The present invention relates to a light guide plate and a liquid crystal display (LCD) using the light guide plate.
A liquid crystal display (LCD) is one kind of the most widely used flat panel displays due to its advantages such as compact volume, low power consumption, and no radiation. A LCD is formed by assembling an array substrate and a color filter substrate that are opposite to each other. A gate line and a data line intersect each other and are formed on the array substrate to define a pixel region in which a pixel electrode and a thin film transistor (TFT) as a switching element are disposed. A gate signal is applied over the gate line to a gate electrode of the TFT to turn on/off the TFT, and image data signal is applied to the pixel electrode over the data line. A black matrix is disposed on the color filter substrate to prevent light leakage in areas other than the pixel region. A color filter layer is disposed in each pixel region on the color filter area, and a common electrode is disposed on the color filter substrate. A liquid crystal (LC) layer is filled in a space between the array substrate and the color filter substrate to form a LCD panel. The LCD displays images by applying voltages to the pixel electrode and common electrode to generate an electric field in the LC layer, which determines orientations of LC molecules in the LC layer to change polarization of the incident light.
A backlight module is an important component of a LCD and used for providing the LCD panel with light for display and for determining the color representation quality of the LCD. A conventional LCD backlight module is shown in FIG. 1. The backlight module comprises a light source 1 (for example, a cold cathode fluorescent lamp or light emitting diode), a reflective cover 2 around the light source 1, and a reflection plate 3, a light guide plate 4, a first diffuse plate 5, a first prism plate 6, a second prism plate 7, and a second diffuse plate 8 that are stacked in order. A portion of the light from the light source 1 directly enters the light guide plate 4, and another portion is reflected back by the reflective cover 2 and then enters the light guide plate 4. The light is reflected by the underlying the reflection plate 3 and exits from the upper surface of the light guide plate 4 to transmit through the overlaying optical sheets such as the first and second diffuse plates 5 and 8 and the first and second prism plates 6 and 7 before entering a LCD panel. The light guide plate 4 in the above backlight module serves as an optical medium. The overlaying optical sheets such as the first and second diffuse plates 5 and 8 and the first and second prism plates 6 and 7 are used to uniform the light and enlarge view angle.