The subpixels in an LCD color screen use liquid crystal molecules that act as dimmer switches to allow light to reach the screen's red, green and blue filters. Depending on the type of TV or monitor, the liquid crystals change their orientation from 60 to 240 times per second. For a monochrome example, see seven-segment display
. See LCD
In a 4K TV, there are eight million of these three-segment pixels (24 million crystal paths). When unenergized, the liquid crystals start out looking like twisted ladders because they orient themselves to microscopic grooves, called "rubbings," in the top and bottom panels. The rubbings are at right angles to each other. When energized by electrodes, they re-orient themselves away from the front polarizer panel, and the more they twist away, the less light reaches the color filters. At full and equal intensities, red, green and blue create white (see RGB
When energized by transparent electrodes (not shown) at the top and bottom, the crystals orient themselves away from the front polarizer, allowing less light to pass through the color filters. In this example, gray is produced when the red, green and blue light is at equal but lower intensities.
TN Vs. IPS
The liquid crystals in the ubiquitous twisted nematic (TN) display become more perpendicular to the top panels when energized. In an "in-plane switching" (IPS) display, they remain on the same plane as the panels. See IPS panel