LCD (Liquid Crystal Display) displays utilize a liquid crystal panel as the core component for image generation. When a certain voltage is applied to the liquid crystal layer within the LCD panel, the orientation of the liquid crystal molecules changes.

At a specific threshold voltage, the long axis of the liquid crystal molecules begins to tilt away from their initial alignment. As the voltage reaches approximately twice the threshold value, the liquid crystal molecules between the two electrode grids within the panel will rotate and align along the direction of the electric field, rather than their original orientation.

This change in liquid crystal molecule alignment affects the 90-degree polarization rotation property of the display. Between the crossed polarizer films, the optical effect caused by the twisted liquid crystal molecules either allows light to pass through (bright pixel) or blocks the light (dark pixel), creating the desired image on the LCD screen.

The fundamental operating principle of LCD display devices is to position the liquid crystal layer between two transparent, conductive glass substrates. Under the influence of the electric field generated between the electrodes, the liquid crystal molecules undergo distortion, which in turn controls the transmission or blocking of the light source. The application or removal of the electric field results in bright and dark areas, effectively exposing the image. By incorporating black and white color filters, monochrome images can be displayed.

Currently, the majority of LCD displays employ the STN (Super-Twisted Nematic) mode, which is still in a relatively nascent and evolving stage in terms of liquid crystal performance. The STN mode shares a similar structure to the traditional TN (Twisted Nematic) mode, but the liquid crystal molecule twist angle is in the range of 180° to 360°, rather than the 90° twist in TN displays.

In TN-mode LCD panels, the twist angle of the liquid crystal molecules within the cell is significantly greater than the visible light wavelength. This is because when the glass substrate orientation differs from the liquid crystal layer alignment, or when the linearly polarized light enters at an angle, the polarization direction will undergo a 90-degree rotation as it passes through the entire liquid crystal layer, emerging from the opposite side. This allows the liquid crystal cell to be placed between crossed polarizers, where it can either block or transmit light, enabling the display of images.

The glass substrates in an LCD panel are coated with alignment layers, which cause the liquid crystal molecules to orient themselves along the grooves in these layers. When the panel is within the magnetic field, the liquid crystal molecules align accordingly, and the polarized light passing through the panel undergoes a 90-degree rotation, resulting in the display of colored pixels.

When the glass substrates are removed from the magnetic field, the liquid crystal molecules realign, and the polarized light passes through the gaps in the liquid crystal layer, maintaining its original orientation and being blocked or transmitted by the polarizers, leading to the display of the desired color image on the LCD panel.