Reflective displays

• US 3,960,438 A
• Filed: 12/01/1972
• Issued: 06/01/1976
• Est. Priority Date: 12/01/1972
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Bonne, Ulrich
• Primary Examiner(s): Rolinec, R. V.
• Assistant Examiner(s): Tokar, Michael J.
• Application Number:
  US05/311,184
• Time in Patent Office: 1,278 Days
• Field of Search: 350/144, 350/150, 350/157, 350/160 LC, 350/288
• US Class Current: 349/96
• CPC Class Codes: G02F 1/0102 Constructional details, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/055 the active material being a ceramic G02F1/035 takes precedence
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133565 inside the LC elements, i.e. between the cell substrates
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence

Abstract

Electrically controllable reflective displays are formed which utilize ambient light and which can be viewed from a wide angular view.

Claims

1. A reflective display utilizing ambient light and having a wide angle of view, the reflective display comprising:

an optical medium having an electrically controllable optical property,

electrode means for applying an electric field to selected regions of the optical medium to vary the electrically controllable optical property of the selected regions, and

diffuse reflector means positioned proximate one surface of the optical medium, the diffuse reflector means comprising a roughened surface and a thin reflective metal layer deposited on the roughened surface.

2. The reflective display of claim 1 wherein the optical medium is a colloidal suspension of dielectric needles.

3. The reflective display of claim 2 wherein the colloidal suspension of dielectric needles is disposed between first and second glass plates.

4. The reflective display of claim 3 wherein the roughened surface is one surface of the second glass plate.

5. The reflective display of claim 4 wherein the thin reflective metal layer is in contact with the colloidal suspension of dielectric needles.

6. The reflective display of claim 1 wherein the optical medium is a fine-grained, optically birefringent ferroelectric ceramic plate.

7. The reflective display of claim 6 wherein the ferroelectric ceramic plate has first and second surfaces and wherein the electrode means are attached to the first surface and the roughened surface is the second surface of the ferroelectric ceramic plate.

8. The reflective display of claim 1 wherein the thin reflective metal layer is aluminum.

9. The reflective display of claim 1 wherein the thin reflective metal layer is silver.

10. A reflective display utilizing ambient light and having a wide angle of view, the reflective display comprising:

circular polarizer means,

non-depolarizing diffuse reflector means comprising a roughened surface and a thin reflective metal layer deposited on the roughened surface,

an electro-optic medium having electrically controllable birefringence, the electro-optic medium being positioned between the circular polarizer means and the non-depolarizing diffuse reflector means, and

electrode means for applying an electric field to selected regions of the electro-optic medium to vary the birefringence of the selected regions.

11. The reflective display of claim 10 wherein the thin reflective metal layer is aluminum.

12. The reflective display of claim 10 wherein the thin reflective metal layer is silver.

13. The reflective display of claim 10 wherein the electro-optic medium is a fine-grained, optically birefringent ferroelectric ceramic plate, and wherein the roughened surface is one surface of the ferroelectric ceramic plate.