Transflective LCD driven by bi-gamma curve

Details Transflective LCD driven by bi-gamma curve Transflective LCD driven by bi-gamma curve

2002-11-15

2004-10-19

Ngo, Huyen (Department: 2871)

Liquid crystal cells, elements and systems

Particular structure

Having significant detail of cell structure only

C349S038000, C349S113000, C349S143000

Reexamination Certificate

active

06806929

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transflective LCD, and particularly to a transflective LCD driven by bi-gamma curve.
2. Description of the Related Art
A pixel of the conventional transflective LCD has a transmission region and a reflective region. Unavoidably, the reflective region has a nearly double phase difference nearly double that of the transmission region. Reduction of cell gap of the reflective region to approach that of the transmission region has been adopted in the past to address this issue.
FIG. 7A
shows a perspective diagram of a pixel of a conventional transflective LCD. The pixel includes a reflective region
10
and a transmission region
20
. The reflective region
20
has a reflective film
12
and a cell gap d
1
. The transmission region
20
has a cell gap d
2
.
An equivalent circuit is shown in FIG.
7
B. The reflective region
10
and the transmission region
20
are both coupled to a storage capacitor Cs and a TFT (thin-film-transistor) transistor T
1
. Thus, only driving voltage is afford to supply. The anti-inversion approach adjusts the cell gap d
1
and the cell gap d
2
to the same phase difference. The cell gap d
1
and d
2
must be optimized to fit the LCD's operation mode, an approach that is difficult to adjust.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a transflective LCD that achieves optimal reflectivity and transmittance.
To achieve the above objects, the present invention provides a pixel with reflective region and transmission regions. The reflective region and the transmission region both have a storage capacitor and a TFT transistor for different driving voltages. The driving voltage for the reflective region can have any phase difference in cell gap such as half wave or quarter wave. The driving voltage for the transmission region can have any phase difference in cell gap such as half wave or quarter wave.
A driving method for the transflective LCD scans all reflective regions first in a frame period, with all transmission regions are scanned later.
Another driving method for the transflective LCD scans all reflective regions of one row first in the row's active period, and all transmission regions of one row thereof latter.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.


REFERENCES:
patent: 6704081 (2004-03-01), Ha et al.
patent: 2001/0052948 (2001-12-01), Okamoto et al.
patent: 2002/0109848 (2002-08-01), Hendriks et al.

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