Method for driving a color liquid crystal display

• US 5,774,197 A
• Filed: 12/10/1996
• Issued: 06/30/1998
• Est. Priority Date: 02/19/1996
• Status: Expired due to Term

• Current Assignee: AU Optronics Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Nakamura, Hajime
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): NGUYEN, TIEP HUU
• Application Number:
  US08/763,988
• Time in Patent Office: 567 Days
• Field of Search: 349/188, 349/108, 349/117
• US Class Current: 349/117
• CPC Class Codes: G02F 1/13306 Circuit arrangements or driving methods for the control of single liquid crystal cells G02F1/132, G02F1/133382 take precedence
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133634 the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
• CPC Class Codes: G02F 1/1395 Optically compensated birefringence [OCB]- cells or PI- cells
• CPC Class Codes: G02F 2202/40 Materials having a particular birefringence, retardation

Abstract

The present invention is directed to the prevention of reversal and deterioration of a screen at right and left viewing angles and upper and lower viewing angles in an OCB-mode liquid-crystal display.

It is possible to prevent deterioration of a screen by obtaining the optimum value of absolute value {R(V₁)} of retardation before correction by phase compensation film!/wavelength (λ) at a lower-side driving voltage for each color of R, G, and B and thereby, preventing an optical rotation of liquid crystal on B wavelength. Specifically, B wavelength is set to R(V₁)/λ≦0.85. By adjusting a cell gap of each color, display characteristics of a screen at right and left viewing angles are improved.

Claims

1. A method for driving a color liquid crystal display for displaying a plurality of colors, the liquid crystal display comprising liquid crystal material sandwiched between electrodes, the thickness of the liquid crystal material comprising a cell gap, the liquid crystal display further comprising a light incident side and a light exiting side, the method comprising the steps of:

applying a voltage (V) between the electrodes;

applying light of wavelength (λ

) to the light incident side;

measuring a phase difference (R) between the incident light and the exiting light; and

adjusting the voltage and wavelength to satisfy the expression 0.4≦

R(V)/λ

≦

0.85.

2. The method of claim 1, further comprising the step of setting the adjusted voltage to be the lowest driving voltage (V₁).

3. The method of claim 1, further comprising the step of setting the adjusted wavelength to be the minimum wavelength (λ

₁) among wavelengths of light of said colors.

4. The method of claim 3, wherein the minimum wavelength (λ

₁) has a value between 400 nm and 500 nm.

5. The method of claim 1, further comprising the step of adjusting the cell gap for each of said colors wherein a transmittance difference of said colors is kept in a range of ±

5%.