1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly, to liquid crystal display pixel and pixel memory.
2. Description of the Prior Art
Recently, with the development of an information-oriented society, electronic products such as personal computer, personal digital assistant (PDA), and others, have been widely used. Small sized and light-weight portable electronic products usable in an office or the outdoors have been required. To meet this requirement, a liquid crystal display (hereinafter referred to as “LCD”) has been widely used. The liquid crystal display enables the portable electronic products to be small-sized and light-weight. Additionally, low power consumption of the portable electronic products can be realized by using the liquid crystal display as a display.
The LCD is mainly divided into a reflective type and a transmissive type according to a movement path of light. The reflective type liquid crystal displays an image by reflecting light entered from a front surface of a liquid crystal panel from a rear surface of the liquid crystal panel. The transmissive type LCD displays the image with transmissive light from a light source (i.e., backlight) located behind the rear surface of the liquid crystal panel. The reflective type LCD does not provide a constant amount of reflective light because of changing environmental conditions. Accordingly, visibility of the reflective type LCD is decreased when the environment is dim. As a result, a transmissive type color LCD using a color filter has been typically used as a display for devices such as a personal computer for displaying full-color images.
The LCD is mainly divided into a twisted nematic (TN) LCD and a super-twisted nematic (STN) LCD according to a driving method. The LCD can be driven by an active matrix display method using a switching element and the twisted nematic LCD, and a passive matrix display method using the super-twisted nematic LCD.
A color LCD is commonly driven by using the active matrix display method. A plurality of LCD cells are respectively included in the LCD panel of the active matrix LCD. A plurality of thin film transistors for switching a data voltage to be applied to each LCD cell are included in the LCD panel of the active matrix LCD. The LCD cells are located at positions where data lines and gate lines cross over. The thin film transistors are also located at the crossings. Display quality of the active matrix LCD is higher than that of the passive matrix LCD. However, the active matrix LCD dissipates high power to operate the thin film transistors of the LCD cells because a driver electrically coupled to the thin film transistors is operated to apply the voltage to the thin film transistors.