Transflective displays with reflective polarizing trasflector

• US 20010008464A1
• Filed: 02/12/2001
• Published: 07/19/2001
• Est. Priority Date: 03/10/1995
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Cobb, Sanford Jr., Weber, Michael F., Ouderkirk, Andrew J., Wortman, David L., Cull, Brian D.
• Granted Patent: US 6,888,675 B2
• Time in Patent Office: Days
• US Class Current: 359/497
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one

Abstract

A transflector is described which increases efficiency and brightness under both ambient and supplemental lighting conditions in visual display applications. In one embodiment, the transflector includes a reflective polarizing element that reflects one polarization of light and transmits the other. In an alternate embodiment, the transflector includes a reflective polarizing element and a diffusing element such that the transflector diffusely reflects light of one polarization and transmits the other. The transflector is useful for both reflective and transflective liquid crystal displays.

Claims

1. A reflective display comprising:

display means;

a transflector located behind the display means, the transflector comprising;

a diffusing element; and

a reflective polarizing element comprising multiple layers of two materials, each layer having an average thickness of not more than 0.5 microns, the reflective polarizing element further having an average transmission of at least 80% for light incident normal to the plane of the film and an average transmission of at least 80% for light incident at 60°

from the normal to the plane of the film; and

an absorber located behind the transflector.

2. The reflective display of

claim 1

further including a dichroic polarizer positioned in front of the display means.

3. The reflective display of

claim 2

wherein the transmission axis of the reflective polarizing element is effectively aligned with the transmission axis of the first dichroic polarizer.

4. The reflective display of

claim 3

further including a second dichroic polarizer located between the display means and the transflector.

5. The reflective display of

claim 4

wherein the transmission axis of the reflective polarizing element is effectively aligned with the extinction axis of the second dichroic polarizer.

6. The reflective display of

claim 1

wherein the reflective polarizing element further has an average reflectance of at least 80% for light incident normal to the plane of the film and an average reflectance of at least 80% for light incident 60°

from normal to the plane of the film.

7. The reflective display of

claim 1

wherein the reflective polarizing element further has an average reflectance of at least 90% for light incident normal to the plane of the film and an average reflectance of at least 90% for light incident 60°

from normal to the plane of the film.

8. The reflective display of

claim 1

wherein the reflective polarizing element further has an average reflectance of at least 95% for light incident normal to the plane of the film and an average reflectance of at least 95% for light incident 60°

from normal to the plane of the film.