Electrophoretic, high index and phase transition control of total internal reflection in high efficiency variable reflectivity image displays

An image display method, comprising the steps of:

• (a) providing a reflective sheet having a prismatic inward surface and an opposed outward surface, said sheet having an index of refraction n1;
• (b) contacting said prismatic surface with an electrophoretic medium having an index of refraction n2;
• (c) suspending a plurality of particles in said medium;
• and,
• (d) applying a voltage across said medium to selectively, electrophoretically move said particles within about 0.25 micron of said prismatic surface to frustrate total internal reflection at said prismatic surface of light rays passing through said sheet;
• wherein n2 is sufficiently larger than n1 that most of said light passing through said sheet undergoes total internal reflection at said prismatic surface in the absence of said applied voltage.

An image display device, comprising:

• (a) a transparent, planar slab waveguide;
• (b) a light source for emitting light into said waveguide;
• and,
• (c) a micro-structured array mounted on a rearward surface of said waveguide, said array for uniformly extracting light rays from said waveguide and redirecting said rays rearwardly of said array at an angle of approximately 45°.

An image display device, comprising:

• (a) a reflective sheet having a prismatic inward surface and an opposed outward surface, said sheet having an index of refraction n1;
• (b) a backing sheet coupled to said reflective sheet to form a liquid and vapour tight chamber between said prismatic inward surface and said backing sheet;
• (c) a liquid within said chamber, said liquid having a low boiling point, a liquid state index of refraction n2 approximately equal to n1, and a vapour state index of refraction n3 substantially unequal to n1;
• and,
• (d) first voltage means for controllably applying a voltage to said prismatic inward surface to heat said prismatic inward surface and vapourize said liquid in a region proximate to said prismatic inward surface.

An image display method, comprising the steps of:

• (a) providing a reflective sheet having a prismatic inward surface and an opposed outward surface, said sheet having an index of refraction n1;
• (b) maintaining a liquid adjacent said prismatic inward surface, said liquid having a low boiling point, a liquid state index of refraction n2 approximately equal to n1, and a vapour state index of refraction n3 substantially unequal to n1;
• and,
• (c) heating said prismatic inward surface to vapourize said liquid in a region proximate to said prismatic inward surface.

An image display device, comprising:

• (a) a transparent, semiconductor channel having a first prismatic surface and having an index of refraction n1;
• (b) a metal oxide layer applied to a surface of said channel, opposite said prismatic surface;
• (c) a source electrode electrically connected to a first end of said channel;
• (d) a drain electrode electrically connected to a second end of said channel, opposite said first end;
• and,
• (e) a gate electrode electrically connected to said metal oxide layer;
• whereby application of a first voltage potential to said gate reduces said channel's light absorption coefficient, permitting total internal reflection of light rays at said first prismatic surface;
• and, application of a second voltage potential to said gate increases said channel's light absorption coefficient, frustrating total internal reflection of light rays at said first prismatic surface.