Database Users

Screensaver?

Is there a way tio get a clock in the screensaver? my just turns totally black.. in my old nokia and SE it was possible to put a clock in there.. i have tried but cant find anything about it.. / Jörgen

It's not a screensaver, that's the screen being turned off to save battery. My guess is that on smaller screens the power drain involved in displaying the clock is quite low as the backlight wasn't on. On the screen on the hero (and pretty much every other colour screen phone brought out in the last 5 years) the screens need to be backlit to show anything and the power drain would be huge.
In short, there might be an application to do it but you are far better off just pressing the on button when you want to see the time.

herman3101 said:
On the screen on the hero (and pretty much every other colour screen phone brought out in the last 5 years) the screens need to be backlit to show anything
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Really? Why is that?

Modern LCDs all have a backlight and the image you see is obtained by filtering this light through individual switchable filters (these make up the pixels). In the past some screens worked by varying how light is reflected from the screen using these filters but these are inferior to modern lcds. We are now seeing a return to non-backlit screens with the new OLED technology but this is still actively lit at the individual pixel level.
If you don't believe me then take apart a laptop or LCD screen and disconnect the power inverter which is responsible to supplying the power to the backlight. The screen will appear to be completely dark unless you shine a very bright light on it and then you will be able to see the image very faintly. Just don't do what I did and snap the inverter, felt very silly.

Screen pixels and battery consumption ...

Would I be correct in the assumption that if you have a program in which you can change the program's appearance, would it consume more battery power if the appearance has more "lit" pixels than "dark" or "unlit" pixels?
For example, I use a calendar program called ThumbCal. It comes with numerous skins. For the purpose of this discussion, let's assume that there are only two skins. One skin is basically a white background with black lettering, while the other is a black background with white lettering.
Clearly, the one with a white background is considerably brighter than the one with a black background. Both are equally legible, but the white background is brighter because more pixels are lit to display the white background.
My question is this, will the program use MORE battery power if the white background skin is used? It seems logical because more pixels are lit, or on.
Am I right?
Thanks,
Peter

No. On an LCD screen, like the HD2 has, there is a uniform backlight under the screen, white pixels let that light through, while black ones block it. Even on a full black image, the same amount of light is still generated, only to be blocked and dissipated in the screen just afterwards. So, consumption is independent of the displayed image.
It would be true on an OLED display, where each pixel is indeed an independent light source.

kilrah said:
No. On an LCD screen, like the HD2 has, there is a uniform backlight under the screen, white pixels let that light through, while black ones block it. Even on a full black image, the same amount of light is still generated, only to be blocked and dissipated in the screen just afterwards. So, consumption is independent of the displayed image.
It would be true on an OLED display, where each pixel is indeed an independent light source.
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Great explanation, and completely understood. Thank you.
Peter

HD2's Screen re: Types of Active Matrix

Here's what I'm wondering. The HD2 has a backlit LCD screen, but is it a Twisted Nematic type, or a Vertical Alignment type. If it's TN, then the white GTX theme should use less power, as the screen's pixels are natively open. If it's VA, then Energy's black theme would use less power, as the screen's are natively closed. It's probably a <1% difference in power consumption, but it's interesting to think about.

[GUIDE] Power Consumption & Battery Saving

[size="5]Power Consumption[/size][/color][/b] [b][size="5"]&[/size] [size="5] Battery Saving[/size].
Hii XDA members & moto g users this thread contains everything u need to know about the battery consumption of ur android phone & how to save it ..because it can add some precious hours or minutes when u run out of battery
Most android users must be very curious to know about the power consumption parameters of their Android phone.
How much Power does each component or a Android service consumes ??
This Guide provides full power consumption distributed and well explained...
This might allow you to save some precious minutes of your Android Smartphone Battery.
DISPLAY: Average - 370mW.
Full white background, 1% brightness - 450mW.
Full white background, 100% brightness - 960mW.
So roughly every percentage of brightness increased accounts to additional 5.2mW.
NOTE :- (Amoled Screen) Now we know why using dark wallpapers and reducing brightness is so important than undervolting.
Virtual Hardware Keys - 40mW
Led lamp next to camera - 1.3W
Camera - 700mW
Bluetooth - 110 to 180mW
GPS - 110 to 180mW
2G to 3G switching - 800mW for 8 seconds. (This is no h/w component, but we should know)
CPU -
1.2 Ghz full load, 100% brightness - 3.8W+
1.2 Ghz average - 3.2W
Deep Sleep - 200mW during suspend state opposed & at deep sleep 8mW without BLN.
Wifi download - 1.51W
2G download - 1.598W
2G upload - 853mW
3G download - 2.403W
3G upload - 3.136W (Stay away from uploading your videos to youtube via 3G)
Press Thanks :thumbup: If I Helped U

This is awesome guide thanks op for great information you shared

It's surprising that there isn't much difference between 2g and 3g download.
Also, could you tell us what's the battery consumption when using black wallpapers, especially on non AMOLED screens?

mahendru1992 said:
It's surprising that there isn't much difference between 2g and 3g download.
Also, could you tell us what's the battery consumption when using black wallpapers, especially on non AMOLED screens?
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Battery consumption using a Black Wallpaper is as same as using a White colored wallpaper on ur Non Amoled display.
But different brightness levels can make a difference on ur battery life. U may reduce battery usage by reducing the brightness on Non Amoled displays as on low brightness the intensity at which it emits light from light source (LED) will be low, so that will SAVE ur smartphones battery & completely opposite at full brightness as the light source emits light at higher intensity, that increases the battery usage.
Using Black Wallpaper on a Non Amoled display does not count to save battery. In Amoled display each pixel backlits itself when its needed.
So there is difference to some extent when u see a Black wallpaper set on a Non Amoled phone & a Amoled phone.
Black color on Amoled displays are Tru Black as compared to LCD displays which doesn't look tru black.
In LCD displays there is a LED bulb behind the display panel which spreads the light across the screen so even if u use a black wallpaper it will not decrease the battery usage ..it will continue to consume same amount of battery as the LED bulb has to generate a black colored pixel by keeping the LED constantly switched on.
But in Amoled displays when u set a black wallpaper the Black part of the wallpaper is not required be lit up (individual pixels have their own light source) & it would look the same as when u turn off the screen.
Ex ... If u set a wallpaper which is divided equally into two parts the upper part is full black & the lower part is full white.
Now on
1) AMOLED :- only the lower part with white color will be active as the Black color part does not need to be lit up by any source because its Tru Black as each individual pixel has its own light source. Hence it save battery
2) NON AMOLED :- here the entire screen will be lit up as the light source is behid the panel and it has to continuously keep on emmiting light to make the white part visible.
So u may notice when u switch off ur moto g when the phone is about to shutdown a black screen appears just for a fraction of seconds & then completely turns off, thats an example of Non Amoled display because ..here even a black pixel needs to be generated by the LED behind the display. Which does not reduce battery consumption.
But black pixel need not to be generated on Amoled as its is can stay off & only display the essential colorful parts which saves battery.
Press Thanks :thumbup: If I Helped U

StariX37 said:
Using Black Wallpaper on a Non Amoled display does not count to save battery. In Amoled display each pixel backlits itself when its needed.
So there is difference to some extent when u see a Black wallpaper set on a Non Amoled phone & a Amoled phone.
Black color on Amoled displays are Tru Black as compared to LCD displays which doesn't look tru black.
In LCD displays there is a LED bulb behind the display panel which spreads the light across the screen so even if u use a black wallpaper it will not decrease the battery usage ..it will continue to consume same amount of battery as the LED bulb has to generate a black colored pixel by keeping the LED constantly switched on.
But in Amoled displays when u set a black wallpaper the Black part of the wallpaper is not required be lit up (individual pixels have their own light source) & it would look the same as when u turn off the screen.
Ex ... If u set a wallpaper which is divided equally into two parts the upper part is full black & the lower part is full white.
Now on
1) AMOLED :- only the lower part with white color will be active as the Black color part does not need to be lit up by any source because its Tru Black as each individual pixel has its own light source. Hence it save battery
2) NON AMOLED :- here the entire screen will be lit up as the light source is behid the panel and it has to continuously keep on emmiting light to make the white part visible.
But u may reduce battery usage by reducing the brightness on Non Amoled displays as on low brightness the intensity at which it emits light from light source will be low, so that will SAVE ur battery & completely opposite at full brightness as the light source emits light of high intensity, that increases the battery usage.
So u may notice when u switch off ur moto g when the phone is about to shutdown a black screen appears just for a fraction of seconds & then completely turns off, thats an example of Non Amoled display because ..here even a black pixel needs to be generated by the LED behind the display. Which does not reduce battery consumption.
But black pixel need not to be generated on Amoled as its is can stay off & only display the essential colorful parts which saves battery.
Press Thanks :thumbup: If I Helped U
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Click to collapse
Wow! Thanks for such a detailed explanation man. I knew the basics of the AMOLED display but you really explained it well.
Oh and so it really doesn't matter much right, if one doesn't change to 2g at all?
Because the battery drain is almost the same? So all we felt was placebo?

mahendru1992 said:
Wow! Thanks for such a detailed explanation man. I knew the basics of the AMOLED display but you really explained it well.
Oh and so it really doesn't matter much right, if one doesn't change to 2g at all?
Because the battery drain is almost the same? So all we felt was placebo?
Click to expand...
Click to collapse
The battery drain on 2G & 3G depends on the frequency of the band that is being used at that moment. But battery consumption is probably more on 3G as it operates on higher frequency bands & switching from 2G to 3G also consumes some amount of battery as the band is reset to default & scaled to a higher band after a 3G network is found by the signal reception counter. 3G consume more battery overall.
Please check the 3G download - power consumption i have updated it.
It was a typing error

An issue I never understood (Ultra power saving mode)

Hi there !
Just call me a noob - but I don't understand a feature of that "Ultra power saving mode". It's the black and white display.
If we dare to ignore the special features of a pentile matrix, it comes down to a pixel consisting of three subpixels: Red, Green, Blue (RGB).
To display greyscales of the color "white" , we need ALL THREE subpixels illuminated: [•••]
For displaying the colors "red", "green" or "blue" we'd need just ONE subpixel illuminated: [•] or [•] or [•]
Clear so far ? - Well.
AMOLED displays control each subpixel directly - many subpixels illuminated = high energy drain, few subpixels illuminated = low energy drain.
So is there any sound reason for choosing a display color (grey) which always needs ALL subpixels illuminated, thus causing three times the battery drain a red, green or blue display would cause ?
Do I overlook something ?

AMOLED display is just multiple lights producing images. The reason the ultra power saving mode is black and white is because AMOLED display will turn off the light in the subpixels to produce the black color.

Chefproll said:
Hi there !
Just call me a noob - but I don't understand a feature of that "Ultra power saving mode". It's the black and white display.
If we dare to ignore the special features of a pentile matrix, it comes down to a pixel consisting of three subpixels: Red, Green, Blue (RGB).
To display greyscales of the color "white" , we need ALL THREE subpixels illuminated: [•••]
For displaying the colors "red", "green" or "blue" we'd need just ONE subpixel illuminated: [•] or [•] or [•]
Clear so far ? - Well.
AMOLED displays control each subpixel directly - many subpixels illuminated = high energy drain, few subpixels illuminated = low energy drain.
So is there any sound reason for choosing a display color (grey) which always needs ALL subpixels illuminated, thus causing three times the battery drain a red, green or blue display would cause ?
Do I overlook something ?
Click to expand...
Click to collapse
U r right ...
So... Instead of white pixel there should be one of 3 main colors ( red blue green ) in order to minimize the power consumption .
Using white pixel makes no sense for AMOLED displays ...

does having a red blue or green tinted display make any sense to you ? that is why.

Found this information, maybe it is useful:
An AMOLED doesn't have a backlight at all.
Instead, each little sub-pixel is like a tiny red, blue, or green colored light.
If the screen is instructed to display black, it doesn't need to block any light, it simply doesn't light up any of the little colored sub-pixels.
So theoretically, black pixels save you a lot of power because those pixels can be turned completely off.
However, people sometimes make the mistake of thinking this is a function of brightness—that dark colors like gray are similarly efficient.
Source: http://www.greenbot.com/article/283...interface-really-save-on-amoled-displays.html
Kind regards, Stefan.

zurkx said:
does having a red blue or green tinted display make any sense to you ? that is why.
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Click to collapse
Did you understand the purpose of an energy saving feature ? - I'll tell you. It's for saving energy.
Not for giving you a pretty sight.
Basic information (I thought everybody knew that): AMOLED indeed is like millions of single LEDs. The more illuminate, the more power you need.
Black screen: NO energy consumption. White screen: Highest energy consumption (because white light consists of red, green and blue light). Red, blue or green screen: 1/3 energy consumption, because just one out of each three subpixel LEDs is lit, thus just one out of three subpixel LEDs consumes energy.
So you need ONE LED for displaying a red, blue or green pixel. But you need THREE LEDs for displaying a white or grey pixel, so it's three times the power consumption.
Now again: It's an energy saving feature. With a green, red or blue screen, energy consumption would be 33 %. But with a grey screen, energy consumption is 100 %.
So where's the sense ?

you're incorrectly making the assumption that an active subpixel always draws full power.
if a subpixel is used to display #808080(which should be a very average grey) it should use around 50% of what it uses when used for displaying #FFFFFF(white)
I don't know how power consumption scales compared to brightness, but using multiple subpixels at 25-40% instead of 1 subpixel at 100% would save a lot of power if power consumption scales with an upward curve as brightness increases.
I don't know the exact characteristics of OLEDs or the effect that pentile has on battery usage so I can't exactly tell why it would drain less in B&W than in color, but grey definitely drains less power than white.
1 interesting thing I just found out:
while I've had several OLED devices, the Note 4 is actually the only one I've ever seen that turns off subpixels to display pure black(#000000)
other devices keep subpixels at their lowest active setting, resulting in a faint green/grey glow.(effectively #010101-#101010, as the lowest setting can vary in brightness between different subpixels)
a downside to this is that black causes ghosting, as it takes a subpixel significantly more time to wake up than to increase brightness.
EDIT: I just did some calculations and comparisons, although this example specifically applies to RGB screens you'd notice a similar effect in RGBG screens.
to create the B&W equivalent of a single colored subpixel at 100% brightness you'd need 3 subpixels to be at only 28%.
even if power consumption is linear to brightness it would still mean a drop in display power consumption of 16%

no its for pretending to save energy not to actually save it. it looks like its an eink screen in that mode so people are happy. thats the sense.

Possibly another reason for choosing black and white instead black and green or other colors to have subpixels "age" at similar rate instead one color loosing brightness at faster rate than others.
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