Reflective and transflective liquid crystal display using a wire grid polarizer

• US 20030210369A1
• Filed: 05/02/2003
• Published: 11/13/2003
• Est. Priority Date: 05/07/2002
• Status: Active Grant

• Current Assignee: InnoLux Corporation
• Original Assignee: TPO Displays Corporation (InnoLux Corporation)
• Inventors: Wu, Shin-Tson
• Granted Patent: US 6,977,702 B2
• Time in Patent Office: Days
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133543 Cholesteric polarisers
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133565 inside the LC elements, i.e. between the cell substrates

Abstract

A device structure for single cell gap reflective and transflective liquid crystal displays (TF-LCDs). For an entirely reflective LCD, the imbedded wire-grid polarizer (WGP) serves as a polarization-dependent for the ambient light. For a transflective TF-LCD, the WGP only covers the reflective pixels. The disclosure also includes a method of using single cell gap liquid crystal displays (LCDs) without phase retardation films by providing a single cell gap LCD having reflective pixels and transmissive pixels, covering solely the reflective pixels, with at least one of: a wire grid polarizer and a broadband cholesteric reflector (BCR), reflecting ambient light off the reflective pixels; and passing back light through the transmissive pixels whereby the cell gap LCD obtains high contrast ratios without using phase retardation films.

Claims

1. A device for single cell gap reflective and transflective liquid crystal displays comprising:

(a) a single cell gap liquid crystal display (LCD) having reflective pixels and transmissive pixels;

(b) a wire grid polarizer (WGP) solely covering the reflective pixels;

(c) ambient light means reflecting off the reflective pixels; and

,

(d) means allowing back light passing through the transmissive pixels,

whereby the cell gap LCD achieves high contrast ratios without using phase retardation films.

2. The device of claim 1, further comprising:

an alignment layer covering the transmissive pixels.

3. The device of claim 2, wherein the alignment layer includes:

indium-tin-oxide (ITO) and polymide (PI).

4. The device of claim 1, further comprising:

an ITO/PI layer above and another ITO/PI layer below the cell gap.

5. The device of claim 1, further comprising:

(a) an upper polarizer layer above the cell gap; and

,

(b) a lower polarizer layer below the cell gap.

6. The device of claim 4, further comprising:

(a) an upper polarizer layer above the cell gap LCD; and

,

(b) a lower polarizer layer below the cell gap LCD.

7. The device of claim 1, wherein the wire grid polarizer is formed by an ion beam etching process.

8. The device of claim 1, wherein the wire grid polarizer is formed by a holographic method.

9. The device of claim 1, further comprising:

a thin-film-transistor (TFT) above the cell gap LCD, wherein.

10. The device of claim 1, further comprising:

a broadband cholesteric reflector (BCR) as a replacement for the wire grid polarizer.

11. A device for single cell gap reflective and transflective liquid crystal displays, comprising:

(a) a single cell gap liquid crystal display (LCD) having reflective pixels and transmissive pixels;

(b) a broadband cholesteric reflector (BCR) solely covering the reflective pixels;

(c) means for reflecting the ambient light off the reflective pixels; and

,

(d) means for passing back light through the transmissive pixels whereby the single cell gap LCD achieves high contrast ratios without using phase retardation films.

12. A method of using single cell gap liquid crystal displays (LCDs) without phase retardation films, comprising the steps of:

(a) providing a single cell gap LCD having reflective pixels and transmissive pixels;

(b) covering solely the reflective pixels with at least one of;

a wire grid polarizer (WGP) and a broadband cholesteric reflector (BCR);

(c) reflecting ambient light off the reflective pixels; and

,

(d) passing back light through the transmissive pixels whereby the cell gap LCD obtains high contrast ratios without using phase retardation films.

13. The method of claim 12 wherein said covering is with a WGP.

14. The method of claim 12 wherein said covering is with a broadband cholesteric reflector (BCR).

15. The method of claim 14 wherein said covering is also with a WGP.