Does a bigger screen mean it uses more power?

[creativename]

On a mobile device, does the screen size affect the power usage at all? For example, does a 4inch 1080p display use any less power than a 5 inch 1080p display. Assume that the rest of the hardware is identical, the only difference being screen size.

 

I was under the assumption that size doesn't affect the power consumption, its the pixels that matter.

[Mao_Zedong]

Size doesn't matter... for screens (for power needed to run)... and it is debated if it matters with other things if you know what I mean... 

[QueenDemetria]

On a mobile device, does the screen size affect the power usage at all? For example, does a 4inch 1080p display use any less power than a 5 inch 1080p display. Assume that the rest of the hardware is identical, the only difference being screen size.

 

I was under the assumption that size doesn't affect the power consumption, its the pixels that matter.

A little bit, but it really depends on the efficiency of the components(like the LED's in the backlight and the LCD itself).

[MegaDave91]

4 or 5 inches does not matter; it's the PPI that does.

[Enderman]

Yes size does affect power consumption because it needs to light up more area for the same brightness.

 

Size is not as power-affecting as pixels are, because more pixels = more CPU power needed to run, and the CPU is one of the the most power intensive part of a phone.

[creativename]

Yes size does affect power consumption because it needs to light up more area for the same brightness.

 

Size is not as power-affecting as pixels are, because more pixels = more CPU power needed to run, and the CPU is one of the the most power intensive part of a phone.

does it really though? I mean, you're not lighting up any more area, there just happens to be less space between the pixels in a larger screen.

[Enderman]

does it really though? I mean, you're not lighting up any more area, there just happens to be less space between the pixels in a larger screen.

if you have a 4" screen and an 8" screen at the same brightness, the 8" has to use more power.

is it much more power that will affect your battery life? not really.

 

also I dont understand what you mean less space between pixels...there is no space between pixels on a screen...they are all beside eachother.

[AlRayes_BRN]

Yeah Youll need a better battery, my galaxy note 4 drains more power because of its bigger screen and PPI

[Kyuubixchidori]

you know, i think so but only barely. i mean for large 70 inch screens, they use just as much power as a 17in tv. that always confused me

[thekeemo]

all that matters is the amount of pixels

[thekeemo]

That's not true, depends on the processing unit, backlight technology, display size, display technology, pixel density, refresh rate, driver software for the display and how well OS uses it.

I meant just the screen

[Glenwing]

Strictly speaking yes, if you want to be scientific about it.  In the sense of it being a buying decision factor, no it doesn't affect battery life, not to a meaningful degree.

 

A larger screen area increases power consumption at a given level of brightness, because the light exiting the display is spread over a larger area, and so you need more of it for the entire area to be lit to a certain level of brightness.  If you had a screen that was a 10 square kilometers, you would need a much more powerful backlight to get the brightness up to the same level as a typical 5" phone screen.  In principle, the same thing applies between a 5" and 5.5" screen, it's just a matter of degree.  At that scale, it's there, just absolutely negligible.

 

Increasing pixel count increases power consumption (again, technically speaking) since each subpixel needs a voltage pulse to change orientations, so the more pixels, the more changes and the more power, and the same goes for refresh rate since each pixel will be changed more frequently.  Again it is a negligible amount though, all the real power consumption comes from the backlight.  Increased pixel count also indirectly increases power consumption through the GPU, because it will demand more computation from the GPU.  Of course, on the home screen and in most apps, a phone's GPU will hardly be used whether you're talking about a 720p screen or 1440p screen, so it is negligible there.  In gaming, it can affect power a lot, although if you're playing a heavy game and the phone's GPU is maxed out, increasing resolution won't increase GPU power consumption since it's maxed out in either case, it's just a difference in how many frames it can generate with that amount of power.

 

Increasing pixel count also increases power consumption indirectly in two other ways.  If the pixel density remains the same, then adding more pixels increases screen area, which demands more backlight power (as I explained though, not enough to worry about).  If the screen area remains the same, then adding more pixels increases pixel density, which means the pixels are smaller and don't let as much light through, requiring more power to the backlight to compensate and bring it up to a certain brightness level.

 

That's how resolution and size affects power consumption, from a purely technical perspective.  In terms of what matters for purchasing decisions or phone comparisons, the only real effect resolution has on power consumption is indirectly through the GPU when running GPU-intensive apps.  Other than that, resolution and size doesn't affect power to any meaningful degree.

[creativename]

-cut-

Your explanation is very detailed, and it seems to apply to LCD screens with a backlight, but does that apply to OLED screens as well? Where each pixel is individually lit. If a 4 inch OLED screen is 1080p, and a 6inch OLED screen is 1080p, would the 6inch consume more power?

[Glenwing]

Your explanation is very detailed, and it seems to apply to LCD screens with a backlight, but does that apply to OLED screens as well? Where each pixel is individually lit. If a 4 inch OLED screen is 1080p, and a 6inch OLED screen is 1080p, would the 6inch consume more power?

 

I'm not sure actually.  I don't know enough detail about OLEDs.  My instinct would be to say at that scale there wouldn't be any noticeable power consumption difference if they were the same resolution.  If you were comparing to a 60" 1080p OLED TV probably larger pixels would take a slightly greater amount of power, but between 5" and 6" it wouldn't be enough to matter.  This is only conjecture though.  OLED power consumption mostly comes from the resolution, brightness, and picture being displayed (white background black text takes a lot more power than black background white text for example).