What Happens to LCD Display Modules When they Become Cold?

Published on Monday, 02 August 2010 21:34

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What happens to LCD’s when they become cold? Liquid crystal displays are just like their name… they contain a liquid between two layers of glass. Liquids begin to freeze as the temperature drops. As the display freezes their response time slows down. In other words, it takes longer for the numbers and letters on the display to change (Turn ON or Turn OFF). Above is a graph showing the response time of a display at -30°C (-22°F). The best way I can think to explain this is a ceiling fan. When you turn off the ceiling fan the blades continue to turn for a few minutes, even though the power if OFF. When you turn ON a ceiling fan the blades will be at full speed in a shorter period of time. At most the blades will be at their max speed within 30 seconds. When talking about an LCD, we talk about when the display is ON (the characters can be seen) or OFF (the characters cannot be seen). On the graph above there are two measurements. The left side is how dark the letters are; the larger the number the darker the letter. Along the bottom of the graph is the amount of time it takes to go from ON to OFF, or to go from OFF to ON. (Note: 1000mS is the same as 1 second). Line ‘A’ displays the amount of time it takes for a character or segment on the display to turn OFF. That is, once you turn OFF the segment, how long does it take before it disappears? The graph above shows that the character actually ‘disappears’ 3500 milliseconds (3.5 seconds) after the display is turned OFF. Line ‘B’ displays the amount of time it takes for the character or segment to turn ON. In the above graph the segment is only 55% ‘ON’ at 8000 milliseconds (8 seconds). That means the character is only ½ (half) ON. It will look grey and not very dark. It requires more time for the display to turn ON than to turn OFF… just the opposite of a ceiling fan. We do not recommend operating our wide temperature (extended temperature) displays below -20°C (-4°F). This is true for all segment displays (static displays or glass displays), 7 (seven) segment, 14 (fourteen) segment and 16 (sixteen) segment LCD’s. Alphanumeric LCD displays such as: 8×1 LCD Display, 8×2 LCD Display, 16×1 LCD Display, 16×2 LCD Display, 16×4 LCD Display, 20×2 LCD Display, 20×4 LCD Display, 24×2 LCD Display, 40×1 LCD Display, 40×2 LCD Display, 40×4 LCD Display will react the same way.