Liquid crystal display device having OCB mode and method of driving the same

A liquid crystal display device (LCD), comprising:

• a liquid crystal display panel having a plurality of pixels, each pixel being positioned at each intersection between a plurality of scan lines and a plurality of data lines and including a liquid crystal capacitor composed of a common electrode, a pixel electrode, and an optically compensated birefringence (OCB) liquid crystal;
• a scan driver for applying a scan signal to the plurality of scan lines;
• a source driver for sequentially applying red, green, blue gray scale data to the plurality of data lines;
• a direct current to direct current (DC-DC) converter for outputting a DC voltage for carrying out a bend transition on the OCB liquid crystal;
• a switch for selecting the output voltage of the DC-DC converter and a common voltage and transferring the voltages to the common electrode;
• a light source controller for controlling red, green, and blue light emitting diodes to sequentially emit light to the liquid crystal display panel;
• and
• a timing controller for controlling operations of the scan driver, the source driver, the switch, and the light source controller,
• wherein one frame is divided into red, green, and blue fields and the switch applies the output voltage of the DC-DC converter to the common electrode before a start of each field to reset the OCB liquid crystal.

A liquid crystal display device (LCD), comprising:

• a liquid crystal display panel having a plurality of pixels, each pixel being positioned at each intersection between a plurality of scan lines and a plurality of data lines and including a liquid crystal capacitor composed of a common electrode, a pixel electrode, and an optically compensated birefringence (OCB) liquid crystal;
• a scan driver for applying a scan signal to the plurality of scan lines;
• a source driver for applying gray scale data to the plurality of data lines;
• a direct current to direct current (DC-DC) converter for outputting a DC voltage for carrying out a bend transition on the OCB liquid crystal;
• a switch for selecting the output voltage of the DC-DC converter and a common voltage and transferring the voltages to the common electrode;
• a light source controller for controlling a backlight for emitting light to the liquid crystal display panel;
• and
• a timing controller for controlling operations of the scan driver, the source driver, the switch, and the light source controller,
• wherein the switch applies the output voltage of the DC-DC converter to the common electrode to reset the OCB liquid crystal before the gray scale data are applied to the plurality of pixels.

A method of driving a liquid crystal display device (LCD) including a plurality of pixels having an optically compensated birefringence (OCB) liquid crystal positioned between a common electrode to which a common voltage is applied and a pixel electrode to which gray scale data are applied, a direct current to direct current (DC-DC) converter outputting a voltage for carrying out a bend transition on the OCB liquid crystal at a fast speed, and a backlight outputting light to the plurality of pixels, the method comprising:

• (a) applying a voltage to the OCB liquid crystal from the DC-DC converter to carry out the bend transition on the OCB liquid crystal at an initial start of the LCD;
• (b) applying the gray scale data of a frame to the pixel electrode in the frame;
• (c) applying a voltage to the common electrode from the DC-DC converter to reset the OCB liquid crystal after the step (b);
• (d) applying the gray scale data of a second frame to the pixel electrode in the second frame;
• and
• (e) repeating the steps (b) to (d).

A method of driving a liquid crystal display device (LCD) including a plurality of pixels having an optically compensated birefringence (OCB) liquid crystal positioned between a common electrode to which a common voltage is applied and a pixel electrode to which red, green, and blue gray scale data are sequentially applied, a direct current to direct current (DC-DC) converter outputting a voltage for carrying out a bend transition on the OCB liquid crystal at a fast speed, and a backlight having red, green, and blue light sequentially transmitted to each of the pixels, the method comprising:

• (a) applying a voltage to the OCB liquid crystal from the DC-DC converter to carry out the bend transition on the OCB liquid crystal at an initial start of the LCD;
• (b) dividing one frame into red, green, and blue fields, and applying the red gray scale data to the pixel electrode in the red field;
• (c) applying a voltage to the common electrode from the DC-DC converter to reset the OCB liquid crystal after the step (b);
• (d) applying the green gray scale data to the pixel electrode in the green field;
• (e) applying a voltage to the common electrode from the DC-DC converter to reset the OCB liquid crystal after the step (d);
• (f) applying the blue gray scale data to the pixel electrode in the blue field;
• (g) applying a voltage to the common electrode from the DC-DC converter to reset the OCB liquid crystal after the step (f);
• and
• (h) repeating the steps (b) to (g).

A method of driving a liquid crystal display device (LCD) including a plurality of pixels having an optically compensated birefringence (OCB) liquid crystal positioned between a common electrode to which a common voltage is applied and a pixel electrode to which gray scale data are applied, a direct current to direct current (DC-DC) converter outputting a voltage for carrying out a bend transition on the OCB liquid crystal at a fast speed, and a backlight outputting light to the plurality of pixels, the method comprising:

• (a) applying a voltage to the OCB liquid crystal from the DC-DC converter to carry out a bend transition on the OCB liquid crystal at an initial start of the LCD;
• (b) applying (n−1)th gray scale data to a pixel electrode of an (n−1)th pixel among the plurality of pixels;
• (c) applying a voltage to the common electrode from the DC-DC converter to reset the OCB liquid crystal after the step (b);
• (d) applying nth gray scale data to a pixel electrode of an nth pixel;
• (e) applying a voltage to the common electrode from the DC-DC converter to reset the OCB liquid crystal after the step (d);
• and
• (f) repeating the steps (b) to (e).