Welcome to the E2E Community Discussion Forum!

I need to maintain the temperature of a ruggedized monitor at 230 degrees C. Does anybody know what my options are for a heater?

---

"We are the dream makers and the dreamers of dreams..."

The main concern with LCD monitors, especially in ruggedized computer or military applications is to keep the temperature above freezing.  Below or near freezing, the response of the LCD is very slow and the image is faded, hard to read and motion on the screen is "ghosted".  Companies make optically clear heaters that are specifically designed for such an application.  They consist of a very fine wire heating element embedded in an optically clear substrate.  This type of heater can be applied on the inner or outer surface of an LCD screen, is usually low power (around 1 watt/in^2) and since it is clear and very thin, the screen can be read through the heater, it even works in touchscreen applications.  BMW is putting a Thermal-clear in the LCD screen navigation system of a lot of their new and existing models in order to improve the usability and visibility of the screen in cold weather conditions.  I know that there are some ruggedized laptops that use these heaters as well.  I guess any LCD screen that is used in a cold environment should have a heater like this integrated. 

---

"A witty saying proves nothing."
-Voltaire

Another consideration when heating large LCD screens is the temperature uniformity.  You may want to design the heating element with more concentration of heat around the edges to counteract the edge losses and thus maintaining a uniform temperature profile across the entire screen.  Temperature gradients across the glass can cause it to crack.  In order to determine the power requirements, the most reliable method is to apply a large heater over the entire area and apply narrow strip heaters around the edges.  By varying the voltage to each heater and monitoring the temperature in each area, you can find the power each area will need to keep the temperature uniform with one profiled element.

---

I plan on living forever. So far, so good.

jthompson wrote:

I need to maintain the temperature of a ruggedized monitor at 230 degrees C. Does anybody know what my options are for a heater?

You need to maintain the monitor 230°C?    That's pretty warm for a monitor.  Is it an LCD or a CRT?  Someone mentioned Optically Clear heaters.  From my experience, they do a great job, but I don't think they're anywhere near rated to 230°C (I think they top out around 120°C).  Without knowing the exact display technology you're using, it's kind of hard to know what you could do.  I know the silicone rubber heaters are good to 235°C and the AP (polyimide) heaters are rated to 260°C.  You may be better with AP as 230°C is pretty close to 235°C and from past experience its nice to have a little margin for error if you overshoot during ramp up.  Obviously you can't but either a rubber or polyimide heater in front of the screen and expect to see anything, but if you have room, you can mount the heaters around the perimeter of the screen on some kind of frame, or maybe mount it behind everything and do some indirect heating.  Just a thought.

---

'Experience is a hard teacher because she gives the test first, the lesson afterward.' --Vernon Law