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LCD becoming dark after few month
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Lunasix:
Hi,
we have a problem with Storm (brand) displays which become dark after few month of outdoor use. It is the "extreme condition" model, given to work up to 70°C. We have hundreds of this display, mounted in big stainless steel boxes. The internal power dissipation is very low, if we consider the size of the box. We do not know the real temperature in summer, but it is mostly self heating due to the sun, and we think it is not above 70°C. We must wait next summer to have precise values. The display is angled at 45°, so the sun can touch the display at right angle. This position was authorized by the manufacturer. And we have lot of theses displays which fail with a dark spot on it. The manufacturer tell us we are the only one to have this problem, and for instance do nothing practical. The shape of the spot let us think that solar ray is mostly responsible, corners of the display are less concerned, due to shadow. Displays facing north seems to survive longer time, but it is not easy to have precise datas as they are throughout the country.
What could be the most probable origin of this problem ? UV-A, UV-B, UV-C, self-heating due to the sun (infrared), temperature, all of these...? Can a UV-A film filter (used for shop windows) minimize the problem ?
I'm fed up of this manufacturer, so, if I want to build my own display (now, I'm able and can find time and money to do that), what lcd should I use, what protection should I add ?
SiliconWizard:
IMO, if the symptom is that the LCD darkens, it's usually due to overheating. Problem is, even though the average internal temperature of the enclosure may never exceed 70°C, the liquid crystals themselves which absorb infrared when in the "on" (black) state can get extremely hot under direct sunlight and become permanently isotropic.
UV is also a problem but I think it will tend to make the display progressively "washed-out" rather than dark.
I think you should use both IR- and UV-blocking filters in front of the displays. Don't know about Storm displays but they don't seem to have efficient filtering.
You can take a look there for instance: https://dontech.com/dontech-heat-shield-transparent-ir-blocking-filters/
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