LCD Performance at High Altitudes
Liquid crystal displays (LCDs) have become a critical element of the technology sector. The LCD has found its way into a variety of uses resulting in a wide range of temperature, pressure, and moisture condition requirements. While elevation alone does not directly affect LCD performance, related factors such as temperature, pressure, and cosmic rays can affect LCD performance at high altitudes.
Cold temperatures at high altitude can affect the liquid crystals, which is typically between liquid and solid-state, making it susceptible to freezing. Rugged enclosures/devices can feature improved insulation, and often include heating elements to protect against extreme cold. LCDs alone can operate at temperatures ranging from -40°F to +176°F depending on manufacturing specifications.
As temperature decreases, the liquid crystals will become less viscous, this is what results in “ghosting” or image burn through discoloration as well as reduced response times. Because of the drop in viscosity, the response time will also decrease. In the case that high altitude performance is prioritized, the best choice of display technology is TFT, or Thin Film Transistor displays which maintain high response times in low-temperature environments because each pixel is driven by an individual transistor.
Finally, low temperatures present at high altitudes can result in the mechanical stress of a display’s seals. The stress can result in microfractures which can become a path for moisture or other contaminants to damage the display. Liquid or pressurized air ingress can result in damage called voiding, which are black void-like spots that will damage the display and impair readability.
Display backlight function is another important consideration when it comes to the practical performance of displays. Pre-mature backlight failures tend to occur because low temperatures at high altitudes will result in a reduced contract of the display, which is likely to require higher backlight power and intensity to be legible.
An LCD is sandwiched between two layers of glass. Both the glass and the crystal’s physical composition will be disrupted when exposed to high pressure. This can lead to pixel damage. Such elevated atmospheric pressure can be experienced when there is a sudden drop from high to low altitude environments which can result in a pressure mark on the display, crack the glass, or otherwise permanently damage the display.
Liquid, when it freezes, expands, distorts, and even cracks. In the case that there is moisture present within display components, sudden altitude changes will result in temperature-drop-related freezing, which can result in cracked displays/glass, pressure marks, or damaged pixels. LCDs that are purpose-built to perform at high altitudes are typically housed in a specialized enclosure that can prevent seepage of moisture.
Another consideration is the reduction of air density and its impact on thermal management. Some LCDs rely on cooling hardware that becomes substantially less effective at high elevations. This can lead to a reduced flow of air particles over warm components resulting in thermal meltdowns. When housed in an enclosure, the heat generated by an LCD must be reduced. This can be done with cooling fans or air vents, but lower air density at higher altitudes makes this process difficult. In situations where extreme elevations are anticipated, additional cooling hardware such as air conditioning can be employed.
A rare, yet non-negligible factor is a phenomenon known as cosmic rays. Cosmic radiation is a phenomenon that results from exploding stars outside of our solar system that is known to impact more than just LCDs. Specifically, these rays are known to affect microprocessors of LCDs at high altitudes. Cosmic radiation increases with altitude and is, therefore, more likely to impact LCD performance in the same. Cosmic radiation can flip a “1” to a “0” in the binary instructions of a processor, this can result in a malfunction of the screen. This is not a practical consideration, however, as nearly 10 feet of concrete is needed to shield electronics from the effects of cosmic radiation.
The LCD has been used in several applications, requiring a wide range of temperature, pressure, and moisture conditions. While altitude does not directly affect LCD performance, other elements like temperature, pressure and cosmic rays certainly can. Such factors can vary depending on the speed of ascent/descent, atmospheric pressure changes, and environmental conditions. Luckily, Focus LCDs have a wide variety of displays that can meet most needs and can even provide custom solutions to ensure that your display works reliably at any elevation.