1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device and a manufacturing method thereof.
2. Description of the Related Art
Recently, an LCD device, which is one of flat display devices in the limelight constantly, changes optical anisotropy by applying an electric field to liquid crystal (LC) having both fluidity of liquid and an optical property of a crystal. The LCD device has a small volume and low power consumption compared to a related art cathode ray tube (CRT), and can be manufactured in a large size and achieve high definition. Accordingly, the LCD device is widely used.
The LCD device can be classified into various mode LCD devices depending on the property of the LC and a pattern structure.
In detail, a twisted nematic mode LCD device controls a director by applying a voltage after the director is disposed such that the director is twisted by 90°. A multi-domain mode LCD device divides one pixel into a plurality of domains, changes a primary viewing angle direction of each domain to realize a wide viewing angle. An optically compensated birefringence (OCB) mode LCD device attaches a compensation film on an outer surface of a substrate to compensate for a phase difference of light depending on a progression direction of light. An in-plane switching (IPS) mode LCD device provides two electrodes on one substrate to allow a director to be twisted on a plane parallel to an alignment layer. A vertical alignment (VA) mode LCD device allows a long axis to be disposed perpendicularly to a plane of an alignment layer using negative type LC and a vertical alignment layer.
A study for allowing an LCD device to have a wide viewing angle as much as possible has been under active progress up to now, but recently, a study for an LCD device having a narrow viewing angle as well as a wide viewing angle is also under active progress.
For example, when an LCD device has only a wide viewing angle in the case where the LCD device is used in order to protect company secret or national secret, and private life, information may leak out to persons located at an adjacent position or private life of a user may be infringed.
For this reason, technology controlling an LCD device to allow an image to be viewed at a desired viewing angle at a desired time is under active progress.
FIG. 1 is a cross-sectional view of a related art LCD device that can selectively operate in a wide viewing angle mode and a narrow viewing angle mode.
Referring to FIG. 1, the related art LCD device selectively driven in a wide viewing angle mode and a narrow viewing angle mode is formed by attaching a first LC panel 11 and a second LC panel 12.
The first LC panel 11 includes a first substrate 10 and a second substrate 20 that face each other and are separated a predetermined distance from each other. A first LC layer 30 is interposed between the first and second substrates 10 and 20.
Though not shown, a thin film transistor (TFT) and a pixel electrode can be formed on an inner surface of the first substrate 10. A color filter and a common electrode can be formed on an inner surface of the second substrate 20.
A second LC panel 12 is formed on an outer surface of the second substrate 20.
The second LC panel 12 includes a third substrate 50 and a fourth substrate 60 that face each other and are separated a predetermined distance from each other. A second LC layer 70 is interposed between the third and fourth substrates 60 and 70.
Though not shown, a first electrode and a second electrode are formed on inner surfaces of the third and fourth substrates 50 and 60, respectively. The first and second electrodes are connected to a predetermined controller in order to apply an electric field to the second LC layer 70.
The second LC layer 70 is aligned horizontally or vertically by an applied electric field.
A first polarizer 81 is formed on an outer surface of the first substrate 10 of the first LC panel 11, and a second polarizer 82 is formed on an outer surface of the fourth substrate 60 of the second LC panel 12.
At least one polarizer can be further provided between the first LC panel 11 and the second LC panel 12.
When the LCD device is driven in a wide viewing angle mode, the second LC panel 12 immediately transmits an image formed by the first LC panel 11 regardless of whether an electric field is applied to the second LC panel 70.
When the LCD device is driven in a narrow viewing angle mode, the second LC panel 12 transmits light processed by the second LC panel 12 in a predetermined direction depending on whether a predetermined electric field is applied or not. Therefore, an image that is generated by the first LC panel 11 and passes through the second LC panel 12 can be viewed at a predetermined narrow viewing angle.
In the case where a viewing angle controlling LC panel is attached onto a main LC panel providing a primary image in order to control a viewing angle in a related art LCD device, the viewing angle controlling LC panel not only should be additionally manufactured, but also the thickness and weight of a product increase two or more times.
Also, misalign may occur when the viewing angle controlling LC panel and the main LC panel are attached to each other. Also, in the case where the LCD device is used in a wide viewing angle mode, light incident from a backlight assembly should passes through the viewing angle controlling LC panel. Accordingly, front brightness considerably reduces.