Illuminated transparent display with microtextured back reflector

• US 5,349,503 A
• Filed: 04/23/1993
• Issued: 09/20/1994
• Est. Priority Date: 12/31/1991
• Status: Expired due to Fees

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Original Assignee: AT&T, Inc.
• Inventors: Blonder, Greg E., Johnson, Bertrand H.
• Primary Examiner(s): Cole, Richard R.
• Application Number:
  US08/052,320
• Time in Patent Office: 515 Days
• Field of Search: 362/31, 362/26, 359/70, 359/530, 359/546, 359/627, 359/850, 359/851
• US Class Current: 362/623
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605

Abstract

Applicants have discovered that a particularly efficient illuminating device for a transparent display comprises a microtextured reflecting surface formed on a major surface of a transparent substrate and a light source for directing light into the transparent substrate approximately parallel to the major surface. Preferably the substrate has two major surfaces separated by a thickness in the range 0.5 to 1.0 mm so that the substrate acts as a light guide. A substantial portion of the light passing into the substrate undergoes total internal reflection until it hits a microelement and is reflected out of the substrate. The result is an efficient illuminating device particularly useful for lighting transparent displays.

Claims

1. An illuminating device comprising:

a transparent substrate comprising a pair of substantially parallel major surfaces;

one of said major surfaces comprising a plurality of spherical segments having smooth, continuous mold-formed surfaces and bases in the range 10-125 micrometers in diameter; and

means for directing light into said substrate in a direction generally parallel to said major surfaces.

2. A device according to claim 1 wherein said major surfaces are spaced apart by a thickness of about 0.5 to 1.00 ram.

3. A device according to claim 1 further comprising a diffusing sheet disposed parallel to said major surfaces.

4. A device according to claim 1 wherein said spherical segments are coated with reflecting material.

5. A device according to claim 1 wherein said spherical segments have altitudes which are 10% to 20% of the diameters of their bases.

6. A device according to claim 1 wherein the combined areas of the spherical segment bases comprises 50 to 90% of the area of the major surface on which they are formed.

7. An illuminated display device comprising a transparent display device and an illuminating device according to claim 1 or 2 or 3 or 4 or 5 or 6.