US 5,381,309 AGranted

Backlit display with enhanced viewing properties

AssigneeHoneywell Inc.

InventorJerry L. Borchardt

Life of this patent

Estimating the term…

Loading patent…

Abstract

A high aspect ratio, backlit liquid crystal display in which light from opposing rows of light emitting diodes is projected into the ends of a thin optical cavity. The optical cavity is bounded by one major wall of which the interior surface is specularly reflective and an opposing major wall including a layer of transparent material having an interior surface formed with an array of regularly spaced, fine, triangular prisms which tend to collimate light received from the cavity and project it outwardly perpendicular to the major wall. A diffusion layer overlays the layer of transparent material, and a brightness enhancing film overlays the diffusion layer and functions to convert diffuse illumination received through the diffusion layer into directed illumination predominantly falling within the a viewing space bounded by predetermined angles.

Claims10

Dependent claims

A high aspect ratio, backlit display device with enhanced viewing properties, comprising:

a message carrying member having a display surface of predetermined length and width of which at least a portion is translucent, said message carrying member having a first side from which the message is to be readable within a viewing space bounded by predetermined angles relative to the first side, said message carrying member having a second side opposite the first side;
an optical structure having first and second generally parallel major walls at least partially enclosing a thin cavity having a length and width at least as great as the predetermined length and width of the display surface, the cavity having a first end substantially parallel with the width of the cavity and transverse to the first and second major walls thereof, the first major wall of said optical structure including an inner layer of transparent material having an interior surface bounding the cavity, an intermediate optical diffusion layer and an outer brightness enhancing film layer having an inner surface adjacent the diffusion layer and an outer surface adjacent the display surface, the interior surface of the inner layer and the outer surface of the outer layer each being configured with an array of regularly spaced triangular prisms parallel with the width of the cavity, the second major wall of said optical structure being adapted to provide specular reflection;
and
a light source adapted to project light from the end of the cavity onto the second major wall of said optical structure in a direction transverse to the triangular prisms on the inner layer at a small angle relative to an interior surface of the second major wall.

1 more element

A high aspect ratio illumination source for backlighting a planar, at least partially translucent, display surface with directed illumination predominantly falling within a viewing space bounded by predetermined angles relative to the display surface, the display surface having a predetermined length and width, the light source comprising:

an optical cavity structure defining an optical cavity having opposite ends, and having a length and width at least equal to the predetermined length and width of the display surface, said optical cavity structure having a first major wall with an interior surface adapted to provide specular reflection and a second major wall including an interior layer of transparent material, the interior layer of transparent material having an interior surface configured with an array of regularly spaced triangular prisms extending across the optical cavity substantially parallel with the ends thereof;
a light source adapted to project light into the optical cavity from at least one end thereof;
a diffusion layer overlaying the exterior surface the interior layer of transparent material in the second major wall of said optical cavity structure;
and
a brightness enhancing film overlaying said diffusion layer, said brightness enhancing film having a first surface adjacent said diffusion layer and a second opposing surface configured with an array of regularly spaced triangular prisms parallel with the triangular prisms formed in the interior layer of the second major wall of said optical cavity structure, the prisms on said brightness enhancing film having faces whose included angles and angular orientations relative to the first surface of said brightness enhancing film provide directed illumination predominantly between the predetermined angles bounding the viewing space.

2 more elements

Dependencies are inferred from the claim text.