Transflective LCD with twist angle less than 90 degrees and 4 compensation films

• US 7,012,662 B2
• Filed: 12/22/2003
• Issued: 03/14/2006
• Est. Priority Date: 12/23/2002
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Jae-Hyun, Jang, Yong-Kyu, Cha, Sung-Eun, Kim, Sang-Woo
• Primary Examiner(s): Schechter, Andrew
• Assistant Examiner(s): Chung, David Y.
• Application Number:
  US10/740,631
• Publication Number:
  US 20040218126A1
• Time in Patent Office: 813 Days
• Field of Search: 349/119, 349/121, 349/117
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 1/1396 the liquid crystal being selectively controlled between a twisted state and a non-twisted state, e.g. TN-LC cell G02F1/141 takes precedence
• CPC Class Codes: G02F 1/1398 the twist being below 90°
• CPC Class Codes: G02F 2202/40 Materials having a particular birefringence, retardation
• CPC Class Codes: G02F 2413/04 Number of plates greater than or equal to 4
• CPC Class Codes: G02F 2413/08 with a particular optical axis orientation

Abstract

A color filter array panel and a TFT array panel face each other, and a liquid crystal layer is interposed between the two panels such that the liquid crystal molecules of the liquid crystal layer are twisted by 72°. A λ/2 compensation film and a λ/4 compensation film are disposed on outer surfaces of the color filter array panel and the TFT array panel, respectively. Upper and lower polarizers are disposed on the respective compensation films. The λ/2 compensation film and the λ/4 compensation film have predetermined retardations and the drawing axes having predetermined azimuthal angles.

Claims

1. A liquid crystal display comprising:

a first substrate having inner and outer surfaces;

a transparent electrode formed on the inner surface of the first substrate;

a reflective electrode formed on the transparent electrode and having a transmissive window overlapping a portion of the transparent electrode;

a thin film transistor connected to the transparent electrode and the reflective electrode;

a second substrate having an inner surface facing the inner surface of the first substrate and an outer surface;

a common electrode formed on the inner surface of the second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a first polarizing film disposed on the outer surface of the first substrate;

first and second compensation films interposed between the first substrate and the first polarizing film;

a second polarizing film disposed on the outer surface of the second substrate; and

third and fourth compensation films interposed between the second substrate and the second polarizing film,

wherein liquid crystal molecules of the liquid crystal layer are aligned twisted from the first substrate to the second substrate by a predetermined twist angle ranging from about 62°

to about 82°

, and

when, from a front view, a horizontal direction is defined as an x direction and a vertical direction is defined as a y direction,

a director of the liquid crystal layer has an azimuthal angle of about 170 to about 250°

;

the first compensation film makes a retardation of about 135–

155 nm for a light with a wavelength of about 550 nm, and a stretch axis of the first compensation film has an azimuthal angle ranging from about 154°

to about 174°

;

the second compensation film makes a retardation of about 260–

280 nm for a light with a wavelength of 550 nm, and a stretch axis of the second compensation film has an azimuthal angle ranging from about 95°

to about 115°

;

the third compensation film makes a retardation of about 130–

150 nm for a light with a wavelength of 550 nm, and a stretch axis of the third compensation film has an azimuthal angle ranging from about 96°

to about 116°

; and

the fourth compensation film makes a retardation of about 250–

270 nm for a light with a wavelength of 550 nm, and a stretch axis of the fourth compensation film has an azimuthal angle ranging from about 154°

to about 174°

.

2. The liquid crystal display of claim 1, wherein the second polarizer has an absorption axis located at an azimuthal angle ranging from about −

10°

to about 10°

, and the first polarizer has an absorption axis located at an azimuthal angle ranging from about 80°

to about 100°

.

3. A liquid crystal display comprising:

a first substrate having inner and outer surfaces;

a transparent electrode formed on the inner surface of the first substrate;

a reflective electrode formed on the transparent electrode and having a transmissive window overlapping a portion of the transparent electrode;

a thin film transistor connected to the transparent electrode and the reflective electrode;

a second substrate having an inner surface facing the inner surface of the first substrate and an outer surface;

a common electrode formed on the inner surface of the second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a first polarizing film disposed on the outer surface of the first substrate;

first and second compensation films interposed between the first substrate and the first polarizing film;

a second polarizing film disposed on the outer surface of the second substrate; and

third and fourth compensation films interposed between the second substrate and the second polarizing film,

wherein liquid crystal molecules of the liquid crystal layer are aligned twisted from the first substrate to the second substrate by a predetermined twist angle ranging from about 62°

to about 82°

, and

when, from a front view, a horizontal direction is defined as an x direction and a vertical direction is defined as a y direction,

a director of the liquid crystal layer has an azimuthal angle of about 170 to about 250°

;

the first compensation film makes a retardation of about 130–

150 nm for a light with a wavelength of about 550 nm, and a stretch axis of the first compensation film has an azimuthal angle ranging from about 152°

to about 172°

;

the second compensation film makes a retardation of about 260–

280 nm for a light with a wavelength of 550 nm, and a stretch axis of the second compensation film has an azimuthal angle ranging from about 94°

to about 114°

;

the third compensation film makes a retardation of about 130–

150 nm for a light with a wavelength of 550 nm, and a stretch axis of the third compensation film has an azimuthal angle ranging from about 96°

to about 116°

; and

the fourth compensation film makes a retardation of about 250–

270 nm for a light with a wavelength of 550 nm, and a stretch axis of the fourth compensation film has an azimuthal angle ranging from about 154°

to about 174°

.

4. The liquid crystal display of claim 3, wherein the second polarizer has an absorption axis located at an azimuthal angle ranging from about −

10°

to about 10°

, and the first polarizer has an absorption axis located at an azimuthal angle ranging from about 80°

to about 100°

.

5. A liquid crystal display comprising:

a first substrate having inner and outer surfaces;

a transparent electrode formed on the inner surface of the first substrate;

a reflective electrode formed on the transparent electrode and having a transmissive window overlapping a portion of the transparent electrode;

a thin film transistor connected to the transparent electrode and the reflective electrode;

a second substrate having an inner surface facing the inner surface of the first substrate and an outer surface;

a common electrode formed on the inner surface of the second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a first polarizing film disposed on the outer surface of the first substrate;

first and second compensation films interposed between the first substrate and the first and the first polarizing film;

a second polarizing film disposed on the outer surface of the second substrate; and

third and fourth compensation films interposed between the second substrate and the second polarizing film,

wherein liquid crystal molecules of the liquid crystal layer are aligned twisted from the first substrate to the second substrate by a predetermined twist angle ranging from about 62°

to about 82°

, and

when, from a front view, a horizontal direction is defined as an x direction and a vertical direction is defined as a y direction,

a director of the liquid crystal layer has an azimuthal angle of about 170 to about 250°

;

the first compensation film makes a retardation of about 130–

150 nm for a light with a wavelength of about 550 nm, and a stretch axis of the first compensation film has an azimuthal angle ranging from about 154°

to about 174°

;

the second compensation film makes a retardation of about 260–

280 nm for a light with a wavelength of 550 nm, and a stretch axis of the second compensation film has an azimuthal angle ranging from about 95°

to about 115°

;

the third compensation film makes a retardation of about 130–

150 nm for a light with a wavelength of 550 nm, and a stretch axis of the third compensation film has an azimuthal angle ranging from about 96°

to about 116°

; and

the fourth compensation film makes a retardation of about 250–

270 nm for a light with a wavelength of 550 nm, and a stretch axis of the fourth compensation film has an azimuthal angle ranging from about 154°

to about 174°

.

6. The liquid crystal display of claim 5, wherein the second polarizer has an absorption axis located at an azimuthal angle ranging from about −

10°

to about 10°

, and the first polarizer has an absorption axis located at an azimuthal angle ranging from about 80°

to about 100°

.