Back-lit displays with high illumination uniformity

• US 8,690,373 B2
• Filed: 11/14/2007
• Issued: 04/08/2014
• Est. Priority Date: 11/15/2006
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Epstein, Kenneth A., Hanley, Kenneth J., Boyd, Gary T.
• Primary Examiner(s): HAN, JASON
• Application Number:
  US12/514,944
• Publication Number:
  US 20100135004A1
• Time in Patent Office: 2,337 Days
• Field of Search: 362 971- 974, 349/64
• US Class Current: 362/97.2
• 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

Abstract

A directly illuminated display unit includes a display panel and one or more light sources disposed behind the display panel. The light sources are capable of producing illumination light. A diffusive light diverting layer is disposed between the one or more light sources and the display panel. The light diverting layer comprises first light diverting elements disposed on one of a first side of the light diverting layer facing display panel and second light diverting elements disposed on a second side of the light diverting layer facing away from the display panel. The diffusive light diverting layer further comprises diffusing particles disposed within a polymeric matrix.

Claims

1. A directly illuminated display unit, comprising:

a display panel;

one or more light sources disposed behind the display panel and being capable of producing illumination light;

a diffusive light diverting layer disposed between the one or more light sources and the display panel, the light diverting layer comprising first light diverting members disposed on a first side of the light diverting layer facing the display panel and second light diverting members disposed on a second side of the light diverting layer facing away from the display panel, the diffusive light diverting layer further comprising diffusing particles disposed within a polymeric matrix, wherein the first side of the light diverting layer comprises at least one flat surface portion between two neighboring first light diverting members.

2. A unit as recited in claim 1, wherein at least one of the first light diverting members is formed as an elongated member extending across the light diverting layer.

3. A unit as recited in claim 2, wherein the elongated member has a height that is constant along the length of the elongated member.

4. A unit as recited in claim 1, further comprising one or more light management films disposed between the diffusive light diverting layer and the display panel.

5. A unit as recited in claim 4, wherein the one or more light management films comprise at least a first brightness enhancing film and a reflective polarizer film.

6. A unit as recited in claim 5, further comprising a second brightness enhancing film having a prismatic structure oriented substantially orthogonal to a prismatic structure of the first brightness enhancing film.

7. A unit as recited in claim 4, wherein the one or more light management films comprises a diffuser layer.

8. A unit as recited in claim 1, wherein the display panel comprises a liquid crystal display (LCD) panel.

9. A unit as recited in claim 1, wherein the one or more light sources comprise at least one of a light emitting diode and a fluorescent lamp.

10. A unit as recited in claim 1, further comprising a control unit coupled to the display panel to control an image displayed by the unit.

11. A unit as recited in claim 1, wherein light incident on the second side of the light diverting layer is diverted substantially in a first light diverting plane and light incident on the first side of the light diverting layer from the second side is substantially diverted in a second light diverting plane non-parallel to the first light diverting plane.

12. A unit as recited in claim 11, wherein the first and second light diverting planes are substantially perpendicular.

13. A unit as recited in claim 1, wherein a first portion of light from the one or more light sources that propagates within the diffusive light diverting layer in a direction substantially perpendicular to the diffusive light diverting layer is substantially transmitted through flat portions of the first light diverting elements and a second portion of light from the one or more light sources that propagates within the diffusive light diverting layer in a direction substantially perpendicular to the diffusive light diverting layer is totally internally reflected at sloped portions of the first light diverting elements.