degrees. So, in this range we are safe, we can go very low with the temperature, and it will not become solid, and we can go very high with the temperature up to 110 degrees and it will not become isotropic.
Maybe you have even seen some displays that were used outdoors and sometimes they become black. We call that the blackening effect. If they become black, that means the crystals become isotropic. You can sometimes see that the part of the display is black or sometimes the whole display becomes black, depending on the temperature. The good thing is that it is not damaging the display, so once the temperature drops it goes back to the nematic phase and the display is working again, but in a high temperature you cannot see anything on the display, it is not working.
On the picture above, we have an example from a data sheet of a display with high temperatures. As we said it’s a liquid crystal from -40 to +110 degrees, and this is the latest technology. But you need to be careful! This is only about the surface of a display, the TFT glass itself. If we have the sunlight going to the display it can increase the temperature of the whole display as a module.
For the whole display module, the operating temperature range can be as low as 0 to +50 degrees or -20 to 70 degrees. We can have two operating temperatures, that means if we use the display outdoors, we are safe from the sunlight, the surface of the display can go very high, but we need to control the ambient temperature inside the display housing to not go too high. +50 or +70 will be maximum, usually we need fans to remove the heat from inside. Typically, in our case we have a computer inside and we have more devices that cannot work at high temperatures like +100 degrees, so we control the temperature anyway. So, the temperature cannot be too high inside and for sure cannot be that high as a liquid crystal itself can withstand, which is +110 degrees.
And that will be all in this article about contrast, brightness, and temperatures. Just one more thing: if you are planning on buying a laptop today, you can find brightness in the specification. Look at this number because this will determine how good your laptop will be outdoors. There are laptops on the market today that will have 1000 candelas or even more. If you are looking for a new device my recommendation also goes for mobile phones. Low brightness mobile phones can have 300, maybe 500 candelas, but nowadays the standard will be around 1000 candelas, but there are phones on the market that already have 1500 or even 1800 candelas. That means if you are in the sunlight you will still be able to see the image clearly. Of course, the battery will be drained faster, but sometimes it is not so important, maybe you just want to check something quickly, to read something and you want to have a clear image just be aware that this number is pretty important when you buy new devices!