Liquid crystal display with touch panel having internal front polarizer

• US 7,190,416 B2
• Filed: 03/27/2003
• Issued: 03/13/2007
• Est. Priority Date: 10/18/2002
• Status: Expired due to Term

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Silverstein, Louis D., Paukshto, Michael V.
• Primary Examiner(s): Schechter; Andrew
• Assistant Examiner(s): Caley; Michael H.
• Application Number:
  US10/402,481
• Publication Number:
  US 20040075779A1
• Time in Patent Office: 1,447 Days
• Field of Search: 349/12, 349/96, 349/101, 349/102, 349/103
• US Class Current: 349/12
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/133528 Polarisers

Abstract

A liquid crystal display with a touch panel is described. The liquid crystal display includes a front panel including an internal front polarizer, a liquid crystal layer, and a rear panel including a rear polarizer. A touch transparent panel is secured to the front surface of the liquid crystal display.

Claims

1. A touchscreen display comprising a transparent touch panel and a liquid crystal display wherein the liquid crystal display comprises a front panel with functional layers, including at least one internal front polarizer, a liquid crystal layer, and a rear panel containing functional layers, wherein the transparent touch panel is secured directly onto the outer surface of the front panel, and the front panel includes a single substrate and said internal front polarizer is placed between said single substrate and said liquid crystal layer;

wherein the liquid crystal is a supertwisted nematic and the functional layers of the rear panel include a polarizer, the transmission axis of the front polarizer is oriented at an angle of 45.0±

2.5°

relative to the director of liquid crystal molecules in the layer adjacent to the front polarizer surface, the transmission axis of the rear polarizer is at an angle of 60.0±

5.0°

to that of the front polarizer, and the twist angle of the liquid crystal is 240–

250°

, and the birefringence of the liquid crystal amounts to 820–

860 nm; and

a compensating optical retardation film with an optical path length difference of 570.0±

10.0 nm is located in front of the rear polarizer at an angle of 40.0±

5.0°

from the transmission axis of the rear polarizer;

said front polarizer possess neutral absorption spectrum with a transmission of 25–

35% in the entire visible range and exhibits uniform loss over virtually all direction and provides a contrast ratio of 40–

50 in the interval of azimuthal angles from 0 to 60 degrees.

2. The touchscreen display according to claim 1, wherein the liquid crystal display is operated in the transmissive, reflective or transflective modes of operation.

3. The touchscreen display according to claim 1, wherein the directors of nematic liquid crystal molecules exhibit rotation along a left-handed helix.

4. The touchscreen display according to claim 1, wherein the directors of nematic liquid crystal molecules exhibit rotation along a right-handed helix.

5. The touchscreen display according to claim 1, which comprises a front substrate, the front polarizer is applied to the internal side of the front substrate, and the polarizer surface facing the liquid crystal layer is covered with a transparent insulating layer.

6. The touchscreen display according to claim 1, comprising the transparent electrode with a transparent insulating planarization on its between the front panel and the front polarizer.

7. The touchscreen according to claim 1, wherein the functional layers include a transparent electrode, a transparent protective layer, and a transparent alignment layer, or a layer performing the function of at least two of the above layers.

8. The touchscreen display according to claim 1, wherein the substrates of panels are made of glass or transparent plastic.

9. The touchscreen display according to claim 1, wherein the touch panel comprises at least two transparent conducting layers, separated by insulating spacers, and wherein at least one of the conducting layers being capable of elastic straining under pressure to contact with the second conducting layer.

10. The touchscreen display according to any of claims 7, 8 or 9, wherein one of the conducting layers is applied onto the surface of a nearest transparent substrate of the liquid crystal display.

11. The touchscreen display according to claim 1, wherein the touch panel comprises at least one conducting layer forming a capacitor whose capacity varies as a finger or a stylus approaching its surface.

12. The touchscreen display according to claim 1, wherein the touch panel comprises at least one textured conducting layer.

13. The touchscreen display according to claim 1, wherein the touch panel comprises the sources and detectors of ultrasound.

14. The touchscreen display according to claim 13, wherein the sources and detectors of ultrasound are situated on a transparent substrate of the liquid crystal cell and this transparent substrate performs the function of a touch panel.

15. The touchscreen display according to claim 1, wherein the touch panel contains the sources and sensors of IR radiation.

16. The touchscreen display according to claim 1, wherein at least one polarizer is made of an optically anisotropic thin crystal film, the material of which contains aromatic rings and is characterized by the interplanar spacing of 3.40±

0.3 Å

along one of the optical axes.

17. The touchscreen display according to claim 16, wherein the layer of optically anisotropic thin crystal film is treated with ions of bivalent and/or trivalent metals.

18. The touchscreen display according to claim 16, wherein the molecules of at least one aromatic compound contain heterocycles.

19. The touchscreen display according to claim 16, wherein the layer of optically anisotropic thin crystal film is made on the basis of a lyotropic liquid crystal based on at least one dichroic dye.

20. The touchscreen display according to claim 1, wherein the thicknesses and sequence of the functional layers are selected so as to ensure the interference extremum at the display exit for at least one wavelength in the interval from 500 to 600 nm.

21. The touchscreen display according to claim 20, wherein the compensating optical retardation film with the rear polarizer are situated on the external side of the rear substrate.

22. The touchscreen display according to claim 20, wherein the compensating optical retardation film with the rear polarizer are situated on the internal side of the rear substrate.

23. The touchscreen display according to claim 1, wherein a reflective layer is formed on the external side of the rear substrate.

24. The touchscreen display according to claim 23, wherein at least a part of the reflective layer exhibits specular reflection.

25. The touchscreen display according to claim 23, wherein at least a part of the reflective layer exhibits diffuse reflection.

26. The touchscreen display according to claim 23, wherein the reflective layer is semitransparent.