ILLUMINATION APPARATUS AND FILM

Abstract

An illumination apparatus comprises: (a) at least one light source;(b) a light guide for accepting light from the at least one light source and for guiding the light using total internal reflection, the light guide having a top surface;(c) a light extracting film having an input surface optically coupled with the top surface and an output surface for providing light,wherein the input surface comprises a plurality of features which are optically coupled to the top surface of the light guide, each feature having: (i) a first side comprising two or more planar segments; and(ii) a second side comprising two or more planar segments, andwherein the first and second sides intersect at an apex.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed description when read with the accompanying drawing figures. It is emphasized that the various features are not necessarily drawn to scale. In fact, the dimensions may be arbitrarily increased or decreased for clarity of discussion. Wherever practical, like reference numerals refer to like elements.

FIG. 1 is a cross sectional view of an illumination apparatus using a film with features according to the present invention.

FIG. 2 is a perspective view of a feature in a discrete embodiment.

FIG. 3 is a perspective view of a feature in a linearly extended embodiment.

FIGS. 4A and 4B are cross-section views of inventive film features.

FIG. 5 is a cross-section view of a portion of inventive film showing light handling behavior.

FIG. 6 is a cross-section view showing light travel from the light source through the light guide and light redirecting film of the present invention.

FIG. 7 is a cross-section view of a feature embedded into an adhesive layer.

FIG. 8A is a cross-section view of a feature embedded into an adhesive layer and registered against the light guide.

FIG. 8B is a side view of a feature embedded into an adhesive layer and registered against the light guide.

FIG. 9 is a perspective view of an illumination apparatus using the film of the present invention.

FIG. 10 is a perspective view, from the bottom side, of an illumination apparatus using the film of the present invention.

FIG. 11 is a perspective view of an illumination apparatus using the film of the present invention.

FIG. 12 is a perspective view, from the light input side, of a film in one embodiment.

FIG. 13 is a perspective view, from the light input side, of a film with light sources in one embodiment.

FIG. 14 is a top schematic view of a film having an optical contact ratio varying across the film in accordance with an example embodiment.

FIG. 15 is a top schematic view of a film where the optical contact ratio varies across the film in accordance with another example embodiment.

FIG. 16 is a cross-sectional view of a film being replicated from a mold in accordance with an example embodiment.

FIGS. 17A and 17B are cross-sectional views of a film as it might be fabricated from a mold created with an example fabrication process in accordance with an example embodiment.

FIG. 18 is a cross-sectional view of a diamond cutter fabricating a mold in multiple cuts in accordance with an example embodiment.

FIGS. 19A and 19B are cross-sectional views of a diamond cutter that might be used to fabricate a mold in accordance with an example embodiment.

FIG. 20 is a graphical representation of viewing angle versus luminance of a film of an example embodiment with known manufacturing errors.

FIG. 21 is a perspective view of a cutter cutting example features in a mold in accordance with an example embodiment.

FIG. 22A is a graphical representation of the feature index from an edge of a film versus feature length in accordance with an example embodiment.

FIG. 22B is a graphical representation of luminance versus distance from a CCFL light source in accordance with an example embodiment.

FIG. 23 is a graphical representation of viewing angle versus luminance of a film of an example embodiment and a known brightness enhancement film (BEF) layer.

FIG. 24 is a graphical representation of viewing angle versus measured luminance of a film in accordance with an example embodiment compared to the measured luminance of a known BEF layer.

FIG. 25 is a graphical representation of viewing angle versus luminance of a film of an example embodiment.

FIG. 26 is a perspective view of a display device in accordance with an example embodiment.

FIGS. 27A and 27B are scanning electron micrographs of a light extracting film in accordance with an example embodiment.

FIG. 28 is a cross-section view showing light redirection from the light source through the light guide and diffusing and light redirecting film in accordance with an example embodiment.

FIGS. 29A and 29B are cross-section views of different embodiments of the diffusing and light redirecting film, with the feature inserted into an adhesive layer.

FIG. 29C is a cross-section view of the light redirecting film with a functional coating, and the feature inserted into an adhesive layer.

FIG. 30 is a perspective view of a display device in accordance with an example embodiment.

Claims

1. An illumination apparatus comprising: (a) at least one light source;(b) a light guide for accepting light from the at least one light source and for guiding the light using total internal reflection, the light guide having a top surface;(c) a light extracting film having an input surface optically coupled with the top surface and an output surface for providing light,wherein the input surface comprises a plurality of features which are optically coupled to the top surface of the light guide, each feature having: (i) a first side comprising two or more planar segments; and(ii) a second side comprising two or more planar segments, andwherein the first and second sides intersect at an apex.

2. The illumination apparatus of claim 1 wherein the features are optically coupled to the light guide by being partially embedded in an optical adhesive.

3. The illumination apparatus of claim 1 wherein the area of optical coupling is a function of the depth of embedment in the optical adhesive.

4. The illumination apparatus of claim 1 wherein there is present a material in contact with both the optical adhesive and the features that has a relatively low refractive index compared to that of the adhesive and the features in order to allow total internal reflection (TIR) on the surface of the features.

5. The illumination apparatus of claim 4 wherein relatively low refractive index material is air.

6. The illumination apparatus of claim 1 wherein the features have a longitudinal axis and wherein each of at least two of the features extends in the direction of its longitudinal axis, and wherein their respective longitudinal axes are substantially in parallel with each other and in parallel with the plane of the top surface of the light guide.

7. The illumination apparatus of claim 1 wherein all or part of the apexes of intersection of the first and second sides lie along a line parallel to the plane of the top surface of the light guide.

8. The illumination apparatus of claim 1 wherein the angle θ3 formed at the apex of intersection is in the range of 61 degrees to 120 degrees.

9. The illumination apparatus of claim 1 wherein at least two features are of different lengths.

10. The illumination apparatus of claim 2 wherein the index of refraction of the adhesive differs from the index of refraction of the features by no more than 0.02.

11. The illumination apparatus of claim 1 wherein the light redirecting features are integral to a film substrate.

12. The illumination apparatus of claim 1 wherein the light redirecting features are attached to a film substrate.

13. The illumination apparatus of claim 1 additionally comprising additional optically functional layers.

14. The illumination apparatus of claim 13 wherein the additional layers comprise a diffuser, a polarizer, or a brightness enhancer.

15. The illumination apparatus of claim 1 wherein the light extracting film is also a diffusing film.

16. The illumination apparatus of claim 15 wherein the light extracting film is rendered diffusive by the presence of a diffusive coating.

17. The illumination apparatus of claim 15 wherein the light extracting film is rendered diffusive by the presence of a diffusive substrate.

18. A light extracting film having an input surface for being optically coupled with the top surface of a light guide and an output surface for providing light, wherein the input surface comprises a plurality of features which are optically coupled to the top surface of the light guide, each feature having: (i) a first side comprising two or more planar segments; and(ii) a second side comprising two or more planar segments, wherein the first and second sides intersect at an apex.

19. The light extracting film of claim 18 wherein the features are optically coupled to the light guide through the presence of an optical adhesive in contact with both the features and the light guide.