No flashing refresh = more battery life?

Fallingwater · 06-24-2011, 08:28 AM

I just got a Cybook Opus. While playing with it, I noticed an option in the menu to disable the all-black reflashing that happens every time a more-than-minimal change occurs on the screen. Disabling it, I finally figured out why it happens - without a full blank refresh, there's noticeable ghosting from what was on the display previously.

But this got me wondering. E-ink displays eat power only when they change their content, with each changed pixel contributing to the power draw. During a full blank the entire display gets energized so all pixels draw power, but during a non-full-blank page change, only the pixels making up the current text and those making up that of the next page need energy to switch state. Since their number is relatively small compared to that of the entire screen, disabling full-blanking should return quite a dramatical increase in battery life.

Is this theory wrong? I don't particularly mind the ghosting, so if I can significantly increase battery life I'll keep full blanking off.

Thanks

HarryT · 06-24-2011, 10:39 AM

Yes, disabling the full screen refresh will increase the battery life, but I suspect you'll find that the results (ghosting) will be extremely undesirable.

siraks · 06-24-2011, 10:48 AM

Quote:

Originally Posted by HarryT

Yes, disabling the full screen refresh will increase the battery life, but I suspect you'll find that the results (ghosting) will be extremely undesirable.

it all depends on your preference and the amount of ghosting.
the new kobo touch comes with a 6 page turn before a refresh (as default - the new update now allows you to control how many pages up to 6 before a refresh )

on my screen if i wasn't looking for the ghosting effect i would never see it, i changed my refresh to be every page to act as my wifi model did. i would charge the wifi model maybe once every 3-4 weeks which in my mind is excellent battery life. i have not charged my kobo touch yet, bought june 10th, so 2 weeks so far and good to go ( refresh was changed 2 days ago with the fw update )

there are many factors that go into battery life, i don't think the refresh has that big of an impact but there may be some.

Billi · 06-24-2011, 11:53 AM

Fallingwater, if you don't mind the ghosting disabling the screen reflash will not only give you a better battery life (which is very good anyway) but also faster page turns. Read a few books to see what will win for you personally.

Fallingwater · 06-24-2011, 01:32 PM

Quote:

Originally Posted by HarryT

Yes, disabling the full screen refresh will increase the battery life, but I suspect you'll find that the results (ghosting) will be extremely undesirable.

Not quite.
Today I finished reading a book I'd previously started on my netbook; I kept the full refresh off, and the results were quite good. Not perfect, but I don't really mind the imperfections. As far as I'm concerned, this feature is great

HarryT · 06-24-2011, 01:34 PM

Ok. I remember switching it off on my Opus and finding the ghosting pretty unbearable.

Zetmolm · 06-24-2011, 05:53 PM

I used to have my Onyx Boox set to one full refresh per 9 page turns. Ghosting was not that bad, but at some point I wanted to see what would happen to battery life if I changed this to full refresh every page turn. Actually, I did not notice any change in battery life at all. So I kept the full refresh on, and I'm perfectly happy.

Dulin's Books · 06-24-2011, 08:32 PM

whats always annoyed me about this feature is that it creates a "block" of ghosting that is actually whiter than the background. which means the background could actually be whiter by default! why do i have this gray background when it could be much more white and give better contrast to the text?

Fallingwater · 06-25-2011, 05:57 AM

I find that each page-turn tends to eliminate part of the ghosting, so it doesn't accumulate - it stays about the same after the second page from the last reflash. As such, reflashing every x pages is unneeded on the Opus.

BenBanned · 06-25-2011, 12:01 PM

My Opus batteryy is more than sufficient. Any attempts to extend battery life seems kinda pointless. I think since Ive had it, the battery died one time.

bob123 · 06-25-2011, 09:17 PM

Quote:

Originally Posted by Dulin's Books

whats always annoyed me about this feature is that it creates a "block" of ghosting that is actually whiter than the background. which means the background could actually be whiter by default! why do i have this gray background when it could be much more white and give better contrast to the text?

I have noticed that too!

TedJ · 06-26-2011, 06:38 AM

Quote:

Originally Posted by Fallingwater

Is this theory wrong? I don't particularly mind the ghosting, so if I can significantly increase battery life I'll keep full blanking off.

No flashing idea.

j.p.s · 07-05-2011, 05:18 PM

Quote:

Originally Posted by Dulin's Books

whats always annoyed me about this feature is that it creates a "block" of ghosting that is actually whiter than the background. which means the background could actually be whiter by default! why do i have this gray background when it could be much more white and give better contrast to the text?

Since apparent whiteness is context dependent, isn't it possible that the white ghosting is where a black area on the previous page has been erased and the darker background is white on both pages, so it was not erased while the old dark areas were erased and the new black areas written?

But after a full erase, since the whitest possible shade is still a bit dark and there are no slightly darker "white" areas for comparison, it looks the same dingy shade that the unerased light area looked when there was no full erase.

If not, then I am annoyed as well. I have noticed those white lines after a pop up menu goes away on the pocketbook 360.

Shaggy · 07-06-2011, 05:35 PM

Quote:

Originally Posted by Fallingwater

But this got me wondering. E-ink displays eat power only when they change their content, with each changed pixel contributing to the power draw... disabling full-blanking should return quite a dramatical increase in battery life.

The main thing you're forgetting is that an E-ink display only uses power to change the content on the screen, but an E-ink device is a lot more than just the display. You may save a little bit of power from what the display draws, but the rest of the electronics are going to be unaffected (CPU... etc).

I think you'll find that the battery life increase, while not zero, will be a lot smaller than you are thinking. Possibly not even noticeable.

06-24-2011, 08:28 AM	#1
Fallingwater Enthusiast Posts: 34 Karma: 4132 Join Date: Jun 2011 Device: Bookeen Cybook Opus	No flashing refresh = more battery life? I just got a Cybook Opus. While playing with it, I noticed an option in the menu to disable the all-black reflashing that happens every time a more-than-minimal change occurs on the screen. Disabling it, I finally figured out why it happens - without a full blank refresh, there's noticeable ghosting from what was on the display previously. But this got me wondering. E-ink displays eat power only when they change their content, with each changed pixel contributing to the power draw. During a full blank the entire display gets energized so all pixels draw power, but during a non-full-blank page change, only the pixels making up the current text and those making up that of the next page need energy to switch state. Since their number is relatively small compared to that of the entire screen, disabling full-blanking should return quite a dramatical increase in battery life. Is this theory wrong? I don't particularly mind the ghosting, so if I can significantly increase battery life I'll keep full blanking off. Thanks

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06-24-2011, 10:39 AM	#2
HarryT eBook Enthusiast Posts: 85,544 Karma: 93383043 Join Date: Nov 2006 Location: UK Device: Kindle Oasis 2, iPad Pro 10.5", iPhone 6	Yes, disabling the full screen refresh will increase the battery life, but I suspect you'll find that the results (ghosting) will be extremely undesirable.

06-24-2011, 11:53 AM	#4
Billi Wizard Posts: 3,388 Karma: 14190103 Join Date: Jun 2009 Location: Berlin Device: Cybook, iRex, PB, Onyx	Fallingwater, if you don't mind the ghosting disabling the screen reflash will not only give you a better battery life (which is very good anyway) but also faster page turns. Read a few books to see what will win for you personally.

06-24-2011, 01:34 PM	#6
HarryT eBook Enthusiast Posts: 85,544 Karma: 93383043 Join Date: Nov 2006 Location: UK Device: Kindle Oasis 2, iPad Pro 10.5", iPhone 6	Ok. I remember switching it off on my Opus and finding the ghosting pretty unbearable.

06-24-2011, 05:53 PM	#7
Zetmolm Guru Posts: 612 Karma: 2031728 Join Date: Jan 2010 Device: PocketBook Touch (622), PocketBook Touch Lux 2, Pocketbook Touch HD 3	I used to have my Onyx Boox set to one full refresh per 9 page turns. Ghosting was not that bad, but at some point I wanted to see what would happen to battery life if I changed this to full refresh every page turn. Actually, I did not notice any change in battery life at all. So I kept the full refresh on, and I'm perfectly happy.

06-24-2011, 08:32 PM	#8
Dulin's Books Wizard Posts: 2,806 Karma: 13500000 Join Date: Nov 2009 Location: Portland, OR Device: Boox PB360 etc etc etc	whats always annoyed me about this feature is that it creates a "block" of ghosting that is actually whiter than the background. which means the background could actually be whiter by default! why do i have this gray background when it could be much more white and give better contrast to the text?

06-25-2011, 05:57 AM	#9
Fallingwater Enthusiast Posts: 34 Karma: 4132 Join Date: Jun 2011 Device: Bookeen Cybook Opus	I find that each page-turn tends to eliminate part of the ghosting, so it doesn't accumulate - it stays about the same after the second page from the last reflash. As such, reflashing every x pages is unneeded on the Opus.

06-25-2011, 12:01 PM	#10
BenBanned Groupie Posts: 168 Karma: 1326166 Join Date: Dec 2010 Location: NJ Device: Paper	My Opus batteryy is more than sufficient. Any attempts to extend battery life seems kinda pointless. I think since Ive had it, the battery died one time.

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