Car Navigation Display

[huchou]

Would it be okay to use a color TFT-LCD dislay with a rated operating temperature of 0 to +60 degree Celsius in a car navigation system designed for Europe and in climatic enviroments where temperatures ranges from -10 to +60 degree C?

 

[RITelectric]

-10 C is about 10 F, right? You could probably expect a warm-up period when turning on the LCD in cold conditions (the contrast/brightness will seem very poor)... but it should only take a few minutes to recover as your cabin heats up. I don't think it will adversely affect the life of the screen to go through those conditions... it's just a matter of picture quality suffering temporarily.

 

[TMJ]

Another consideration is where the screen will be mounted/located. Touch temperatures in the area of the Instrument Panel can reach very high values when subject to long exposure to the sun through the vehicle windows.

 

[PatMa]

You are optimistic!. Operating temperature range is usually of -20deg to +75deg. And this is the minimal specification!

 

[navmate]

I have design three navigation systems for the OEM market. All three of these systems have been used in the US, and Europe. I chose TFT LCD's for these products, which had the widest operating range. (Check out Sharps line-up of TFT's) The goal is of course -40degC to +85degC degrees for automotive electronics in the OEM world. Unfortunately the mercury vapor in the backlight CCFL tubes which are commonly used in TFT LCD's will freeze and disable the tube at STP is -38.8degC. (

http://pearl1.lanl.gov/periodic/elements/80.html)

Repeated exposure to these low temperature will destroy the tube forever. Since this temperature is usually only achieved in a wind chill environment and Navigation display's get to sit in the cozy "wind-free" environment of the car insides the lower temperature is usually not a problem. Yes you are going to have a couple of customers who insist on using the display in -40C deg and blizzarding weather with the top down on their convertible citron, but those customers know that they have to bring their cell phones in or they get destroyed during the really cold spells--They should also know when to bring in their Nav-display.

If your customer has deep pockets and high key off-current budgets then look into self-heating CCFL circuits. (Check out

http://www.microsemi.com/micnotes/1402.pdf)

-Jim Nolan
jnolan@horizonnav.com
Director of Hardware
Horizon Navigation

http://www.horizonnav.com