Always read the patent info.
Apple's unapproved APPLICATION is another example of Apple's sometimes awkward way of dealing with temperature, from not having enough cooling in computers, to having the iPhone simply stop dead and put up an over/under temperature warning. (I think a lot of it is due to Apple devices being designed in temperate California, similar to the way that British cars never seem to understand the need for really cold air conditioning.)
First off, lighting up a small section of an OLED panel is not gonna put out much heat. Heck, most of you have had full white screens.... did you notice any heat coming off your display? The entire panel uses less than a Watt, so a small radius curve section is likely to use so little power that it would take a long time at full output to raise the temp a few degrees. Nothing like walking around with a phone with its edge in constant brilliance, either.
Secondly, a primary intent of the patent application is to suggest adding electromagnetic locks to prevent opening/closing the panel. Yeah, that would make users happy, being unable to open or store away their phone if it got too cold. Nice.
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As for the naive notion that Samsung isn't aware of temperature effects, knowledgeable people understand that Korea gets both very hot and very, very COLD. Which is why we see APPROVED PATENTS such as this one filed before Apple's application: