in which light propagates and (ii) homogenizes light with directionality, said micro-sculpted surface structure having been formed by replicating in said sheet of deformable material a prior micro-sculpted surface structure that (i) controls the direction in which light propagates and (ii) homogenizes light with directionality, said prior micro-sculpted surface structure having been formed in a photosensitive medium having a refractive index by;

(a) generating random, disordered and non-planar speckle in said photosensitive medium using coherent light, said coherent light having been diffused through a diffuser, so as to define non-discontinuous and smoothly varying changes in said refractive index of said photosensitive medium, said non-discontinuous and smoothly varying changes scattering collimated light into a controlled pattern with smooth brightness variation; and

(b) developing said photosensitive medium; and

B. a reflective layer deposited on and conforming to said micro-sculpted surface structure, whereby light incident on said homogenizer is reflected into an output area by said micro-sculpted surface structure,

wherein light scattered from said micro-sculpted surface structure is characterized by said random, disordered and non-planar speckle.

9. The liquid crystal display system as defined in claim 8, wherein said output area has an output area normal axis which is off the normal axis of said homogenizer.

10. The liquid crystal display system as defined in claim 8, wherein said micro-sculpted surface structure is made by recording said prior micro-sculpted surface structure in said photosensitive medium, making a replica of said prior micro-sculpted surface structure from said photosensitive medium, making a metal master of said replica from said replica, and embossing said sheet of deformable material with said metal master.

11. The liquid crystal display system as defined in claim 8, wherein said photosensitive medium includes dichromated gelatin.

12. The liquid crystal display system as defined in claim 8, wherein said diffuser is a master holographic diffuser.

13. A light emitting diode system having a homogenizer spaced from a light source, the homogenizer made by a process including:

A. generating random disordered non-planar speckle in a photosensitive medium having a refractive index by exposing said photosensitive medium with coherent light, said coherent light having been diffused through a holographic diffuser, so as to define non-discontinuous and smoothly varying changes in said refractive index of said photosensitive medium, said non-discontinuous and smoothly varying changes scattering collimated light into a controlled pattern with smooth brightness variation;

B. developing said photosensitive medium to form a micro-sculpted surface structure that (i) controls the direction in which light propagates and (ii) homogenizes light with directionality; and

C. making a replica of said micro-sculpted surface structure from said photosensitive medium,

wherein light scattered from said replica of said micro-sculpted surface structure is characterized by said random, disordered and non-planar speckle.

14. The light emitting diode system as defined in claim 13, wherein said micro-sculpted surface relief structure is characterized by peaks and valleys in a surface of said homogenizer so as to yield an output that is selected from the group consisting of circular, elliptical, and rectangular.

15. The light emitting diode system as defined in claim 13, wherein said output area is elliptical and said peaks and valleys are substantially straight and of random length.

16. The light emitting diode system as defined in claim 13, wherein said output area is rectangular and said micro-sculpted surface relief structure includes two intersecting sets of peaks and valleys.

17. The light emitting diode system as defined in claim 13, having an output intensity which is constant over a field of view.

18. A liquid crystal display comprising:

a display screen;

a light source disposed behind the display screen for illuminating the display screen; and

a homogenizer spaced from the light source;

wherein the homogenizer includes a sheet of deformable material having formed therein a micro-sculpted surface structure that both controls the direction in which light propagates and homogenizes light with directionality, the homogenizer having been formed by generating random, disordered and non-planar speckle in a photosensitive medium using coherent light, the coherent light having been diffused through a diffuser, so as to define non-discontinuous and smoothly varying changes in a refractive index of the photosensitive medium, such that the non-discontinuous and smoothly varying changes scatter collimated light into a controlled pattern with a smooth brightness variation and then developing the photosensitive medium, wherein light scattered from the micro-sculpted surface structure is characterized by the random, disordered and non-planar speckle.

19. The liquid crystal display according to claim 18, wherein the homogenizer is disposed between the light source and the display screen and wherein the homogenizer transmits light through the homogenizer to the display screen.

20. The liquid crystal display according to claim 18, wherein the light source is disposed between the display screen and the homogenizer and wherein the homogenizer further comprises a reflective layer deposited on and conforming to the micro-sculpted surface structure, whereby light incident on the homogenizer is reflected into the display screen.

21. The liquid crystal display according to claim 20, wherein the diffuser is a master holographic diffuser.

22. A light emitting diode comprising:

a display surface;

a light source disposed behind the display surface for providing light thereto; and

a homogenizer, spaced from the light source;

wherein the homogenizer includes a sheet of deformable material having formed therein a micro-sculpted surface structure that both controls the direction in which light propagates and homogenizes light with directionality, the homogenizer having been formed by generating random, disordered and non-planar speckle in a photosensitive medium using coherent light, the coherent light having been diffused through a diffuser, so as to define non-discontinuous and smoothly varying changes in a refractive index of the photosensitive medium, such that the non-discontinuous and smoothly varying changes scatter collimated light into a controlled pattern with a smooth brightness variation, and then developing the photosensitive medium, wherein the light scattered from the micro-sculpted surface structure is characterized by the random, disordered and non-planar speckle.

23. The light emitting diode according to claim 22, wherein the homogenizer is disposed between the light source and the display screen and wherein the homogenizer transmits light through the homogenizer to the display screen.

24. The light emitting diode according to claim 22, wherein the light source is disposed between the display screen and the homogenizer and wherein the homogenizer further comprises a reflective layer deposited on and conforming to the micro-sculpted surface structure, whereby light incident on the homogenizer is reflected into the display screen.

25. The light emitting diode according to claim 22, wherein the diffuser is a master holographic diffuser.