Electronic device including a flexible display with variable region and method of heating the variable region of the flexible display

1. An operating method of an electronic device, the method comprising:

measuring an external temperature of the electronic device by using at least one sensor;

calculating, from an entire region of a flexible display, a fixed region that is visually exposed to an outside regardless of a screen size of the electronic device, and a variable region that is visually exposed at least in part to the outside in a screen expansion or screen size change state of the electronic device;

comparing the external temperature with a preset first threshold temperature, thereby determining heating of the variable region in response to the external temperature being less than the preset first threshold temperature; and

heating the variable region by controlling at least one of a luminance or a driving frequency of the variable region.

2. The method of claim 1 , comprising:

in a screen reduction state of the electronic device in which the fixed region of the flexible display is visually exposed and the variable region is not visually exposed, heating the variable region by causing pixels of the variable region to emit light.

3. The method of claim 2 , comprising:

dividing the variable region into a plurality of regions; and

differently adjusting a light emission luminance of pixels of the plurality of region,

wherein pixels of a first region adjacent to the fixed region among the plurality of regions emit light at a first luminance, and

wherein pixels of a second region spaced apart from the fixed region among the plurality of regions emit light at a second luminance lower than the first luminance.

4. The method of claim 2 , comprising:

driving pixels of the fixed region at a driving frequency; and

driving pixels of the variable region at a heating frequency higher than the driving frequency.

5. The method of claim 1 , comprising:

in the screen size change state of the electronic device in which a part of the variable region is visually exposed to the outside, heating the variable region by causing, in the variable region, pixels of a first region visually exposed to the outside and pixels of a second region not visually exposed to the outside to emit light.

6. The method of claim 5 , comprising:

driving pixels of the fixed region at a driving frequency; and

driving the pixels of the first region and the pixels of the second region at a heating frequency higher than the driving frequency.

7. The method of claim 5 , comprising:

in response to the flexible display being turned on in the screen size change state, causing the pixels of the first region visually exposed to the outside and the pixels of the second region not visually exposed to the outside to emit light at different luminances.

8. The method of claim 1 , comprising:

in a screen expansion state of the electronic device in which the entire variable region is visually exposed to the outside, heating the variable region by causing pixels of the variable region to emit light.

9. The method of claim 2 , comprising:

in response to the flexible display being turned on in the screen reduction state, distinctively heating the fixed region and a non-exposed region of the variable region in the flexible display,

wherein a light emission luminance of the variable region is higher than a light emission luminance of the fixed region.

10. The method of claim 2 , comprising:

in response to the flexible display being turned off in the screen reduction state, heating only the variable region.

11. An electronic device comprising:

a housing;

a flexible display comprising a variable region drawn out from the housing to an outside or inserted into the housing from the outside in response to a screen size being changed;

a display driver controlling the flexible display;

a plurality of sensors sensing an external temperature of the electronic device, a temperature of the flexible display, and the variable region depending on a change in the screen size of the electronic device;

a processor controlling the display driver and the plurality of sensors; and

a memory operatively connected to the processor,

wherein the memory stores instructions that cause, when executed, the processor to:

measure the external temperature of the electronic device by using at least one of the plurality of sensors,

calculate, from an entire region of the flexible display, a fixed region that is visually exposed to the outside regardless of the screen size of the electronic device, and a variable region that is visually exposed at least in part to the outside in a screen expansion or screen size change state of the electronic device,

compare the external temperature with a preset first threshold temperature, thereby determining heating of the variable region in response to the external temperature being less than the preset first threshold temperature, and

heat the variable region by controlling at least one of a luminance or a driving frequency of the variable region.

12. The electronic device of claim 11 , wherein the instructions further cause the processor to:

in a screen reduction state of the electronic device in which the fixed region is visually exposed and the variable region is not visually exposed, heat the variable region by causing pixels of the variable region to emit light.

13. The electronic device of claim 12 , wherein the instructions further cause the processor to:

divide the variable region into a plurality of regions, and

differently adjust a light emission luminance of pixels of the plurality of region,

wherein pixels of a first region adjacent to the fixed region among the plurality of regions emit light at a first luminance, and

wherein pixels of a second region spaced apart from the fixed region among the plurality of regions emit light at a second luminance lower than the first luminance.

14. The electronic device of claim 12 , wherein the instructions further cause the processor to:

drive pixels of the fixed region at a driving frequency, and

drive pixels of the variable region at a heating frequency higher than the driving frequency.

15. The electronic device of claim 11 , wherein the instructions further cause the processor to:

in the screen size change state of the electronic device in which a part of the variable region is visually exposed to the outside, heat the variable region by causing, in the variable region, pixels of a first region visually exposed to the outside and pixels of a second region not visually exposed to the outside to emit light.

16. The electronic device of claim 15 , wherein the pixels of the second region emit light at a higher luminance than the pixels of the first region.

17. The electronic device of claim 11 , wherein the instructions further cause the processor to:

in a screen expansion state of the electronic device in which the entire variable region is visually exposed to the outside, heat the variable region by causing pixels of the variable region to emit light.

18. The electronic device of claim 11 , wherein the instructions further cause the processor to:

identify a charge level of a battery of the electronic device, and

adjust a light emission luminance value of pixels of the variable region for heating the variable region based on the charge level of the battery.

19. The electronic device of claim 11 , wherein the instructions further cause the processor to:

identify a charge level of a battery of the electronic device, and

adjust a driving frequency of pixels of the variable region for heating the variable region based on the charge level of the battery.