LCD Basic Knowledge
- May 28, 2018 -


Positive display: It is white (LCD screen color) with black numerals and letters on the bottom. It is also a dark background with a dark background. The contrast ratio is relatively high. It looks clear under normal conditions.

Negative display: is the black bottom, numbers and letters are white (LCD screen color) display, that is, dark background light-colored characters, generally have to add backlight to achieve the display effect, in the sun and outdoor look better, more use For e-book software. Can match the watch color, visual impact is good, not easy to reflect, good concealment.


In a fundamental sense, LCD LCD screens can be called LCD screens. LED screens do not contain liquid crystal materials, so they cannot be called LED LCD screens. They can only be called LED screens.

LCD basic knowledge

The liquid crystal display is a passive display, it can not emit light, can only use the ambient light. It shows only a small amount of energy for patterns or characters. Because of low power consumption and miniaturization, LCDs have become a better display method.

The liquid crystal material used in the liquid crystal display is an organic material having both liquid and solid properties. Its rod-like structure is generally arranged in parallel within the liquid crystal cell, but it can change its alignment direction under the action of an electric field.

For a positive TN-LCD, when no voltage is applied to the electrode, the LCD is in the "OFF" state and light energy is transmitted through the LCD to a white state; when a voltage is applied to the electrode, the LCD is in an "ON" state, the long axis direction of the liquid crystal molecules Arranged in the direction of the electric field, the light cannot pass through the LCD and appears black. Selectively applying a voltage across the electrodes, different patterns can be displayed.

For the STN-LCD, the twist angle of the liquid crystal is larger, so the contrast is better and the viewing angle is wider. STN-LCD is based on the principle of birefringence display, its basic color is generally yellow-green, font blue, yellow green

mold. When using a purple polarizer, the base color turns gray to become a gray mold. When using a polarizing film with a compensation film, the base color will become nearly white. At this time, the STN becomes a black and white mode, that is, FSTN. Polarization of the above three modes is used.

When the film turns 90°, it becomes a blue model and the effect will be better.

The LCD has three display modes: reflective, fully transmissive, and transflective. A reflective plate is attached behind the bottom polarizer of the reflective LCD. It is generally used outdoors and in well-lit offices. The bottom polarizer of the transflective LCD is a completely transmissive polarizer, which requires the continuous use of a backlight, and is generally used in a poor light environment. The semi-transparent LCD is between the above two. The bottom polarizer can partially reflect light, and generally also has a backlight. When the light is good, the backlight can be turned off. When the light is poor, the backlight can be used to illuminate the LCD. LCD display is also divided into positive and negative. Positive LCDs display black letters on a white background and are best viewed in reflective and transflective LCDs; negative LCDs are shown in white on black, and are generally used for full-thickness LCDs. With a backlight, the fonts are clear and easy to read.

Positive display mode (black on white) POSITIVE TYPE

Negative display mode (white on black) NEGATIVE TYPE