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I've been reading how the new Samsung Galaxy 8 phone has an "always on" OLED screen. Which basically means it can show a very limited amount of info on screen (like the time) at all times. Your screen never is completely black. They've apparently got the tech so that it uses only around 1% of battery life to have this feature enabled.

I'd love for Apple to use this tech in any new Apple Watch. Imagine the face of the watch could always be on. No having to raise wrist to see it. I've always thought an Apple Watch with the face visible is very beautiful, but with just the blank black screen, looks rather ugly. And most people only see the blank screen while you're wearing it so it's not very fashionable compared to real watches. The always on screen though could be game changer.
 

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Perhaps Samsung is onto something lighting only part of the display.
However, the display uses only part of the power. The display also
needs to be calculated and updated to show the time. That power
may be the same independent of how many pixels are lit. It may be a
matter of scaling of the various components. That Samsung phone's
battery is 11 times the size of the battery in the Apple watch 2 (38mm).


Thanks,
rationaltime
 

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Meh. I'm happier that they added a "theater mode" that keeps the screen off unless you tap it.

(it won't light up due to an incoming message or accidental wrist raise, which avoids disturbing other people in a movie theater.. hence "theater mode")
 

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There should be a way just to show hours and minutes only, without a lot of battery drain.
Do I have it right? The Apple watch can display photos and video.

Sure, you could show just hours and minutes, but this goes beyond software.
This is not a 7-segment display. In principle you could compute the display
you want, latch all the display information, and shut down the graphics
process until the next update. Using a minimal number of lit pixels would
reduce the power dissipation.

In practice I think the watch display is strobed to save power, meaning
with the display on the display clock is always running with its full load.
Most likely the graphics process is also running when the display is on.
That burns some unseen power.

I would guess, though, most of the display power goes to making light.
You aren't going to be happy with "hours and minutes only". You are
going to want a watch dial without seconds or, with just four digits
displayed, you are going to want full width. Four times as many pixels
lit costs four times as much power.

Next, you are going to want white or blue. Those colors use more power
to generate than green or red. I don't know if it would be more efficient
to display lower intensity near the peak of human vision (about 555 nm)
or display only red, but one of those is necessary to save power.

If you could live with a small, red dot and a small green dot that moved
around the perimeter of the display to indicate hours and minutes then
maybe it could be on most of the time.

I pretty much believe in "direct law". However, in this case given the
OLED display I would save the power before I would allow the user to
choose always on.

Well, that is my opinion, but I am open to others. What do you suggest?


Thanks,
rationaltime
 

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Do I have it right? The Apple watch can display photos and video.

Sure, you could show just hours and minutes, but this goes beyond software.
This is not a 7-segment display. In principle you could compute the display
you want, latch all the display information, and shut down the graphics
process until the next update. Using a minimal number of lit pixels would
reduce the power dissipation.

In practice I think the watch display is strobed to save power, meaning
with the display on the display clock is always running with its full load.
Most likely the graphics process is also running when the display is on.
That burns some unseen power.

I would guess, though, most of the display power goes to making light.
You aren't going to be happy with "hours and minutes only". You are
going to want a watch dial without seconds or, with just four digits
displayed, you are going to want full width. Four times as many pixels
lit costs four times as much power.

Next, you are going to want white or blue. Those colors use more power
to generate than green or red. I don't know if it would be more efficient
to display lower intensity near the peak of human vision (about 555 nm)
or display only red, but one of those is necessary to save power.

If you could live with a small, red dot and a small green dot that moved
around the perimeter of the display to indicate hours and minutes then
maybe it could be on most of the time.

I pretty much believe in "direct law". However, in this case given the
OLED display I would save the power before I would allow the user to
choose always on.

Well, that is my opinion, but I am open to others. What do you suggest?


Thanks,
rationaltime
I believe it is a matter of style and not tech. For a glance at the time, a minimal mono display is enough. Write pixels not show images.
 

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Moderator German Watches Forum
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I believe it is a matter of style and not tech. For a glance at the time, a minimal mono display is enough. Write pixels not show images.
I can't argue with your personal beliefs, but I am not convinced.

Apple included features in the design to limit the time the display is lit.
That is sufficient for me to think they were concerned about power
used by the display rather than style.

There is another concern we have not mentioned yet. OLEDs have a
history of degradation after continued use. The technology has improved,
but there may be some lingering conservatism at Apple to prevent display
degradation from affecting customers.

Though it could be implemented in some other way, I think there is no
"write pixels". Every pixel is part of an image. To light just one pixel
you need to load the entire screen buffer and keep it active. The
power used would be some base number for the electronics plus
some number roughly proportional to the light emitted for each color.

Because of the power used by the display I expect Apple is working
on improving the display technology. It is not only Apple. Other
companies and universities are also working on improving the materials
and techniques used in making LEDs, whether "OLED" or otherwise.
I expect there to be increasing LED efficiency demonstrated over the
next several years.


Thanks,
rationaltime
 

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Keeping it very simple the "O" in OLED hides a lot of technical difference behind it. The one that applies here is that in OLED, you can light up specific elements (pixels) independently. That is how in Samsung phones you can have the screen showing at all times. Out of the 2560x1440 pixels in the screen only the ones that are part of the numbers are lit up, thus having very low power consumption.
Doing that on an LED display is not possible. The screen has a lighting substrate which is either on or off. That is what consumes the power.

edit: as correctly noted by BarrackSi, the Apple Watch does indeed feature an OLED display. As such, my post is largely informative if irrelevant to the topic. My apologies.
 

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I agree!

That's my biggest gripe about my Apple Watch Series 2 Nike+.
 
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IIRC, one issue with always on screens is that some faces drain battery more than others. That’s no problem for a geek to understand as they’ll just find something that balances what they need vs. battery life. But try explaining to the folks who view computers not as tools but as appliances why their favorite face drains the battery in only a few hours and that they should switch to a lesser featured face with more black space—they’ll either look at you blankly, or complain that they expected well-featured faces (with lots of lit pixels).

It’s just easier to tell people, raise wrist vs. theater mode.
 

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Meh. I'm happier that they added a "theater mode" that keeps the screen off unless you tap it.

(it won't light up due to an incoming message or accidental wrist raise, which avoids disturbing other people in a movie theater.. hence "theater mode")
An always-on screen would be nice for timing things, or setting clocks exact to the second. But, yeah, that’s all I can think of for needing an always-on screen.

Also, there are times when always-on could be really annoying—at the movies, sleeping, watching tv in the dark, etc. This isn’t an issue for traditional watches, because most of them don’t light up indefinitely. The nice thing about a Timex Indiglo is that you release the crown and the backlight turns off, so it’s not on for more than a second or two. But, how do you (quickly) turn off an always-on screen? And then how do you (quickly) turn it back on?


I wanted and needed theater mode much more than always-on.
 

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Always on is close to the top of my wish list, right below making it thinner. It's not a huge problem to solve, though.

The OLED display consumes zero power for black pixels (thus why the interface is dark) Limit time displayed in Always On to hours and minutes (someone objected earlier, but - come on, it's good enough for 99% of users). When Watch is not raised, dim display (brightness ~ 30%), lock touch functionality. When Watch is raised, increase brightness to 100%, unlock touch functionality and fade in complications and colors.
 

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I guess I am so used to the raise wrist and turn to view function that turns on the light on my GShocks that I don't even notice that the Apple Watch's screen is not always on. Also, used to have an iPod Nano on a wristband so was used to touching the screen to see the time before the Apple Watch was released.
 
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