Transmissive is an display mode when light from a backlight passes through the LCD glass. The LCD glass or LCD panel functions as an “optical switch” where light from the backlight passes through the LCD cell depending on the orientation of liquid crystal molecules. The orientation can be “switched” on or off by an electrical field. Backlight produces a lot of light, making the display content very bright. The negative side of using backlights is that they require a significant amount of energy within an LCD display module, especially because the backlight is required to be on all the time even if there’s no content showing on the display. In direct sunlight, a transmissive LCD screen can become ‘washed-out’ if the sunlight overpowers the luminance of the backlight. Strong enough backlights is needed to maintain sufficient contrast in direct sunlight.
The luminance of an average LCD display reaches approximately 250-500 cd/m². If we place a LCD display outdoors in the sunlight (brightness approximately 10,000 cd/m²), reflected light will be too bright for the user to view the LCD. The luminance of an outdoor use LCD display must be greater than 686 cd/m² to display an acceptable picture. As a result, many enhanced LCD displays with increased luminance, are available on the market and are designed to overcome the challenges of an outdoor viewing environment.